TY - CONF A1 - Oster, Simon A1 - Maierhofer, Christiane A1 - Mohr, Gunther A1 - Hilgenberg, Kai A1 - Ulbricht, Alexander A1 - Altenburg, Simon T1 - Investigation of the thermal history of L-PBF metal parts by feature extraction from in-situ SWIR thermography N2 - Laser powder bed fusion is used to create near net shape metal parts with a high degree of freedom in geometry design. When it comes to the production of safety critical components, a strict quality assurance is mandatory. An alternative to cost-intensive non-destructive testing of the produced parts is the utilization of in-situ process monitoring techniques. The formation of defects is linked to deviations of the local thermal history of the part from standard conditions. Therefore, one of the most promising monitoring techniques in additive manufacturing is thermography. In this study, features extracted from thermographic data are utilized to investigate the thermal history of cylindrical metal parts. The influence of process parameters, part geometry and scan strategy on the local heat distribution and on the resulting part porosity are presented. The suitability of the extracted features for in-situ process monitoring is discussed. T2 - Thermosense: Thermal Infrared Applications XLIII CY - Online meeting DA - 12.04.2021 KW - SWIR camera KW - Additive manufacturing (AM) KW - Selective laser melting (SLM) KW - Laser beam melting (LBM) KW - In-situ monitoring KW - Infrared thermography PY - 2021 SN - 978-1-5106-4324-6 U6 - https://doi.org/10.1117/12.2587913 VL - 11743 SP - 1 EP - 11 PB - SPIE - The international society for optics and photonics AN - OPUS4-52535 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Scheuschner, Nils A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Maierhofer, Christiane T1 - Towards the determination of real process temperatures in the LMD process by multispectral thermography N2 - Due to the rapid thermal cycles involved in additive manufacturing of metals, high internal stresses and peculiar microstructures occur, which influence the parts mechanical properties. To systematically examine their formation, in-process measurements of the temperature are needed. Since the part emissivity is strongly inhomogeneous and rapidly changing in the process, the applicability of thermography for the determination of thermodynamic temperatures is limited. Measuring the thermal radiation in different wavelengths simultaneously, temperature and emissivity can be separated. Here, we present results of a preliminary study using multispectral thermography to obtain real temperatures and emissivities in directed energy deposition (DED) processes. T2 - Thermosense: Thermal Infrared Applications XLIII CY - Online meeting DA - 12.04.2021 KW - Additive Manufacturing KW - Process monitoring KW - Multispectral thermography KW - Laser metal deposition KW - TES KW - LMD KW - Temperature emissivity separation PY - 2021 U6 - https://doi.org/10.1117/12.2587881 VL - 2021 SP - 77 EP - 83 PB - SPIE AN - OPUS4-52516 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Scheuschner, Nils A1 - Maierhofer, Christiane A1 - Mohr, Gunther A1 - Hilgenberg, Kai T1 - Thermography in laser powder bed fusion of metals: time over threshold as feasible feature in thermographic data N2 - Thermography is one on the most promising techniques for in-situ monitoring of metal additive manufacturing processes. Especially in laser powder bed fusion processes, the high process dynamics and the strong focus of the laser beam cause a very complex thermal history within the produced specimens, such as multiple heating cycles within single layer expositions. This complicates data interpretation, e.g., in terms of cooling rates. A quantity that is easily calculated is the time a specific area of the specimen is at a temperature above a chosen threshold value (TOT). Here, we discuss variations occurring in time-over-threshold-maps during manufacturing of an almost defect free cuboid specimen. T2 - 15th Quantitative InfraRed Thermography conference CY - Online meeting DA - 21.09.2020 KW - Additive Manufacturing KW - Process monitoring KW - Thermography KW - L-PBF KW - Time over threshold PY - 2020 U6 - https://doi.org/10.21611/qirt.2020.005 SP - 1 EP - 5 PB - QIRT Council CY - Quebec, Canada AN - OPUS4-52014 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Altenburg, Simon A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Maierhofer, Christiane T1 - In-situ monitoring of a laser metal deposition (LMD) process: comparison of MWIR, SWIR and high-speed NIR thermography N2 - Additive manufacturing offers a range of novel applications. However, the manufacturing process is complex and the production of almost defect-free parts with high reliability and durability is still a challenge. Thermography is a valuable tool for process surveillance, especially in metal additive manufacturing processes. The high process temperatures allow one to use cameras usually operating in the visible spectral range. Here, we compare the results of measurements during the manufacturing process of a commercial laser metal deposition setup using a mid wavelength infrared camera with those from a short wavelength infrared camera and those from a visual spectrum high-speed camera with band pass filter in the near infrared range. KW - Additive Manufacturing KW - Process monitoring KW - Thermography KW - LMD KW - Metal KW - MWIR KW - SWIR KW - NIR PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-516318 VL - 19 IS - 2 SP - 97 EP - 114 PB - Taylor & Francis Group CY - London, UK AN - OPUS4-51631 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mohr, Gunther A1 - Nowakowski, Susanna A1 - Altenburg, Simon A1 - Maierhofer, Christiane A1 - Hilgenberg, Kai T1 - Experimental Determination of the Emissivity of Powder Layers and Bulk Material in Laser Powder Bed Fusion Using Infrared Thermography and Thermocouples N2 - Recording the temperature distribution of the layer under construction during laser powder bed fusion (L-PBF) is of utmost interest for a deep process understanding as well as for quality assurance and in situ monitoring means. While having a notable number of thermal monitoring approaches in additive manufacturing (AM), attempts at temperature calibration and emissivity determination are relatively rare. This study aims for the experimental temperature adjustment of an off-axis infrared (IR) thermography setup used for in situ thermal data acquisition in L-PBF processes. The temperature adjustment was conducted by means of the so-called contact method using thermocouples at two different surface conditions and two different materials: AISI 316L L-PBF bulk surface, AISI 316L powder surface, and IN718 powder surface. The apparent emissivity values for the particular setup were determined. For the first time, also corrected, closer to real emissivity values of the bulk or powder surface condition are published. In the temperature region from approximately 150 °C to 580 °C, the corrected emissivity was determined in a range from 0.2 to 0.25 for a 316L L-PBF bulk surface, in a range from 0.37 to 0.45 for 316L powder layer, and in a range from 0.37 to 0.4 for IN718 powder layer. KW - Emisssivity KW - Laser Powder Bed Fusion (L-PBF) KW - Selective Laser Melting (SLM) KW - Additive Manufacturing (AM) KW - Process monitoring KW - Infrared thermography PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-516148 VL - 10 IS - 11 SP - 1546 PB - MDPI CY - Basel, Schweiz AN - OPUS4-51614 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Moskovchenko, A. I. A1 - Vavilov, V. P. A1 - Bernegger, Raphael A1 - Maierhofer, Christiane A1 - Chulkov, A. O. T1 - Detecting Delaminations in Semitransparent Glass Fiber Composite by Using Pulsed Infrared Thermography N2 - Thanks to its good strength/mass ratio, a glass fibre reinforced plastic (GFRP) composite is a common material widely used in aviation, power production, automotive and other industries. In its turn, active infrared (IR) nondestructive testing (NDT) is a common inspection technique for detecting and characterizing structural defects in GFRP. Materials to be tested are typically subjected to optical heating which is supposed to occur on the material surface. However, GFRP composite is semitransparent for optical radiation of both visual and IR spectral bands. Correspondingly, the inspection process represents a certain combination of both optical and thermal phenomena. Therefore, the known characterization algorithms based on pure heat diffusion cannot be applied to semi-transparent materials. In this study, the phenomenon of GFRP semi-transparency has been investigated numerically and experimentally in application to thermal NDT. Both Xenon flash tubes and a laser have been used for thermal stimulation of opaque and semi-transparent test objects. It has been shown that the Penetration of optical heating radiation into composite reduces detectability of shallower defects, and the signal-to-noise ratio can be enhanced by applying the technique of thermographic signal reconstruction (TSR). In the inspection of the semi-transparent