MecMovies 4.0 : M6.22: Maximum Torque Applied to Coaxial Shaft

Diagram shows a shaft A B with aluminum segment marked 1 of length 400 millimeters inside which is a brass shaft marked 2. Both the shafts are centered on the central axis x. A torque T is applied at B.

The procedure to solve this problem can be outlined as:

• Stress relationship
Expressions for shaft torques can be obtained from the elastic torsion formula. Substituting these expressions into the compatibility equation gives a relationship between the shear stresses in the shafts.

• Controlling shear stress
Using the relationship between shear stresses in the two shafts and the allowable stresses, the shaft that controls the design can be determined.

• Shaft torques
Once the shaft stresses are known, the internal torques $T_{1}$ and $T_{2}$ and the maximum external torque $T$ can be computed.