Fracture Mechanics and Mechanisms of Impact-Induced Delamination in Laminated Composites

Abstract

The fracture mechanism of impact-induced delamination is studied in carbon fiber/PEEK (polyetheretherketone) cross-ply laminates under drop weight impact. The study is based on the energy theory of fracture mechanics and the concept of crack arrest toughness. The damaged laminate is modeled by a finite element method which simulates delaminations and transverse cracks. The numerical results are combined with test data to study the delamination behavior. It is found that the delamination occurs in a deflection-controlled condition and is a process of Mode II dominated unstable crack growth and subsequent arrest. The fracture behavior can be described by strain energy release rate and the delamination size is governed by the delamination arrest toughness of the composite.