Chemie und Prozesstechnik
Filtern
Erscheinungsjahr
- 2022 (36) (entfernen)
Dokumenttyp
- Beitrag zu einem Tagungsband (36) (entfernen)
Sprache
- Englisch (36) (entfernen)
Schlagworte
- Concrete (5)
- Non-destructive testing (4)
- LIBS (3)
- NDT (3)
- Ultrasound (3)
- Air-coupled ultrasound (2)
- Circular economy (2)
- Civil engineering (2)
- DLP (2)
- DMD (2)
- Dimensional metrology (2)
- Inspection (2)
- Internal defects (2)
- Material classification (2)
- Nondestructive testing (2)
- Open Guided Waves Platform (2)
- Recycling (2)
- Super resolution (2)
- Thermography (2)
- Ultrasonic Guided Waves (2)
- Acoustic damping (1)
- Additive manufacturing (1)
- Additive manufacturing of concrete (1)
- Aeroacoustics (1)
- Ait-coupled ultrasound (1)
- Algorithmic Differentiation (1)
- Artificial Neural Network (1)
- Atmospheric pressure discharges (1)
- Basic qualification (1)
- Bingham fluid (1)
- Bistable amplifier (1)
- Bridge (1)
- Building materials (1)
- CT (1)
- CT simulation, spherical step-wedge (1)
- Calibrated reference standards (1)
- Capillary conductivity (1)
- Cascade impactor (1)
- Certification (1)
- Chlorine (1)
- Competencies (1)
- Composites (1)
- Computed Tomography (1)
- Conformity assessment (1)
- Conformity assessment body (1)
- Conical hole sheet (1)
- Contact area (1)
- Corrosion (1)
- Crack depth (1)
- Curriculum (1)
- Damage evolution (1)
- Data fusion (1)
- Diffusion (1)
- Digital maturity (1)
- Digital transformation (1)
- Digitalization (1)
- Durability assessment (1)
- Epitaxially grown 4H-SiC layers (1)
- FMEA (1)
- Failure Modes and Effects Analysis (1)
- Fluidic oscillators (1)
- Fluidics (1)
- Frequency modulation (1)
- Geometrical misalignment (1)
- Geometry (1)
- Herculaneum (1)
- High-entropy alloy (1)
- Human Factors (1)
- Hydrogen (1)
- Image processing (1)
- Image-based models (1)
- Imaging ellipsometry (1)
- Indirect noise (1)
- Insulation material (1)
- Inverse Methods (1)
- Laboratory (1)
- Liner (1)
- Main-flow oriented vorticity-nozzle interaction (1)
- Material testing (1)
- Microplastics (1)
- Multi-geometry cuboid (1)
- Multiple principal element alloy (1)
- Muon tomography (1)
- NDT Reliability (1)
- NDT-CE (1)
- Nondestructive evaluation (1)
- Nuclear magnetic resonance (1)
- Performance assessment (1)
- Plasma acoustics (1)
- Pore-size distribution (1)
- Probability of Detection (1)
- Process monitoring (1)
- Python (1)
- Quadtree meshes (1)
- Quality infrastructure (1)
- Quantification (1)
- Radiographic XCT geometry determination (1)
- Radiographic simulation software (1)
- Reconstruction (1)
- SAFT (1)
- SBFEM (1)
- Scaled Boundary Finite Element Method (1)
- Simulation (1)
- Software (1)
- Structural Health Monitoring (1)
- Structural health monitoring (1)
- Synchrotron radiation (1)
- Task specific numerical measurement uncertainty (1)
- Tendon duct (1)
- Testing (1)
- Thermal desorption analysis (1)
- Thermal extraction (1)
- Transient analysis (1)
- Tungsten-Edge (1)
- Tunnel Inspection (1)
- UFP (1)
- Ultrasonic (1)
- Ultrasonics (1)
- University (1)
- Validation (1)
- Water samples (1)
- Wave defect interaction (1)
- White light interference microscopy (1)
- Wide bandgap compound semiconductor (1)
- X-ray refraction radiography (1)
- X-ray tomography (1)
- XCT machine geometry (1)
- XRF (1)
- Zero Massflow Liner (ZML) (1)
- ink (1)
- inspection (1)
- papyrus (1)
- traceability (1)
Organisationseinheit der BAM
- 8 Zerstörungsfreie Prüfung (30)
- 8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen (10)
- 8.4 Akustische und elektromagnetische Verfahren (10)
- 8.0 Abteilungsleitung und andere (8)
- 8.5 Röntgenbildgebung (5)
- 4 Material und Umwelt (2)
- 6 Materialchemie (2)
- 7 Bauwerkssicherheit (2)
- 4.2 Material-Mikrobiom Wechselwirkungen (1)
- 4.5 Kunst- und Kulturgutanalyse (1)
Temperature Compensation Strategies for Lamb Wave Inspection using Distributed Sensor Networks
(2022)
The application of temperature compensation strategies is crucial in structural health monitoring approaches based on guided waves. Actually, the varying temperature influences the performance of the inspection system inducing false alarms or missed detection, with a consequent reduction of reliability. This paper quantitatively describes a method to compensate the temperature effect, namely the optimal baseline selection (OBS), extending its application to the case of distributed sensor networks (DSN). The effect of temperature separation between baseline time-traces in OBS are investigated considering multiple couples of sensors employed in the DSN. A combined strategy that uses both OBS and frequent value warning is considered. Theoretical results are compared, using data from two several experiments, which use different frequency analysis with either predominantly A0 mode or S0 mode data or both. The focus is given on the fact that different paths are available in a sensor network and several possible combination of results are available. Nonetheless, introducing a frequent value warning it is possible to increase the efficiency of the OBS approach making use of fewer signal processing algorithms. These confirm that the performance of OBS quantitatively agrees with predictions and also demonstrate that the use of compensation strategies improve detectability of damage.