GFRP composite, the most efficient has been the laser heating followed by the TSR data processing. The perspectives of defect characterization of semi-transparent materials by using laser heating are discussed. A neural network has been used as a candidate tool for evaluating defect depth in composite materials, but its training should be performed in identical with testing conditions. KW - Infrared thermography KW - Thermal testing KW - GFRP KW - Semi-transparent composite KW - Laser heating PY - 2020 U6 - https://doi.org/10.1007/s10921-020-00717-x VL - 39 SP - 69 PB - Springer Science+Business Media, LLC, part of Springer Nature 2020 AN - OPUS4-51179 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Altenburg, Simon A1 - Scheuschner, Nils T1 - Prozessüberwachung in der additiven Fertigung von Metallen - das Projekt ProMoAM N2 - Prozessüberwachung in der additiven Fertigung von Metallen - das Projekt ProMoAM. In diesem Vortrag wird das gesamte Projekt vorgestellt. Dabei wird auf die Thermografie im LMD und L-PBF Prozess näher eingegangen. Hierbei werden sowohl stationäre als auch mit bewegte Systeme vorgestellt. T2 - Webinar: Inline-Messtechnik und –Prozessüberwachung CY - Online meeting DA - 01.07.2020 KW - Pulverbettverfahren KW - Laser Metal Deposition KW - Thermografie KW - Optische Tomografie PY - 2020 UR - https://quality-engineering.industrie.de/webinarreihe-additive-verfahren/#Inline-Messtechnik AN - OPUS4-50962 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bernegger, Raphael A1 - Maierhofer, Christiane A1 - Altenburg, Simon T1 - Quantification of delaminations in semitransparent solids using pulsed thermography and mathematical 1D models N2 - Material defects in fiber reinforced polymers such as delaminations can rapidly degrade the material properties or can lead to the failure of a component. Pulse thermography (PT) has proven to be a valuable tool to identify and quantify such defects in opaque materials. However, quantification of delaminations within semitransparent materials is extremely challenging. We present an approach to quantify delaminations within materials being semitransparent within the wavelength ranges of the optical excitation sources as well as of the infrared (IR) camera. PT experimental data of a glass fiber reinforced polymer with a real delamination within the material were reconstructed by one dimensional (1D) mathematical models. These models describe the heat diffusion within the material and consider semitransparency to the excitation source as well to the IR camera, thermal losses at the samples surfaces and a thermal contact resistance between the two layers describing the delamination. By fitting the models to the PT data, we were able to determine the depth of the delamination very accurately. Additionally, we analyzed synthetic PT data from a 2D simulation with our 1D-models to show how the thermal contact resistance is influenced by lateral heat flow within the material. KW - Pulsed thermography KW - Quantification KW - Numerical simulation KW - Analytical model KW - Semitransparent KW - GFRP KW - Delamination PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-505766 VL - 41 IS - 5 SP - Article number: 67 PB - Springer AN - OPUS4-50576 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mohr, Gunther A1 - Altenburg, Simon A1 - Ulbricht, Alexander A1 - Heinrich, Ph. A1 - Baum, D. A1 - Maierhofer, Christiane A1 - Hilgenberg, Kai T1 - In-Situ Defect Detection in Laser Powder Bed Fusion by Using Thermography and Optical Tomography—Comparison to Computed Tomography N2 - Among additive manufacturing (AM) technologies, the laser powder bed fusion (L-PBF) is one of the most important technologies to produce metallic components. The layer-wise build-up of components and the complex process conditions increase the probability of the occurrence of defects. However, due to the iterative nature of its manufacturing process and in contrast to conventional manufacturing technologies such as casting, L-PBF offers unique opportunities for in-situ monitoring. In this study, two cameras were successfully tested simultaneously as a machine manufacturer independent process monitoring setup: a high-frequency infrared camera and a camera for long time exposure, working in the visible and infrared spectrum and equipped with a near infrared filter. An AISI 316L stainless steel specimen with integrated artificial defects has been monitored during the build. The acquired camera data was compared to data obtained by computed tomography. A promising and easy to use examination method for data analysis was developed and correlations between measured signals and defects were identified. Moreover, sources of possible data misinterpretation were specified. Lastly, attempts for automatic data analysis by data Integration are presented. KW - Laser powder bed fusion (L-PBF) KW - Selective laser melting (SLM) KW - Additive manufacturing (AM) KW - Process monitoring KW - Infrared thermography KW - Optical tomography KW - Computed tomography (CT) KW - Data fusion KW - Lack-of-fusion PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-502417 VL - 10 IS - 1 SP - 103 PB - MDPI CY - Basel, Schweiz AN - OPUS4-50241 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Metz, Christian A1 - Franz, Philipp A1 - Fischer, C. A1 - Wachtendorf, Volker A1 - Maierhofer, Christiane T1 - Active thermography for quality assurance of 3D-printed polymer structures N2 - Additively manufactured test specimens made of polyamide 12 (PA 12) by Laser Sintering as well as of acrylonitrile butadiene styrene (ABS) by Fused Layer Modelling, were characterised with active thermography directly after manufacturing and after artificial weathering. For this, two different excitation methods (flash and pulse heating) were used and compared, regarding their suitability for the detection of constructed and imprinted defects inside the test specimens. To increase the quality of the thermograms, data processing methods like thermal signal reconstruction (TSR) and Fourier Transformation after TSR were applied. To further investigate the long-term stability of the additively manufactured test specimens towards environmental stress, like UV radiation, heat, humidity, water contact and frost with active thermography, an artificial weathering test over 2000 hours (~3 months) was applied to the specimens. The monitoring of the changes in the optical properties of the weathered plastics was supplemented by spectral reflectance and UV/VIS spectroscopy. KW - Additive manufacturing KW - Polymers KW - Artificial weathering KW - Active thermography KW - UV/VIS spectroscopy PY - 2019 U6 - https://doi.org/10.1080/17686733.2019.1686896 SN - 1768-6733 (Print) 2116-7176 (Online) VL - 18 IS - 1 SP - 50 EP - 72 PB - Taylor & Francis AN - OPUS4-49817 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hilgenberg, Kai A1 - Daum, Werner A1 - Maierhofer, Christiane A1 - Altenburg, Simon A1 - Bruno, Giovanni A1 - Heckel, Thomas A1 - Skrotzki, Birgit A1 - Zerbst, Uwe A1 - Kranzmann, Axel A1 - Bettge, Dirk A1 - Sommer, Konstantin A1 - Seeger, Stefan A1 - Nitsche, Michael A1 - Günster, Jens A1 - Evans, Alexander T1 - Additive manufacturing at the BAM: We focus on Safety N2 - In Germany, the Federal Institute for Materials Research and Testing (BAM) is addressing challenges in the implementation of additive manufacturing on the industrial landscape for safety-critical applications. KW - Process development KW - Additive Manufacturing KW - In-situ Process Monitoring KW - Non-destructive Materials KW - Characterisation KW - Safety KW - Fatigue KW - Environment KW - Standardisation PY - 2019 UR - https://static.asminternational.org/amp/201910/22/ SN - 0882-7958 VL - 177 IS - 7 SP - 22 EP - 26 PB - ASM International CY - Materials Park, OH, USA AN - OPUS4-49780 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Metz, Christian A1 - Franz, Philipp A1 - Fischer, C. A1 - Wachtendorf, Volker A1 - Maierhofer, Christiane T1 - Zerstörungsfreie Charakterisierung der Alterung additiv gefertigter Kunststoffbauteile N2 - Das vorgestellte Projekt beschäftigt sich mit den optischen, thermophysikalischen und mechanischen Materialeigenschaften von additiv gefertigten Kunststoffteilen und deren Alterung. Dazu wurden mittels Fused Layer Modeling (FLM) Probekörper aus ABS hergestellt, die anschließend für drei Monate einer künstlichen Bewitterung unterzogen wurden. Die dabei erzeugte definierte Alterung wurde nach drei Zeitabschnitten jeweils mit zerstörungsfreien Methoden charakterisiert. Dabei wurde neben den spektroskopischen Standardmethoden auch die aktive Thermografie eingesetzt. Die Ergebnisse zeigen, dass sich mittels der Thermografie sowohl chemische Veränderungen als auch mechanische Schädigungen (Fehlstellen) darstellen lassen. Die Bewitterung beeinflusst die Teiltransparenz der Proben zumindest im sichtbaren Spektralbereich, was bei der Charakterisierung der Fehlstellen, die mittels optisch angeregter aktiver Thermografie detektiert wurden, berücksichtigt werden muss. T2 - DGZfP-Jahrestagung 2019 CY - Friedrichshafen, Germany DA - 27.05.2019 