A rectangular block of a ductile metal is con?ned on two sides by a rigid die as shown in Figure. A uniform pressure p is applied to the upper surface of the block as shown. Derive an expression for the pressure p required to cause the material to yield in terms of the uniaxial yield stress SY and the elastic constants of the material E, ν. Assume that the contact between the block and the die is frictionless and that yield is governed by the maximum shear stress. Is your result signi?cantly in?uenced by Poisson's ratio?