Hardening/Softening Plastic Analysis of Adhesive Joint

Abstract

Closed‐form solutions for the plastic response of a symmetric double‐lap joint are presented. The adherends are assumed to behave linear elastically in pure tension, whereas the adhesive is assumed to be in a state of pure shear. The shear stress‐strain behavior of the adhesive is approximated by a bilinear curve, and both hardening plasticity approximating ductile adhesive, behavior and softening plasticity approximating brittle adhesive behavior are considered. The main emphasis is given to the softening behavior, as it includes some particularly intriguing features of joint behavior, e.g., limited ductility, limited bearing capacity, and the occurrence of local failure in the adhesive. For softening plasticity, two fundamentally different behaviors are identified depending on the joint parameters: one in which no local failure will occur before the bearing capacity of the joint has been completely exhausted, and another where local failure will begin at the boundary of the joint and spread until the softening zone has reached the center of the joint. In the subsequent response, the failed region will remain constant in size. Shakedown considerations are also included.