Torsion Testing

Topics: Shear stress, Shear strength, Tensile strength Pages: 7 (1684 words) Published: April 18, 2011
Torsion Testing
Sharmini Jegachandra Mohan
Group members
Cheok Jia Shiung
Sameer Razi Ansari
Yeap Dee Ken
Cynthia Gan Xin Lin
School of Engineering
Taylor’s University
Date of Experiment: 30.03.2011|
Report due date: 6.04.2011|
Report submission date: 6.04.2011|
Checked by:|

Item/marks| |
Format/10| |
Abstract and Introduction/10| |
Figures and Diagrams/15| |
Materials and Method/10| |
Results & Discussion/45| |
References/10| |
Total| |

30th March 2011

Table of Contents
1) Introduction1
2) Experiment Design2
* Apparatus2
* Methods2
* Procedure2
3) Results & Discussion
* Table and discussion3
* Graph and discussion 4-6
4) Conclusions & Recommendations6-7
References 7

This experiment highlights the procedure to determine such properties as modulus of elasticity in shear and the torsion yield strength. During the experiment, aluminium and mild steel was used to demonstrate how the materials behave during the testing condition. By measuring the applied torque with respect to the angle of twist, the Torsional rigidity (GJ), the Modulus of Rigidity (G) and the shear yield stress (τ) for ductile materials, mild steel and aluminium. INTRODUCTION

The purpose of this experiment is to study and to compare the behaviour of ductile and brittle materials under torsion. This experiment is done using the torsion testing machine. The torsion apparatus used in this experiment has a diameter of 6mm with hexagonal ends. This experiment also serves to calculate the Torsional rigidity (GJ), the Modulus of Rigidity (G) and the shear yield stress (τ) for ductile materials, mild steel and aluminium. The modulus of rigid (G) serves as the ultimate goal, can be found by G = T.lJ∅ ,

where T is the applied torque (N.m),l is the length of object the torque being applied and ∅ is the angle of twist in radian. J is the polar moment of inertia. The value of J can be found using J = 132πd4 ,

where d is the diameter of the cross-sectional area.
The maximum shear stress, τ can be expressed and found by
τ = T.RJ

Deflection arm
Input shaft
Hexagonal sockets
Torque shaft
Input handwheel
Torquemeter output socket
Locking screws
Dial gauge
Levelling hand wheel

Figure 1: Torsion Testing Machine [1]
1) Aluminium and mild steel
2) Torsion Testing Equipment
In this experiment, the specimen (aluminium or the mild steel) was secured to the torsion testing equipment. One end of the specimen was twisted by applying a rotational torque while the other end of the specimen was kept straight in a horizontal motion by attaching it to the arm structure that is calibrated to read the torque applied. The control used to generate the twisting was used to balance the arm and torque gage. When the apparatus was set to read zero degrees twist and torque, the angle of twist can be induced. PROCEDURE

The mild steel specimen was secured to the loading device on the torsion testing machine. It was ensured that there was no preload on the specimen. The hand wheel at the input worm gear was calibrated until the read out at the amplifier is zero before the experiment was started. Both indicators at the input and the output shaft of the gear were set to zero reading. The dial gauge of the compensation unit was also set to zero. Revolution counter is then reset. To record the reading, the hand wheel is turned through 90º and the value from the worm gear input and the torque value from the digital meter were recorded. The steps were repeated until 1080º and then the rotation of the hand wheel is continued until fracture. The number of resolution and maximum torque applied was recorded. Same procedure was applied for aluminium and...
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