Finite Element Based Simulation for Fatigue Crack Initiation in Thick Composites

Abstract

The fatigue life prediction of specimens with their structural complexity, including bolted joints and mixed types of loading should be computationally efficient, without sacrificing the accuracy. In order to achieve this goal in a manner that would be effective for fatigue analysis of thick-section composites, a few alterations to the existing fatigue model described in the literature are made. The use of constituent level stress field in the criterion to compare with lamina level stress fatigue results is the main objective of this study. In this work, a comparison is made between the results that are obtained with and without these enhancements. To enable comparative studies this implementation uses the Hashin criterion and Modified LaRC criterion. The focus is on crack initiation life rather the complete failure of the specimen since the interest of the aerospace industries is on the crack initiation life of composite component. The fatigue model considered in this study makes use of nonlinear interlaminar shear stress-strain properties and fatigue curves for unidirectional laminate to incorporate the inter-laminar constitutive properties in ABAQUS finite element-based failure models of IM7/8552 composite coupons subject to fatigue loading.