The Plane Hydrostatic Test as a Means for Selecting Appropriate Failure Criteria in Fibre Composites

Abstract

Biaxial tests in anisotropic plates of composite materials do not provide a conclusive evidence for the selection of the appropriate version of the failure tensor polynomial criterion (FTP). On the other hand triaxial tests, which could be decisive, present difficulties and inaccuracies when anisotropic materials should be tested. It was shown in this paper that a simple biaxial hydrostatic test in the transverse isotropic plane of a transversely isotropic material constitutes an accurate technique to decide which version of the criterion is valid. It was proved that the anisotropy along the strong stress axis of the material increases considerably the differences in failure in the transverse isotropic plane between the various criteria and it constitutes a safe test for deciding the validity of the appropriate criterion. Tests in biaxial hydrostatic tension or compression with different composite materials indicated clearly the superiority of the elliptic paraboloid failure surface criterion (EPFS).