TY - CONF A1 - Gaal, Mate A1 - Kotschate, Daniel A1 - Bente, Klaas T1 - Advances in air-coupled ultrasonic transducers for non-destructive testing N2 - Conventional ultrasonic testing involves the application of a fluid couplant for impedance matching. Increasing use of lightweight structures, composite materials and adhesive joints mostly in aerospace and automotive industry created an increasing interest in air-coupled ultrasonic testing methods, to protect sensitive surfaces and simplify maintenance. Commercially available air-coupled transducers consist of a piezocomposite material and matching layers to reduce the impedance mismatch between the transducer and air. This contribution is an overview of innovative approaches using new piezoelectric materials and other physical principles to transmit and receive an ultrasonic pulse in air. Capacitive and piezoelectric micromachined ultrasonic transducers (CMUTs and PMUTs) produce high pressure levels, but they exhibit a very narrow bandwidth. Optical laser-based methods for transmitting and receiving ultrasound promise a higher bandwidth, but do not achieve the same sensitivity as conventional air-coupled transducers. Ferroelectrets are charged cellular polymers exhibiting piezoelectric properties, having a very small acoustic impedance well matched to air. Ferroelectret transducers achieve about the same bandwidth as the most broadband conventional air-coupled transducers, having a higher sensitivity. Thermoacoustic transducers use heat to initiate an acoustic wave, acting as transmitters in ultrasonic range. Thermoacoustic transducers enable excitation of extremely broadband pulses while producing high pressure levels, which opens new possibilities for advanced signal processing. The newest member of the family of air-coupled ultrasonic transmitters is the plasma-based transducer, using both the thermoacoustic effect and the movements of the ions (so called ionic wind) to create acoustic waves. T2 - International Congress on Ultrasonics CY - Bruges, Belgium DA - 03.09.2019 KW - Air-coupled transducers KW - Non-destructive testing KW - Ferroelectret KW - Thermoacoustics KW - Plasma acoustics PY - 2019 AN - OPUS4-48963 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Küttenbaum, Stefan A1 - Braml, T. A1 - Maack, Stefan T1 - Refining stochastic models for the reassessment of bridges using advanced NDT-methods N2 - Increasing requirements on the infrastructure caused by more and heavier traffic coincide with both the aging and the progressive degradation of bridge constructions. These exemplary issues lead to a non-negligible need for reassessments of existing bridges. Compared to the new building design, safety reserves can be used in the evaluation of such existing structures, since uncertainties that may arise during the design, construction and previous Service time are better known or no longer present. Uncertainties can be evaiuated more precisely by measurements. In the meantime, the application of advanced NDT-methods on concrete structures have become so capable, that crucial structure Parameters like certain material properties or geometrical dimensions can be quantified without significant destructive interventions. The measured data can be explicitly incorporated into the probabilistic computation models used for the bridge reassessment in form of random variables. Therewith, a previously insufficient model can be refined to achieve a higher level of approximation. This contribution emphasises two fundamental steps of the measured data based probabilistic reassessment: The sensitivity analyses to identify the cruciai Parameters and the needed accuracy of the related information as well as the comparison with expected uncertainties of non-destructively measured Parameters. T2 - 17th International Probabilistic Workshop CY - Edinburgh, UK DA - 11.09.2019 KW - Measurement KW - Reassessment KW - NDT KW - Concrete bridges PY - 2019 SP - 99 EP - 105 AN - OPUS4-48998 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Küttenbaum, Stefan A1 - Braml, T. A1 - Maack, Stefan T1 - Refining stochastic models for the reassessment of bridges using NDT-methods N2 - Increasing requirements on the infrastructure caused by more and heavier traffic coincide with both the aging and the progressive degradation of bridge constructions. These exemplary issues lead to a non-negligible need for reassessments of existing bridges. Compared to the new building design, safety reserves can be used in the evaluation of such existing structures, since uncertainties that may arise during the design, construction and previous Service time are better known or no longer present. Uncertainties can be evaiuated more precisely by measurements. In the meantime, the application of advanced NDT-methods on concrete structures have become so capable, that crucial structure Parameters like certain material properties or geometrical dimensions can be quantified without significant destructive interventions. The measured data can be explicitly incorporated into the probabilistic computation models used for the bridge reassessment in form of random variables. Therewith, a previously insufficient model can be refined to achieve a higher level of approximation. This contribution emphasises two fundamental steps of the measured data based probabilistic reassessment: The sensitivity analyses to identify the cruciai Parameters and the needed accuracy of the related information as well as the comparison with expected uncertainties of non-destructively measured Parameters. T2 - 17th International Probabilistic Workshop CY - Edinburgh, UK DA - 11.09.2019 KW - Measurement KW - Reassessment KW - Structural safety KW - Concrete bridges KW - NDT PY - 2019 AN - OPUS4-48999 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bulling, Jannis A1 - Gravenkamp, H. A1 - Birk, C. T1 - A high-order finite element technique with automatic treatment of stress singularities by semi-analytical enrichment N2 - This paper presents an approach to the automatic enrichment of finite elements in the vicinity of a stress singularity. The enrichment consists of semi-analytical singular modes constructed using the Scaled Boundary Finite Element Method (SBFEM). In contrast to analytical methods, the SBFEM provides modes for inhomogeneous and anisotropic materials without additional effort. The finite element basis can be of arbitrary order and remains unaltered by the enrichment. The approach requires enrichment in only one layer of elements around a node. Due to the compatibility of SBFEM with FEM, there is no Need for transitional elements, and there are no parasitic terms. The approach is tested for several benchmark problems. The stress intensity factors are computed based on techniques inspired by the SBFEM. The proposed procedure is compared to a Standard finite element implementation and shows a significant improvement in the error of the displacement field for problems involving singular stresses. KW - Enriched finite element method KW - Scaled boundary finite element method KW - Stress intensity factors KW - Singular stress PY - 2019 DO - https://doi.org/10.1016/j.cma.2019.06.025 VL - 355 SP - 135 EP - 156 PB - Elsevier B.V. AN - OPUS4-48979 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Boehm, Rainer A1 - Heckel, Thomas A1 - Brackrock, Daniel A1 - Spruch, W. A1 - Beggerow, T. ED - Bond, L. J. ED - Holland, S. ED - Laflamme, S. T1 - High Speed Hollow Axle Inspection with a New Designed Cone Type Phased Array N2 - Hollow axle inspection can be performed without demounting the axles and without dismantling the wheels and the brake discs by using the drilling for the scan. To increase inspection reliability and inspection speed, the application of phased array systems instead of conventional probes is a good choice. For solid shaft inspection phased array setups became standard in the recent years. Nevertheless, for hollow axle inspection typically a number of conventional probes rotating through the axles drilling are applied. The new approach uses an electronically steered rotating sound field from a phased array for the circumferential scan. This is realized by a cone shaped phased array which operates in immersion technique. That allows a significant increase in inspection speed and a reduction of the mechanical effort of the inspection system. The inspection can be carried out by a linear movement of the probe setup along the axles drilling. Applying additional focal laws allows exact inclination and focusing of the sound beam in the plane vertical to the specimen axis to concentrate the sound in the zones close to the external surface. An additional focus in the plane of incidence increases overall resolution and sensitivity. The cone type phased array probe has been optimized to detect transversal flaws in and close to the outer surface of the hollow axle with orientation in the radial-radial plane. The prototype probe system, sound field simulations and measurement results are presented. T2 - 45th Annual Review of Progress in Quantitative Nondestructive Evaluation CY - Portland, Oregon, USA DA - 13.07.2019 KW - Cone Shaped Phased Array KW - Hollow Axle Inspection KW - High Speed Testing PY - 2019 SN - 978-0-7354-1832-5 DO - https://doi.org/10.1063/1.5099834 SN - 0094-243X VL - 2102 IS - 1 SP - UNSP 100006-1 EP - UNSP 100006-11 PB - American Institute of Physics CY - Maryland, Vereinigte Staaten AN - OPUS4-48936 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Xu, W. A1 - Zscherpel, Uwe A1 - Peng, J. A1 - Luo, L. A1 - Gao, X. A1 - Li, J. T1 - Investigation on Wall Thickness Ranges Using Digital Radiography for Tangential Projection Technique N2 - X-ray testing is based on the attenuation of X-rays when passing through matter. Image detectors acquire the X-ray information which is defined by the local penetrated wall thickness of the tested sample. By X-ray absorption in the detector and following read-out and digitization steps a digital image is generated. As detectors a radiographic film and film digitization, a storage phosphor imaging plate and a special Laser scanner (Computer Radiography - CR) or a digital detector array (DDA) can be used. The digital image in the computer can then be further analyzed using many types of image processing. In the presented work the automated evaluation of wall thickness profiles are investigated using a test steel pipe with 9 different wall thicknesses and various X-ray voltages and different filter materials at the tube port and intermediate between object and detector. In this way the influence of different radiation qualities on the accuracy of the automated wall thickness evaluation depending on the penetrated wall thickness of the steel pipe was investigated. T2 - 10th International Conference on Information Optics and Photonics CY - Beijing, China DA - 08.07.2018 KW - Image evaluation KW - Computed radiography (CR) KW - Digital Detector Array (DDA) KW - Tangential radiography KW - Wall thickness measurement PY - 2018 SN - 978-1-51062580-8 DO - https://doi.org/10.1117/12.2506324 SN - 0277-786X VL - 10964 SP - Article Number: UNSP 109645B PB - SPIE CY - Bellingham, WA AN - OPUS4-47346 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Küttenbaum, Stefan A1 - Taffe, A. A1 - Braml, T. A1 - Maack, Stefan T1 - Reliability assessment of existing bridges based on NDT-results N2 - The non-destructive testing methods available for civil engineering (NDT-CE) enable the measurements of quantitative parameters, which realistically describe the characteristics of existing buildings. In the past, methods for quality evaluation and concepts for validation expanded into NDT-CE to improve the objectivity of measured data. Thereby, a metrological foundation was developed to collect statistically sound and structurally relevant information about the inner construction of structures without destructive interventions. More recently, the demand for recalculations of structural safety was identified. This paper summarizes a basic research study on structural analyses of bridges in combination with NDT. The aim is to use measurement data of nondestructive testing methods as stochastic quantities in static calculations. Therefore, a methodical interface between the guide to the expression of uncertainty in measurement and probabilistic approximation procedures (e.g. FORM) has been proven to be suitable. The motivation is to relate the scientific approach of the structural analysis with real information coming from existing structures and not with those found in the literature. A case study about the probabilistic bending proof of a reinforced concrete bridge with statistically verified data from ultrasonic measurements shows that the measuring results fulfil the requirements concerning precision, trueness, objectivity and reliability. T2 - 5th ICCRRR 2018 - International Conference on Concrete Repair, Rehabilitation and Retrofitting CY - Cape Town, South Africa DA - 19.11.2018 KW - NDT KW - Concrete KW - Stochastic model KW - Reassessment KW - Reliability PY - 2018 AN - OPUS4-46768 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Völker, Tobias A1 - Gornushkin, Igor B. A1 - Kazakov, Alexander Ya. A1 - Wilsch, Gerd T1 - Application of two calibration-free LIBS techniques for synthetic spectra of cement samples N2 - Two calibration-free LIBS techniques are used for the quantitative analysis of synthetic cement samples: the CF-LIBS based on the Boltzmann plot method and the Monte Carlo (MC) LIBS based on the iterative spectrum fitting. In CF-LIBS, the inverse problem is solved, i.e. the elemental concentrations are determined by the reconstruction of plasma parameters from spectra. The MC-LIBS technique solves the direct problem by finding the highest correlation between the model-generated and experimental spectrum. The accuracy of both calibration-free LIBS methods suffers from factors such as inaccurately determined instrumental function, the deviation of experimental plasma from the mathematical model used, not taking into account the collection geometry and from the uncertainty of spectroscopic data. Therefore, the both calibration-free LIBS approaches are applied to synthetic spectra which perfectly suit the mathematical model of the method. This test yields the accuracy of both the approaches for the ideal case. In addition, the accuracy of both methods is investigated for non-isothermal plasma, because real laser-induced plasma often has high gradients in temperature. Both methods assume an isothermal plasma. T2 - Xth international conference on Laser-Induced Breakdown Spectroscopy CY - Atlanta, GA, USA DA - 21.10.2018 KW - Cement KW - MC-LIBS KW - LIBS KW - CF-LIBS PY - 2018 AN - OPUS4-46774 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Evsevleev, Sergei A1 - Müller, Bernd R. A1 - Lange, Axel A1 - Kupsch, Andreas T1 - Refraction driven X-ray caustics at curved interfaces N2 - X-ray refraction related interaction has received rising interest since about two decades in the field of imaging, beam shaping and analysis although being discovered a century ago. Due to refraction at interfaces in inhomogeneous media X-rays undergo natural focusing (or defocusing) of waves, revealing caustics. Such Kind of intensity patterns are well-known for visible light, but have been sparsely discussed for X-rays. The Variation of irradiation density may be predicted in case of known shapes. Analogously to light optics, the intensity distributions cover several orders of magnitude including complete extinction. The partly convergent (and divergent) caustic stripes originate from narrow zones of typical size of some 10−6 of the boundary curvature radius. For the deflection of plane wave synchrotron radiation (energy in the range of some keV to some ten keV) at rods and tubes of several μm diameter, we find good Agreement between experiments and