Failure strain and stress fields of a chopped glass-reinforced polyester under biaxial loading

We perform experimental tests to obtain biaxial stress states in a chopped glass-reinforced polyester composite, applying in-plane perpendicular tensile loads to cruciform specimens. Three different specimens’ geometries have been considered for obtaining adequate failure modes with different loading cases. The scope is to estimate the strain and the stress failure states by measuring with gages the strains developed in the central zone, where a plane stress state with zero shear component occurs. We develop numerical simulations using the Finite Element Method in order to achieve a better understanding of the behaviour of the cruciform specimens under loading and to compare the numerical results with the experimental data. Maximum stress, Maximum strain, Tsai-Hill and Tsai-Wu biaxial failure theories are evaluated for the assumption of isotropic behaviour and contrasted with the experimental results.