Assumptions made in deriving torsional formulas:

What are assumptions made in deriving torsional formulas?                                          

Sol.: The torsion equation is based on following assumptions:

1. The material of shaft is uniform throughout.

2. The shaft circular in section remains in circular after loading.

3. A plane section of shaft normal to the axis before loading remains  plane after torques have been applied.

4. The twist along length of shaft is uniform throughout.

5. The distance between any 2 normal cross-sections remains same after application of torque.

6. Maximum shear stress induced in shaft because of application of torque does not exceed the elastic limit value.