modeling by ray tracing according to Snell’s law without additional diffraction contributions. Apart from Basic Research implications, caustics may influence the performance of irradiation technologies such as sterilization or molecular cross-linking. KW - X-ray caustics KW - X-ray refraction KW - Irradiation KW - Radiation shielding KW - Synchrotron Radiation PY - 2019 UR - http://www.sciencedirect.com/science/article/pii/S0168900218314591 DO - https://doi.org/10.1016/j.nima.2018.10.152 SN - 0168-9002 SN - 1872-9576 VL - 916 SP - 275 EP - 282 PB - Elsevier AN - OPUS4-46924 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bertovic, Marija T1 - How can we use psychology to optimize the NDT inspection process and prevent human error N2 - The aim of this presentation is to highlight how psychology can be used to prevent human error. It starts with examples of accidents, incidents and events that have happened due to too little attention being dedicated to human factors. It continues arguing that human factors are one of the main factors influencing the reliability of non-destructive testing and gives definitions of the main terms. Furthermore, it presents a method used to identify risks in mechanized NDT to be used for the purposes of the final disposal of spent nuclear fuel and presents a study, in which human-centred design and eye tracking have been used to optimism the inspection procedure. The conclusion is that human factors methods can be used to identify problems during the inspection process and generate mitigation strategies that can be used to decrease human error and enhance safety. T2 - The Nordic Symposium on Nuclear Power CY - Stockholm, Sweden DA - 26.11.2018 KW - Zerstörungsfreie Prüfung KW - Human factors KW - Human error KW - Risk management PY - 2018 AN - OPUS4-46938 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maack, Stefan A1 - Villalobos, S. A1 - Scott, D. T1 - Validation of artificial defects for Non-destructive testing measurements on a reference structure N2 - Non-destructive testing was established over the last decades as an important tool for assessing damages, material characterization and quality assurance in civil engineering. For example, Ground Penetrating Radar (GPR) can be used to scan large areas of concrete structures to determine the spatial position of the reinforcement. With the ultrasonic echo method, the thickness of concrete structures can be easily determined even if a high density of reinforcement is given. Various methods and processes have been developed for the validation of NDT procedures aiming at ensuring the quality of measurements in practical use. The Probability of Detection (POD) for example, is an available method to compare different technical devices with each other quantitatively regarding their performance. With this method, the best suited testing device for a specific inspection task under defined boundary conditions can be selected. By using the Guide to the Expression of Uncertainty in Measurement (GUM), it is possible to quantify the measurement uncertainty of an inspection procedure for a specific task. Another important aspect to improve the acceptance of non-destructive testing methods is the development of reference specimens. Reference specimens serve for the calibration and further development of NDT methods under realistic conditions in different laboratories under the same conditions. This is an essential prerequisite for round robin tests. A particular challenge here is the most realistic representation of a damage that can occur at building sites. Possible damages include for example horizontal and vertical cracks or honeycombs in concrete. Such a reference structure was built for the development of a new design of power plant constructions. Comparative studies on the manufacturing of realistic honeycombs and delaminations were carried out in advance on a test specimen. The results of this study are presented here. T2 - ICCRRR 2018 - Concrete Repair, Rehabilitation and Retrofitting CY - Cape Town, South Africa DA - 19.11.2018 KW - Zerstörungsfreie Prüfung KW - Nondestructive testing KW - Ultraschall KW - Kiesnest KW - Honeycomb KW - Ultrasonic Echo PY - 2018 AN - OPUS4-46974 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hüllmann, Dino A1 - Neumann, Patrick P. A1 - Lilienthal, A. J. T1 - Aerial-based Gas Source Localisation using an Open-Path Gas Detector N2 - Presentation of the aerial robotic platform to localise gas sources with an open-path gas detector based on the tunable diode laser absorption spectroscopy (TDLAS) and project overview. T2 - Seminarserie an der Universität Örebro CY - Örebro, Sweden DA - 28.11.2018 KW - Gas Source Localisation KW - Gas Spectroscopy KW - UAV KW - TDLAS PY - 2018 AN - OPUS4-46870 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Helmerich, Rosemarie ED - Hu, Chang Bin T1 - Engineering Education in Europe N2 - The book chapter first analyses the history of higher education in Europe. Second step describes the current Bologna process. Finally, the rule of the Bundesanstalt für Materialforschung und -Prüfung (BAM) in supporting PhD-students during their research and preparation of theire theses in cooperation with Universities is described KW - History of education KW - Bologna process KW - BAM PY - 2018 SN - 978-7-114-14938-2 SP - 61 EP - 71 PB - China Communication Press Co., Ltd. CY - Fuzhou, China ET - 1. AN - OPUS4-46871 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wilsch, Gerd A1 - Gottlieb, Cassian A1 - Günther, Tobias A1 - Millar, Steven ED - Forde, Mike T1 - Application of laser induced breakdown spectroscopy N2 - A big part of the infrastructure is made of concrete, which is a multiphase system made of cement, aggregates, water and pores. Concrete is often used in combination with steel as reinforced concrete. Environmental influences, especially the ingress of harmful ions in combination with the ingress of water, trigger different damage processes which reduce the designed lifetime of a structure. The ingress of chlorides from de-icing salt or sea water leads to corrosion of the reinforcement. In addition, the carbonation of the concrete may trigger the corrosion of the reinforcement. The ingress of alkalis from deicing salts may cause the expansion of the amorphous silica aggregates (alkali-silica reaction) through formation of a swelling gel of calcium silicate hydrate if water is present. The ingress of sulphates may cause spalling of the concrete surface due to ettringite formation. For the standard procedure in civil engineering cores are taken, cut in slices, grinded and the obtained homogenized powder is solved in acid and investigated by standard procedures. BAM has developed the LIBS technique for the 2D evaluation of the chemical composition of concrete. The technique is established for automated laboratory use with high numbers of samples to investigate transport processes of harmful species (Cl-, CO2 , SO4 2-and alkalis) in concrete. Information about ingress depth and the quantitative values are important to estimate the remaining lifetime of the infrastructure. LIBS is a surface technique. To get information about the ingress depth, a drill core has to be taken and cut in the middle. The measurements are carried out at the cross section. The main advantages of LIBS are the direct measurement on the surface of the concrete, fast analysis (sample rate 100 Hz) with a spatial resolution of up to 100 µm, the consideration of the heterogeneity of the concrete and the possibility of automated measurements which save a lot of manpower and time. As an example the investigation of ingress profiles for standard diffusion and migration tests in civil engineering takes hours in comparison to just a few minutes using LIBS. At the same time a 2D-evaluation provides information about hot spots of elemental concentration which may not be found by standard methods. The state of the art of LIBS technique for applications in civil engineering will be presented, including typical results of 2D investigation of concrete in laboratory. The performance is also demonstrated by examples for onsite applications using a mobile LIBS system. The road map to standardization is presented as well. T2 - Structural Faults + Repair-2018 CY - Edinburgh, UK DA - 15.05.2018 KW - Sulphate KW - Chloride KW - Concrete KW - LIBS PY - 2018 SN - 0-947644-86-5 DO - https://doi.org/10.25084/sfr.2018.0030 SP - 1 EP - 7 PB - University of Edinburgh CY - Edinburgh AN - OPUS4-46947 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wilsch, Gerd A1 - Gottlieb, Cassian A1 - Günther, Tobias A1 - Millar, Steven A1 - Sankat, Nina T1 - Application of LIBS for the chemical investigation of concrete infrastructure N2 - Overview about LIBS applications in civil engineering T2 - Structural Faults + Repair-2018 CY - Edinburgh, UK DA - 15.05.2018 KW - On-site measurements KW - LIBS KW - Concrete KW - Chloride KW - Sulfates PY - 2018 AN - OPUS4-46948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Algernon, D. A1 - Arndt, R.W. A1 - Denzel, W. A1 - Ebsen, B. A1 - Feistkorn, S. A1 - Friese, M. A1 - Große, C.U. A1 - Kathage, S. A1 - Keßler, S. A1 - Köpp, Christian A1 - Küttenbaum, Stefan A1 - Lohse, C. A1 - Maack, Stefan A1 - Niederleithinger, Ernst A1 - Schickert, M. A1 - Schröder, G. A1 - Taffe, A. A1 - Timofeev, Juri A1 - Walther, A. A1 - Wilcke, M. A1 - Wolf, J. A1 - Wöstmann, Jens T1 - Test specimen concepts in regard to quality assurance and validation of nondestructive testing in civil engineering N2 - The process of ensuring reliability of NDT applications contains various aspects, such as determining the performance and probability of success, the uncertainty in measurement, the provision of clear and functional procedures and ensuring the correct application accordingly. Test specimens have become powerful elements in supporting many of these aspects. Within the committee for NDT in Civil Engineering (NDT-CE) of the German Society for Nondestructive Testing (DGZfP), the subcommittee on Quality Assurance (UA-QS) therefore addresses the design and the integration of test specimens in the quality assurance process. Depending on the specific purpose, the requirements on test specimens can vary significantly based on the defined simulated scenario. The most prominent purposes of test specimens might be seen in providing references for inspection systems in regard to function control, calibration and validation. Further aspects can be parametric studies, basic investigation of physical principles related to NDT or a simplified and therefore comprehensive demonstration of inspection concepts (e.g. for teaching purposes). The specific purpose of a test specimen dictates the requirements regarding its conception, including the exact design, the material or the fabrication accuracy and the conditioning. In the development of a general guideline by the UA-QS for application-specific procedures and their validation, the use of test specimens is addressed and specific concepts for the design of test specimens are made. This includes the analysis of the measurement process regarding any given application, deriving an adequate calibration approach for it and designing test specimens (calibration specimens) accordingly. Furthermore, it includes the validation of the procedure taking into account all conditions related to the specific application in the field. The validation requires a statistically sufficient number of trials. Thorough evaluation of each trial can only be established if the ground-truth is known. Therefore, test specimens providing a realistic but controlled simulation of the inspection problem are valuable and indispensable elements in the validation process. The requirement of being fully realistic will often not be possible to fulfill due to practical restrictions. Any aspect that cannot be included in the simulation realistically needs to be simulated conservatively. This again, requires a sufficient understanding of the inspection principle and technique to ensure conservativeness. Among other quality-assurance-related aspects, the UA-QS establishes concepts and guidelines regarding sound and efficient approaches for the specific purposes of test specimens. This subcommittee brings together representatives of different Groups along the entire value chain of NDT-CE, including researchers, practitioners, manufacturers and clients. They all work together in establishing a common understanding and level of quality assurance in the industry. T2 - SMT and NDT-CE 2018 CY - New Brunswick, NJ, USA DA - 27.08.2018 KW - Quality assurance KW - Procedure KW - Reliability KW - Validation KW - Reference specimen PY - 2019 UR - https://asnt.org/smt18papers SN - 978-1-57117-456-7 VL - 11/19 SP - 39 EP - 48 PB - The American Society for Nondestructive Testing, Inc. CY - Columbus, OH, USA AN - OPUS4-47240 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bassil, A. A1 - Wang, Xin A1 - Chapeleau, X. A1 - Niederleithinger, Ernst A1 - Abraham, O. A1 - Leduc, D. T1 - Distributed fiber optics sensing and coda wave interferometry techniques for damage monitoring in concrete structures N2 - The assessment of Coda Wave Interferometry (CWI) and Distributed Fiber Optics Sensing (DFOS) techniques for the detection of damages in a laboratory size reinforced concrete beam is presented in this paper. The sensitivity of these two novel techniques to micro cracks is discussed and compared to standard traditional sensors. Moreover, the capacity of a DFOS technique to localize cracks and quantify crack openings is also assessed. The results show that the implementation of CWI and DFOS techniques allow the detection of early subtle changes in reinforced concrete structures until crack formation. With their ability to quantify the crack opening, following early detection and localization, DFOS techniques can achieve more effective monitoring of reinforced concrete structures. Contrary to discrete sensors, CWI and DFOS techniques cover larger areas and thus provide more efficient infrastructures asset management and maintenance operations throughout the lifetime of the structure. KW - Distributed fiber optic sensors KW - Coda wave interferometry KW - Reinforced concrete KW - Cracks KW - Damage detection KW - Structural health monitoring PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-472549 DO - https://doi.org/10.3390/s19020356 SN - 1424-8220 VL - 19 IS - 2 SP - 356, 1 EP - 15 PB - MDPI AN - OPUS4-47254 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Seismic methods to test concrete strcutures N2 - Seismic methods are increasingly used to improve ultrasonic imaging and monitoring of concrete. At BAM, we are research mainly the use of Reverse Time Migration to get better images from ultrasonic echo data of thick, complex concrete structures. Coda wave interferometry is used to detect subtle changes in concrete constructions, e. g. using embedded ultasonic transducers. T2 - Geophysikalisches Seminar der Universität Potsdam CY - Potsdam,. Germany DA - 25.01.2019 KW - Concrete KW - Ultrasound KW - Monitoring KW - Imaging PY - 2019 AN - OPUS4-47302 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhua, L A1 - Ewert, Uwe A1 - Xianga, X. A1 - Pengc, Y. A1 - Wanga, X. T1 - Synchrotron phase-contrast CT to segment the structure boundaries of a TRISO-coated particle N2 - Tri-structural Isotropic (TRISO)-coated particle is the fission energy source and the first safety barrier in high temperature gas-cooled reactors (HTGRs). The integrity of TRISO particle should be carefully tested before operation because the shape may affect the failure possibility of the particles, leading to increased risk of fission product release. Due to the large difference in density between the kernel and the coating layers in TRISO particles, traditional X-ray radiography cannot achieve a good image quality