Abstract: Under natural conditions, geomaterials under gravity usually exhibit transversely isotropic properties. In this study, a new failure criterion for transversely isotropic brittle materials has been developed. The derivation of this failure criterion is driven by the strain energy density, rather than a completely phenomenological approach. So the form of the failure criterion can be coordinated with elastic strain energy density. This coordination explain the terms in the failure criterion as well as those in the elasticity theory. Obtained by series expansion this new failure criterion includes five independent material parameters and five terms which can be coordinated with those of the elastic energy. These material parameters can be determined by corresponding independent test, and are not just fitting parameters. The shapes of the failure surface in the stress space and in the π-plane of the proposed criterion are compared with Tsai-Wu criterion. Although the derivation of the criterion is totally different, the comparison results show this failure criterion is similar to Tsai-Wu criterion. In addition, this failure criterion can be degenerated into the criterion suggested by Christensen for isotropic materials. Comparisons with three sets of experimental data are compared to illustrate the proposed criterion. the results illustrated the prediction ability of the criterion.

Key words: strength theory, transversely isotropy, failure criterion, elastic energy, brittle materials