1. Two aluminium strips and a steel strip are to be bonded together to form a composite bar. The modulus of elasticity of steel is 200 GPa and 75 GPa for aluminium. The allowable normal stress in steel is 220 MPa and 100 MPa in aluminium. Determine the largest permissible bending moment when the composite bar is bent about horizontal axis. a

1.933 KN-M

Explanation:

Determine the largest permissible bending moment when the composite bar is bent  horizontally

Given data :

modulus of elasticity of steel = 200 GPa

modulus of elasticity of aluminum = 75 GPa

Allowable stress for steel = 220 MPa

Allowable stress for Aluminum = 100 MPa

a = 10 mm

First step

determine moment of resistance when steel reaches its max permissible stress

next : determine moment of resistance when Aluminum reaches its max permissible stress

Finally Largest permissible bending moment of the composite Bar = 1.933 KN-M

attached below is a detailed solution