Procedure

1. Measure the overall length and the diameter at about three places and take the average value of the test specimen.

2. Draw a line down the length of the test section of the specimen with a chalk; this serves as a visual aid to the degree of twist being put on the specimen during loading.

3. Select the driving dogs to suit the size of the specimen and clamp it in the machine by means of a sliding spindle.

4. Choose the appropriate range by capacity change lever.

5. Set the maximum load pointer to zero.

6. Set the protector to zero for convenience and clamp it by means knurled screw.

7. Carry out straining by rotating the hand wheel in either direction.

8. Load the machine in suitable increments, taking note of the torque and the corresponding angle of twist.

9. Plot a graph between torque and angle of twist and calculate the value of G by using the following relation

   T/J = Gϴ/L
   

   Where
   T = Torque applied
   J = polar moment of inertia of the shaft = πd⁴/32
   C = rigidity modulus of the material
   ϴ = relative angle of twist in radians
   L = gauge length (length of the shaft over which the relative angle of twist is measured)
   

Virtual Procedure

1. Start the Experiment by clicking the play button.
2. Observe the torque applied by the rotating wheel on the rod.
3. As the simulation continues the different value of angle and torque is observerd.
4. A Graph is plotted between the angle-torque values observed.
5. The Experiment allows you to pause/play/restart the simulation to view the values of different parameters at every stage of simulation.

NOTE: There are various features available for the graphs such as zoom, etc. The function/feature of each icon above the graphs becomes visible upon hovering over the concerned icon.