KW - 3D Druck KW - Additive Fertigung KW - Thermografie KW - Polymere KW - Künstliche Bewitterung PY - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-491561 UR - https://jt2019.dgzfp.de/Portals/jt2019/bb/Di.3.B.1.pdf SN - 978-3-947971-02-2 VL - 171 SP - 1 EP - 8 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-49156 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scheuschner, Nils A1 - Altenburg, Simon A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Maierhofer, Christiane T1 - In-situ thermographic monitoring of the laser metal deposition process N2 - In this paper shortwave infrared (SWIR) thermographic measurements of the manufacturing of thin single-line walls via laser metal deposition (LMD) are presented. As the thermographic camera is mounted fixed to the welding arm, an acceleration sensor was used to assist in reconstructing the spatial position from the predefined welding path. Hereby we could obtain data sets containing the size of the molten pool and the oxide covered areas as functions of the position in the workpiece. Furthermore, the influence of the acquisition wavelength onto the thermograms was investigated in a spectral range from 1250 nm to 1550 nm. All wavelengths turned out to be usable for the in-situ process monitoring of the LMD process. The longer wavelengths are shown to be beneficial for the lower temperature range, while shorter wavelengths show more details within the molten pool. T2 - Sim-AM 2019 - 2. International Conference on Simulation for Additive Manufacturing CY - Pavia, Italy DA - 11.09.2019 KW - Additive manufacturing KW - 3D printing KW - Thermography KW - Direct energy deposition KW - Laser Metal Deposition KW - 3D Druck KW - Laser Pulver Auftragsschweißen KW - Additive Fertigung KW - Thermografie PY - 2019 UR - http://congress.cimne.com/SIM-AM2019/frontal/Doc/proceedings.pdf SN - 978-84-949194-8-0 SP - 246 EP - 255 AN - OPUS4-49086 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias T1 - Application of thermographic testing for the characterization of impact damage during and after impact load N2 - Low-velocity impact damages were monitored in-situ using an infrared camera before, during and after Impact load. Thermal images were recorded as a function of time at the front side (impact) as well as at the rear side of the plates using a high frame rate. In CFRP and GFRP specimens with different thicknesses and made of various types of fibers and matrix materials, different kind of damages were observed. The sizes of the heated areas being related to the damages and the amount of energy dissipated into heat was determined quantitatively as a function of impact energy and are a measure of the resistance of the different materials against impact load. KW - Laminates KW - Impact behaviour KW - NDT KW - Thermal analysis PY - 2019 U6 - https://doi.org/10.1016/j.compositesb.2019.106899 SN - 1359-8368 SN - 1879-1069 VL - 173 SP - 106899, 1 EP - 17 PB - Elsevier AN - OPUS4-48881 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Metz, Christian A1 - Franz, Philipp A1 - Maierhofer, Christiane A1 - Wachtendorf, Volker A1 - Fischer, C. ED - Ziegahn, K.-F. T1 - Untersuchung der Beständigkeit additiv gefertigter Bauteile durch Thermografie nach künstlicher Bewitterung N2 - Additiv gefertigte Prüfkörper aus Polyamid 12 (Laser Sinter Verfahren) und Acrylnitril-Butadien-Styrol (Fused Layer Modeling Verfahren) wurden über 2000 Stunden künstlich bewittert und ihr Alterungsverhalten untersucht. Die Ergebnisse wurden anschließend mit denen von Prüfkörpern verglichen, welche auf dieselbe Weise künstlich bewittert, aber mittels konventionellem KunststoffSpritzguss hergestellt wurden. T2 - 48. Jahrestagung der GUS 2019 CY - Stutensee, Germany DA - 27.03.2019 KW - Polymere KW - Additive Fertigung KW - 3D Druck KW - Künstliche Bewitterung KW - Thermografie PY - 2019 SN - 978-3-9818507-3-4 VL - 48 SP - 207 EP - 216 CY - Pfinztal (Berghausen) AN - OPUS4-48502 LA - deu 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-479016 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 - JOUR A1 - Bernegger, Raphael A1 - Altenburg, Simon A1 - Maierhofer, Christiane T1 - Iterative numerical 2D-modelling for quantification of material defects by pulsed thermography N2 - This paper presents a method to quantify the geometry of defects such as flat bottom holes (FBH) and notches in opaque materials by a pulse thermography (PT) experiment and a numerical model. The aim was to precisely describe PT experiments in reflection configuration with a simple and fast numerical model in order to use this model and a fit algorithm to quantify defects within the material. The algorithm minimizes the difference between the time sequence of a line shaped region of interest (ROI) on the surface (above the defect) from the PT experiment and the numerical data. Therefore, the experimental data can be reconstructed with the numerical model. In this way, the defect depth of a notch or FBH and its width or diameter was determined simultaneously. A laser was used for heating which was widened to a top hat spatial profile to ensure homogeneous illumination (rectangular impulse profile in time). The numerical simulation considers heating conditions and takes thermal losses due to convection and radiation into account. We quantified the geometry of FBH and notches in steel and polyvinyl chloride plasticized (PVC-U) materials with an accuracy of < 5 %. KW - Pulsed thermography KW - Numerical modelling KW - Data reconstruction KW - Opaque materials KW - 2D model KW - Flat bottom holes KW - Notches PY - 2019 U6 - https://doi.org/10.1063/1.5099719 SN - 0094-243X SP - 020015-1 EP - 11 PB - AIP AN - OPUS4-47974 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Maierhofer, Christiane A1 - Hilgenberg, Kai A1 - Mohr, Gunther A1 - Gumenyuk, Andrey A1 - Straße, Anne A1 - Pittner, Andreas A1 - Günster, Jens A1 - Gornushkin, Igor B. A1 - Pelkner, Matthias A1 - Ehlers, Henrik A1 - Heckel, Thomas A1 - Zscherpel, Uwe A1 - Seeger, Stefan A1 - Bruno, Giovanni T1 - ProMoAM - Verfahrensentwicklung für das Prozessmonitoring in der additiven Fertigung N2 - Verfahren zum in-situ Monitoring der Prozess- und Bauteilparameter sollen Fehlstellen und Inhomogenitäten bereits während der Fertigung nachweisen und zukünftig auch die Regelung der Prozessparameter ermöglichen. T2 - Challenges in Additive Manufacturing: Innovative Materials and Quality Control, Berlin Partner Workshop CY - Berlin, Germany DA - 12.09.2018 KW - Additive Fertigung KW - Prozessmonitoring KW - ProMoAM PY - 2018 AN - OPUS4-46300 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ziegler, Mathias A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias T1 - Characterization of defects in fibre reinforced composites (FRC) using passive and active thermography N2 - Impact damages and delaminations in fibre-reinforced composites (FRC) might not be visible at the surface, but could have an influence on the resistance and on the long-term behaviour of the component. Therefore, and especially for safety relevant structures, non-destructive methods are required for the assessment of such damages. Active thermography methods are suitable to characterize damages after loading using different kind of excitation techniques and various configurations of infrared (IR) camera and heating sources. Here, flash lamps, impulse excitation with infrared radiator and lock-in technique with halogen lamps or widened laser beams are suited. In addition, non-optical sources like sonotrodes (requiring direct contact to the structure) or induction generators (only suited for carbon fibre reinforced polymer (CFRP) structures) could be applied as well. For the investigation of the evolution of the damage during the impact, passive thermography can be applied in-situ. Elastic and plastic deformations alter the temperature of the structure and thus the temperature on the surface. In this contribution, at first the general principles of quantitative defect characterisation in FRC using active thermography with flash, impulse and lock-in excitation are described. Optical and thermal properties of the FRC material and its anisotropy are considered. Results of phase differences obtained at flat bottom holes with flash and lock-in thermography are compared for qualifying both methods for quantitative defect characterization. Secondly, the damage evolution of CFRP and GFRP structures under impact load and static tensile loading is described. The spatial and temporal evolution of the surface temperature enables us to distinguish matrix cracks or fibre-matrix separation from delaminations between the layers. Afterwards, all results for loading defects, obtained by passive and active thermography, are compared with each other. Fig. 1 and 2 show the difference of passive and flash thermography obtained at impact and tensile loaded CFRP plates, respectively. As one purpose of these investigations is the development of standards within national (DIN) and European (CEN) standardisation bodies, new draft and final standards are presented and further needs are discussed at the