- The document discusses several failure criteria theories for predicting failure in materials including brittle and ductile materials. - Rankine's criteria and Mohr's criteria are based on maximum normal stresses and are applicable to brittle materials. Failure occurs when principal stresses reach ultimate tensile or compressive strengths. - Maximum shear stress and von Mises criteria predict failure in ductile materials based on limiting shear stresses and distortion energy. Failure occurs when maximum shear stresses or distortion energy equals values from uniaxial tension tests.