Question

A hollow circular shaft of inner radius 10 mm outer radius 20 mm and length 1 m is to be used as a torsional spring. If the shear modulus of the material of the shaft is 150 GPa, the torsional stiffness of the shaft (in kN-m/rad) is _______ (correct to two decimal places).

• A. 35.343

Answer 1

The correct option is A 35.343
Torsional stiffness

$=\frac{G{I}_p}{L}$

$=\frac{150\times {10}^9\times \frac{\pi }{32}[{0.04}^4-{0.02}^4]}{1}$

=35343 Nm/rad

=35.343 kNm/rad