Delamination in composites: Non-linear effects

Abstract

This study explores the non-linear geometric effects on the displacements, stresses and strain energy release rates of delaminated composite specimens subjected to multi-axial loads. A numerical solution is obtained using an incremental finite element formulation in which large displacements and rotations, but small strains are assumed. An Updated Lagrangian formulation is adopted in the development of the finite element model. The stress field obtained is used with the crack closure technique to evaluate the total strain energy release rate as well as the three components: opening, shearing and twisting modes. Comparisons of non-linear and linear results are presented for tension cases to illustrate the effects of large deformations on the displacements, stresses and strain energy release rates.