Torsion Test

Submitted By:

Name: Ankit Suchanti Roll no: 10003013

Mechanical Engineering

Objective:

To familiarize oneself with torsion test technique and equipment and determine the values of maximum torque , ultimate shear strength and fracture strength for the given specimens.

Standard:

ASTM A938-07

Apparatus:

Torsion testing machine

Specimen:

Aluminium, Mild Steel, Stainless Steel, Brass, Grey cast iron

Schematic Diagram:

Figure shows a representtion of the torsion machine.

Movable Chuck Stationary (Rotating) Chuck

Specimen

Weights

Manual Control Board

Procedure:

1. Measure the diameter of the specimen rods using vernier callipers at three different points and take their mean as the mean diameter of the rod.

2. Measure the length of the rod.3. Next the software, TestXpert II is started on the computer attached to the machine.4. Switch on the main power supply.5. Turn on the UPS.6. Switch on the machine and establish the link between the machine and the computer.7. Now set the position of the rotating chuck to 180o.8. The lid of the machine is opened and the specimen is mounted in the chucks after

which the lid is closed and locked.9. Now set the torque initial value (if non zero) to zero.10. Now input the parameters of the specimen such as shape, diameter and length into the

software.11. Next set the rotation speed and ensure other settings before starting the test.12. Once the settings are done start the test and wait until the specimen breaks down.13. The software records the test results continuously over time and stops as soon as the

specimen breaks down.14. Then open the lid and remove the specimen and rstore the machine to default settings

for testing other specimens.

Observations:

Observations made during the test are as summarized in the table below.

Specimen D1(mm) D2(mm) D3(mm) D avg

(Order of performing the Exp.)

Experiment performed by:

Brass 7.08 7.08 7.1 7.086 1Nakul Nuwal

Stainless Steel 7.1 7.08 7.1 7.093 3Shubham Bhargav

Cast iron* 7.1 7.12 7.14 7.12 4Ankit Suchanti

Aluminum 7.04 7.06 7.02 7.04 2Shashank Agarwal

Mild Steel 7.08 7.06 7.06 7.066 5Dhwanil Shukla

* This experiment was performed by me.

The Test Report for all the specimen:

Calculations:

Ultimate Shear Strength (τmax) = MR/J =16M/pi(d3)Modulus of Rigidity (G) = ML/Jβ M is Torque appliedL is Length of specimenJ is Area moment of inertia ( πd4/32)β is angle of twist

Results:

The values of maximum torque, ultimate shear strength and fracture strength for the given specimens are:

Serial number

SpecimenMaximum

Torque(in Nm)

Ultimate Shear Strength (in MPa)

Fracture Strength

(in Nm)(mod)

1 Brass 16.54 236.87 10.63

2 Mild Steel 24.07 347.65 9.14

3 Aluminum 5.67 82.8 1.02

4 Grey Cast Iron 9.51 134.26 9.63

5 Stainless Steel 65.46 934.71 11.7

Discussion:

1. The breakage occurred only due to shear force applied.2. Cast Iron being brittle fractured in the least time and in the least strain angle.3. The application of torque was at a speed well below the prescribed maximum

speed(As per ASTM standard).4. The specimen fractured at its centre(roughly) making the result of the test valid.5. The fracture of brittle material and ductile material were completely different while

the fracure was parallel to its surface for ductile material, it was at 45 deg for brittle material.

Figure shows the difference in fracture for brittle(left) and ductile(right) material.