A piece of ductile metal is confined on two sides by a rigid die. A uniform compressive stress is applied to the surface of the metal.

A piece of ductile metal is confined on two sides by a rigid die. A uniform compressive stress is applied to the surface of the metal. Assume there is no friction between the metal and the die and also that the von Mises yield criterion applies. Determine, in terms of elastic constants and uniaxial yield strenght of the material, the value necessary to cause yielding