end of the presentation. T2 - INTERNATIONAL SCHOOL OF QUANTUM ELECTRONICS, 62nd Course, Progress in Photoacoustic & Photothermal Phenomena CY - Erice, Italy DA - 06.09.2018 KW - Thermography KW - Flash thermography KW - Lock-in thermography KW - CFRP KW - GFRP PY - 2018 AN - OPUS4-46283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Thiel, Erik A1 - Altenburg, Simon A1 - Mohr, Gunther A1 - Thiede, Tobias A1 - Mishurova, Tatiana A1 - Paul, Andrea A1 - Kranzmann, Axel A1 - Hilgenberg, Kai A1 - Pittner, Andreas A1 - Bruno, Giovanni A1 - Sommer, Konstantin A1 - Gumenyuk, Andrey T1 - Quality control in additive manufacturing via in-situ monitoring and non-destructive testing N2 - More than 80 representatives of SMEs, industrial companies and research institutes met on September 12 at the workshop "Challenges in Additive Manufacturing: Innovative Materials and Quality Control" at BAM in Adlershof to discuss the latest developments in materials and quality control in additive manufacturing. In special lectures, researchers, users and equipment manufacturers reported on the latest and future developments in additive manufacturing. Furthermore, funding opportunities for projects between SMEs and research institutions on a national and European level were presented. T2 - Challenges in Additive Manufacturing: Innovative Materials and Quality Control CY - Berlin, Germany DA - 12.09.2018 KW - Additive manufacturing KW - Quality control KW - Non-destructive testing KW - In-situ monitoring PY - 2018 AN - OPUS4-46072 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Maierhofer, Christiane A1 - Straße, Anne A1 - Gumenyuk, Andrey T1 - Comparison of MWIR thermography and high-speed NIR thermography in a laser metal deposition (LMD) process N2 - Additive manufacturing (AM) offers a range of novel applications. However, the manufacturing process is complex and the production of defect-free parts with high reliability and durability is still a challenge. Thermography is a valuable tool for process surveillance, especially in metal AM processes. The high process temperatures allow one to use cameras usually operating in the visible spectral range. Here, we compare the results of measurements during the manufacturing process of a commercial laser metal deposition setup using a mid-wavelength-IR camera with those from a visual spectrum high-speed camera with band pass filter in the near-IR range. T2 - Conference QIRT 2018 CY - Berlin, Germany DA - 25.06.2018 KW - Additive manufacturing KW - Laser metal deposition KW - ProMoAM KW - Thermography PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-454993 UR - http://www.qirt.org/archives/qirt2018/papers/p35.pdf SP - 1 EP - 5 PB - QIRT Council CY - Quebec, Canada AN - OPUS4-45499 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias A1 - Heckel, Thomas A1 - Brackrock, Daniel A1 - Gaal, Mate T1 - Quantification of impact damages in CFRP and GFRP structures with thermography and ultrasonics N2 - The extent of damage caused by impacts in fibre reinforced composites depends on the energy of the impacts, on the velocity and the shape of the impacting body, on the material and structure of the composite and on the geometry of the structure. Here, mainly the thickness of the component is essential. The non-destructive evaluation of these damages can be carried out using both ultrasound and active thermography methods. A comparison of the detection sensitivity of these methods for the different damages is carried out in this paper depending on the fibre composite material used (CFRP and GFRP), the thickness of the material and the impact energy. The NDT methods used after the damage are supplemented by thermographic measurements with high temporal resolution, which were already recorded during the impact. T2 - 14th Quantitative InfraRed Thermography Conference CY - Berlin, Germany DA - 25.06.2018 KW - Active thermography KW - Passive thermography KW - Ultrasonics KW - CFRP KW - GFRP KW - Impact PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-454952 UR - http://www.qirt.org/archives/qirt2018/papers/126.pdf SP - 933 EP - 940 PB - DGZfP e. V. AN - OPUS4-45495 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Altenburg, Simon A1 - Röllig, Mathias A1 - Myrach, Philipp T1 - Passive and active thermography applied to buildings and cultural heritage - Cracks and protection layers N2 - Artificial and natural cracks have been investigated with active and passive thermography. For the determination of the thickness of protection layers on concrete, an active thermography method has been developed. T2 - Short Courses of the QIRT 2018 Conference CY - Berlin, Germany DA - 25.6.2018 KW - Active themrography KW - Passive thermography KW - Cracks KW - Concrete PY - 2018 AN - OPUS4-45456 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias A1 - Heckel, Thomas A1 - Brackrock, Daniel A1 - Gaal, Mate T1 - Quantification of impact damages in CFRP and GFRP structures with thermography and ultrasonics N2 - For the quantification of impact damage in CFRP and GFRP structures, first passive thermography measurements have been performed at the front and rear side of the test specimens during low velocity impact load. After loading, the damaged structures have been investigated non-destructively with active thermography with flash excitation and with step heating and with two different ultrasonic methods (phased array and air coupled ultrasonics). The damage sizes quantified with all methods are evaluated and compared. In addition, the depth of the greatest damage inside the different test specimens is analysed. T2 - QIRT Conference 2018 CY - Berlin, Germany DA - 25.06.2018 KW - Thermography KW - Ultrasonics KW - CFRP KW - GFRP KW - Impact PY - 2018 AN - OPUS4-45458 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Metz, Christian A1 - Franz, Philipp A1 - Fischer, C. A1 - Wachtendorf, Volker A1 - Maierhofer, Christiane T1 - Active thermography for quality assurance of 3D-printed polymer structures N2 - Additively manufactured test specimens made of polyamide 12 (PA 12) by Laser Sintering (LS) as well as of acrylnitril-butadien-styrol (ABS) by Fused Layer Modeling (FLM), were tested with active thermography. For this, two different excitation methods (flash and impulse excitation) were used and compared, regarding the suitability for the detection of constructed and imprinted defects. To increase the quality of the thermograms, data processing methods like thermal signal reconstruction (TSR) and Fourier-Transformation were applied. Furthermore, the long-term stability of the probes towards environmental stress, like UV-radiation, heat, water contact and frost is being investigated in the presented project with artificial weathering tests. T2 - 14th Quantitative InfraRed Thermography Conference CY - Berlin, Germany DA - 25.06.2018 KW - Additive manufacturing KW - Active thermography KW - Artificial weathering PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-453919 SP - Tu.3.A.2, 1 EP - 9 AN - OPUS4-45391 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krankenhagen, Rainer A1 - Ziegler, Mathias A1 - Maierhofer, Christiane ED - Maldague, X. T1 - Systematic errors in the evaluation of uncorrected data from thermographic lock-in measurements N2 - Lock-in thermography (LT) is based on the correct evaluation of phase differences between the temperature oscillations at different surface regions of the object under test during periodic heating. Since the usual heating procedures contain a DC component, the actual heating pattern achieved is not harmonic. This causes systematic deviations when phase differences are determined by means of harmonic analysis, e.g. with FFT analysis. The resulting errors depend clearly on the ratio between DC and AC amplitude, which is demonstrated at simulated and experimentally recorded temperature transients. Further experimental LT data obtained by different oscillating energy inputs showed a variety of possible shapes of transients with different DC components. T2 - 14th QIRT Conference CY - Berlin, Germany DA - 26.06.2018 KW - NDT KW - Lock-in Thermography KW - FFT PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-453768 SP - 539 EP - 547 PB - QIRT Council AN - OPUS4-45376 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krankenhagen, Rainer A1 - Maierhofer, Christiane A1 - Heckel, Thomas A1 - Brackrock, Daniel A1 - Gower, M. A1 - Lodeiro, M. A1 - Baker, G. T1 - Quantitative comparison of different non-destructive techniques for the detection of artificial defects in GFRP N2 - In order to test their suitability different non-destructive methods were performed to inspect a GFRP plate with artificial defects. These defects were manufactured by means of thin PTFE sheets inserted between two plies in three different depth. The inspection methods were microwave reflection, flash thermography and phased array ultrasonics, all applied to the same specimen. Selected results are shown for all methods demonstrating opportunities and limits of the particular inspection methods. The achieved detection limits and further application aspects are compared directly to provide a useful information for the planning of inspection tasks. T2 - ECNDT CY - Gothenburg, Sweden DA - 11.06.2018 KW - Fiber resisted polymers KW - Non-destructive testing KW - Thermographic testing KW - Ultrasonic testing PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-453728 SP - ECNDT-0247-2018 AN - OPUS4-45372 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Krankenhagen, Rainer A1 - Maierhofer, Christiane T1 - Corrigendum to "Measurement of the radiative energy output of flash lamps by means of thermal thin probes" [Infrared Phys. Technol. 