Aluminum and brass composite

Two aluminum strips are securely bonded to a 40 × 40-mm square brass section. The moduli of elasticity for the aluminum and brass materials are 70 GPa and 105 GPa, respectively.

Determine the largest moment about the z axis that can be applied to the composite bar if the allowable normal stress in the aluminum is 100 MPa and the allowable normal stress in the brass is 140 MPa.