Performance assessment for GuidedWave (GW)-based Structural Health Monitoring (SHM) systems is of major importance for industrial deployment.
With conventional feature extraction methods like damage indices, pathbased probability of detection (POD) analysis can be realized. To achieve reliability quantification enough data needs to be available, which is rarely the case.
Alternatives like methods for performance assessment on system level are still in development and in a discussion phase. In this contribution, POD results using an Artificial Intelligence (AI)-based data analysis are compared with those delivered by conventional data analysis. Using an open-access dataset from Open Guided Wave platform, the possibility of performance assessment for GW-based SHM systems using AI-based data analysis is shown in detail. An artificial neural network (ANN) classifier is trained to detect artificial damage in a stiffened CFRP plate. As input for the ANN, classical damage indicators are used. The ANN is tested to detect damage at another position, whose inspection data were not previously used in training. The findings show very high detection capabilities without sorting any specific path but only having a global view of current damage metrics. The systematic evaluation of the ANN predictions with respect to specific damage sizes allows to compute a probability of correct identification versus flaw dimension, somehow equivalent to and compared with the results achieved through classic path-based POD analysis. Also, sensitive paths are detected by ANN predictions allowing for evaluation of maximal distances between path and damage position. Finally, it is shown that the prediction performance of the ANN can be improved significantly by combining different damage indicators as inputs.
Reliability assessment of Structural Health Monitoring (SHM) systems
poses new challenges pushing the research community to address many questions which are still open. For guided wave-based SHM it is not possible to evaluate the system performance without taking into account the target structure and applied system parameters. This range of variables would result in countless measurements.
Factors like environmental conditions, structural dependencies and wave characteristics demand novel solutions for performance analysis of SHM systems compared to those relying on classical non-destructive evaluation. Such novel approaches typically require model-assisted investigations which may not only help to explain and understand performance assessment results but also enable complete studies without costly experiments. Within this contribution, a multi input multi output approach using a sparse transducer array permanently installed on a composite structure to excite and sense guided waves is considered. Firstly, the method and the analysis of path-based performance assessment are presented considering an open-access dataset from the Open Guided Wave platform. Then, a performance analysis of a guided wave-based SHM system using Probability of Detection is presented. To explain some unexpected results, the model-assisted investigations are used to understand the physical phenomena of wave propagation in the test specimen including the interaction with damage. Finally, issues and future steps in SHM systems’ performance assessment and their development are discussed.
In this study, the concept of a Zero Mass Flow Liner is evaluated. The concept enables impedance control by the induction of periodic bias flow through the perforated facing sheet of the liner. The periodic bias flow is generated by a secondary high amplitude acoustic actuation. By means of the periodic bias flow, the liner can be tuned to different operating points in a given range of grazing flow velocities. The equivalent fluid impedance model for perforated plates is modified to account for the effects of periodic bias flow and grazing flow. An optimization routine, based on a genetic algorithm, is implemented. The method is applicable to any liner concept and uses the impedance of the lined surface as boundary condition in a numerical simulation. Thereby, a set of liner parameters is derived in order to obtain the desired damping characteristics. Based on the results of the optimization, a Zero Mass Flow Liner is manufactured and consequently evaluated experimentally. The damping characteristics are evaluated in form of the dissipated energy along the lined surface. Prediction and measurements show agreement. The Zero Mass
Flow Liner delivers broad band dissipation of high peak value over a range of grazing flow Mach numbers. Under grazing ow conditions, the effect of periodic bias flow is reduced. This poses high energy requirements in high Mach number flow regimes which might restrict the applicability of the Zero Mass Flow concept to grazing flows of low Mach numbers.
