Torsion Test : Lab Report



Torsion Test : Lab Report

[pic]

Task:

The purpose of this experiment is using a Torsion Tester we set out to find the Modulus of Rigidity or Shear Modulus of the specimen being tested.

Specimen:

The specimen being tested today is a 6.35mm or ¼ inch metal rod approximately 720mm long.

Equipment:

The equipment being used for the test is a Torsion Tester, it has one fixed end that is holding the metal rod with a grub screw and does not rotate .The other end is fixed with a grubbing also but is free spinning with a pulley. It has string wound onto the pulley in the opposite direction that the torque is going to be applied , it also has a platform/carriage that is to house the weights that will be added with each measurement. The pulley end of the equipment also has a 360 degree readout that is to measure the difference in angle as the different weights that are applied, this readout measures in degree increments.

Procedure:

1- Measure diameter and length of rod, radius of pulley, mass and any other relevant data. Then we need to reset the angle.

2- Add mass and measure angle.

3- Repeat step 2 until enough measurements are taken to draw a graph.

Results:

|Mass (kg) |Angle in degrees |Angle in radians | Force (N) |

| 1.1 |7 |0.122 |10.791 |

|2.1 |13 |0.227 |20.601 |

|3.1 |19 |0.332 |30.411 |

|4.1 |25 |0.436 |40.221 |

|5.1 |30 |0.524 |50.031 |

| | | | |

Shear Modulus of 18.2 GPa was calculated.

Published Shear Modulus is 40 GPa

Conclusions:

It was noticed that after the first 1 kg weight was applied totaling 1.1 kg including the weight of the platform/carriage at 0.1 kg, the angular reading taken was 7 degrees, the next three times 1 kg weights were added and angular readings were taken, The angle had increased by 6 degrees with each weight increment. The final time weight was added it brought the total weight up to 5.1 kg, The last angular increment 6 degrees bringing all the weight to a total angle of 30 degrees. A conclusion made is that we probably didn’t take enough measurement as we should have, approximately 20 measurements should have probably been taken for a more accurate experiment.

Errors:

• The first error to be noted is the resolution or limitation of precision of the 360 degree readout that we have on the Torsion tester, it is measuring in whole degree increments, Therefore we could have a MPE of one degree divided by 2 or simply half a degree.

• There has also been rounding off with some of the calculations and or figures recorded which can also bring slight inaccuracy.

• There could have been better precision with measuring the overall length of the metal rod being tested.

• Absolute error = (0.0277mm) + (0.5mm) = +/- 0.5277mm

• Relative error = 0.5277/31.669 = 0.01666 or 01.666%

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download