Question

The solid shaft shown in Figure 5.1 is made of an aluminium alloy 6061-T6, assumed to be elastoplastic with G = 26 GPa and yield shear strength ty= 140 (a) i. The torque T required to initiate yielding The radius of elastic core if the torque T is increased 15% of case (1) Angle of twist at the free end to reach case (ii) (8 marks) 1.2 m 36 mm

Answer 1

1)Use the formula,

   equation (1)

Where

radius r=18 mm

Calculate the polar moment of inertia   

Now, from equation (1)

This is the torque required to initiate yielding.

(2)If the Torque is increased by 15% of case (1),

Using equation (1) to prevent yielding,

Solving one will get d=37.17 mm thus

radius r=d/2=18. 585 mm

(3) Finding the Angle of twist for the case (2)  

Use  

Solving we will get,

or