Thermographic stepwise assessment of impact damage in sandwich panels

Thermographic stepwise assessment of impact damage in sandwich panels Metal-polymer-metal sandwiches can find promising applications in the automotive field thanks to their lightweight and formability. The paper focuses on the effect of low velocity impacts on the residual mechanical behavior. Experimental stepwise tests are run on undamaged and impacted specimens with different combinations of thickness and grade for the outer steel skins and the inner polymeric core. Surface temperature evolution is thermally monitored during the tests with the aim to characterize the induced damage and to identify a parameter able to quantify the residual strength of the panel. Several approaches have been considered. The analysis of the thermal amplitude trend with the lock-in thermography evidences a variation in the thermal behavior of the specimens, defining a corresponding damage stress σD. We found a 20% σD difference between undamaged and damaged specimens. Moreover, impacted specimens experience a temperature and stress concentration at the impact area dependent on the indentation.Based on these results, we evidence the possibility to relate impact indentation with the damage stress estimated by thermography and with the stress concentration factor induced by the impact. Therefore, thermography is a useful and valid tool for post-impact damage detection, monitoring and quantification of these multi-layer sandwich materials. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Composite Structures Elsevier

Thermographic stepwise assessment of impact damage in sandwich panels

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Publisher
Elsevier
Copyright
Copyright © 2017 Elsevier Ltd
ISSN
0263-8223
eISSN
1879-1085
D.O.I.
10.1016/j.compstruct.2017.10.001
Publisher site
See Article on Publisher Site

Abstract

Metal-polymer-metal sandwiches can find promising applications in the automotive field thanks to their lightweight and formability. The paper focuses on the effect of low velocity impacts on the residual mechanical behavior. Experimental stepwise tests are run on undamaged and impacted specimens with different combinations of thickness and grade for the outer steel skins and the inner polymeric core. Surface temperature evolution is thermally monitored during the tests with the aim to characterize the induced damage and to identify a parameter able to quantify the residual strength of the panel. Several approaches have been considered. The analysis of the thermal amplitude trend with the lock-in thermography evidences a variation in the thermal behavior of the specimens, defining a corresponding damage stress σD. We found a 20% σD difference between undamaged and damaged specimens. Moreover, impacted specimens experience a temperature and stress concentration at the impact area dependent on the indentation.Based on these results, we evidence the possibility to relate impact indentation with the damage stress estimated by thermography and with the stress concentration factor induced by the impact. Therefore, thermography is a useful and valid tool for post-impact damage detection, monitoring and quantification of these multi-layer sandwich materials.

Journal

Composite StructuresElsevier

Published: Jan 15, 2018

References

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