Effects of Elastoplasticity, Damage and Environmental Exposure 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 quasistatic loading conditions under the simultaneous presence of plasticity, damage and hygrothermal 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 environmental excitations. It is shown that the assumption of using elastoplastic failure as being the only behavior defining the failure of the adhesive, may not be an adequate assumption for designing and qualifying ASLJs. Specifically, consideration of the presence of plasticity, damage and environmental effects indicates that there are reasons to re-examine the design practices of such joints and to determine the relevant material constants associated with the multiphysics cross-coupling effects.