Sound production due to main-flow oriented vorticity-nozzle interaction in absence of a net swirl
(2022)
The downstream acoustic response due to the interaction of main-flow oriented vorticity with a choked nozzle in a swirl-free flow was experimentally demonstrated. The response was obtained by means of impulsive radial air injection in the pipe upstream from the nozzle. The resulting downstream acoustic data are shown to obey a scaling rule that differs, from the one for swirl-nozzle interaction, which according to the literature is proportional to the square of the swirl number. In contrast, here evidence is presented that points to the scaling of main-flow oriented vorticity noise with the cross-sectional average of the square of the transversal velocity at the throat divided by the square of the critical sound speed.
Hybrid optical measurement technique for detection of defects in epitaxially grown 4H-SiC layers
(2022)
Recent developments in power electronics require the use of new wide bandgap compound semiconductor. We demonstrate the use of the ellipsometry and white light interference microscopy to detect defects in epitaxially grown SiC layers on SiC substrates. Such hybrid optical metrology methods can be used to better understand the mechanism of the development of the defects as well as their effects on the material´s optoelectronic properties.
Laser Induced Breakdown Spectroscopy – A Tool for Imaging the Chemical Composition of Concrete
(2022)
One of the most common causes of damage is the ingress of harmful ions into the concrete, which can lead to deterioration processes and affect structural performance. Therefore, the increasingly aging infrastructure is regularly inspected to assess durability. Regular chemical analysis can be useful to determine the extent and evolution of ion ingress and to intervene in a timely manner. This could prove more economical than extensive repairs for major damage, particularly for critical infrastructure. In addition to already established elemental analysis techniques in civil engineering such as potentiometric titration or X-ray fluorescence analysis, laser-induced breakdown spectroscopy (LIBS) can provide further important complementary information and benefits. The possibilities of LIBS are demonstrated using the example of a drill core taken from a parking garage.
Hundreds of papyrus rolls, carbonized during the 79CE eruption of Mount Vesuvius, were discovered in 1754 at Herculaneum. Sophisticated mechanical methods for unrolling the best-preserved scrolls have been applied, with varying success. However, such processes have been abandoned, to prevent risk from irremediable damage or loss and to preserve the integrity of the extremely fragile rolls. Following the development of X-ray based non-invasive techniques, attempts to virtually unroll the scrolls were made. The most common ink in Antiquity was carbon-based, and the main element of carbonized papyrus is carbon, making these investigations difficult. However, some attempts with synchrotron X-ray phase-contrast tomography (XPCT) were successful. Recently, the identification of antique inks containing metals raised hope that if some of the inks contain metal the rolls can be virtually unrolled using conventional CT- technique. We investigated the inks of a selection of partially unrolled fragments stored at the Biblioteca Nazionale di Napoli with X-ray fluorescence in order to select the best candidates for tomography. Despite the many difficulties (analysis of several layers sticking together, letters barely visible, difficulty to separate contribution from the ink and from the papyrus, inhomogeneity of the support, fragility of the fragments…), encouraging results were found, with a number of inks from Greek fragments found to contain additions to the soot (Fe, Pb, Cu P).
High-entropy alloys (HEAs) are innovative high-performance materials that have attracted more and more research attention. HEAs are characterized by a solid solution of typically five equiatomic metallic elements. In addition, medium-entropy alloys (MEA, with three elements) are of interest and become more and more important. Depending on the alloy concept, HEAs and MEAs show exceptional mechanical properties, especially high-strength and ductility combinations at both cryogenic and elevated temperatures combined with excellent corrosion resistance. Future structural HEA/MEA components can be exposed to potential applications with hydrogen containing environments like high-temperature water in pressurized nuclear reactors or aerospace structures. Other potential applications could be in materials for vessel walls in the field of cryogenic and high-pressure hydrogen storage. So far, the susceptibility of HEAs/MEAs to hydrogen assisted cracking (if any) and the hydrogen diffusion is not investigated in detail yet and can limit or extend possible applications of HEA/MEA as structural materials. In our work, we focused on the hydrogen absorption, diffusion, and distribution in a HEA (CoCrFeMnNi the original Cantor-alloy) and a MEA (CoCrNi). Cathodic hydrogen charging was carried out for the hydrogen ingress, and thermal desorption analysis (TDA) revealed complex hydrogen trapping in both alloy types up to 300 °C. The absorbed total hydrogen concentrations were > 100 ppm for the HEA and > 40 ppm for MEA. In addition, the assessment of the peak deconvolution is not trivial and must consider both experimental and microstructure influences.
Attenuation of ultrasonic signals in concrete has the potential to carry much information about the microstructure of the material. In this work a series of concrete specimens of varying porosities and pore size distributions were internally imaged with x-ray computed tomography (CT), and then subsequently examined with throughtransmission ultrasound. The CT images were used to quantify both capillary porosity of cement paste as well as internal interfaces that are likely to produce elastic wave scattering. Ultrasound signals were represented as a diffusion process such that absorption and scattering attenuation could be isolated. As implemented, the diffusion model was a poor predictor of capillary porosity, while diffusivity was a reasonable predictor of scattering interfaces. Diffusivity was found to scale extremely well with small scale porosity, which made it a good predictor of compressive strength.