Crack nucleation in hyperelastic adhesive bonds

Abstract

ABSTRACTAdhesively bonded glass‐to‐metal connections using structural silicone sealants are investigated in the present study of structural failure. Different failure modes are shown to be relevant depending on the geometry of the adhesive. Dilatational failure corresponding to abrupt growth of cavities in the bulk material may occur in heavily constraint applications where triaxial stress states are present. Distortional failure, i.e. failure owing to change in shape, can be observed when the adhesive can deform comparatively unconstrained. It typically originates from notches such as bi‐material points between adherend and adhesive. This work presents (i) a criterion for cavitation failure surfaces of materials with finite porosity such as Dow Corning® TSSA and (ii) an equivalent stretch concept capable of describing distortional bulk material failure surfaces of various rubber‐like materials. It is further shown that (iii) for notch‐induced crack nucleation a coupled stretch and energy criterion must be fulfilled simultaneously. The coupled criterion is capable of predicting size effects observed in tests of ETAG 002 shear specimen bonded using Dow Corning® 993.