17 - Physics-based methodology for predicting ply cracking and laminate failure in symmetric composite laminates under multiaxial loading condition

Abstract

This chapter introduces a physics-based methodology for predicting ply cracking initiation, propagation, and its impact on laminate strength in general symmetric laminates under combined triaxial normal and shear loads while the effects of thermal residual stresses and statistical distribution of fracture energies caused by manufacturing defects are considered. Ply cracking in multiple off-axis plies of laminates is considered by implementing an accurate stress transfer model, namely, variational approach. A ply-level homogenization methodology is introduced to predict accurately the effective in-plane and out-of-plane properties of a damaged ply. To predict ply cracking initiation and propagation, a multiaxial energy-based framework is introduced formulated based on intrinsic material properties. The methodology is implemented in conjunction with a strain-based fibre failure criterion to predict the effects of stacking sequence and ply thickness on laminate strength. The effect of different modelling features (e.g., thermal residual stresses and statistical distribution of fracture energies, etc.) on crack initiation and propagation is discussed.