Abstract

The purpose of the present study is the evaluation of the bending-twisting coupling effect in the analysis of the DCB test by means of the analytical determination of the energy release rate of angle-ply laminated composites. The aim is to extend a previous work done by the same authors to new laminate configurations. Angle-ply laminates with symmetrical arms are analyzed, since in this case the application of a bending moment by means of the piano hinges causes a torsional rotation in each of the arms. That torsion is prevented by the hinges, due to the configuration of the test. Therefore, there is a non-uniform load distribution applied by the hinges, whose resultant is the applied load P and the resultant moment is an unknown twisting moment mt, which prevents rotation at the point of application. The resolution of the resulting system of forces and moments allows obtaining analytically the energy release rate, and analyzing the terms due exclusively to the bending-twisting coupling.

Abstract

The “edge effect” problem in laminates is a redundant topic in the literature since the seventies because of its influence on the reduction of the laminate strength. In previous works analytic solutions for angle-ply and quasi-isotropic symmetric laminates were obtained. In this work, a new model for obtaining solutions in the general case of symmetric laminates is presented. It is based on a new assumed displacement field in which the transverse bending of the laminate is not constrained. An strategy for solving the system of differential equations is proposed, as well as different hypotheses for the boundary conditions. Different solutions for the interlaminar stresses can be derived from the proposed technique.