67 (2014) 363-370] N2 - This is a corrigendum to the original article "Measurement of the radiative energy output of flash lamps by means of thermal thin probes" that was published in the journal "Infrared physics & technology", vol. 67 (2014), pp. 363-370. PY - 2018 U6 - https://doi.org/10.1016/j.infrared.2017.11.011 SN - 1350-4495 VL - 91 SP - 278 PB - Elsevier CY - Amsterdam AN - OPUS4-50505 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kulla, Hannes A1 - Haferkamp, Sebastian A1 - Akhmetova, Irina A1 - Röllig, Mathias A1 - Maierhofer, Christiane A1 - Rademann, Klaus A1 - Emmerling, Franziska T1 - In situ investigations of mechanochemical one-pot syntheses N2 - We present an in situ triple coupling of synchrotron X-ray diffraction with Raman spectroscopy, and thermography to study milling reactions in real time. This combination of methods allows a correlation of the structural evolution with temperature information. The temperature information is crucial for understanding both the thermodynamics and reaction kinetics. The reaction mechanisms of three prototypical mechanochemical syntheses, a cocrystal formation, a C@C bond formation (Knoevenagel condensation), and the formation of a manganese-phosphonate, were elucidated. Trends in the temperature development during milling are identified. The heat of reaction and latent heat of crystallization of the product contribute to the overall temperature increase. A decrease in temperature occurs via release of, for example, water as a byproduct. Solid and liquid intermediates are detected. The influence of the mechanical impact could be separated from temperature effects caused by the reaction. KW - In situ studies KW - Mechanochemistry KW - Raman spectroscopy KW - Thermography KW - X-ray diffraction PY - 2018 U6 - https://doi.org/10.1002/anie.201800147 SN - 1433-7851 SN - 1521-3773 VL - 57 IS - 20 SP - 5930 EP - 5933 PB - Wiley-VCH CY - Weinheim AN - OPUS4-44946 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Franz, Philipp A1 - Metz, Christain A1 - Brackrock, Daniel A1 - Fischer, C. A1 - Wachtendorf, Volker A1 - Maierhofer, Christiane T1 - Zerstörungsfreie Charakterisierung und Qualitätssicherung der Materialeigenschaften und Beständigkeit additiv gefertigter Kunststoffteile N2 - Mit additiven Fertigungsverfahren hergestellte Bauteile und Produkte aus Kunststoffen werden zunehmend nicht mehr nur als Prototypen, sondern als voll funktionsfähige Bauteile und Produkte gefertigt. Bedingt durch die Fertigungsprozesse und den schichtweisen Aufbau resultieren physikalische Materialeigenschaften, die stark von den Fertigungsparametern abhängen und zudem anisotrop sind. Von den Fertigungsparametern werden auch die Oberflächeneigenschaften beeinflusst, sodass zu erwarten ist, dass sich die Beständigkeit gegenüber äußeren Umwelteinflüssen bei additiv gefertigten Bauteilen von der konventionell gefertigter unterscheiden kann. Nachfolgend wird daher die Entwicklung eines Qualitätssicherungskonzeptes basierend auf spektroskopischen und zerstörungsfreien Prüfverfahren vorgestellt, in dem der Alterungsprozess von mittels Fused Deposition Modelling (FDM) und mittels Lasersintering (LS) hergestellten Probekörpern untersucht wird. T2 - DGZfP-Jahrestagung 2018 CY - Leipzig, Germany DA - 07.05.2018 KW - Additive Fertigung KW - Kunststoffe KW - Zerstörungsfreie Prüfung PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-449016 SN - 978-3-940283-92-4 VL - DGZfP BB 166 SP - Mo.2.A.1, 1 EP - 9 AN - OPUS4-44901 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias A1 - Heckel, Thomas A1 - Brackrock, Daniel A1 - Gaal, Mate T1 - Charakterisierung von Impactschäden während und nach dem Impact mit thermografischen Verfahren und mit Ultraschall N2 - Der Umfang der durch Impacts in Faserverbundmaterialien erzeugten Schäden ist abhängig von der Energie des Impacts, von der Zusammensetzung und dem Aufbau der Faserverbundwerkstoffe und von der Geometrie der Bauteile und hier im Wesentlichen von der Dicke des Bauteils. Der zerstörungsfreie Nachweis dieser Schädigungen kann sowohl mit Ultraschallverfahren als auch mit Verfahren der aktiven Thermografie erfolgen. Ein Vergleich der Nachweisempfindlichkeiten dieser Verfahren für die unterschiedlichen Schädigungen wird in diesem Beitrag in Abhängigkeit vom verwendeten Faserverbundwerkstoff (CFK und GFK), der Dicke des Materials und von der Impactenergie durchgeführt. Ergänzt werden die im Anschluss an die Schädigung eingesetzten ZfP-Verfahren mit zeitlich hochaufgelösten Thermografiemessungen, die bereits während des Impacts aufgenommen wurden. T2 - DGZfP Jahrestagung 2018 CY - Leipzig, Germany DA - 07.05.2018 KW - Thermografie KW - Ultraschall KW - Faserverbundwerkstoffe KW - Impactschäden PY - 2018 AN - OPUS4-44878 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krankenhagen, Rainer A1 - Maierhofer, Christiane A1 - Röllig, Mathias A1 - Heckel, Thomas A1 - Brackrock, Daniel A1 - Gaal, Mate T1 - Charakterisierung von Impactschäden während und nach der Belastung mit thermografischen Verfahren und mit Ultraschall N2 - Der Umfang der durch Impacts in Faserverbundmaterialien erzeugten Schäden ist abhängig von der Energie des Impacts, von der Zusammensetzung und dem Aufbau der Faserverbundwerkstoffe und von der Geometrie der Bauteile und hier im Wesentlichen von der Dicke des Bauteils. Der zerstörungsfreie Nachweis dieser Schädigungen kann sowohl mit Ultraschallverfahren als auch mit Verfahren der aktiven Thermografie erfolgen. Ein Vergleich der Nachweisempfindlichkeiten dieser Verfahren für die unterschiedlichen Schädigungen wird in diesem Beitrag in Abhängigkeit vom verwendeten Faserverbundwerkstoff (CFK und GFK), der Dicke des Materials und von der Impactenergie durchgeführt. Ergänzt werden die im Anschluss an die Schädigung eingesetzten ZfP-Verfahren mit zeitlich hochaufgelösten Thermografiemessungen, die bereits während des Impacts aufgenommen wurden. T2 - DGZfP Jahrestagung 2018 CY - Leipzig, Germany DA - 07.05.2018 KW - Thermografie KW - Ultraschall KW - Faserverbundwerkstoffe KW - Impactschäden PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-448773 SN - 978-3-940283-92-4 VL - 166 SP - 1 EP - 8 PB - Deutsche Gesellschaft für zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-44877 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maierhofer, Christiane A1 - Röllig, Mathias A1 - Gower, M. A1 - Lodeiro, M. A1 - Baker, G. A1 - Monte, C. A1 - Adibekyan, A. A1 - Gutschwager, B. A1 - Knazowicka, L. A1 - Blahut, A. T1 - Evaluation of different techniques of active thermography for quantification of artificial defects in fiber-reinforced composites using thermal and phase contrast data analysis N2 - For assuring the safety and reliability of components and constructions in energy applications made of fiber-reinforced polymers (e.g., blades of wind turbines and tidal power plants, engine chassis, flexible oil and gas pipelines) innovative non-destructive testing methods are required. Within the European Project VITCEA complementary methods (shearography, microwave, ultrasonics and thermography) have been further developed and validated. Together with partners from the industry, test specimens have been constructed and selected on-site containing different artificial and natural defect artefacts. As base materials, carbon and glass fibers in different orientations and layering embedded in different matrix materials (epoxy, polyamide) have been considered. In this contribution, the validation of flash and lock-in thermography to these testing problems is presented. Data analysis is based on thermal contrasts and phase evaluation techniques. Experimental data are compared to analytical and numerical models. Among others, the influence of two different types of artificial defects (flat bottom holes and delaminations) with varying diameters and depths and of two different materials (CFRP and GFRP) with unidirectional and quasi-isotropic fiber alignment is discussed. KW - Active thermography KW - CFRP KW - GFRP KW - Delaminations KW - Flash excitation KW - Lock-in excitation PY - 2018 U6 - https://doi.org/10.1007/s10765-018-2378-z SN - 0195-928X SN - 1572-9567 VL - 39 IS - 5 SP - Article 61, 1 EP - 37 PB - Springer AN - OPUS4-44687 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Metz, Christian A1 - Franz, Philipp A1 - Wachtendorf, Volker A1 - Maierhofer, Christiane A1 - Fischer, C. ED - Ziegahn, K.