Three-Parameter Twin τ2 Strength Theory for Brittle Materials under Multiaxial Stress State and Its Application

The strength failure of brittle materials under complex stress is an important problem. Herein, we propose a novel three-parameter twin τ2 theory considering the influence hydrostatic pressure and normal on principal shear-stress surface, derive mathematical expression for theory, compare theoretical predictions several states with existing experimental data. results show that different ultimate ratios, α β, correspond to theories materials. σ1 increases gradually increase in σ2 (=σ3) state > = σ3; (=σ2) σ3 σ3. Furthermore, biaxial compressive considerably higher than uniaxial 0, 0. When fixed relatively small maximum increasing σ2. large as decreases σ2, effect law intermediate obtained.