In a strained body, the three principal stresses at a point are denoted by σ1,σ2andσ3 such that σ1>σ2>σ3.. If σ0 denoted yield stress, then according to the maximum shear stress theory
σ1−σ3=σ0
Max[(σ1−σ22),(σ2−σ32),(σ3−σ12)]≤σ02
Given that σ1>σ2>σ3
σ1−σ32=σ02