Quantitative Defect Reconstruction in Active Thermography for Fiber-Reinforced Composites

Please always quote using this URN: urn:nbn:de:0297-zib-58374
  • Carbon-fiber reinforced composites are becoming more and more important in the production of light-weight structures, e.g., in the automotive and aerospace industry. Thermography is often used for non-destructive testing of these products, especially to detect delaminations between different layers of the composite. In this presentation, we aim at methods for defect reconstruction from thermographic measurements of such carbon-fiber reinforced composites. The reconstruction results shall not only allow to locate defects, but also give a quantitative characterization of the defect properties. We discuss the simulation of the measurement process using finite element methods, as well as the experimental validation on flat bottom holes. Especially in pulse thermography, thin boundary layers with steep temperature gradients occurring at the heated surface need to be resolved. Here we use the combination of a 1D analytical solution combined with numerical solution of the remaining defect equation. We use the simulations to identify material parameters from the measurements. Finally, fast heuristics for reconstructing defect geometries are applied to the acquired data, and compared for their accuracy and utility in detecting different defects like back surface defects or delaminations.

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Author:Sebastian GötschelORCiD, Christiane Maierhofer, Jan P. Müller, Nick Rothbart, Martin WeiserORCiD
Document Type:ZIB-Report
Tag:geometry identification; inverse problems; nondestructive testing; parameter identification; thermography
MSC-Classification:80-XX CLASSICAL THERMODYNAMICS, HEAT TRANSFER (For thermodynamics of solids, see 74A15) / 80Axx Thermodynamics and heat transfer / 80A23 Inverse problems
80-XX CLASSICAL THERMODYNAMICS, HEAT TRANSFER (For thermodynamics of solids, see 74A15) / 80Mxx Basic methods / 80M10 Finite element methods
Date of first Publication:2016/03/23
Series (Serial Number):ZIB-Report (16-13)
Published in:Appeared in: Proceedings 19th World Conference on Non-Destructive Testing (WCNDT 2016)