Elasto-Plasticity, Damage and Multiphysics Effects on the Behavior of Adhesive Step Lap Joints

The presence of damage in the adhesive material as well as combined environmental excitation in multi-material adhesive step-lap joints (ASLJ) often encountered in aircraft industries are frequently neglected. Historically, their design is based only within the scope of elasto-plastic failure. The present work describes the implementation and application of a computational framework enabling the performance evaluation of such joints under quasi-static loading conditions under the simultaneous presence of plasticity, damage and environmental stimulus. In particular, a ASLJ involving Ti-6Al-4V alloy adherents with a FM-300K adhesive is modeled under the proposed framework for various material responses and mutliphysics excitations. It is shown that the assumption of assuming elasto-plastic failure as being the only behavior defining the failure of the adhesive, may not be an adequate assumption for designing and qualifying ASLJs. Specifically, considering presence of plasticity, damage and environmental effects indicates that there are reasons to re-examine the design practices of such joints.