Abstract
In the present study, an interlaminer fracture toughness of orthgonal CFRP laminates under mixed mode state is evaluated using 2-Dimensional boundary element analysis. MMB (Mixed Mode Bending) test are carried out to determine complex stress intensity factors which are definded on the interfrace crack between dissimilar orthotropic laminates. The complex stress intensity factors and mixed mode ratio are extrapolated from stress distribution around the crack tip, then fracture toughness on the interface are calculated by the critical load on the MMB test. It is shown that the fracture toughness of the orthogonal CFRP laminate depends on mode ratio of the stress intensity factors K_1 and K_2. The criterion of the delamination growth is discussed from a standpoint of the mode dependency of the fracture toughness.
