A square block of surface area A on all sides is under pure shear deformation due to the uniformly distributed load F on the top surface, as shown in the figure. The deformation of the block is such that the deformed coordinates can be written as
x1 = X1 + αX2, x2 = X2, x3 = X3
Calculate Cauchy stress and the first and second Piola-Kirchhoff stresses.