in terms of identifying coating layers reliably, while phase-contrast CThas the advantageof being sensitive to boundaries. This paperpresents a non-destructive test and evaluation (NDT&E) method to facilitate 3-dimensional (3D) measurement of a TRISO particle's structure, using a synchrotron phase-contrast CT. After reconstructed, the TRISO particle was rendered in a 3D space and the thickness and asphericity of the TRISO particle's layers were measured. It was found that the thickness of coating layers of the tested particle obeys Gaussian distribution. The deviation of thicknesses of the kernel and the other four layers is −2.42%, −16.32%, 26.51%, 0.98% and 7.49% compared with the design parameters. The deviation of asphericity of the kernel, IPyC and OPyC layers is −11.51%, −0.41% and 3.39%, respectively. The effect of the deviations on the temperature distribution and failure probability calculation of the particle will be investigated in the future. KW - TRISO KW - 3D visualization KW - 3D particle analysis KW - Three-dimensional measurement PY - 2019 DO - https://doi.org/10.1016/j.ndteint.2019.01.003 VL - 103 SP - 12 EP - 18 PB - Elsevier Ltd. AN - OPUS4-47303 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Abraham, O. A1 - Niederleithinger, Ernst A1 - Chapeleau, X. A1 - Klikowicz, P. A1 - Brühwiler, E. A1 - Bassil, A. A1 - Wang, Xin A1 - Chakraborty, J. A1 - Bayane, I. A1 - Leduc, D. A1 - Salamak, M. A1 - Katunin, A. A1 - Sørensen, J.D. T1 - Addressing the need to monitor concrete fatigue with nondestructive testing: Results of infrastar European project N2 - Fatigue is one of the most prevalent issues, which directly influences the service life expectancy of concrete structures. Fatigue has been investigated for years for steel structures. However, recent findings suggest that concrete structures may also be significantly subjected to fatigue phenomena that could lead to premature failure of certain structural elements. To date, fatigue of reinforced concrete has been given little focus. Knowledge on the influence factors and durability/capacity effects on this material should be improved. Current technological means to measure fatigue in civil structures like bridges and wind turbines (both onshore and offshore) are outdated, imprecise and inappropriate. Meanwhile, this topic has got much more attention as time-variant loading on concrete structures plays an increasing role, e.g. in bridges with increasing traffic and heavier trucks, and for wind turbines for renewable energy production, e.g. for offshore wind turbine support structures affected by wind and waves. The European Innovative Training Networks (ITN) Marie Skłodowska-Curie Actions project INFRASTAR (Innovation and Networking for Fatigue and Reliability Analysis of Structures - Training for Assessment of Risk) provides research training for 12 PhD students. The project aims to improve knowledge for optimizing the design of new structures as well as for more realistic verification of structural safety and more accurate prediction of the remaining fatigue lifetime of existing concrete structures. First, the INFRASTAR research framework is detailed. Then it will be exemplified through the presentation of the major results of the four PhD students involved in the work package dealing with auscultation and monitoring. This includes the development and improvement of Fiber Optics (FO) and Coda Wave Interferometry (CWI) for crack sizing and imagery, new sensor technologies and integration, information management, monitoring strategy for fatigue damage investigation and lifetime prediction. T2 - SMT and NDT-CE 2018 CY - New Brunswick, NJ, USA DA - 27.08.2018 KW - Concrete KW - Fatigue KW - Crack KW - Monitoring KW - Non-destructive testing PY - 2019 UR - https://asnt.org/smt18papers SN - 978-1-57117-456-7 VL - 11/19 SP - 2 EP - 13 PB - The American Society for Nondestructive Testing, Inc. CY - Columbus, OH, USA AN - OPUS4-47237 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst A1 - Wiggenhauser, Herbert T1 - The LAUS: First Applications of a New System for Ultrasonic Imaging of Very Concrete Structures N2 - The LAUS (Large Aperture Ultrasonic System) has been developed to image very thick concrete structures, which are not accessible for commercial systems. The device and the corresponding software is the result of joint Research of BAM, an ultrasonic instrument manufacturer and University of Kassel, Germany. It consists of 12 separate Arrays of 32 point-contact shear wave transducers each, which can be deployed in flexible configurations. Each array is combined with battery and transmitter, receiver and wireless communication electronics. Three case histories are presented. First the system was deployed on a 5-m thick heavily reinforced foundation slab. The reflection of the slab’s bottom was imaged clearly. In addition, a multiple reflection was registered, thus giving hope that even thicker elements might be imaged by the instrument. Second, the LAUS was used to investigate a massive bridge girder where a heavy rainstorm during concreting had led to imperfections that were visible after removing the formwork was removed. The LAUS could image tendon ducts in 1.8m depth and the backwall closely behind them. Some limited areas showed blurred reflections and were checked by drill holes; these areas were affected by diffuse damage which could be repaired by injections. Third, a large retaining wall was checked for thickness. Meanwhile, the LAUS has been used in underground waste deposits (nuclear and other) for quality assurance of sealing plugs. A confirmed penetration depth of about 7 m has been reached. T2 - SMT and NDT-CE 2018 CY - New Brunswick, NJ, USA DA - 27.08.2018 KW - LAUS (Large Apertur Ultrasonic System) KW - Ultrasonic echo KW - Deep penetration KW - Concrete PY - 2019 UR - https://asnt.org/smt18papers SN - 978-1-57117-456-7 VL - 11/19 SP - 208 EP - 213 PB - The American Society for Nondestructive Testing, Inc. CY - Columbus, OH, USA AN - OPUS4-47238 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Algernon, D. A1 - Arndt, R.W. A1 - Denzel, W. A1 - Ebsen, B. A1 - Feistkorn, S. A1 - Friese, M. A1 - Große, C.U. A1 - Kathage, S. A1 - Keßler, S. A1 - Köpp, Christian A1 - Küttenbaum, Stefan A1 - Lohse, C. A1 - Maack, Stefan A1 - Niederleithinger, Ernst A1 - Schickert, M. A1 - Schröder, G. A1 - Taffe, A. A1 - Timofeev, Juri A1 - Walther, A. A1 - Wilcke, M. A1 - Wolf, J. A1 - Wöstmann, Jens T1 - NDT procedures in relation to quality assurance and validation of nondestructive testing in civil engineering N2 - The field of non-destructive testing of civil structures (NDT-CE) has been continuously growing. Due to the complexity and diversity of civil constructions as well as the heterogeneity of concrete, specific standards or guidelines for the application of modern NDT-CE are still missing. The development of individual solutions is the current approach, which is just as challenging as it is common for NDT-CE. With the increasing development and commercialization of NDT-CE technology, the group of practitioners is growing. To ensure a good level of quality in the industry, it appears necessary to establish adequate means. Naturally, the performance of NDT-CE methods regarding a specific application is strongly dependent on choosing the most suitable inspection technique and applying it correctly, generally referred to as the inspection procedure in the field of NDT. There are well-defined guidelines regarding procedure documentation and handling in many fields of NDT (e.g. nuclear, aerospace or automotive) according to the high importance of procedures in assuring a successful and reliable application. For a long time, this has not always been the case with NDT-CE, which is still considered a unique discipline of NDT. Part of the reason for that might be the young development state of NDTCE, the heterogeneity of building materials like concrete, timber or masonry as a material and the diversity of civil structures. In consequence, NDT-CE procedure development is considered challenging. Among other aspects, addressed in the subcommittee on Quality Assurance (UA-QS) within the committee for NDT-CE of the German Society for Nondestructive Testing (DGZfP), part of its work aims at establishing an adequate basis for NDT-CE procedure development. While some of the highly developed approaches from other industries are taken into consideration, they need to be analyzed regarding their suitability for NDT-CE and adapted accordingly. For a procedure to be as defined as possible, it needs to contain sufficient information, such as the scope and limitations regarding material, geometry and condition of the test object, inspection parameters, calibration, data acquisition, analysis criteria as well as requirements regarding the inspection personnel. For a successful implementation in the field, it is important to define the specific procedure as precisely as possible. Despite the necessity of a great amount of information to be included, the procedure needs to be suitable for efficient field application. The UA-QS is developing a guideline for NDT-CE procedures suitable for application in this field of NDT to ensure correct and reproducible application. To demonstrate and evaluate this concept, specific examples of procedures are also produced. In particular, the UA-QS has developed a procedure for the detection and positioning of tendon ducts using Ground Penetrating Radar (GPR). This procedure is tested regarding the practical applicability in a roundrobin on a defined type of reference test block. T2 - SMT and NDT-CE 2018 CY - New Brunswick, NJ, USA DA - 27.08.2018 KW - Quality assurance KW - Procedure KW - Reliability KW - Validation KW - Reference specimen PY - 2019 UR - https://asnt.org/smt18papers SN - 978-1-57117-456-7 VL - 11/19 SP - 31 EP - 38 PB - The American Society for Nondestructive Testing, Inc. CY - Columbus, OH, USA AN - OPUS4-47239 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bellon, Carsten A1 - Burger, Karin A1 - Gollwitzer, Christian T1 - Virtual CT acquisition and reconstruction of complex and noisy scanning trajectories in aRTist N2 - In modern CT imaging, simulation has become an important tool to minimize cost- and time-intensive measurements. It is increasingly used to optimize techniques for complex applications, to support the preparation of written procedures, and for educational purposes. We extended the CT simulation software ‘aRTist’ with a module to set-up arbitrary trajectories including disturbing influences during the scan. Moreover, such geometric deviations can be compensated by the internal reconstruction tool. T2 - 9th Conference on Industrial Computed Tomography (iCT) CY - Padua, Italy DA - 13.02.2019 KW - Simulation KW - Arbitrary trajectories KW - Projection matrix KW - Filtered back projection PY - 2019 AN - OPUS4-47476 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Buljak, V. A1 - Oesch, Tyler A1 - Bruno, Giovanni T1 - Simulating fiber-reinforced concrete mechanical performance using CT-based fiber orientation data N2 - The main hindrance to realistic models of fiber-reinforced concrete (FRC) is the local materials property variation, which does not yet reliably allow simulations at the structural level. The idea presented in this paper makes use of an existing constitutive model, but resolves the problem of localized material variation through X-ray computed tomography (CT)-based pre-processing. First, a three-point bending test of a notched beam is considered, where pre-test fiber orientations are measured using CT. A numerical model is then built with the zone subjected to progressive damage, modeled using an orthotropic damage model. To each of the finite elements within this zone, a local coordinate system is assigned, with its longitudinal direction defined by local fiber orientations. Second, the parameters of the constitutive damage model are determined through inverse analysis using load-displacement data obtained from the test. These parameters are considered to clearly explain the material behavior for any arbitrary external action and fiber orientation, for the same geometrical properties and volumetric ratio of fibers. Third, the effectiveness of the resulting model is demonstrated using a second, “control” experiment. The results of the “control” experiment analyzed in this research compare well with the model results. The ultimate strength was predicted with an error of about 6%, while the work-of-load was predicted within 4%. It demonstrates the potential of this method for accurately predicting the mechanical performance of FRC components. KW - Fiber-reinforced concrete KW - X-ray computed tomography (CT) KW - Anisotropic fiber orientation KW - Inverse analysis PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-474728 DO - https://doi.org/10.3390/ma12050717 SN - 1996-1944 VL - 12 IS - 5 SP - 717, 1 EP - 16 PB - MDPI AN - OPUS4-47472 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ziegler, Mathias A1 - Thiel, Erik A1 - Ahmadi, Samim A1 - Hirsch, Philipp Daniel A1 - Burgholzer, P. A1 - Mayr, G. T1 - Thermography using High-Power Laser Arrays N2 - Due to their high irradiance and wide modulation bandwidth, high-power lasers open up a wide field of application. For example, the classical methods of pulse and lock-in thermography can be realized in high quality. In addition, structured heating is also possible by using arrays of such lasers. This makes it possible to implement new thermographic methods, such as interference-based detection of cracks or super resolution. T2 - Fifth NDTonAIR Training Event: Thermography Workshop CY - Linz, Austria DA - 13.02.2019 KW - Thermography KW - Laser Thermography KW - Super Resolution KW - Thermal Waves KW - NDT PY - 2019 AN - OPUS4-47491 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vössing, Konrad A1 - Gaal, Mate A1 - Niederleithinger, Ernst T1 - Air‑coupled ferroelectret ultrasonic transducers for nondestructive testing of wood‑based materials N2 - Air-coupled ultrasound (ACU) is used in through transmission to detect delamination, rot, and cracks in wood without altering the structure permanently. Novel ferroelectret transducers with a high signal-to-noise ratio enable high-precision structure recognition. Transducers made of cellular polypropylene are quite suitable for ACU testing due to their extremely low Young’s modulus and low density resulting in a favorable acoustic impedance for the transmission of ultrasonic waves between the transducer and air. Thus, structures with great dimensions, with a thickness of up to 300 mm and material densities below 500 kg/m3, can be inspected. Promising results were obtained under laboratory conditions with frequencies ranging from 90 to 200 kHz. The advantage of ACU transducers is that they do not equire contact to the sample; they are accurate and cost-effective. Ultrasonic quality assurance for wood is an important avenue to increase the acceptance of wooden structures and toward sustainability in civil engineering in general. KW - Ultrasound KW - Wood KW - Defect KW - Air-coupled PY - 2018 DO - https://doi.org/10.1007/s00226-018-1052-8 VL - 52 IS - 6 SP - 1527 EP - 1538 PB - Springer AN - OPUS4-46653 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gaal, Mate A1 - Kotschate, Daniel A1 - Wendland, Saskia T1 - Airborne testing of molded polymer compounds N2 - Modern and energy-efficient materials are essential for innovative designs for aerospace and automotive industries. Current technologies for rapid manufacturing such as additive manufacturing and liquid composite moulding by polymer Extrusion allow innovative ways of creating robust and lightweight constructions. Commercially available printing devices often use polylactide (PLA) or acrylonitrile butadiene styrene (ABS) as raw material. Therefore, parameters like the infill