Course Number:
EMC 2043
Course Name :
Mechanics of Materials
Section:
Name
ID
1
2
3
Torsion Test
OBJECTIVES:
To carry out a torsion test to destruction in order to determine the following for a steel rod specimen:
1. To compare the experimental shear modulus (modulus of rigidity) with the tabulated values.
2. The maximum shear stress at the limit of proportionality or the proportional limit shear stress,
3. The general characteristics of the torque, angle of twist relationship.
The proportional limit shear stress: the highest shear stress that the material can withstand and still return to its original geometry is at the limit of the proportional portion of the graph and is known as the proportional limit shear stress.
REFERENCES:
1. Hibbeler, R. C. "Mechanics of Materials", Prentice-Hall, 7th Edition.
2. Instruction Bulletin of Tecquipment Ltd.
MATERIAL:
Mild Steel rod 6 mm diameter over 3" length (overall length including hexagon ends = 5⅝").
EQUIPMENT:
1. Torsion testing Machine and Torsiometer of Tecquipment Ltd.
2. Steel rule and micrometer.
THEORY:
(1)
(2)
(3)
Where,
G = Shear Modulus (GPa)
L = Length (m)
T = Torque (N.m)
J = Polar moment of inertia = Twist angle in radians
EXPERIMENTAL PROCEDURE:
1 Measure the overall length and test diameter of the specimen.
2 Draw a line down the length of the degree of the section of the specimen with a pencil this serves as a visual aid to the degree of twist being put on the specimen during loading.
3 Mount the specimen firmly in the Torsion Testing Machine as indicated in the operating instructions—see later.
If the Torsimeter is to be used the fixing procedure should be carried out as prescribed.
For each increment of strain record the following:
a) Angle of twist of the specimen () in degrees.
b) Applied torque (T)
c) When the elastic limit has been passed continue to test to destruction