Experimental Determination of the Tensile and Shear Behaviour of Adhesives under Impact Loading

Abstract

A robust analysis of adhesively bonded joints requires valuable input data for simulation. Mechanical properties of adhesives in tensile and shear directions at high deformation rates are necessary, particularly for crash scenarios. Butt joint specimens and lap shear specimens were, therefore, tested under impact loading using a tensile split Hopkinson bar (SHB). In this study, the adhesive deformation was measured using a high-speed camera and digital image correlation (DIC). The method was compared to a measurement of the adhesive deformations using the classical SHB analysis. It could be shown that the accuracy of the deformation measurement was significantly increased using high-speed imaging and DIC. In the butt joint specimens, the adhesive stiffness was 12.28 times higher and the energy absorbed was 1.83 times smaller using the DIC measurement than when using the classical SHB measurement of the deformations. In the lap shear specimens, the adhesive stiffness was 6.13 times higher and the energy absorbed was 1.29 times smaller compared to a classical SHB measurement of deformations. Additionally, a 3D finite element analysis showed that the design of the specimens has a minor influence on the stress–deformation relation. Therefore, accurate stress–deformation relations of adhesives under impact loading can be obtained in SHB experiments using DIC measurement.