ratio, influencing the ability to resist mechanical stress, may have a beneficial impact on the lifetime of components. These manufacturing technologies require a good knowledge about materials and even adapted non-destructive testing technologies and methods. Airborne ultrasonic testing has beneficial advantages for testing those lightweight constructions. It is a contact-free testing method, which does not require a liquid couplant. Therefore, it allows fast test cycles without any unwanted alternations of the material properties due to interactions with any coupling liquid. This contribution deals with the characterisation of printed specimens based on PLA by using airborne ultrasound and presents the current edge of non-destructive testing and evaluation using airborne ultrasonic transducers. The specimens, manufactured by polymer extrusion, are printed as thin plates. The infill ratio, as well as the material thickness, were varied to model density imperfections with different geometric shapes and properties. For better understanding of the limits of airborne ultrasonic testing in transmission, we compared own-developed transducers based on different physical principles: on ferroelectrets, on the thermoacoustic effect, as well as a new type of transducers based on gas discharges. T2 - 10th International Symposium on NDT in Aerospace CY - Dresden, Germany DA - 26.10.2018 KW - Airborne ultrasonic testing KW - Transducers KW - Ferroelectret KW - Thermoacoustic KW - Plasma KW - Polymer testing PY - 2018 AN - OPUS4-46655 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gaal, Mate A1 - Schadow, Florian A1 - Nielow, Dustin A1 - Trappe, Volker T1 - Air-coupled ultrasonic ferroelectret transducers with additional bias voltage for testing of composite structures N2 - Common air-coupled transducers for non-destructive testing consist of a piezocomposite material and several matching layers. Better acoustical matching to air is achieved by transducers based on charged cellular polypropylene (PP). This material has about hundred times lower acoustic impedance than any piezocomposite, having about the same piezoelectric coefficient. The piezoelectric properties of cellular PP are caused by the polarization of air cells. Alternatively, a ferroelectret receiver can be understood as a capacitive microphone with internal polarization creating permanent internal voltage. The sensitivity of the receiver can be increased by applying additional bias voltage. We present an ultrasonic receiver based on cellular PP including a high-voltage module providing bias voltage up to 2 kV. The application of bias voltage increased the signal by 12 to 15 dB with only 1 dB increase of the noise. This receiver was combined with a cellular PP transmitter in through transmission to inspect several test specimens consisting of glass-fiber-reinforced polymer face sheets and a porous closed-cell PVC core. These test specimens were inspected before and after load. Fatigue cracks in the porous PVC core and some fatigue damage in the face sheets were detected. These test specimens were originally developed to emulate a rotor blade segment of a wind power plant. Similar composite materials are used in lightweight aircrafts for the general aviation. The other inspected test specimen was a composite consisted of glass-fiber-reinforced polymer face sheets and a wooden core. The structure of the wooden core could be detected only with cellular PP transducers, while commercial air-coupled transducers lacked the necessary sensitivity. Measured on a 4-mm thick carbon-fiber-reinforced polymer plate, cellular PP transducers with additional bias voltage achieved a 32 dB higher signal-to-noise ratio than commercial air-coupled transducers. T2 - 10th International Symposium on NDT in Aerospace CY - Dresden, Germany DA - 26.10.2018 KW - Airborne ultrasonic testing KW - Air-coupled ultrasonic testing KW - Ferroelectret KW - Composites KW - Rotor blade PY - 2018 AN - OPUS4-46656 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gaal, Mate A1 - Schadow, Florian A1 - Nielow, Dustin A1 - Trappe, Volker T1 - Air-coupled ultrasonic ferroelectret transducers with additional bias voltage for testing of composite structures N2 - Common air-coupled transducers for non-destructive testing consist of a piezocomposite material and several matching layers. Better acoustical matching to air is achieved by transducers based on charged cellular polypropylene (PP). This material has about hundred times lower acoustic impedance than any piezocomposite, having about the same piezoelectric coefficient. The piezoelectric properties of cellular PP are caused by the polarization of air cells. Alternatively, a ferroelectret receiver can be understood as a capacitive microphone with internal polarization creating permanent internal voltage. The sensitivity of the receiver can be increased by applying additional bias voltage. We present an ultrasonic receiver based on cellular PP including a high-voltage module providing bias voltage up to 2 kV. The application of bias voltage increased the signal by 12 to 15 dB with only 1 dB increase of the noise. This receiver was combined with a cellular PP transmitter in through transmission to inspect several test specimens consisting of glass-fiber-reinforced polymer face sheets and a porous closed-cell PVC core. These test specimens were inspected before and after load. Fatigue cracks in the porous PVC core and some fatigue damage in the face sheets were detected. These test specimens were originally developed to emulate a rotor blade segment of a wind power plant. Similar composite materials are used in lightweight aircrafts for the general aviation. The other inspected test specimen was a composite consisted of glass-fiber-reinforced polymer face sheets and a wooden core. The structure of the wooden core could be detected only with cellular PP transducers, while commercial air-coupled transducers lacked the necessary sensitivity. Measured on a 4-mm thick carbon-fiber-reinforced polymer plate, cellular PP transducers with additional bias voltage achieved a 32 dB higher signal-to-noise ratio than commercial air-coupled transducers. T2 - 10th International Symposium on NDT in Aerospace CY - Dresden, Germany DA - 26.10.2018 KW - Airborne ultrasonic testing KW - Air-coupled ultrasonic testing KW - Ferroelectret KW - Composites KW - Transducers PY - 2018 SP - 1 EP - 6 AN - OPUS4-46657 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Delbeck, S. A1 - Vahlsing, Thorsten A1 - Leonhardt, S. A1 - Steiner, G. A1 - Heise, H.M. T1 - Non-invasive monitoring of blood glucose using optical methods for skin spectroscopy - opportunities and recent advances N2 - Diabetes mellitus is a widespread disease with greatly rising patient numbers expected in the future, not only for industrialized countries but also for regions in the developing world. There is a need for efficient therapy, which can be via self-monitoring of blood glucose levels to provide tight glycemic control for reducing the risks of severe health complications. Advancements in diabetes technology can nowadays offer different sensor approaches, even for continuous blood glucose monitoring. Non-invasive blood glucose assays have been promised for many years and various vibrational spectroscopy-based methods of the skin are candidates for achieving this goal. Due to the small spectral signatures of the glucose hidden among a largely variable background, the largest signal-to-noise ratios and multivariate calibration are essential to provide the method applicability for self-monitoring of blood glucose. Besides multiparameter approaches, recently presented devices based on photoplethysmography with wavelengths in the visible and near-infrared range are evaluated for their potential of providing reliable blood glucose concentration predictions. KW - Non-invasive glucose sensing KW - Vibrational spectroscopy KW - Photoplethysmography KW - Multivariate calibration KW - Validation studies PY - 2019 DO - https://doi.org/10.1007/s00216-018-1395-x SN - 1618-2650 SN - 1618-2642 VL - 411 IS - 1 SP - 63 EP - 77 PB - Springer-Verlag GmbH Germany, part of Springer Nature AN - OPUS4-46714 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vahlsing, Thorsten A1 - Delbeck, S. A1 - Leonhardt, S. A1 - Heise, H.M. T1 - Noninvasive monitoring of blood glucose using color-coded photoplethysmographic images of the illuminated fingertip within the visible and near-infrared range: Opportunities and questions N2 - Noninvasive blood glucose assays have been promised for many years and various molecular spectroscopy-based methods of skin are candidates for achieving this goal. Due to the small spectral signatures of the glucose used for direct physical detection, moreover hidden among a largely variable background, broad spectral intervals are usually required to provide the mandatory analytical selectivity, but no such device has so far reached the accuracy that is required for self-monitoring of blood glucose (SMBG). A recently presented device as described in this journal, based on photoplethysmographic fingertip images for measuring glucose in a nonspecific indirect manner, is especially evaluated for providing reliable blood glucose concentration predictions. KW - Color sensing KW - Noninvasive glucose sensing KW - Plethysmographic skin imaging KW - Skin tissue spectroscopy KW - Visible/near-infrared spectroscopy PY - 2018 DO - https://doi.org/10.1177/1932296818798347 SN - 1932-2968 VL - 12 IS - 6 SP - 1169 EP - 1177 PB - Sage Publishing AN - OPUS4-46715 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gollwitzer, Christian A1 - Scholz, Philipp A1 - Ulbricht, Alexander A1 - Joshi, Yogita A1 - Weidner, Steffen T1 - Synchrotron based absorption edge tomography for the analysis of 3D printed polymer MOF N2 - Absorption edge tomography is a method which exploits the sudden change of the attenuation coefficient, when the photon energy crosses the absorption edge of an element. The beamline BAM line at BESSY II, which is operated by the Federal Institute for Materials Research and Testing, can provide a monochromatized beam in a photon energy range from 5 keV up to 80 keV with a bandwidth of 2%. Together with the microtomography setup, this enables differential tomography sensitive to any element with N >= 24 (Cr) by using an appropriate K- or L-edge in this range. Here, a polymer filament embedding metal organic framework (MOF) was prepared and used for 3D printing. Absorption edge tomography at the copper K edge was employed to perform a non-destructive 3D characterization of the microstructure of the embedded MOF. Data fusion was then used to determine the size distribution of the embedded MOF. T2 - iCT 2019 CY - Padua, Italy DA - 12.02.2019 KW - Synchrotron tomography KW - BAMline KW - MOF KW - Absorption edge tomography PY - 2019 AN - OPUS4-47391 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gollwitzer, Christian A1 - Scholz, Philipp A1 - Ulbricht, Alexander A1 - Joshi, Yogita A1 - Weidner, Steffen T1 - Synchrotron based absorption edge tomography for the analysis of 3D printed polymer MOF N2 - Absorption edge tomography is a method which exploits the sudden change of the attenuation coefficient, when the photon energy crosses the absorption edge of an element. The beamline BAM line at BESSY II, which is operated by the Federal Institute for Materials Research and Testing, can provide a monochromatized beam in a photon energy range from 5 keV up to 80 keV with a bandwidth of 2%. Together with the microtomography setup, this enables differential tomography sensitive to any element with N >= 24 (Cr) by using an appropriate K- or L-edge in this range. Here, a polymer filament embedding metal organic framework (MOF) was prepared and used for 3D printing. Absorption edge tomography at the copper K edge was employed to perform a non-destructive 3D characterization of the microstructure of the embedded MOF. Data fusion was then used to determine the size distribution of the embedded MOF. T2 - iCT 2019 CY - Padua, Italy DA - 12.02.2019 KW - Synchrotron tomography KW - BAMline KW - MOF KW - Absorption edge tomography PY - 2019 AN - OPUS4-47392 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zscherpel, Uwe A1 - Lübbehüsen, J. T1 - Computer Tomography used for inspection of critical Zones in AM parts N2 - Overview on CT for AM, starting from the CT principle, the added value of CT in Additive Manufacturing (AM), examples of CT results on AM workpieces and conclusions. T2 - IIW Annual Assembly 2018, joint seminar on AM CY - Bali, Indonesia DA - 15.07.2018 KW - Computed Tomographie KW - Additive Manufacturing KW - Added Value PY - 2018 AN - OPUS4-47357 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Oesch, Tyler A1 - Weise, Frank A1 - Meinel, Dietmar A1 - Gollwitzer, Christian T1 - Quantitative in-situ analysis of water transport in concrete completed using X-ray computed tomography N2 - This paper describes a novel methodology for quantitative in-situ moisture measurement without tracking agents using X-ray computed tomography (XCT). The high levels of grey-scale precision required for the measurement of moisture without tracking agents resulted in the need for an additional image calibration procedure to correct for water-related X-ray scattering and for equipment-variability related artefacts arising during in-situ testing. This calibration procedure was developed on the basis of existing principles of XCT image cor-rection. Resulting images of moisture distribution exhibit a high level of agreement with expected material behaviour. This research demonstrated that XCT can be successfully used to measure both moisture-front movement over time and changes in 3D moisture distribution within samples. This approach to moisture measurement lays the groundwork for the planned future investigation of the interaction between cracking induced by varying chemical and mechanical processes and water transport in concrete. KW - X-ray computed tomography (XCT) KW - In-situ testing KW - Water transport KW - Quantitative moisture measurement KW - Concrete PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-474395 DO - https://doi.org/10.1007/s11242-018-1197-9 SN - 1573-1634 VL - 127 IS - 2 SP - 371 EP - 389 PB - Springer Netherlands AN - OPUS4-47439 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heckel, Thomas T1 - Is phased array the future in modern ultrasonic rail inspection? N2 - Compared to standard ultrasonic testing methods the application of phased arrays offers advantages and flexibility by the electronic steering possibilities to control the transmitted and received sound fields as well as the image based evaluation of the recorded scans. For more than one decade phased array systems have been introduced and used in the railway sector for the inspection of wheelsets in the workshops. Up to the present field applications of phased array systems in rail inspection are rather rare. On the other hand a lot of scientific work on rail testing using phased arrays has been carried out in the recent past. Mechanized ultrasonic rail inspection poses strong challenges e.g. due to the harsh environment, complex flaw types and high inspection speeds. Different tasks have to be carried out by non-destructive testing ranging from manufacturing inspection of thermite welds to in-service inspection for operational induced flaws in the rail head, rail web and rail foot as well as rolling contact fatigue. This work will give an overview and categorization of different present approaches for rail testing using phased array. Phased array systems typically offer digital image based inspection results. This make these systems become the perfect candidates to feed inspection data into a modern big data based workflow, using e.g. cloud computing, signal processing and data fusion for