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MT-204 / ROBO-240 Lab
FILL OUT THIS SECTION IN PEN
Course Code and Section _________________
Name ______________________________ Student Number _______________
Attendance for Part A (dd/mm/yy) ___ /___ /___ Lab Instructor’s signature ______________
Attendance for Part B (dd/mm/yy) ___ /___ /___ Lab Instructor’s signature ______________
TORSION TEST
OBJECTIVE
To experimentally determine the angle of twist due to torsion, for a circular (round) steel shaft using
different shaft diameters and different shaft lengths, then to compare the experimental angles of twist with
the theoretically predicted angles.
PART A – TORSION TESTING OF CIRCULAR SHAFTS
1- Turn ON the Torsion Tester and install a steel shaft with a diameter D = 4.6 mm and
a free length L = 300 mm.
2- With no weight mounted on the hanger, zero the angle of twist indicator.
3- Mount a 10-N weight on the hanger and record the angle of twist, to the nearest 0.1°, in the given table,
noting that the lever arm radius for calculating the torsional moment, or torque, is 100 mm.
4- Repeat Step 3 increasing the mounted weight as indicated in the given table, until the maximum
allowable angle of twist of 9°, built into the tester, or the maximum weight of 60 N, is reached.
5- Repeat Steps 1 to 4 using steel shafts having D = 6.3 mm with L = 300 mm, D = 7.9 mm
with L = 300 mm, and D = 6.3 mm with L = 600 mm.
Experimental Angle of Twist ϕ (°)
Weight (N) Torque (N.mm)
D = 4.6 mm
L = 300 mm
D = 6.3 mm
L = 300 mm
D = 7.9 mm
L = 300 mm
D = 6.3 mm
L = 600 mm
10
1000
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20
2000
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30
3000
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40
4000
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50
5000
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60
6000
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PART B – ANALYSIS OF THE RESULTS
1- Using the following graph (with labelled axes) plot the experimental angle of twist ϕ versus the torsional
moment, or torque T, for the three shafts with L = 300 mm, using dark crosses (+) to indicate the actual
data points; label each set of data points according to its shaft diameter, “D = - - - mm”.
(30 points)
2- Using the following graph (with labelled axes) plot the experimental angle of twist ϕ versus the torsional
moment, or torque T, for the two shafts with D = 6.3 mm, using dark crosses (+) to indicate the actual
data points; label each set of data points according to its shaft length, “L = - - - mm”.
(30 points)
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3- Using the following theoretical relationship, determine the theoretical relationship between the angle of
twist ϕ versus the torsional moment, or torque T, by first calculating the torque, to the nearest 50 N.mm,
required for an angle of twist of 3°, converted to radians, for the four shafts
(15 points)
φ=
ϕ:
T:
L:
G:
TL
GJ
Angle of twist in radians (1 rad = 57.3°)
Torque in N.mm
Length of shaft in mm
Shear modulus, for steel G = 77 GPa = 77,000 MPa = 77,000 N/mm²
J : Polar moment of inertia J =
π
4
d 4 in mm .
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Theoretical Torque (N.mm) for an Angle of 3°
D = 4.6 mm
L = 300 mm
D = 6.3 mm
L = 300 mm
D = 7.9 mm
L = 300 mm
D = 6.3 mm
L = 600 mm
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4- Noting that the theoretical relationship indicates that ϕ is a linear function of T, plot in each of the two
previous graphs, the theoretical relationship, as a dashed line, by connecting the appropriate theoretical
torque at 3°, calculated in Step 3 of Part B, to the origin, extending each line to match the experimental
data points. (15 points)
5- By observing where the experimental data points are located relative to the theoretical line, comment on
the agreement between the experimental and theoretical relationships, in the space below. (10 points)
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