The maximum stress criterion assumes that a material fails when the maximum principal stress σ 1 {\displaystyle \sigma _{1}} in a material element exceeds the uniaxial tensile strength of the material. Alternatively, the material will fail if the minimum principal stress σ 3 {\displaystyle \sigma _{3}} is less than the uniaxial compressive strength of the material. If the uniaxial tensile strength of the material is σ t {\displaystyle \sigma _{t}} and the uniaxial compressive strength is σ c {\displaystyle \sigma _{c}} , then the safe region for the material is assumed to be