recording, positioning and tracking of flaws and artefacts in rails and to gain additional benefit. Evaluation of promising innovative approaches and solutions for phased array based ultrasonic rail inspection in the frame of “Industry 4.0” will be discussed. T2 - QNDE - Annual Review of Progress in Quantitative Nondestructive Evaluation CY - Burlington, VT, USA DA - 15.07.2018 KW - Rail Inspection Phased Array Ultrasound PY - 2018 AN - OPUS4-47211 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heckel, Thomas A1 - Maierhofer, Christiane A1 - Gaal, Mate A1 - Schadow, Florian A1 - Brackrock, Daniel A1 - Blankschän, Michel A1 - Hosseini, Seyed A1 - Lodeiro, M. A1 - Segur, D. T1 - Comparison of the performance of ultrasonic non-destructive testing methods on inspection of fibre reinforced plastics N2 - In the last twenty years, components made of fibre-reinforced plastic became a prominently used material in safety-relevant structures. Periodic in-service inspection of these structures using reliable non-destructive testing methods became a relevant issue in the field. The goal of the EMRP-funded project VITCEA (Validated Inspection Techniques for Composites in Energy Applications) aims on the evaluation of the performance of various non-destructive testing methods on the inspection of fibre-reinforced plastics. In this talk the results of the comparison of different ultrasonic testing methods will be discussed. There are two challenges for the ultrasonic inspection of fibre-reinforced plastics. Firstly, different material properties of the fibre and the resin cause anisotropic acoustical behaviour of the material. Secondly, the physical layout of fibre layers leads to complex structures of fibre-reinforced plastic parts, and thus to a complex acoustical response. Both result in a reduction of the signal to noise ratio and make interpretation of measurement results rather extensive. During the VITCEA project, the acoustical behaviour of fibre-reinforced plate materials has been simulated. Specimens with artificial flaws for the evaluation of the detection thresholds have been designed and manufactured. Various mechanized ultrasonic testing methods including phased-array sensors, air-coupled transducers, immersion tank testing and contact technique have been evaluated on the specially designed specimen. Laboratory scale tests and a round robin test have been carried out. The probability of detection and the detection thresholds for each method have been estimated. T2 - ECNDT - European Conference on Non-Destructive Testing 2018 CY - Gothenburg, Sweden DA - 11.06.2018 KW - Comparison ndt methods FRP fibre reinforced plastics ultrasound PY - 2018 AN - OPUS4-47213 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heckel, Thomas A1 - Casperson, Ralf A1 - Rühe, Sven A1 - Mook, Gerhard T1 - Signal processing for non-destructive testing of railway tracks N2 - Increased speed, heavier loads, altered material and modern drive systems result in an increasing number of rail flaws. The appearance of these flaws also changes continually due to the rapid change in damage mechanisms of modern rolling stock. Hence, interpretation has become difficult when evaluating non-destructive rail testing results. Due to the changed interplay between detection methods and flaws, the recorded signals may result in unclassified types of rail flaws. Methods for automatic rail inspection (according to defect detection and classification) undergo continual development. Signal processing is a key technology to master the challenge of classification and maintain resolution and detection quality, independent of operation speed. The basic ideas of signal processing, based on the Glassy-Rail-Diagram for classification purposes, are presented herein. Examples for the detection of damages caused by rolling contact fatigue also are given, and synergetic effects of combined evaluation of diverse inspection methods are shown. T2 - QNDE - Annual Review of Progress in Quantitative Nondestructive Evaluation CY - Provo, UT, USA DA - 16.07.2017 KW - Rail KW - Inspection KW - Train KW - Ultrasound KW - Signal KW - Processing PY - 2018 DO - https://doi.org/10.1063/1.5031528 VL - 1949 SP - 030005-1 EP - 030005-7 AN - OPUS4-47217 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Beckmann, Jörg A1 - Spranger, Holger A1 - Ewert, Uwe T1 - THz Applications for Non-Destructive Testing N2 - Up to now THz-TDS-systems aren’t considered to be nondestructive testing facilities for large scale industrial applications, despite it was proven that they provide a comprehensive set of quality parameters. A practical approach to bring THz-TDS in addition to already existing testing systems into the industrial mainstream is systematic development of future test procedures and test facilities for dielectrics. For this purpose polyeth-ylene test specimen with introduced artefacts were designed, to evaluate the detection sensitivity of Time of Flight measurements based on dielectrics. SAFT reconstructed tomograms are presented which visualize the sizes and location of artificially introduced flaws. T2 - 2017 Far East NDT New Technology & Application Forum (FENDT) CY - XI'an, China DA - 22.06.2017 KW - THz radiation KW - Dielectric materials KW - Image reconstruction KW - Terahertz synthetic aperture PY - 2018 DO - https://doi.org/10.1109/FENDT.2017.8584511 VL - 12 SP - 272 EP - 276 PB - IEEE Conference Publication CY - USA AN - OPUS4-47220 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zscherpel, Uwe T1 - Image Quality in Industrial Radiology N2 - Overview on Concepts and Methodology used for quality ensurance in industrial radiology. The past, present and future. T2 - General Assembly of Academia NDT International CY - Brescia, Italy DA - 12.10.2018 KW - Image quality KW - Computed radiography (CR) KW - Digital Detector Array (DDA) KW - Film radiography PY - 2018 AN - OPUS4-47347 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ewert, Uwe A1 - Zscherpel, Uwe A1 - Vogel, Justus A1 - Zhang, F. A1 - Long, N.X. A1 - Nguyen, T.P. T1 - Visibility of Image Quality Indicators (IQI) by Human Observers in Digital Radiography in Dependence on Measured MTFs and Noise Power Spectra N2 - Digital radiographic images were analysed to predict the visibility of image quality indicators (IQI), based on normalized noise power spectra (NNPP) and modulation transfer function (MTF) measurements. The fixed pattern noise of some digital detectors result in different noise spectra, which influence the visibility of different IQIs, depending on the hole diameter. Studies, based on measurement of basic spatial resolution and contrast to noise ratio were performed together with presampled MTF measurements and the NNPS in dependence on the spatial frequency. Plate hole IQIs, step hole IQIs, and equivalent penetrameter sensitivity (EPS) IQIs based on ASTM E 746 were measured to verify the influence of the different parameters. Modelling of digital images was used to verify the applied numeric tools. A study has been performed for imaging plates and digital detector arrays to analyse differences. Formulas for the prediction of the visibility functions for hole type IQIs are derived. In consequence the standards for characterization and classification of computed radiography (ASTM E 2446) and radiography with DDAs (ASTM E 2597) need to be revised. T2 - 12th ECNDT 2018 CY - Gothenburg, Sweden DA - 11.06.2018 KW - Image evaluation KW - Computed radiography (CR) KW - Digital Detector Array (DDA) KW - Detail detection PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-473486 UR - www.ndt.net/?id=22967 SN - 1435-4934 VL - 23 IS - 8 SP - 1 EP - 7 PB - NDT.net CY - Kirchwald AN - OPUS4-47348 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zscherpel, Uwe A1 - Ewert, Uwe T1 - Optimum Magnification Factor in Digital Radiography - Selection Criteria and Formulas N2 - The transition from X-ray film to digital detectors in radiography is accompanied by an increase of unsharpness due to the larger inherent digital detector unsharpness in comparison to film. The basic spatial resolution of digital detectors (see EN ISO 17636-2) is used today to describe this unsharpness. The geometrical unsharpness of the radiographic projection of object structures onto the detector plane is determined by the focal spot size of the X-ray tube and the magnification. The focal spot size is measured today (see ASTM E 1165) from pin hole camera exposures or edge unsharpness (see ASTM E 2903). The final image unsharpness is a result of a convolution of the geometrical and inherent detector unsharpness function, divided by the magnification factor of the object onto the detector plane. Different approximations of this convolution result in ASTM E 1000 and ISO 17636-2 in different optimum values for the magnification factor for a given focal spot size of a X—ray tube and the basic spatial resolution of the detector. The higher contrast sensitivity, an advantage of digital radiography, compared to film radiography is furthermore improved when using higher X-ray voltages as used with film and smaller focal spots of the X-ray tubes. This allows a higher distance between object and detector resulting in reduced object scatter in the image. The interactions between all these parameters will be discussed and simple rules for practitioners will be derived in this contribution. T2 - 12th ECNDT 2018 CY - Gothenburg, Sweden DA - 11.06.2018 KW - Digital Radiology KW - Image unsharpness KW - Optimum magnification PY - 2018 AN - OPUS4-47351 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zscherpel, Uwe A1 - Ewert, Uwe T1 - Annual Report of Sub-Commission V-A "Radiography-based weld inspection" N2 - A Summary pf the activities of the IIW sub-commission V-A in 2018 for radiographic weld inspection. T2 - Annual Assembly of IIW CY - Bali, Indonesia DA - 15.07.2018 KW - Radiograpgy KW - Weld Inspection KW - International Institute of Welding PY - 2018 AN - OPUS4-47355 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zscherpel, Uwe A1 - Stegemann, Robert T1 - Update on Revision of ISO 24497 - NDT - MMM - Technique N2 - Presentation of the final compromise reached in 2018 for revision of ISO 24497, final draft for voting at ISO can be prepared now. T2 - IIW Annual Assembly 2018 CY - Bali, Indonesia DA - 15.07.2018 KW - NDT - Metal Magnetic Memory KW - Revision of ISO 24497 KW - New ISO draft PY - 2018 AN - OPUS4-47356 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Munsch, Sarah Mandy A1 - Strangfeld, Christoph A1 - Kruschwitz, Sabine ED - Kärger, J. ED - Heitjans, P. T1 - Determining the pore size distribution in synthetic and building materials using 1D NMR N2 - NMR is gaining increasing interest in civil engineering applications for the use of microstructure characterization as e.g. pore size determination and monitoring of moisture transport in porous materials. In this study, the use of NMR as a tool for pore size characterization was investigated. For our study we used screed and synthetic materials at partial and full saturation. A successful determination could be achieved when having a reference or calibration method, although partly diffusion effects have been registered. Due to these diffusion effects, for the determination of pore size distributions of synthetic materials another NMR device was needed. Finally, the determination of the surface relaxivity of screed (50 μm/s) led to a higher value than first expected from literature. T2 - 14th International Bologna Conference on Magnetic Resonance in Porous Media CY - Gainesville, FL, USA DA - 18.02.2018 KW - NMR relaxometry KW - Pore size distribution KW - Building materials KW - Porous materials KW - Surface relaxivity PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-483680 UR - https://diffusion.uni-leipzig.de/pdf/volume31/diff_fund_31(2019)02.pdf SN - 1862-4138 N1 - Geburtsname von Munsch, Sarah Mandy: Nagel, S. M. - Birth name of Munsch, Sarah Mandy: Nagel, S. M. VL - 31 IS - 2 SP - 1 EP - 9 PB - University of Leipzig CY - Leipzig AN - OPUS4-48368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lugovtsova, Yevgeniya A1 - Bulling, Jannis A1 - Prager, Jens T1 - Fantastic guided modes and how to find them N2 - Ultrasonic guided waves (UGW) have been shown to be suitable for non-destructive testing (NDT) and structural health monitoring (SHM) of many engineering structures. Development of a technique based on UGWs requires careful understanding obtained through modelling and analysis of wave propagation and mode-damage interaction due to their dispersion and multimodal character. This presentation will provide insights into the Scaled Boundary Finite Element Method and its applicability for tackling wave propagation problems. Features and limitations of the SBFEM will be presented on an example of a multi-layered plate structure consisting of isotropic and anisotropic materials bonded together. You will be guided through the process of picking up the wave modes for your application. Starting from the calculation of dispersion curves and mode shapes to the analysis of wave propagation and mode-damage interaction. The main highlight of the presentation lies in the ability to detect damage in a certain layer depending on the mode used. The resulting deeper understanding of the wave propagation in multi-layered structures is the key to further developments of NDT and SHM for engineering structures consisting of multiple layers. T2 - Von CEA Eingeladener Vortrag CY - Saclay, France DA - 07.06.2019 KW - Structural Health Monitoring KW - Pressure tanks KW - Hydrogen storage KW - Natural gas KW - Composites KW - Scaled Boundary Finite Element Method PY - 2019 AN - OPUS4-48375 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bulletti, A. A1 - Capineri, L. A1 - Lugovtsova, Yevgeniya A1 - Prager, Jens T1 - Charachterization of piezopolymer interdigital transducer's vibrational modes N2 - Lamb waves are widely used for monitoring the health of structures made of laminated materials (metals, composites). Piezoelectric ultrasonic transducers transmit and receive acoustic guided waves that interact with the elastic properties and the defects of the material under test. In recent years, DINFO developed piezopolymer Interdigital Transducers (IDTs) proven to be suitable to build SHM systems for aerospace applications. Their base material is a Cr/Au-coated PVDF-TrFE copolymer sheet, having a thickness of 100μm and a metallization of 0.1μm on both sides. IDTs are attractive for SHM systems for their capability to select specific Lamb wave modes when designed with appropriate electrode pattern. For a reliable application, it is crucial to characterize the in-plane and out-of-plane displacement of the transducer and to correlate the ultrasonic propagating signal with the Lamb waves dispersion curves in laminates. For example, for a 2 mm aluminum plate A0 mode has dominant out-of-plane displacement, whereas S0 mode has dominant in-plane displacement at the plate's surface. In collaboration with BAM the characterization of free vibrational modes using a 3D laser doppler vibrometer was performed. The analysis in the frequency domain was performed using the following parameters: a chirp excitation with frequencies 50-500 kHz and 0.5-1 MHz with 195 Hz and 390 Hz frequency resolution respectively at 100 Vpp for a total of 90 averaged measurements per point. Also propagating modes were characterized by bonding the IDT on a 2 mm aluminum plate and analyzing the in-plane and the out-of-plane components. A0-mode was successfully excited having the main lobe aligned with the main axis of the IDT, confirming the dominant presence of this propagating mode. The results could be used as a basis for design and optimization of the IDTs in terms of directivity and mode selection, and to facilitate interpretation of the ultrasonic guided waves propagating