Compute the reduced stiffness q and compliance s matrices

Question

1. Define the plane stress assumption used in the context of laminated composite materials?

2. Compute the reduced stiffness [Q] and compliance [S] matrices, and the intralaminar shear stiffness [Q∗ ] and compliance [S ∗ ] matrices for a lamina with E₁ = 35 GP a, E₂ = 3.5 GP a, ν₁₂ = 0.3, G₁₂ = 1.75 GP a, G₂₃ = 0.35 GP a.