An angle-ply laminate is a simple and basic component of many composite laminates, and the comprehensive understanding of its fracture behavior is of fundamental importance to the structural design and integrity of advanced fibrous composites.
Free edge delamination is one of the most frequently observed types of fracture in angle-ply laminates.
In this paper, the stability of delamination crack is investigated for angle-ply laminates subjected to uniform displacement and thermal loading. Due to the complexities of the problem, a quasi 3-dimensional finite element method is used to obtain strain energy release rates. The effect of parameters such as temperature change, loading type (tension/compression), stacking sequence, laminate width and laminate thickness are considered.
Some results of this study show that thicker laminates will delaminate at a lower strain level than thinner laminates. And the presence of thermal residual stresses prohibits the initiation and growth of delamination under tensile loading compared with compressive loading. The effect of delamination crack on the tensile strength of angle-ply laminates for small fiber orientation is evaluated by using a rule of mixtures and the energy release rate concept in classical fracture mechanics.
Finally, failure modes and tensile strengths were predicted and compared with experimental results. The predicted tensile strength for angle-ply lamitate with small fiber orientation agrees well with the experimental data which are approximately 30-40 percent belows the value predicted by a general failure criterion.