in laminated structures. T2 - 51th Annual Meeting of the Associazione Societa Italiana Di Elettronica CY - Rome, Italy DA - 26.06.2019 KW - Structural Health Monitoring KW - Interdigital Transducer KW - PVDF KW - Ultrasonic guided waves KW - Lamb waves PY - 2019 AN - OPUS4-48382 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bellon, Carsten T1 - Virtual CT with Complex scanning trajectories in aRTist N2 - The simulator aRTist combines analytical and Monte Carlo methods to efficiently model the radiographic process of industrial radiology. In this contribution we focus on virtual computer tomography, the simulation of tomographic scans. The possibilities to simulate complex scanning trajectories are shown in combination with the tomographic reconstruction using individual projection matrices. T2 - The 4th Annual Advances in X-Ray Imaging Workshop CY - Diamond Light Source, Didcot, UK DA - 11.06.2019 KW - X-ray Computer-tomography simulation PY - 2019 AN - OPUS4-48297 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaenisch, Gerd-Rüdiger A1 - Waske, Anja A1 - Ewert, U. A1 - Bircher, B. A1 - Korpelainen, V. A1 - Costin, M. A1 - Yang, F. A1 - Hörauf, F. A1 - Steffen, J. P. A1 - Dai, G. A1 - Deresch, A. A1 - Graf vom Hagen, C. T1 - EMPIR Project NanoXSpot N2 - The overall objective of project NanoXSpot (Nanometre X-ray Focal Spot Measurement) is to develop traceable measurement methods for determining the focal spot size, shape, and position of nanometre resolution X-ray tubes. The impact of the technical results will be ensured by preparing prenormative documents for submission to CEN TC 138 (Non-destructive testing) WG 1 (Radiographic testing), which directly addresses the research needs of CEN, currently revising standards in the series 12543 for focal spot measurements below 5 µm spot size to harmonise standards and measurement method between ASTM and CEN. T2 - DACH-Tagung CY - Friedrichshafen, Germany DA - 27.05.2019 KW - Standardization KW - X-Ray tube KW - Focal spot measurement PY - 2019 AN - OPUS4-48298 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Vahlsing, Thorsten A1 - Raum, Hanne A1 - Casperson, Ralf A1 - Pohl, Rainer A1 - Heckel, Thomas A1 - Beilken, D. A1 - Dilz, K. A1 - Rühe, S. T1 - FE-simulation of eddy current signals produced from basic model cracks for running surface rail defects N2 - Non-destructive testing for surface crack detection and head check depth quantification at the gauge corner of railway tracks can be achieved using eddy current methods. With the extension of the tested zone to the running surface, rail defect signal types other than head checks can be measured. Due to their mostly irregular shape, a quantitation based on a calibration against regular test cracks of varying depth may not be linear. Estimates of the expected influence of more complex crack patterns may be obtained by a finite element simulation of sufficiently simple limiting cases, like two displaced or intersecting cracks or a simply branched or flexed crack. As a first step, a 3D finite element model of the HC10 eddy current probe distributed by Prüftechnik Linke und Rühe (PLR), Germany was built and verified against measured results from an (easily fabricated) reference block with isolated long cracks. T2 - 15th Railway Engineering Conference CY - Edinburgh, UK DA - 03.07.2019 KW - Finite element analysis KW - Eddy current testing KW - Rail inspection PY - 2019 SP - 1 EP - 11 AN - OPUS4-48529 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heckel, Thomas A1 - Vahlsing, Thorsten A1 - Raum, Hanne A1 - Casperson, Ralf A1 - Pohl, Rainer A1 - Heckel, Thomas A1 - Beilken, D. A1 - Dilz, K. A1 - Rühe, S. T1 - FE-simulation of eddy current signals produced from basic model cracks for running surface rail defects N2 - Non-destructive testing for surface crack detection and head check depth quantification at the gauge corner of railway tracks can be achieved using eddy current methods. With the extension of the tested zone to the running surface, rail defect signal types other than head checks can be measured. Due to their mostly irregular shape, a quantitation based on a calibration against regular test cracks of varying depth may not be linear. Estimates of the expected influence of more complex crack patterns may be obtained by a finite element simulation of sufficiently simple limiting cases, like two displaced or intersecting cracks or a simply branched or flexed crack. As a first step, a 3D finite element model of the HC10 eddy current probe distributed by Prüftechnik Linke und Rühe (PLR), Germany was built and verified against measured results from an (easily fabricated) reference block with isolated long cracks. T2 - Railway Engineering 2019 CY - Edinburgh, UK DA - 03.07.2019 KW - Finite element analysis KW - Eddy current testing KW - Rail inspection PY - 2019 AN - OPUS4-48530 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wasmer, Paul A1 - Bulling, Jannis A1 - Gravenkamp, Hauke A1 - Prager, Jens T1 - Acoustic-structure interaction in the scaled boundary finite element method for primsatic geometries N2 - Due to the short wavelength compared to the dimensions of the structure, the simulation of ultrasonic waves is still a challenging task. A numerical method well suited for this purpose is the semi-analytical Scaled Boundary Finite Element Method (SBFEM). When applying this method, only the boundary of a computational domain is discretized using finite elements, while the interior is described by an analytical ansatz. Hence, the number of degrees of freedom is reduced significantly compared to the classical Finite Element Method (FEM). In recent years, a particular formulation of the SBFEM for the simulation of ultrasonic guided waves was developed. The method constitutes an efficient algorithm for prismatic structures of arbitrary length, such as plates, pipes, or beams. Wave propagation phenomena in such structures can be modeled for isotropic and anisotropic inhomogeneous waveguides. Even though the method is an efficient tool for the simulation of guided waves in solid media, a reliable model for the simulation of acoustic wave propagation in fluids as well as acoustic-structure interaction in terms of SBFEM is still missing. In principle, the fluid can be described by a displacement-based formulation and thus be implemented in existing SBFEM algorithms for solid bodies. However, due to the discretization with classical finite elements, spurious modes occur, which cannot be separated from the physical modes straightforwardly. The spurious modes can be suppressed using a penalty parameter. Although very accurate results were achieved for some problems, this procedure has been proven unreliable for certain cases. For this reason, we propose a different approach in this contribution. We employ a pressure model to simulate the acoustic behavior of fluids. The implementation of the pressure model results in a higher effort due to the necessity of incorporating coupling terms, but it presents a stable alternative without spurious modes. The accuracy of the method is demonstrated in comparison with analytical solutions and results obtained using the FEM. T2 - GACM 2019 CY - Kassel, Germany DA - 28.08.2019 KW - Scaled Boundary Finite Element Method KW - Guided Waves KW - Acoustic-structure interaction PY - 2019 AN - OPUS4-48846 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst A1 - Abraham, Odile A1 - Larose, Eric T1 - A review on ultrasonic monitoring of concrete: coda wave interferometry and beyond N2 - The propagation of ultrasonic waves in concrete is affected by its micro- and macro-structure, geometry and properties as well as external influences as stress, temperature or moisture. In addition, age and degradation have a strong influence. Therefore, Ultrasound has been used to monitor concrete samples and structures since decades. However, early applications using conventional techniques as time-of flight or changes in amplitudes have been limited to detect changes in a late stage close to serviceability or ultimate load states. Around 2000, several new, more sensitive techniques adopted from geophysics or other field of material sciences have been introduced to research in ultrasonic monitoring of concrete. The most discussed methodologies are coda wave interferometry, a technique which allows to detect very subtle changes from repeated ultrasonic measurements. Nonlinear acoustic techniques help to identify e. g. cracks even in an inhomogeneous background. Both techniques can be combined. This paper reviews methods and results achieved so far on the laboratory scale and with full scale models the directions for future research and application is given as well. T2 - QNDE 2019 CY - Portland, OR, USA DA - 14.07.2019 KW - Ultrasound KW - Coda wave interferometry KW - Concrete KW - Nonlinear KW - Monitoring PY - 2019 SP - Paper 1234 AN - OPUS4-48686 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst A1 - Abraham, O. A1 - Larose, E. T1 - A review on ultrasonic monitoring of concrete: coda wave interferometry and beyond N2 - The propagation of ultrasonic waves in concrete is affected by its micro- and macro-structure, geometry and properties as well as external influences as stress, temperature or moisture. In addition, age and degradation have a strong influence. Therefore, Ultrasound has been used to monitor concrete samples and structures since decades. However, early applications using conventional techniques as time-of flight or changes in amplitudes have been limited to detect changes in a late stage close to serviceability or ultimate load states. Around 2000, several new, more sensitive techniques adopted from geophysics or other field of material sciences have been introduced to research in ultrasonic monitoring of concrete. The most discussed methodologies are coda wave interferometry, a technique which allows to detect very subtle changes from repeated ultrasonic measurements. Nonlinear acoustic techniques help to identify e. g. cracks even in an inhomogeneous background. Both techniques can be combined. This paper reviews methods and results achieved so far on the laboratory scale and with full scale models the directions for future research and application is given as well. T2 - QNDE 2019 CY - Portland, OR, USA DA - 14.07.2019 KW - Ultrasound KW - Coda wave interferometry KW - Concrete KW - Nonlinear KW - Monitoring PY - 2019 AN - OPUS4-48688 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lugovtsova, Yevgeniya A1 - Johannesmann, S. A1 - Henning, B. A1 - Prager, Jens T1 - Analysis of Lamb wave mode repulsion and its implications to the characterisation of adhesive bonding strength N2 - Lamb waves are widely used for non-destructive evaluation of material parameters as well as for detection of defects. Another application of Lamb waves is quality control of adhesive joints. Researchers are currently investigating shear horizontal and zero-group velocity modes for characterisation of the adhesive bonding strength. In a new approach, Lamb wave mode repulsion is used to obtain the coupling strength between different layers to characterise the adhesive bonding strength. The modes of the individual layers become coupled in the multilayered systems forming particular regions, the so-called mode repulsion regions. This study investigates these modes and their interaction in two-layered plate-like structures with varying coupling strength both numerically, with the Scaled Boundary FEM, and experimentally. T2 - International Congress on Ultrasonics CY - Bruges, Belgium DA - 03.09.2019 KW - Lamb waves KW - Multi-layered system KW - Adhesive joint KW - Mechanical strength KW - Scaled Boundary FEM PY - 2019 AN - OPUS4-48910 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lugovtsova, Yevgeniya A1 - Johannesmann, S. A1 - Henning, B. A1 - Prager, Jens T1 - Analysis of Lamb wave mode repulsion and its implications to the characterisation of adhesive bonding strength N2 - Lamb waves are widely used for non-destructive evaluation of material parameters as well as for detection of defects. Another application of Lamb waves is quality control of adhesive joints. Researchers are currently investigating shear horizontal and zero-group velocity modes for characterisation of the adhesive bonding strength. In a new approach, Lamb wave mode repulsion is used to obtain the coupling strength between different layers to characterise the adhesive bonding strength. The modes of the individual layers become coupled in the multilayered systems forming particular regions, the so-called mode repulsion regions. This study investigates these modes and their interaction in two-layered plate-like structures with varying coupling strength both numerically, with the Scaled Boundary FEM, and experimentally T2 - International Congress on Ultrasonics CY - Bruges, Belgium DA - 03.09.2019 KW - Lamb waves KW - Multi-layered system KW - Adhesive joint KW - Mechanical strength KW - Scaled Boundary FEM PY - 2019 SP - 1 EP - 4 AN - OPUS4-48911 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baensch, Franziska A1 - Brunner, A. J. T1 - Towards predictor development for assessing structural integrity of components made from wood materials using Acoustic Emission monitoring and signal analysis N2 - Against the background of sustainable resource management and efficiency, wood-based materials are currently experiencing a revival and, among others, plywood, Laminated Veneer Lumber and glued laminated timber are becoming increasingly more important in the building sector. Even though these materials are so-called engineered products, the element wood is naturally grown with intrinsic variability in mechanical properties and requires professional handling on-site. Otherwise, load-bearing structures made of wood materials may entail certain risks. Critical situations can, in principle, be avoided by implementing a structural health monitoring system into components or structures made from wood material. The aim is to indicate accumulation of mechanical damage and to eliminate or at least significantly reduce the risk of unexpected failure. Toward this purpose, the failure behavior of several layered wood materials under quasi-static tension was investigated in laboratory-scale experiments by means of acoustic emission (AE) measurement. Based on spectral analysis and pattern recognition, two classes of AE signals are identified for each investigated lay-up that are characterized by either low or high frequency contents in the respective power spectra. AE activity and intensity of both signal classes are analyzed, striving for predictors appropriate for AE monitoring concepts. T2 - 5th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures CY - Potsdam, Germany DA - 27.08.2019 KW - Wood materials KW - Acoustic Emission KW - Structural integrity PY - 2019 AN - OPUS4-48802 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bertovic, Marija A1 - Lindt, Stanislav T1 - Human-machine interaction in the era of NDT 4.0 N2 - This presentation discusses industry 4.0 from the perspective of human machine interaction (HMI). Based on available literature the changes, new demands and possible problems related to people’s jobs as a result of increased digitisation and use of artificial intelligence are addressed. Combining literature with own experience in non-destructive testing (NDT), the author addresses the possible challenges and chances for the NDT personnel in the era of NDT 4.0. T2 - The BINDT Aerospace Event 2019 CY - National Composites Centre NCC, Bristol, UK DA - 09.04.2019 KW - ZfP 4.0 KW - Human Factors KW - NDT 4.0 PY - 2019 AN - OPUS4-48850 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bertovic, Marija A1 - Ronneteg, U. T1 - Usability of the written procedures: an eye tracking study N2 - Usability of the written procedures: an eye tracking study Non-destructive