Chapter 4 - Localized damage models and implicit finite element analysis of notched carbon fiber/epoxy composite laminates under tension

Abstract

Laminated composite structures show complicated damage and failure mechanisms including intralaminar damage and interlaminar delamination as well as their interactions. Furthermore, localized damage that means high-gradient strain, severe damage, and spurious energy dissipation occur at a narrow area, leading to the ill-posedness of stress boundary value problem and the spurious mesh dependency using finite element analysis (FEA). This paper develops a unified progressive failure model for predicting both localized intralaminar damage and interlaminar delamination of composite laminates. Numerical algorithm using FEA is developed using ABAQUS-UEL (user element subroutine), UMAT (user material subroutine), USDFLD (user-defined field subroutine), and UEXTERNALDB (user external data utility) for notched composite laminates under tension. The localization issue is solved by introducing the nonlocal integral theory and the mesh sensitivity issue is eliminated by discussing the effects of the hole radius and layup patterns on the load responses of composites.