Consider biaxial stretch of an incompressible rectangular slab -L1/2

Consider biaxial stretch of an incompressible rectangular slab -Ll/2 Xl Ll/2 , - L2/2 S X2 L2/2; H/2 S X3 H/2, resulting from the application of forces f1 and f2 parallel to the directions Xl and respectively. The slab extends A1 and A2times in the directions Xl and respectively. Find the components of the strain gradient, FiJ, components of the strain tensor, Eij, components of the Cauchy, tij, first Piola-Kirchhoff , P}, and second Piola-Kirchhoff, S], stress tensors.