evaluation (NDE) is regarded as one of the key elements in ensuring quality of engineering systems and their safe use. A failure of NDE to detect critical defects in safety-relevant components, such as those in the nuclear industry, may lead to catastrophic consequences for the environment and the people. NDE inspection procedure is one of the most important tools in the everyday life of an NDE inspector. Experience and research studies have shown that NDE procedures are not always used as foreseen and may need to be optimized. Both the content and format play an important role in producing reliable procedures. Whereas the content aids in the understanding of the task and in its subsequent correct execution, the format determines the efficiency and frequency of the procedure’s use. For the purposes of this study, an inspection procedure - designed to be used in the inspection of components used in the final disposal of spent nuclear fuel - was further developed by adopting a user-centered design. This was achieved by following the eye movements during a data evaluation task whilst using the procedure, by interviews and group discussions, accompanied by a review from a human factors’ perspective, the suggestions from relevant literature and by reiterating the entire process once again. This process resulted in identifying shortcomings and in suggesting alterations to the existing procedure. The newly created procedure was empirically tested for its usability using eye tracking. By comparing the old instruction format to the newly developed one, the results showed that appropriately highlighting warnings, exceptions, or reminders, and placing them at a logical position assures that they will be read and identified with ease rather than overlooked. The presentation of the information in a stepwise manner, with one action per step, allows the user to follow more easily the steps that must be carried out to save time and effort. This study - the first of its kind in the field of non-destructive evaluation - showed that the procedure can be improved by applying human factors principles to the design and by involving the users into the process of procedure development and quality assurance. Introduction of the speaker – Marija Bertovic Marija Bertovic has a degree in psychology and a PhD in human factors. Since 2006 she has been working on topics related to human factors in non-destructive testing at the BAM Federal Institute for Materials Research and Testing, German Society for Non-Destructive Testing and as an independent consultant. The focus of her research has been on identifying and studying human factors’ related risks during NDT inspections and suggesting ways of optimizing the inspections and inspection procedures. She is currently a research staff member at BAM responsible for probabilistic safety and reliability analyses AND human factors analyses. She is the chairwoman of the German Society for Non-Destructive Testing’s (DGZfP) subcommittee on human machine interaction and the winner of the DGZfP Science Award in 2018. T2 - AHFE International, 10th International Conference on Applied Human Factors and Ergonomics CY - Washington Hilton, Washington D.C., USA DA - 24.07.2019 KW - Human Factors KW - ZfP KW - NDE PY - 2019 AN - OPUS4-48851 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bertovic, Marija A1 - Wall, M. T1 - Human-Factors in model-assisted POD approaches N2 - It is known that human factors (HF) affect the reliability of non-destructive testing (NDT). However, reliability is often expressed in probability of detection (POD) curves, obtained in practical trials, where human and organisational factors are considered only indirectly, through the few people taking part in the trials. Recently, we have observed an increase in the use of numerical modelling to obtain POD curves outside of practical trials. The so-called model-assisted POD(MAPOD) approaches have so far only very rarely included some kind of variation to account for HF. This talk presents different possibilities to include HF in MAPOD and discusses the advantages and disadvantages of each approach. T2 - The BINDT Aerospace Event 2019 CY - National Composites Centre NCC, Bristol, UK DA - 09.04.2019 KW - Human Factors KW - NDT KW - ZfP KW - MAPOD PY - 2019 AN - OPUS4-48852 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bornemann-Pfeiffer, Martin A1 - Kern, Simon A1 - Jurtz, N. A1 - Thiede, Tobias A1 - Kraume, M. A1 - Maiwald, Michael T1 - Design and validation of an additively manufactured flowCell–static mixer combination for inline NMR spectroscopy N2 - There have been an increasing number of publications on flow chemistry applications of compact NMR. Despite this, there is so far no comprehensive workflow for the technical design of flow cells. Here, we present an approach that is suitable for the design of an NMR flow cell with an integrated static mixing unit. This design moves the mixing of reactants to the active NMR detection region within the NMR instrument, presenting a feature that analyses chemical reactions faster (5–120 s region) than other common setups. During the design phase, the targeted mixing homogeneity of the components was evaluated for different types of mixing units based on CFD simulation. Subsequently, the flow cell was additively manufactured from ceramic material and metal tubing. Within the targeted working mass flow range, excellent mixing properties as well as narrow line widths were confirmed in validation experiments, comparable to common glass tubes. KW - Inline NMR Spectroscopy KW - Integrated Processes KW - Reaction Monitoring KW - Process Analytical Technology KW - Flow Chemistry KW - Static Mixing KW - Modular Production PY - 2019 UR - https://pubs.acs.org/doi/abs/10.1021/acs.iecr.9b03746 DO - https://doi.org/10.1021/acs.iecr.9b03746 SN - 0888-5885 SN - 1520-5045 N1 - Geburtsname von Bornemann-Pfeiffer, Martin: Bornemann, M. - Birth name of Bornemann-Pfeiffer, Martin: Bornemann, M. VL - 58 IS - 42 SP - 19562 EP - 19570 PB - American Chemical Society CY - Washington AN - OPUS4-49041 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baensch, Franziska A1 - Brunner, A. J. ED - Rosemarie, Helmerich ED - Ilki, A. ED - Motavalli, M. T1 - Towards predictor development for assessing structural integrity of components made from wood materials using Acoustic Emission monitoring and signal analysis N2 - Against the background of sustainable resource management and efficiency, wood-based materials are currently experiencing a revival and, among others, plywood, Laminated Veneer Lumber and glued laminated timber are becoming increasingly more important in the building sector. Even though these materials are so-called engineered products, the element wood is naturally grown with intrinsic variability in mechanical properties and requires professional handling on-site. Otherwise, load-bearing structures made of wood materials may entail certain risks. Critical situations can, in principle, be avoided by implementing a structural health monitoring system into components or structures made from wood material. The aim is to indicate accumulation of mechanical damage and to eliminate or at least significantly reduce the risk of unexpected failure. Toward this purpose, the failure behavior of several layered wood materials under quasi-static tension was investigated in laboratory-scale experiments by means of acoustic emission (AE) measurement. Based on spectral analysis and pattern recognition, two classes of AE signals are identified for each investigated lay-up that are characterized by either low or high frequency contents in the respective power spectra. AE activity and intensity of both signal classes are analyzed, striving for predictors appropriate for AE monitoring concepts. T2 - 5th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures (SMAR 2019) CY - Potsdam, Germany DA - 27.08.2019 KW - Acoustic Emission Monitoring KW - Signal Analysis KW - Structural Integrity KW - Wood Materials PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-491198 SN - 978-3-947971-07-7 SP - Paper Tu.2.D.4, 1 EP - 8 PB - German Society for Non-Destructive Testing (DGZfP e.V.) AN - OPUS4-49119 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Burgholzer, P. A1 - Berer, T. A1 - Ziegler, Mathias A1 - Thiel, Erik A1 - Ahmadi, Samim A1 - Gruber, J. A1 - Mayr, G. A1 - Hendorfer, G. T1 - Blind structured illumination as excitation for super-resolution photothermal radiometry N2 - Photothermal radiometry with an infrared camera allows the contactless temperature measurement of multiple surface pixels simultaneously. A short light pulse heats the sample. The heat propagates through the sample by diffusion and the corresponding temperature evolution is measured at the sample’s surface by an infrared camera. The main drawback in radiometric imaging is the loss of the spatial resolution with increasing depth due to heat diffusion, which results in blurred images for deeper lying structures. We circumvent this information loss due to the diffusion process by using blind structured illumination, combined with a non-linear joint sparsity reconstruction algorithm. The structured illumination is realized by parallel laser lines from a vertical-cavity surface-emitting laser (VCSEL) array controlled by a random binary pattern generator. By using 150 different patterns of structured illumination and our iterative joint sparsity algorithm, it was possible to resolve 1 mm thick lines at a distance down to 0.5 mm, which results in a resolution enhancement of approximately a factor of four compared to the resolution of 5.9 mm for homogenous illuminated thermographic reconstruction. KW - Super-resolution imaging KW - Thermography KW - Blind structured illumination KW - VCSEL array PY - 2019 DO - https://doi.org/10.1080/17686733.2019.1655247 SN - 1768-6733 VL - 17 IS - 4 SP - 268 EP - 278 PB - Taylor & Francis Group CY - Milton, UK AN - OPUS4-49122 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bernegger, Raphael A1 - Altenburg, Simon A1 - Maierhofer, Christiane T1 - Pulsed thermography on semitransparent materials - what has to be considered? N2 - Pulsed thermography is a well-known non-destructive testing technique and has proven to be a valuable tool for examination of material defects, to determine thermal material parameters, and the thickness of test specimens through calibration or mathematical models. However, the application to semitransparent materials is quite new and demanding, especially for semitransparent materials like epoxy, polyamide 12, or glass fiber reinforced polymers with epoxy or polyamide matrix. In order to describe the temporal temperature evolution in such materials, which are recorded with an infrared camera during pulse thermography experiments, much more influences have to be considered, compared to opaque materials: - The wavelength of the excitation source and the spectral range of the infrared camera - The angles between the specimen, the excitation source and the infrared camera - The area behind the specimen - The roughness of the material surface - The scattering mechanism within the material Here, we will consider all these influences and describe how they can be treated mathematically in analytical or numerical models (using COMSOL Multiphysics software). These models describe the temperature development during the pulse thermography experiment in reflection and transmission configuration. By fitting the results of the mathematical models to experimental data it is possible to determine the thickness or the optical and thermal properties of the specimen. T2 - 20-th International Conference on Photoacoustic and Photothermal Phenomena CY - Moscow, Russia DA - 07.07.2019 KW - Numerical simulation KW - Pulsed thermography KW - Semitransparent KW - Analytical model KW - Delamination KW - GFRP PY - 2019 AN - OPUS4-49215 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gaal, Mate A1 - Caldeira, Rui A1 - Bartusch, Jürgen A1 - Schadow, Florian A1 - Vössing, Konrad A1 - Kupnik, M. T1 - Air-coupled ultrasonic ferroelectret receiver with additional bias voltage N2 - High sensitivity is an important requirement for air-coupled ultrasonic sensors applied to materials testing. With a lower acoustic impedance than any piezoelectric material, charged cellular polypropylene (PP) offers better matching to air with a similar piezoelectric coefficient. The piezoelectric properties of charged cellular PP originate from their polarization, creating permanent internal voltage. The sensitivity of the sensor can be increased by applying additional dc bias voltage, as it has been done already for transmitters. This work presents the first ultrasonic sensor based on charged cellular PP including a high-voltage module providing dc bias voltage up to 2 kV. This bias voltage led to an increase in the signal-to-noise ratio of up to 15 ± 1 dB. The measurement of the received signal depending on the applied bias voltage is proposed as a new method of determining the internal voltage of ferroelectrets. The sensor combined with a cellular PP transmitter was applied to nondestructive testing of a rotor blade segment and glued-laminated timber, enabling imaging of the internal structure of these specimens with a thickness around 4 cm. KW - Acoustic sensors KW - Ferroelectret KW - Nondestructive testing KW - Ultrasonic imaging KW - Ultrasonic transducers PY - 2019 DO - https://doi.org/10.1109/TUFFC.2019.2925666 SN - 0885-3010 SN - 1525-8955 VL - 66 IS - 10 SP - 1600 EP - 1605 PB - IEEE AN - OPUS4-49131 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stelzner, Ludwig A1 - Weise, Frank A1 - Oesch, Tyler A1 - Dlugosch, R. A1 - Powierza, Bartosz T1 - Transport and reconfiguration of moisture in HPC due to unilateral heating N2 - Explosive spalling is caused by, among others, the thermohydraulic spalling mechanism. During this process, vaporization, dehydration, moisture-transport and condensation processes interact. As a result, a drying and dehydration zone as well as a saturated zone, known as a moisture clog, are observed inside the unilaterally-heated concrete. The presented research is focused on the experimental investigation of the underlying thermohydraulic processes. To investigate these, a test methodology based on X-ray computed tomography (CT) and nuclear magnetic resonance (NMR) was developed. Thereby, the X-ray CT scans are carried out simultaneously during the application of a defined unilateral-heating regime on a specially-constructed specimen. This miniaturized specimen, equipped with a double-layer casing, reproduces the condition within a planar, unilaterally-heated building component. A preliminary test methodology and the first experimental results were presented at the 5th International Workshop on Concrete Spalling in Borås, Sweden (2017). The contribution for the upcoming workshop presents an improved version of this test methodology and new results for a high-performance concrete (HPC) mixture exposed to temperatures up to 500 °C. Regarding the CT measurements, a higher time-resolution of 15 min was achieved and a quantification of the moisture changes was implemented. Due to an increase in signal quality of the NMR measurements, a pore-size specific moisture distribution can now be resolved. This allows to conclude about the moisture reconfiguration between small gel pores and larger interhydrate pores. Additionally, the NMR measurement are no longer limited to first 2.5 cm below the heated surface but a one-dimensional moisture distribution can now be estimated over the whole 10 cm long specimen. The presented results demonstrate that the combination of X-ray CT and NMR measurements enables to image and quantify the thermally-induced moisture transport and reconfiguration from small gel pores up to macro pores. This provides important insights into the