-F. T1 - Additiv gefertigte Polymerbauteile: Untersuchung der Beständigkeit durch künstliche Bewitterung und zerstörungsfreie Charakterisierung N2 - Es wird ein Verfahren zur Charakterisierung der Beständigkeit und Langzeitstabilität von additiv gefertigten Kunststoff-Bauteilen vorgestellt. Dabei sollen die Prüfkörper über 2000 Stunden künstlich bewittert und währenddessen die Änderungen der Eigenschaften der Bauteile zerstörungsfrei untersucht werden. T2 - 47. Jahrestagung der Gesellschaft für Umweltsimulation e.V. CY - Stutensee, Germany DA - 21.03.2018 KW - Additive Fertigung KW - Künstliche Bewitterung KW - Thermografie KW - Additive manufacturing PY - 2018 VL - 47. SP - 99 EP - 105 PB - Gesellschaft für Umweltsimulatin e.V. AN - OPUS4-44638 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bernegger, Raphael A1 - Altenburg, Simon A1 - Roellig, Mathias A1 - Maierhofer, Christiane T1 - Applicability of a 1D analytical model for pulse thermography of laterally heterogeneous semitransparent materials N2 - Pulse thermography (PT) has proven to be a valuable non-destructive testing method to identify and quantify defects in fiber-reinforced polymers. To perform a quantitative defect characterization, the heat diffusion within the material as well as the material parameters must be known. The heterogeneous material structure of glass fiber-reinforced polymers (GFRP) as well as the semitransparency of the material for optical excitation sources of PT is still challenging. For homogeneous semitransparent materials, 1D analytical models describing the temperature distribution are available. Here, we present an analytical approach to model PT for laterally inhomogeneous semitransparent materials.We show the validity of the model by considering different configurations of the optical heating source, the IR camera, and the differently coated GFRP sample. The model considers the lateral inhomogeneity of the semitransparency by an additional absorption coefficient. It includes additional effects such as thermal losses at the samples surfaces, multilayer systems with thermal contact resistance, and a finite duration of the heating pulse. By using a sufficient complexity of the analytical model, similar values of the material parameters were found for all six investigated configurations by numerical fitting. KW - Absorption coefficient KW - Analytical model KW - GFRP KW - Heterogeneous KW - Pulse thermography KW - Semitransparent PY - 2018 U6 - https://doi.org/10.1007/s10765-018-2362-7 SN - 0195-928X SN - 1572-9567 VL - 39 IS - 3 SP - Article 39, ICPPP 19, 1 EP - 17 PB - Springer International Publishing AG AN - OPUS4-44003 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni A1 - Maierhofer, Christiane T1 - Neue Abenteuer an der BAM: die Projekte AGIL und ProMoAM N2 - Zwei neue Projekte wurden in der BAM gestartet: AGIL und ProMoAM, die mit der Charakterisierung additiv gefertigter Wrkstoffe und mit dem Prozessmonitoring in der AF sich befassen. Die sind in diesem Vortrag dargestellt T2 - Symposium Materialcharakterisierung CY - BAM, Berlin, Germany DA - 28.11.2017 KW - Additive Fertigung KW - Prozess Monitoring KW - Alterung KW - Metallische Werkstoffen KW - Laser Metal Deposition KW - Selective Laser Melting PY - 2017 AN - OPUS4-43273 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias A1 - Unnikrishnakurup, Sreedhar A1 - Monte, C. A1 - Adibekyan, A. A1 - Gutschwager, B. A1 - Knazowicka, L. A1 - Blahut, A. A1 - Gower, M. A1 - Lodeiro, M. A1 - Baker, G. A1 - Aktas, A. T1 - Einfluss thermischer und optischer Materialeigenschaften auf die Charakterisierung von Fehlstellen in Faserverbundwerkstoffen mit aktiven Thermografieverfahren T1 - Influence of thermal and optical material properties on the characterization of defects in fiber reinforced composites with active thermography methods N2 - In diesem Beitrag werden zerstörungsfreie Untersuchungen mittels aktiver Thermografie an Probekörpern aus CFK und GFK mit unterschiedlichen künstlichen Fehlstellen vorgestellt. Dabei wird die zeitliche und örtliche Temperaturverteilung nach der Erwärmung mit Blitzlampen oder mit einem Infrarot-Strahler mit einer Infrarot-Kamera erfasst. Zur späteren Rekonstruktion der Messdaten wurde ein numerisches Modell entwickelt. Dazu war die Bestimmung der thermophysikalischen und optischen Materialeigenschaften erforderlich, was in diesem Beitrag ebenfalls beschrieben wird. Die Ergebnisse der numerischen Modellierung werden mit den experimentellen Untersuchungen der aktiven Thermografie verglichen. Weiterhin werden die experimentellen Untersuchungen hinsichtlich der beiden Materialsysteme CFK und GFK und unter Berücksichtigung der Teiltransparenz des GFK-Materials sowie der unterschiedlichen Anregungsquellen bewertet. N2 - This paper presents results of the non-destructive evaluation of CFRP and GFRP test specimens with various artificial defects using active thermography. After heating the specimens with flash lamps or with an infrared radiator, the temporal and spatial resolved temperature distribution is recorded with an infrared camera. For the reconstruction of the experimental data, a numerical model was developed. For the numerical simulations, the thermal and optical material parameters had to be determined, which is described in this contribution as well. The results of numerical modelling are compared to experimental data of active thermography. Additionally, the experimental results are assessed related to the two materials CFRP and GFRP by considering the partial transmissivity of the GFRP material, and to the different excitation sources. T2 - Temperatur 2017 CY - Berlin, Germany DA - 17.05.2017 KW - Zerstörungsfreie Prüfung KW - Aktive Thermografie KW - Faserverbundwerkstoffe (CFK, GFK) KW - Numerische Simulation PY - 2017 U6 - https://doi.org/10.1515/teme-2017-0078 SN - 0171-8096 SN - 2196-7113 VL - 85 IS - 1 SP - 13 EP - 27 PB - DE GRUYTER CY - Oldenburg AN - OPUS4-42395 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krankenhagen, Rainer A1 - Maierhofer, Christiane A1 - Röllig, Mathias A1 - Myrach, Philipp T1 - Quantitative Fehlstellencharakterisierung mit Puls- und Lock-in-Thermografie N2 - Seit dem Beginn der Anwendung der aktiven Thermografie für die zerstörungsfreie Prüfung werden für die optische Anregung zwei alternative Anregungstechniken eingesetzt: die Puls- oder Blitzthermografie und die Lock-in-Thermografie. Bei der Puls-Thermografie ist der Anregungspuls wesentlich kürzer als die Zeit, die für die Wärmediffusion in das Bauteil hinein benötigt wird. Die Auswertung der erfassten Abkühlsequenzen wird zurzeit im Wesentlichen mit zwei Verfahren durchgeführt. Für die Auswertung im Zeitbereich werden verschiedene Auswertungsmodi des TSR-Verfahrens (TSR: thermal signal reconstruction) und Verfahren zur möglichst frühzeitigen Detektion des Intensitäts- oder Temperaturkontrastes der Fehlstellen herangezogen. Alternativ kann die Auswertung im Frequenzbereich nach dem Verfahren der Puls-Phasen-Thermografie (PPT) erfolgen. Dabei wird die Abkühlsequenz als Überlagerung vieler Einzelschwingungen betrachtet (Fouriersynthese). Die entsprechenden Phasenkontraste können unter bestimmten Umständen zur Abschätzung der Fehlstellentiefe genutzt werden. Bei der Lock-in Anregung wird das zu untersuchende Prüfobjekt periodisch mit einer bestimmten Frequenz erwärmt und die Wärmestrahlung von der Oberfläche zeitgleich mit der Infrarotkamera erfasst. Für jede Anregungsfrequenz ist daher eine Einzelmessung erforderlich. Die Auswertung bezieht sich in den meisten Fällen allein auf die Berechnung des Phasen- und Amplitudenbildes bei der Anregungsfrequenz. Diese Berechnung kann bereits während der Messung (on-line) oder erst nach der Erfassung der Thermogrammsequenz (off-line) erfolgen. Gemäß dem Superpositionsprinzip, das wegen des linearen Charakters der Wärmeleitungsgleichung für alle Lösungen der Differentialgleichung gilt, besteht Äquivalenz zwischen einer monofrequenten Anregung bei Lock-in-Thermografie und einer entsprechenden Komponente gleicher Frequenz bei der Puls-Thermografie. Daher sollten die Puls-Thermografie und die Lock-in-Thermografie in den Phasenbildern für die gleichen Fehlstellen die gleichen Phasenkontraste ergeben. Die experimentelle Bestätigung dieser Äquivalenz für unterschiedliche Fehlstellenarten ist der Schwerpunkt dieses Beitrages. Mögliche Gründe für Abweichungen werden benannt und sind Grundlage für weitere Diskussionen. T2 - Thermografie-Kolloquium 2017 CY - Berlin, Germany DA - 28.09.2017 KW - Zerstörungsfreie Prüfung KW - Aktive Thermografie KW - Impuls-Thermografie KW - Lock-in-Thermografie PY - 2017 AN - OPUS4-42397 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Ziegler, Mathias T1 - Neue Normen und Richtlinien für die Thermografie in der zerstörungsfreien Prüfung N2 - Da die Thermografie als zerstörungsfreies Prüfverfahren noch vergleichsweise neu in der Anwendung ist, beziehen sich die aktuell veröffentlichten und überarbeiteten Normen und Richtlinien im Wesentlichen auf die grundlegenden Prinzipien des Verfahrens und die verschiedenen Anregungs- und Auswertungstechniken, auf die Begriffe und auf die Gerätetechnik. Die grundlegenden Normen zum Prinzip des Prüfverfahrens, zu den Geräten und zu den Begriffen