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Published in:
2021 | OriginalPaper | Chapter
Nondestructive and Destructive Testing on Intrinsic Metal-CFRP Hybrids
Authors : Hendrik Jost, Michael Schwarz, Felix Grossmann, Jonas Sauer, Alexander Hell, Hans-Georg Herrmann
Published in: Technologies for economic and functional lightweight design
Publisher: Springer Berlin Heidelberg
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Abstract
Motivated by legislative and environmental restrictions, cost efficient lightweight design for automotive applications is becoming more and more important. While designing the automotive body completely out of CFRP is too expensive for series production, multi-material hybrid structures represent a good compromise between cost and weight reduction.
The presented approach is a CFRP specimen containing an intrinsic aluminium inlay that is overmoulded with a thermoplastic polymer reducing the stiffness difference between the used different materials.
Defects like delamination and fibre cracking often are not clearly visible, but have a significant influence on the mechanical properties of fibre-reinforced composites in general and more particularly of such an intrinsic hybrid as presented in this paper. In order to identify and evaluate these defects nondestructive testing can be a powerful tool. Furthermore, a combination of nondestructive and destructive testing methods can be used to develop a better understanding of the damage mechanisms of such a hybrid specimen under various environmental conditions.
In this approach, the presented specimens are tested under quasistatic and cyclic tension load using in situ passive thermography and digital image correlation. In this way, damage progression like delamination growth can be monitored.
Besides characterising hybrid samples during mechanical load, the samples are also tested before and after mechanical testing. Active thermography characterises defects in the CFRP component as well as defects at the interface of CFRP and thermoplastic whereas EMAT (electromagnetic acoustic transducers) characterise the interface between metal and thermoplastic.
By combining EMAT and active thermography before and after mechanical testing the whole hybrid structure with its multiple interfaces can be examined for defects. The results are validated with computer tomography (CT).