Predictions of tensile behavior and strengths of a Si(sub 3)N(sub 4) ceramic at high temperatures based on a viscoplastic model

摘要

Tensile deformation and rupture behavior were simulated using a viscoplastic model developed recently. The model was formulated based on the state variable approach, which provides flexibility and versatility for characterizing the time-dependent behavior of ceramic materials under general thermomechanical loading conditions. Simulations portrayed by the model were compared with experimental tensile data obtained under two different tensile stressing rates. Results showed that the model was capable of simulating deformation behavior for all practical engineering purposes, but estimated high-temperature fracture strengths somewhat conservatively.