wurden in 2016 grundlegend überarbeitet und als CEN-Normen neu veröffentlicht. Im Anschluss dazu wird in 2017 der überarbeitete Normentwurf zur aktiven Thermografie veröffentlicht. Mit der Bearbeitung einer europäischen Norm zur Laserthermografie wurde begonnen. Auf nationaler Ebene werden zur Zeit Normen zu den verschiedenen Anregungstechniken erarbeitet. Anfang 2017 wurde der Normentwurf zur Impuls-Thermografie mit optischer Anregung veröffentlicht. Geplant sind weiterhin Entwurfsveröffentlichungen zur induktiv angeregten Thermografie sowie zur Lock-in-Thermografie mit optischer Anregung. Parallel dazu wurde die Überarbeitung der Norm zur Thermografischen Prüfung elektrischer Anlagen publiziert. Mit der Richtlinie VDI/VDE 3511 Blatt 4 bis 4.4 gibt es ein anerkanntes Regelwerk für die rückführbare Temperaturmessung und Kalibrierung von Strahlungsthermometern, die bisher für Thermografiekameras fehlte. In 2016 wurde daher die VDI/VDE Richtlinie 5585 Blatt 1 zur messtechnischen Charakterisierung von Thermografiekameras als Entwurf veröffentlicht. In Bearbeitung ist momentan Blatt 2 zur Kalibrierung von Thermografiekameras mit dem Ziel, auch für Thermografiekameras anerkannte Regeln zur rückführbaren Temperaturmessung zu erstellen. Im Beitrag werden die Anwendungsbereiche dieser Normen und Richtlinien vorgestellt und neue zukünftige Anwendungsbereiche in der Fertigung und Instandhaltung diskutiert. T2 - Thermografie-Kolloquium 2017 CY - Berlin, Germany DA - 28.9.2017 KW - Zerstörungsfreie Prüfung KW - Aktive Thermografie KW - Normung PY - 2017 AN - OPUS4-42396 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Rothbart, N. T1 - A multi-parameter probability of detection (POD) model for flash thermography N2 - In most cases where a POD is calculated based on continuous data obtained by active thermography, the signal-to-noise ratio (SNR) of the signal, the difference of the defect signal to the background or the absolute signal is analyzed as a function of the aspect ratio (ratio of the size of a defect to its overage), although a distinct linear relationship on a linear or logarithmic scale could not be satisfactorily shown and is also not expected. Therefore, a multi-parameter probability of detection (POD) model was developed, where an â versus a continuous signal analysis was based on the linear relationship between the SNR and a multi-parameter a. This POD model is based on data which were recorded within a flash thermography round robin test with nine participants. Metal test specimens with flat bottom holes (FBHs) were analyzed by calculating the SNR of the defect signatures in the thermograms as well as in the phase images as a function of defect parameters. The linear relationship of the experimental data to the multi-parameter a was verified by comparison to data obtained from an analytical model that is considering lateral thermal heat diffusion as well as to data obtained by numerical simulation. The resulting POD curves for the thermograms and phase images give an estimation for the detectability of the FBHs with known geometry in steel using different equipment and obtained by different participants. By comparing the SNRs of FBHs with similar geometries, this POD model was transferred to aluminum and copper as well. T2 - 7th European-American Workshop on Reliability of NDT CY - Potsdam, Germany DA - 05.09.2017 KW - NDT KW - Active thermography KW - POD model KW - Standardization PY - 2017 AN - OPUS4-41882 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Röllig, Lodeiro A1 - Krankenhagen, Rainer A1 - Unnikrishnakurup, Sreedhar A1 - Gower, M. A1 - Lodeiro, M. A1 - Baker, G. A1 - Monte, C. A1 - Adibekyan, A. A1 - Gutschwager, B. T1 - Evaluation of different techniques of active thermography for quantification of artificial and natural defects in fiber reinforced composites N2 - For assuring the safety and reliability of components and constructions in energy applications made of fiber reinforced polymers (e. g. blades of wind turbines and tidal power plants, engine chassis, flexible oil and gas pipelines) innovative non-destructive testing methods are required. Within the EMRP project VITCEA complementary methods (shearography, microwave, ultrasonics and thermography) are further developed and validated. Together with partners from the industry, test specimens were constructed and selected on-site containing different artificial and natural defect artefacts. As base materials, carbon and glass fibers in different orientations and layering embedded in different matrix materials (epoxy, polyamide) were considered. In this contribution, the validation of different techniques of active thermography like flash, step heating and lock-in thermography to these testing problems is presented. Experimental data are compared to analytical and numerical models. Among others shows that although flash and lock-in thermography have the same detectability of flat bottom holes in the phase images, the detectability of delaminations is different. In another example, it is demonstrated that for GFRP, the transmissivity of the material has to be considered for the quantitative data analysis. T2 - 19th International Conference on Photoacoustic and Photothermal Phenomena - ICPPP 2017 CY - Bilbao, Spain DA - 16.07.2017 KW - CFRP KW - GFRP KW - Active thermography KW - Flash excitation KW - Lock-in excitation PY - 2017 AN - OPUS4-41103 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Röllig, Mathias A1 - Myrach, Philipp A1 - Unnikrishnakurup, Sreedhar T1 - Theory and data anaylsis of pulse and lock-in thermography N2 - CFRP and GFRP test specimens have been investigated with pulse and lock-in thermography. Both methods are compared quantitatively. T2 - Training Course Ultrasonics and Active Thermography CY - Berlin, Germany DA - 28.03.2017 KW - CFRP KW - GFRP KW - Active thermography KW - Flash excitation KW - Lock-in excitation PY - 2017 AN - OPUS4-41092 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Gower, M. A1 - Lodeiro, L. A1 - Baker, G. A1 - Aktas, A. A1 - Shaw, R. T1 - Introduction into the EMRP-Project VITCEA N2 - Defects in FRP structures may be introduced during the processing and fabrication of composite components and can initiate or grow in-service. In the context of this JRP, the term ‚defect‘ refers to imperfections introduced during manufacture/processing and/or secondary machining operations, as well as damage sustained during a component‘s service life. One of the challenges facing accurate and repeatable defect detection in FRP composites is the multitude of defect types that exist, each with characteristics that present different challenges to the NDE practitioner. In order for a particular NDE technique to achieve broad acceptance by industry, it is desirable for the technique to be able to detect a range of defect types with a high level of confidence. Project VITCEA (Validated Inspection Techniques for Composites in Energy Applications) is developing and validating traceable procedures for novel NDE techniques with contrasting detection capabilities, which will underpin the increased use of FRP composites for improved efficiency and reliability in energy related applications e.g. wind and marine turbine blades, nacelles, oil and gas flexible risers. T2 - Training Course Ultrasonics and Active Thermography CY - Berlin, Germany DA - 28.03.2017 KW - CFRP KW - GFRP KW - Active thermography KW - Ultrasonics KW - Microwaves KW - Shearography PY - 2017 AN - OPUS4-41091 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias A1 - Hosseini, Seyed A1 - Heckel, Thomas A1 - Gaal, Mate A1 - Schadow, Florian A1 - Brackrock, Daniel A1 - Gower, M. A1 - Lodeiro, M. A1 - Baker, G. T1 - Quantitative Bewertung künstlicher und natürlicher Fehler in Faserverbundwerkstoffen mit aktiver Thermografie und Ultraschall N2 - Im EMRP-Projekt VITCEA werden komplementäre ZFP-Verfahren zur Prüfung von Faserverbundwerkstoffen weiterentwickelt und validiert. In diesem Beitrag werden Ergebnisse verschiedener Techniken der aktiven Thermografie und des Ultraschalls vorgestellt. Die Nachweisempfindlichkeiten bezüglich künstlicher und natürlicher Fehler mit unterschiedlichen lateralen Ausdehnungen und in verschiedenen Tiefen werden miteinander verglichen. T2 - DGZfP Jahrestagung 2017 CY - Koblenz, Germany DA - 22.05.2017 KW - CFK KW - GFK KW - Aktive Thermografie KW - Phased Array Ultraschall KW - Luftultraschall PY - 2017 AN - OPUS4-41089 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias A1 - Unnikrishnakurup, Sreedhar A1 - Monte, C. A1 - Adibekyan, A. A1 - Gutschwager, B. A1 - Knazowicka, L. A1 - Blahut, A. A1 - Gower, M. A1 - Lodeiro, M. A1 - Baker, G. A1 - Aktas, A. T1 - Einfluss thermischer und optischer Materialeigenschaften auf die Charakterisierung von Fehlstellen in Faserverbundwerkstoffen mit aktiven Thermografieverfahren N2 - In diesem Beitrag werden zerstörungsfreie Untersuchungen mittels aktiver Thermografie an Probekörpern aus CFK und GFK mit unterschiedlichen künstlichen Fehlstellen vorgestellt. Dabei wird die zeitliche und örtliche Temperaturverteilung nach Erwärmung mit Blitzlampen oder