ENERGY RELEASE RATE OF LOCAL DELAMINATIONS IN COMPOSITE LAMINATES

摘要

The transverse-crack-tip delamination problem has been studied with the fracture mechanics approach. The problem is formulated by a higher order plate theory which considers both the transverse shear effect and thickness-stretch deformation in the analysis. The local delamination behavior of [+-25/90_n]_s graphite/epoxy laminates in simple tension is analyzed. A closed form of strain energy release rate has been derived by a path-independent J-integral. Critical stresses for local delamination onset and laminate failure stresses of laminates [+-25/90_n]_s (n = 1,2,3,4,6,8) are predicted and compared with the testing data. Results based on the present theory are in good agreement with the test data for laminates [+-25/90_n]s with n = 3,4,6,8.