Predicting delamination of hybrid laminate via stress modification on interlaminar matrix layer

Abstract

Prediction of delamination in a hybrid laminate made of steel sheet and carbon fiber reinforced plastic (CFRP) plate has been simply achieved by modifying the stresses of an interlaminar matrix layer in between the sheet and the plate. The normal and shear stresses of the matrix layer are modified with two coefficients Khn and Khs, which are determined by the critical displacements corresponding to the peak loads applied to the double cantilever beam (DCB) and end‐notched flexure (ENF) tests on the hybrid laminate. Once the modified stresses of a matrix layer element attain a tensile or shear failure, it is deleted from an incremental finite element solution process, and delamination of the laminate in between the matrix layer is considered to occur. The whole load-deflection curves of the DCB and ENF tests, and the spring back induced delamination of the steel sheet in the hybrid laminate after a U-shape drawing have been simulated. All of the predicted results using the independent input data without any adjustment agree well with the measured counterparts, indicating that the stress modification method on interlaminar matrix layers is efficient for predicting delamination of a hybrid laminate. The method can be applicable to the analysis of any interlaminar fracture or delamination of an arbitrary laminated structure, as long as the laminate is adhered from individual layers using the matrix or thin adhesive films.