mit einem Infrarot-Strahler mit einer Infrarot-Kamera erfasst. Zur Rekonstruktion der Messdaten wurde ein numerisches Modell entwickelt. Dazu war die Bestimmung der thermischen und optischen Materialeigenschaften erforderlich. T2 - Temperatur 2017 CY - Berlin, Germany DA - 17.05.2017 KW - CFK KW - GFK KW - Aktive Thermografie KW - Numerische Simulation KW - Emissivität PY - 2017 AN - OPUS4-41087 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias A1 - Hosseini, Seyed A1 - Heckel, Thomas A1 - Gaal, Mate A1 - Schadow, Florian A1 - Brackrock, Daniel A1 - Gower, M. A1 - Lodeiro, M. A1 - Baker, G. T1 - Quantitative Bewertung künstlicher und natürlicher Fehler in Faserverbundwerkstoffen mit aktiver Thermografie und Ultraschall N2 - Im EMRP-Projekt VITCEA werden komplementäre ZFP-Verfahren zur Prüfung von Faserverbundwerkstoffen weiterentwickelt und validiert. In diesem Beitrag werden Ergebnisse verschiedener Techniken der aktiven Thermografie und des Ultraschalls vorgestellt. Die Nachweisempfindlichkeiten bezüglich künstlicher und natürlicher Fehler mit unterschiedlichen lateralen Ausdehnungen und in verschiedenen Tiefen werden miteinander verglichen. T2 - DGZfP Jahrestagung 2017 CY - Koblenz, Germany DA - 22.05.2017 KW - CFK KW - GFK KW - Aktive Thermografie KW - Phased Array Ultraschall KW - Luftultraschall PY - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-410902 SN - 978-3-940283-85-6 VL - BB 162 SP - Di1B1, 1 EP - Di1B1, 8 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung e. V. AN - OPUS4-41090 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias A1 - Unnikrishnakurup, Sreedhar A1 - Monte, C. A1 - Adibekyan, A. A1 - Gutschwager, B. A1 - Knazowicka, L. A1 - Blahut, A. A1 - Gower, M. A1 - Lodeiro, M. A1 - Baker, G. A1 - Aktas, A. T1 - Einfluss thermischer und optischer Materialeigenschaften auf die Charakterisierung von Fehlstellen in Faserverbundwerkstoffen mit aktiven Thermografieverfahren N2 - In diesem Beitrag werden zerstörungsfreie Untersuchungen mittels aktiver Thermografie an Probekörpern aus CFK und GFK mit unterschiedlichen künstlichen Fehlstellen vorgestellt. Dabei wird die zeitliche und örtliche Temperaturverteilung nach Erwärmung mit Blitzlampen oder mit einem Infrarot-Strahler mit einer Infrarot-Kamera erfasst. Zur Rekonstruktion der Messdaten wurde ein numerisches Modell entwickelt. Dazu war die Bestimmung der thermischen und optischen Materialeigenschaften erforderlich. N2 - This paper presents results of the non-destructive evaluation of CFRP and GFRP test specimens with various artificial defects using active thermography. After heating the samples with flash lamps or with an infrared radiator, the temporal and spatial resolved temperature distribution is recorded with an infrared camera. For the reconstruction of the experimental data, a numerical model was developed. For the numerical simulations, the thermal and optical material parameters had to be determined. T2 - Temperatur 2017 CY - Berlin, Germany DA - 17.05.2017 KW - CFK KW - GFK KW - aktive Thermografie KW - numerische Simulation KW - Emissivität PY - 2017 SN - 978-3-944659-04-6 SP - 15 EP - 20 AN - OPUS4-41088 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias A1 - Rehmer, Birgit A1 - Gower, M. A1 - Baker, G. A1 - Lodeiro, M. A1 - Aktas, A. A1 - Monte, C. A1 - Adibekyan, A. A1 - Gutschwager, B. T1 - Defect characterisation of tensile loaded CFRP and GFRP laminates used in energy applications by means of infrared thermography N2 - The increased use of fibre reinforced plastic (FRP) composites for improved efficiency and reliability in energy related applications, e.g. wind and marine turbine blades, nacelles, oil and gas flexible risers, also increases the demand for innovative non-destructive testing technologies. In this contribution, results concerning the characterisation of CFRP and GFRP during and after quasi-static tensile loading are presented. It includes the measurement of optical properties in the infrared spectral range, tensile loading tests with the observation of the temperature distribution at one or both sides of the specimens using an infrared camera for the preparation and monitoring of intended natural defects, and active thermography inspections after tensile loading. It is shown that the defect preparation was successful. Thermographic monitoring during and active thermography testing after tensile loading enable the detection of the lateral extend of the generated defects. Differences between CFRP and GFRP materials are discussed. KW - Tensile loading KW - Fibre reinforced composites KW - Active and passive thermography KW - Emissivity PY - 2017 U6 - https://doi.org/10.1080/17686733.2017.1334312 SN - 1768-6733 SN - 2116-7176 VL - 15 IS - 1 SP - 17 EP - 36 PB - Taylor and Francis CY - London AN - OPUS4-40968 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Jan P. A1 - Götschel, S. A1 - Weiser, M. A1 - Maierhofer, Christiane T1 - Thermografie mit optimierter Anregung für die quantitative Untersuchung von Delaminationen in kohlenstofffaserverstärkten Kunststoffen N2 - Da kohlenstofffaserverstärkte Kunststoffe (CFK) in anspruchsvollen sicherheitsrelevanten Einsatzgebieten wie im Automobilbau und in der Luftfahrt eingesetzt werden, besteht ein zunehmender Bedarf an zerstörungsfreien Prüfmethoden. Ziel ist die Gewährleistung der Sicherheit und Zuverlässigkeit der eingesetzten Bauteile. Aktive Thermografieverfahren ermöglichen die effiziente Prüfung großer Flächen mit hoher Auflösung in wenigen Arbeitsschritten. Ein wichtiges Teilgebiet der Prüfungen ist die Ortung und Charakterisierung von Delaminationen, die sowohl bereits in der Fertigung als auch während der Nutzung eines Bauteils auftreten können, und dessen strukturelle Integrität schwächen. In diesem Beitrag werden CFK-Strukturen mit künstlichen und natürlichen Delaminationen mit Hilfe unterschiedlich zeitlich modulierter Strahlungsquellen experimentell untersucht. Verwendet werden dabei Anregungen mit Blitzlampen und mit frequenzmodulierten Halogenlampen. Mittels Filterfunktionen im Zeit- und Frequenzbereich wird das Kontrast-zu-Rausch-Verhältnis (CNR) der detektierten Fehlstellen optimiert. Verglichen werden anschließend die Nachweisempfindlichkeit, das CNR und die Ortsauflösung der zu charakterisierenden Delaminationen für die unterschiedlichen Anregungs- und Auswertungstechniken. Ergänzt werden die Experimente durch numerische Simulationen des dreidimensionalen Wärmetransportes. T2 - DGZfP Jahrestagung 2017 CY - Koblenz, Germany DA - 22.05.2017 KW - CFK KW - Contrast Noise Ratio KW - Lock-in Thermografie KW - Gepulste Thermografie KW - Kurzzeit-Fouriertransformation PY - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-404276 SN - 978-3-940283-85-6 VL - DGZfP BB 162 SP - Mi.1.A.4, 1 EP - 11 AN - OPUS4-40427 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pohl, Rainer A1 - Casperson, Ralf A1 - Maierhofer, Christiane A1 - Müller, Jan A1 - Pelkner, Matthias T1 - Gegenüberstellung von Wirbelstromprüfung und aktiver Thermografie an CFK-Versuchskörpern N2 - In vielen Bereichen der Technik haben Konstruktionen unter Einsatz von CFK-Bauteilen und Komponenten die klassischen Metalle abgelöst. Die zerstörungsfreie Prüfung solcher CFK-Bauteile gewinnt somit zunehmend an Bedeutung. Ein mögliches Prüfverfahren ist dabei die Wirbelstromprüfung. Aufgrund der relativ geringen elektrischen Leitfähigkeit von CFK-Komponenten kommt hierbei häufig die sogenannte HF-Wirbelstromprüfung zum Einsatz. In verschiedenen Untersuchungen der BAM konnten jedoch auch mit Wirbelstromprüfsystemen in niedrigen Frequenzbereichen gute Ergebnisse erzielt werden. Um die Möglichkeiten und Grenzen dieser konventionellen Wirbelstromprüfung auszuloten, wurden Messungen an Versuchskörpern durchgeführt, welche bereits bei der Validierung der Blitz- und Lock-in-Thermografie für neue Verfahrensnormen erfolgreich eingesetzt wurden. Ein Typ dieser Versuchskörper sind Flachproben aus CFK von 6 mm Dicke. In diesen wurden Flachbodenbohrungen mit Durchmessern zwischen 4 mm und 24 mm eingebracht. Die Restwandstärken liegen zwischen 0,06 mm und 3,66 mm. Ein weiterer CFK-Versuchskörper hat die Geometrie eines Stufenkeiles. Bei verschiedenen Stufenkeilen sind Wanddicken zwischen 1,4 mm und 5,4 mm realisiert worden. In diesen wurden künstliche quadratische Delaminationen mit Kantenlängen zwischen 2 mm und 20 mm eingebracht. Die Ergebnisse der Wirbelstromprüfung werden denen der aktiven Thermografie gegenübergestellt. Zur Nachbildung von Kompositwerkstoffen wurden die flachen Versuchskörper mit geeigneten Versuchskörpern aus Aluminium und Stahl kombiniert. Die Wirbelstromprüfungen wurden mit einem handelsüblichen Prüfgerät im Frequenzbereich zwischen 500 Hz und 3 MHz und entsprechend angepassten Sensoren durchgeführt. T2 - DGZfP Jahrestagung 2017 CY - Koblenz, Germany DA - 22.05.2017 KW - Wirbelstromprüfung KW - Aktive Thermografie KW - CFK PY - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-403607 SN - 978-3-940283-85-6 VL - 162 SP - 1 EP - 10 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-40360 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -