Prediction of failure envelopes and stress–strain curves of fiber composite laminates under triaxial loads: Comparison with experimental results

This paper represents the authors’ contribution to Part B of the second world wide failure exercise, in which the failure predictions and stress–strain curves of 12 test cases are compared with experimental data. The paper briefly reviews the methodology presented in second world wide failure exercise Part A, which includes a semi-analytical stress analysis model and Christensen’s failure criteria. A further development in this paper is to introduce a new failure criterion developed also by Christensen and the application of the criterion in conjunction with the stress model. These failure criteria have no adjustable parameters and only depend upon a minimal number of measurable failure properties. Comparisons between the theoretical predictions using different criteria and the experimental results provided by the second World-Wide Failure Exercise organizers are shown in diagrams. It appears that Christensen’s failure criteria for anisotropic fiber composite materials predict the failure strength satisfactorily in most of the test cases. Christensen’s Polynomial invariants theory compares also well with the experimental results. However, the layup-dependent strength properties required in the criterion are sometimes very difficult to evaluate without performing experimental tests.