A reduced-input cohesive zone model with regularized extended finite element method for fatigue analysis of laminated composites in Abaqus

Abstract

A cohesive zone model (CZM) for fatigue crack propagation was integrated within the Regularized eXtended Finite Element Method (Rx-FEM) discrete damage modeling framework. This CZM constitutive model, which is formulated in terms of S-N stress-life curves rather than the more usual rates of crack propagation described with a Paris law, can predict both crack initiation and propagation by relying on the intrinsic relationships between S-N and the Paris law. This feature of the model is of significant practical interest since S-N curves can be synthesized with few parameters and simple engineering assumptions, while the experimental characterization of the Paris law parameters for all required stress ratios, mode mixities, and material interfaces in a composite structure is very difficult and often impractical. Used in combination with the Rx-FEM method, this CZM can predict mesh-independent crack networks in composite structures subjected to cyclic or quasi-static loads. The Rx-FEM methodology for fatigue damage was implemented in Abaqus using two superimposed sets of standard Abaqus elements to represent the enriched displacement field. The capabilities of the proposed methodology are demonstrated by comparing the experimental and predicted response of a mixed-mode bending (MMB) test, as well as a Clamped Tapered Beam (CTB) sub-element designed to study matrix crack initiation, delamination propagation, and subsequent delamination migration from one ply interface to another.