thermohydraulic damage mechanism and leads to a better understanding of spalling avoidance strategies, like the addition of polypropylene fibres. T2 - 6th International Workshop on Concrete Spalling due to fire exposure CY - Sheffield, UK DA - 19.09.2019 KW - Moisture clog KW - X-ray CT KW - NMR KW - Moisture transport KW - HPC PY - 2019 AN - OPUS4-49159 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bernard, D. A1 - Léonard, Fabien A1 - Plougonven, E. A1 - Bruno, Giovanni T1 - On the use of autocorrelation functions, permeability tensors, and computed tomography to characterize the anisotropy of Diesel particulate filter materials N2 - 3D images such as those produces by X-ray tomography can provide a wealth of information on the internal structure of materials, but quantification of specific geometrical or topological characteristics linked to some bulk physical property is far from being straightforward. This study focuses on methods to quantify the differences in physical properties as a function of direction, i.e. their anisotropy, and how it can be linked to measures of anisotropy of the internal structure of the material. The auto-correlation function gives a similarity measure in the volume as a function of distance and direction. This is a cross-correlation of the image with itself fast to compute and relatively insensitive to noise. It is why we focus on this method to compare with the physical property of our DPF material. Diesel Particulate Filter (DPF) materials are porous ceramics that; a) can be used at very high temperatures; b) have very good thermal shock resistance; c) are inert; d) can be manufactured with tailored porosity. Their usual way of production consists of the extrusion of a slurry into the desired filter shape, with successive ceramming at high temperature. This process causes anisotropy at both microscopic and macroscopic levels. T2 - ICTMS 2019 CY - Cairns, Australia DA - 22.07.2019 KW - Structure-property relationship KW - Anisotropy estimate KW - Porous ceramics KW - Autocorrelation PY - 2019 AN - OPUS4-49226 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, I. A1 - Moll, J. A1 - Kexel, C. A1 - Schubert, L. A1 - Tschöke, K. A1 - Prager, Jens A1 - Lugovtsova, Yevgeniya A1 - Bach, M. A1 - Vogt, T. T1 - SHM using Guided Waves – Recent Activities and Advances in Germany N2 - Issues that prevent Structural Health Monitoring (SHM) based on Guided Waves (GW) from being a part of today’s monitoring solutions in industry are not all obvious to the scientific community. To uncover and overcome these issues, scientists working on SHM and GW problems joined in an expert committee under the patronage of the German Society for Non-Destructive Testing. An initiated online survey among more than 700 experts and users reveals the hurdles hindering the practical application of GWbased SHM. Firstly, methods for proof of reliability of SHM approaches are missing. Secondly, detailed understanding of phenomenological described wave-damage interactions is needed. Additionally, there are significant unsolved implementation issues and unsolved problems of signal processing including handling of environmental influences. To enable substantial proof of reliability without unaffordable experimental effort also efficient simulation tools including realistic damage interaction are needed, enabling the joint use of experimental and simulated data to predict the capabilities of the Monitoring system. Considering these issues, the committee focusses on simulation, signal processing, as well as probability of detection and standardization. In the presented work, recent activities of the expert committee starting with survey results are summarized. An open access data basis of life-like measurements is presented to allow testing and comparison of signal processing and simulation algorithms. Finally, a strategy for efficient proof of reliability increasing the acceptance of SHM in industry and for successful Integration of SHM into real-world engineering structures is proposed. T2 - The 12th International Workshop on Structural Health Monitoring (IWSHM) CY - Stanford, California, USA DA - 10.09.2019 KW - Structural Health Monitoring KW - Ultrasonic Guided Waves KW - Non-Destructive Testing KW - Survey KW - Probability of Detection KW - Reliability PY - 2019 AN - OPUS4-49231 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, I. A1 - Moll, J. A1 - Kexel, C. A1 - Schubert, L. A1 - Tschöke, K. A1 - Prager, Jens A1 - Lugovtsova, Yevgeniya A1 - Bach, M. A1 - Vogt, T. T1 - SHM using Guided Waves – Recent Activities and Advances in Germany N2 - Issues that prevent Structural Health Monitoring (SHM) based on Guided Waves (GW) from being a part of today’s monitoring solutions in industry are not all obvious to the scientific community. To uncover and overcome these issues, scientists working on SHM and GW problems joined in an expert committee under the patronage of the German Society for Non-Destructive Testing. An initiated online survey among more than 700 experts and users reveals the hurdles hindering the practical application of GWbased SHM. Firstly, methods for proof of reliability of SHM approaches are missing. Secondly, detailed understanding of phenomenological described wave-damage interactions is needed. Additionally, there are significant unsolved implementation issues and unsolved problems of signal processing including handling of environmental influences. To enable substantial proof of reliability without unaffordable experimental effort also efficient simulation tools including realistic damage interaction are needed, enabling the joint use of experimental and simulated data to predict the capabilities of the Monitoring system. Considering these issues, the committee focusses on simulation, signal processing, as well as probability of detection and standardization. In the presented work, recent activities of the expert committee starting with survey results are summarized. An open access data basis of life-like measurements is presented to allow testing and comparison of signal processing and simulation algorithms. Finally, a strategy for efficient proof of reliability increasing the acceptance of SHM in industry and for successful Integration of SHM into real-world engineering structures is proposed. T2 - The 12th International Workshop on Structural Health Monitoring (IWSHM) CY - Stanford, California, USA DA - 10.09.2019 KW - Structural Health Monitoring KW - Ultrasonic Guided Waves KW - Non-Destructive Testing KW - Survey KW - Probability of Detection KW - Reliability PY - 2019 SP - 1 EP - 10 AN - OPUS4-49232 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lugovtsova, Yevgeniya A1 - Bulling, Jannis A1 - Boller, Christian A1 - Prager, Jens T1 - Analysis of Guided Wave Propagation in a Multi-Layered Structure in View of Structural Health Monitoring N2 - Guided waves (GW) are of great interest for non-destructive testing (NDT) and structural health monitoring (SHM) of engineering structures such as for oil and gas pipelines, rails, aircraft components, adhesive bonds and possibly much more. Development of a technique based on GWs requires careful understanding obtained through modelling and analysis of wave propagation and mode-damage interaction due to the dispersion and multimodal character of GWs. The Scaled Boundary Finite Element Method (SBFEM) is a suitable numerical approach for this purpose allowing calculation of dispersion curves, mode shapes and GW propagation analysis. In this article, the SBFEM is used to analyse wave propagation in a plate consisting of an isotropic aluminium layer bonded as a hybrid to an anisotropic carbon fibre reinforced plastics layer. This hybrid Composite corresponds to one of those considered in a Type III composite pressure vessel used for storing gases, e.g., hydrogen in automotive and aerospace applications. The results show that most of the wave energy can be concentrated in a certain layer depending on the mode used, and by that damage present in this layer can be detected. The results obtained help to understand the wave propagation in multi-layered structures and are important for further development of NDT and SHM for Engineering structures consisting of multiple layers. KW - Lamb waves KW - Composite KW - Ultrasonic Testing KW - Numerical Modelling KW - Pressure Vessels PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-494385 DO - https://doi.org/10.3390/app9214600 VL - 9 IS - 21 SP - 4600 PB - MDPI CY - 4052 Basel, Switzerland AN - OPUS4-49438 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gaal, Mate A1 - Heckel, Thomas A1 - Brackrock, Daniel T1 - Linear and matrix phased array inspection of complex thin wall components N2 - The application of phased arrays in either linear or matrix arrangement in combination with signal processing opens the door for the mechanized inspection of different thin wall materials itself as well as their joining methods. Modern lightweight components are typically manufactured by a composition of different types of e.g. steels, metals, fiber reinforced plastics and glass. Dependent on the material combinations e.g. welding, brazing, bonding, cladding or coating may be applied during the manufacturing process to join different semi-finished products to form the component. The resulting complex material composition and different damage mechanisms pose new challenges to non-destructive testing with ultrasound due to the different material properties and the overall arrangement of the materials employed. The sound field variation capabilities of array probes may be helpful to overcome some of these challenges if adapted to the specific inspection task. Examples for the non-destructive mechanized phased array inspection of different types of materials and joining methods will be presented. T2 - KINT Symposium CY - Amsterdam, The Netherlands DA - 30.10.2019 KW - Matrix array KW - Phased array KW - Joints PY - 2019 AN - OPUS4-49538 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stroh, Julia A1 - Ali, Naveed Zafar A1 - Maierhofer, Christiane A1 - Emmerling, Franziska T1 - Ettringite via Mechanochemistry: A Green and Rapid Approach for Industrial Application N2 - Here, we report on a first mechanochemical synthesis of ettringite, an important cement hydrate phase. The mineral compound ettringite ([Ca3Al(OH)6]2·(SO4)3·26H2O) occurs rarely in nature, but is common for cement-based materials. Ettringite has wide technical application in the ceramic and paper industry. However, its typical wet-chemical synthesis is cumbersome and produces waste water and CO2 emissions. Here, we investigate the first mechanochemical synthesis of ettringite for developing an easy and sustainable alternative for industrial application. The mechanosynthesis was monitored in situ by coupled synchrotron X-ray diffraction (XRD) and infrared thermography (IRT). The consumption of the reactants and the formation of the reaction product were monitored with time-resolved XRD. IRT showed the temperature increase based on the exothermic reaction. The reaction conversion was significantly improved changing the strategy of the mechanosynthesis from a one- to a two-step process. The latter included neat pregrinding of solid reactants followed by a delayed addition of the stoichiometric amount of water. Thus, an increase of reaction conversion from 34 to 94% of ettringite could be achieved. KW - XRD KW - Mechanochemistry KW - Ettringite KW - In situ PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-479016 DO - https://doi.org/10.1021/acsomega.9b00560 SN - 2470-1343 VL - 4 IS - 4 SP - 7734 EP - 7737 PB - ACS Publications CY - Washington, DC AN - OPUS4-47901 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph A1 - Stolpe, Heiko A1 - Kruschwitz, Sabine ED - Schumann, R. T1 - Correlation between the electric impedance and the water layer thickness in partially saturated screed samples N2 - The moisture content of screed samples is monitored by means of embedded sensors. Relative humidity sensors and multi-ring-electrodes are used to measure the spatial moisture distribution during desorption. Based on the humidity data and the pore volume distribution, the moisture and the water layer thickness within the pore space are predicted. Slit shape as well as cylindrical pores are evaluated. Finally, the measured real part of the electrical impedance and the calculated water layer thickness are correlated. Based on the available data, a significant trend change of the impedance is documented at a water layer thickness of approximately 3 nm. This water layer thickness corresponds to a relative humidity of 88.3%. T2 - 10. CMM Tagung CY - Ettlingen, Germany DA - 10.10.2019 KW - Material moisture KW - Screed KW - Embedded sensors KW - Electric impedance KW - Water layer thickness PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-494636 VL - 10 SP - 79 EP - 102 PB - CMM, Karlsruher Institut für Technologie CY - Karlsruhe AN - OPUS4-49463 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scholz, Philipp A1 - Ulbricht, Alexander A1 - Joshi, Y. A1 - Gollwitzer, Christian A1 - Weidner, Steffen T1 - Microstructure of polymer-imprinted metal–organic frameworks determined by absorption edge tomography N2 - Mechanochemically synthesized metal–organic Framework material HKUST-1 in combination with acrylonitrile butadiene styrene polymer was used to form a polymer metal–organic framework composite material by a simple extruder. This composite filament was used for 3D printing. Xray diffraction measurements were used to prove the homogeneous distribution of the metal–organic framework in the polymer on a centimeter scale, whereas X-ray Absorption Edge Tomography using a synchrotron radiation source was able to evaluate the 3D distribution of the metal–organic framework material both in the filament and the resultant printed sample with a resolution of a few lm. Our very first data indicate that, apart from a few clusters having significantly higher Cu concentration, HKUST-1 is distributed homogeneously down to the 100 lm length scale in both polymer bulk materials in the form of clusters with a size of a few lm. Absorption Edge Tomography in combination with data fusion also allows for the calculation of the metal–organic framework amount located on the external polymer surface. KW - MOF KW - Polymer KW - AET PY - 2019 DO - https://doi.org/10.3139/146.111817 SN - 1862-5282 SP - 1 EP - 10 PB - Carl Hanser Verlag AN - OPUS4-49483 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Johann, Sergej A1 - Kohlhoff, Harald A1 - Gawlitza, Kornelia A1 - Bell, Jérémy A1 - Mansurova, Maria A1 - Tiebe, Carlo A1 - Bartholmai, Matthias T1 - Semi-automatic Gas Measurement Device Based on Fluorescent Multi-gas Sensors N2 - This paper describes the development of a semi-automatic gas measurement device presenting potentially a broad range of applications, noteworthy in the agricultural sector. Non-reversible fluorescent molecular sensors were designed and syn-thesized. Upon, integration into a hydrogel matrix with an optimal ratio of co-solvents, the sensors reacting selectively to ammonia were illuminated by excitation light to produce a concentration-correlated fluorescence emission. An automated mechanical-elec-trical device initiates a given gas mixture and thus simulates con-centrations similar to a threshold value. The aim of this project is to develop a sensor or a low-cost method which can monitor low concentrations of harmful gases and aid in their elimination or regulation in livestock housing, barns or stables. T2 - IEEE Sensors 2019 CY - Montreal, Canada DA - 27.10.2019 KW - gas analysis KW - fluorescence KW - embedded sensor KW - spectroscopy KW - environment KW - agricultural economy PY - 2019 SN - 978-1-7281-1634-1 SP - 88 EP - 92 PB - IEEE AN - OPUS4-49506 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -