Torsion test machine design

Higher Colleges of Technology, Abu Dhabi

June 5
Design
Torsion
Machine 2011
By
Waleed Alyafee Torsion Test for
Khaled Alhosani MTRX322
Mohed Khalfan Engineering
Darweish Ali design
Mechanical engineering students.
for contacts: ggc@windowslive.com

Design Torsion Machine 2011

1 Contents
1. Introduction ....................................................................................... 4
1.1 Objectives .................................................................................... 4
1.2 THEORY ..................................................................................... 4
2 Morphological charts of torsion testing machine ................................ 5
2.1 Brain storming ............................................................................. 6
3 Maintenance ......................................................................................... 7
3.1 Calibrating a Torque Wrench ...................................................... 7
3.2 Calibrating a laser distance sensor .............................................. 7
3.3 Lubricating the gear ..................................................................... 8
4 Method used to select design method. ................................................. 9
4.1 Date used for design .................................................................. 10
5 Main part and function table .............................................................. 13
6 Device used for measurement ............................................................ 15
6.1 Torque ........................................................................................ 15
6.2 Measuring the angle. ................................................................. 16
6.3 Specification of laser sensor ...................................................... 20
6.4 Griping device to hold specimen ............................................... 20
7 Material selection ............................................................................... 22
8 Ease of safe operation ........................................................................ 24
8.1 Equipment and Clothing ............................................................ 24
8.2 Surrounding Area ...................................................................... 24
8.3 Starting a Machine ..................................................................... 24
2
8.4 Operating a Machine ................................................................. 25
9 Machine summary .............................................................................. 26

MTRX-322 | HTC, Abu Dhabi


10 References ....................................................................................... 27

3



1. Introduction

In structural design, torsional moment may, on occasion, be a significant force for which
provision must be made. The most efficient shape for carrying a torque is a hollow circular shaft;
extensive treatment of torsion and torsion combined with bending and axial force is to be found
in most texts on mechanics of materials.
When a simple circular solid shaft is twisted, the shearing stress at any point on a transverse
cross-section varies directly as the distance from the center of the shaft. Thus, during twisting,
the cross-section which is initially planar remains a plane and rotates only about the axis of the
shaft.
Torsion members are frequently encountered in structures and machines. A structural member
may need to resist torques induced by a load, such as wind or gravity. Machinery examples
include motor vehicle drive shafts, torsion bar suspensions, ship propeller shafts, and centrifugal
pump shafts. In the analysis of torsionally loaded members, we are primarily concerned with the
torsion stress and the angle of twist on the shaft. In our laboratory experiment, the primary
emphasis is on the recognition of torsion on the usual structural members, how the torsion
stresses may be approximated and how such members may be selected to resist torsion effects.

1.1 Objectives

The torsion test is used the most to evaluate the shear forces and resultant stresses on the circular
bar. This test demonstrates the state of pure shear stress in the rod twisted. Based on Mechanics
of Materials, equations to evaluate the different mechanical properties of metals were used in this
machine design. By experimental mechanics, the torsion state of the specimen was obtained to
measure the different mechanical properties such as the yield shear stress, the ultimate shear
stress, and the shear modulus. Analysis provides cognitive relations between shear strain and
toque. In this report the design layout and the concept of torsion machine design are included in
this report. Laboratory, specimens in torsion were subjected to force applied. After the
measurement, different mechanical properties were determined from the equation based on the
Mechanics of Materials. Analytical results based on the three different methods were compared
to the data measured during the experiment.

1.2 THEORY

From the general torsion theory for a circular specimen.

