Estimation of an Interlaminer Fracture Toughness for Orthogonal CFRP Laminate (Boundary Element Analysis of an Interface Crack between Dissimilar Orthotropic Material)

摘要

In the present study, an interlaminer fracture toughness of orthogonal CFRP (carbon fiber reinforced plastic) under mixed mode is evaluated using DCB (double cantilever beam), ENF (end notched flexure) and ELS (end loaded split) specimens. The fracture toughness of the delamination is determined by complex stress intensity factors which are defined on the interface crack between dissimilar orthotropic laminates. The complex stress intensity factors are extrapolated from stress distribution around the crack tip. Two dimensional deformation of the CFRP specimens is calculated numerically by the boundary element method with experimental results. It is shown that the fracture toughness of the orthogonal CFRP laminate depends on mode ratio of the stress intensity factors K and K_2 The criterion of the delamination growth and occurrence of the transverse crack are discussed from a standpoint of the mode dependency of the fracture toughness.