Capturing progressive interfacial decohesion and thermal residual stress effect in unidirectional elastoplastic composites

An asymptotic homogenization framework is presented for predicting the effective response and local stress fields of unidirectional composites exhibiting progressive interfacial debonding and elastoplastic deformation. The interfacial traction-separation relation is modelled using a coupled cohesive zone model (CZM), where interface degradation is represented by a scalar damage variable that progressively reduces the interfacial stiffness. To accurately capture the initiation of interfacial damage, thermal residual stresses arising from the consolidation process are incorporated into the micromechanics simulations prior to the application of mechanical loading. In addition, a fully connected neural network, trained using a Bayesian regression approach, is employed to identify the parameters associated with interfacial damage and matrix plasticity from macroscopic transverse stress–strain data. The proposed framework is further validated against experimental results under complex oligocyclic and off-axis loading conditions. The numerical results demonstrate that the developed approach can reliably capture the progressive interfacial degradation and the resulting nonlinear mechanical response of composites.