Comparison of non-destructive and destructive Tests of thin Structural Bonds in the Forming Technology

Comparison of destructive and nondestructive testing methods on thin polymer-based sheet metal composites. Steel/polymer/steel composites show several advantages in comparison to monolithic materials when strength, stiffness and damping characteristics are set to a global optimum. Although their mechanical properties were improved over the last years, the application of such hybrid materials in the automotive industry is not well-established due to insufficient knowledge about forming characteristics. However, it is difficult to detect the delamination during the forming process between the interlayer and the cover sheet. Delamination is the failure of the polymer interlayer and the metal sheet while both of the layers stay in contact. After failure, they are still bonded and stick together because of the weak van der Waals forces (kissing bonds), which makes it difficult to detect those defects. In this paper, various nondestructive testing methods are used to investigate the applicability and practicability in the detection of delamination on thin structural, polymer-based sheet metal composites.