Research on Strain Rate-Dependent Tsai-Hill Strength Criterion for Ethylene Propylene Diene Monomer Film

Abstract

EPDM film is an innovative insulation material used in the Solid Rocket Motor. It is a kind of unidirectional single layer fiber-reinforced composite plate. To analyze its mechanical behavior uniaxial tests with different loading directions and rates were performed. The test results indicated that the EPDM film is anisotropic and its mechanical properties are obviously rate-dependent. To create a rate-dependent anisotropic strength criterion, two methods were adopted to extend the Tsai-Hill strength criterion; the first was to substitute all the strength components in the Tsai-Hill criterion with the fitted rate-dependent ones, the second was to introduce a special factor named the rate-dependency factor !(!) into the criterion. The second method is simpler in form and more suitable for an engineering application. The two rate-dependent criteria were examined by comparing the predicted results with the experimental ones, and the results showed good agreement which verified that the strength criteria were able to reveal the anisotropic rate-dependent properties of the EPDM film.