T G  
 
J L r
Where,
4
T = Applied Torque ……………………………………… Nm or lbf in



J = Polar second moment of area………………………… mm 4 or in 4

N lbf
G = Modulus of rigidity …………………………………. or
mm 2
in 2

 = Angle if twist (over length L)……………………….. Radians

 = Shear stress at radius „r‟……………………………
N
or
lbf
mm 2
in 2

r = radius…………………………………………………. mm or in

2 Morphological charts of torsion testing machine

Torsion Test Machine Concepts
Function Possible Solutions
Torque Motor Moment Arm Torque Wrench Socket Extension
Application
Torque Main shaft Specimen grip Torque cell Friction
measurements holders
Angel of Twist Crank angle Boom angle Rack and pinion Absolute position
Application sensor sensor gear with laser angel sensor
distance sensor
Angel of Twist Pinion gear laser distance Rack gear Distance used
Measurement sensor
Polar second Body resistance to shape Mass Reference axis
moment of area torsion
measurements

5



2.1 Brain storming

6



3 Maintenance
3.1 Calibrating a Torque Wrench

 Step 1 – Marking Points
Use a pencil or marker to mark the center point of the
wrench head on the back of the torque wrench.
 Step 2 – Taking the Measurements
Next, take the measurements. Measure the center point to
the point where you apply the most pressure when you
use the wrench. Write this measurement down as
'distance one'. If the wrench measures in inch pounds,
write down this measurement in inches as 'distance one'.
If the wrench measures in feet pounds, write down the distance measurement in feet.
 Step 3 – Using the Weights
Use the vise to horizontally clamp the wrench bit. Hang a twenty pound weight from the wrench
handle using the string.
 Step 4 – Total Measurements
Move the weight along the wrench handle until it measures at 40 foot pounds or 480-inch
pounds. Measure the distance from the center point on the wrench head to the string and write
this measurement down as "distance 2."
 Step 5 – Calibration Ratio
Using a calculator, divide distance 2 by distance 1 and this will give you the calibration ratio.
The ratio is the difference between the wrench settings and the force needed to get a “click” at
that setting.
 Step 6 – Setting Torque Wrench
Set your torque wrench for a specific application. You can do this by taking the torque of the bolt
and multiplying the required torque of the bolt by the calibration ratio.
Torque wrenches should be calibrated annually. Expect this to cost about $25 to $35 if you take
your torque wrench to a decent shop to be calibrated properly. You can purchase a digital adapter
for torque which lets you calibrate the wrench yourself. The digital torque costs around $50.
Adjustment and repair of the torque wrench usually runs around $15 per quarter hour.
 Step 7 - Storage
Keep the torque wrench lubricated and clean. After each use, always turn the scale back to zero
to prevent the spring inside the wrench from setting and causing the calibration to drift. The
torque wrench is the only practical way to measure bolt tension. Proper maintenance ensures a
longer life for the torque wrench.

3.2 Calibrating a laser distance sensor

 Step1
Switch on the calibration power meter and place it on an optical bench. The calibration power
meter will come with a broadband light source which is guided through an optical fiber. Once 7
switched on, the calibrated power of the light source will be displayed on its display.
 Step 2



Place the optical fiber from the calibration meter into the sensor of the laser meter, and take note
of the measured power on both devices. The power displayed will be measured in Watts (W) or
milli-Watts (mW).
 Step 3
Determine the calibration factor by dividing the value displayed on the calibration power meter
by the number shown on the laser meter. The laser meter has now been calibrated and can be
used on other light sources to determine the power. The measured power now needs to be
multiplied by the calibration factor determined above to obtain the correct value.

3.3 Lubricating the gear

When used in a gearbox the lubricant provides two primary two benefits: to lubricate the teeth
and to remove heat generated from the gear operation. The lubricant is also often used for
lubricating the various bearing found in the gearbox. If the correct lubricant is selected for use in
a gear system it will provide slip-free power transmission at high mechanical efficiency, with
good reliability, low maintenance, and long life.
To meet the lubrication needs of modern enclosed industrial gear drives, a gear lubricant
must possess the following key performance properties:
Thermal and oxidative stability

Thermal durability

Compatibility with seal materials

Protection against excessive gear and bearing wear

High-temperature extreme pressure protection (EP gear oils)

Gear and bearing cleanliness

Emulsibility characteristics

Rust and corrosion protection, especially to yellow metal components

Antifoaming characteristics
Grease Lubrication:

