Biaxial direct tensile tests in a large range of strain rates. Results on a ferritic nuclear steel

Constitutive equations are usually calibrated only trough the experimental results obtained by means of uniaxial tests because of the lack of adequate biaxial experimental data especially at high strain rate conditions. These data are however important for the validation of analytical models and als o for the predictions of mechanical behaviour of real structures subjected to multiaxial loading by numerical simulations. In this paper some developm ents are shown concerning biaxial cruciform specimens and different experim ental machines allowing biaxial tests in a large range of strain rates. This experimental campaign has also allowed study of the influence of chang ing the strain paths. Diagrams of equivalent stress versus straining direct ion and also equivalent plastic fracture strain versus straining direction are shown.