Abstract :
This paper represents the authorʹs contribution to Part B of the worldwide failure exercise. An assessment is made of the correlation between the predictions, published in Part A, and experimental results provided for 14 test cases involving bi-axial initial and final failure envelopes and stress strain curves of various unidirectional and multidirectional laminates. The theory, implemented into a computer code, employs 3D failure criteria for UD laminae together with non-linear modelling of laminae and laminate. The criteria are based on the authorʹs Failure Mode Concept (FMC). Some simplifications of the failure criteria have been made and an improvement in the computer code so that large strains to failure may be captured. Special emphasis has been put on the difference between an isolated and an embedded UD lamina. The correlation between the predictions and the test data is very satisfactory for the UD laminae, and is generally satisfactory for the laminates, especially where Fibre Failure (FF) is the dominant mode, which is the case for well-designed (according to netting theory) laminates. Discrepancy between predictions and test data was largest for the±55° angleply glass/epoxy laminates and also in areas of large deformations (involving post failure progression beyond the occurrence of the various Inter Fibre Failure (IFF) modes). Further steps, including testing and modelling, are identified for achieving a better understanding of failure prediction.
