Maximum Shear Stress
Definition
The largest shear stress that occurs at a point, equal to half the difference between maximum and minimum principal stresses: τ_max = (σ₁ - σ₂)/2. On Mohr's Circle, it equals the circle radius.
Practical Note
Maximum shear stress occurs on planes at 45° to principal planes. The Tresca yield criterion uses this value: yielding occurs when τ_max reaches the shear yield strength.