Grease lubrication is suitable for any gear system that is open or enclosed, so long as it
runs at low speed. The grease should have a suitable viscosity with good fluidity
especially in an enclosed gear unit. Grease is not suitable for high loads and continuous
operation and there is virtually not cooling effect. The must be sufficient grease to ensure
the gear teeth are lubricated but an excess can result in viscous drag and power losses. 8



4 Method used to select design method.

Method used for measuring the angle Total
selection of group member with score of 5
Khaled Darweish Mohamed Waleed
Digital 2 5 4 1 11
angle
sensor
protractor 2 2 2 2 8
Use rack 5 3 4 4 16
and pinion
with laser
sensor

Method used for measuring the torque Total
selection of group member with score of 5
Khaled Darweish Mohamed Waleed
Torque 3 5 5 5 18
wrench
Strain gauge 4 2 2 2 12
Pulley and 3 3 3 2 11
weight
From that we decided to use rack and pinion and laser sensor to measure the angle. And the
torque wrench as a driver mechanism and to indicate the torque.

9



4.1 Date used for design

To find out what is maximum torque will be required and how much rotation will be resultant
from the testing of material, we should study and apply the equation to find the angle of twist of
each material and required torque
Table 2: Shear strength and shear modulus for selected materials
material shear strength MPa modulus of rigidity GPa
96% alumina 330
304 stainless steel 186 73
Copper 42-220 44
Aluminum 30-483 26
Sn63 solder 28860 6
epoxy resin 10 – 40

Looking to the table 2 in more details we can find that if we compare steel, copper and
Aluminum we can find that 304 steel has the higher of Modulus rigidity with 73 Gpa.

From that we can indicate the larger torque will be required for our design.

To calculate the J value we should use the following equation
= 981.7477mm4
So from that we can notes that J ,r and L are same for all specimens J is 981.7477mm4 r= 5 mm
and L= 200

We can calculate the to find the unknowing data such as angle of twist and torque
for steel is =3.72 N/m3
for cooper is =8.4 N/m3
for aluminum is =6 N/m3

by having the value of
=that will give us angle of twist

= 0.102 rad
=0.1326 rad=7.59 degree
10
=0.0381 rad
=0.199644 rad=11.439 degree



=0.046 rad
=0.7406 rad=42.433 degree

To measure the torque the following equation is used.

That give us

Since J are same for 10 mm diameter rod =981.7477mm4= 9.817 m4
Torque required for steel is
= N/m3 9.817 m4=36.5 N.m
TUS=TY =48.545 N.m

Torque required for copper is
= N/m3 9.817 m4= 8.24628 N.m
TUS=TY =43.2 N.m

Torque required for aluminum is
= N/m3 9.817 m4= 5.89 N.m
TUS=TY =94.829 N.m

11



From the calculation we can determine the required specification for our machine in rigidity
modulus state, ultimate state and maximum as it mention in the following table.
Specification Amount
Specimen diameter 10 mm
Specimen length 200 mm
torque (yield) 36.5 N.m
Angle of twist (yield) 0.102 rad =5.84 degree
Torque (ultimate) 94.829 N.m
Angle of twist(ultimate) aluminum 0.7406 42.433 degree
Safety factor 3
Max angle of twist=42.433 * 3 127.299 N.m
ANG ultimate * SF
Max Torque =94.829 * 3 284.5 N.m
T ultimate * SF

12



5 Main part and function table

Component Name Function Picture
Frame To hold and carry
the weight of all
component

Safety guard To protect from
injury due to break
of metal

Torque wrench  To generate
enough
torsion
force to
twist the
material.
 To measure
the torque

13



Drill chock To hold the
specimen in both
the moving end and
fixed end

Rack and pinion To change the
gear rotary motion of the
shaft in to linear
motion to measure
the angle of twist

Laser distance To measure the
sensor displacement of the
rack gear to
represent the angle
of twist

14



6 Device used for measurement
6.1 Torque
By using the torque wrench we can determine the
applied torque wrench.

Electronic Torque Wrench
Price: $199

4 Models
DTW-265i - 265 in-lb / 30 N-m - 1/4" Drive
DTW-1200i - 1200 in-lb / 145 N-m - 3/8" Drive
DTW-100f - 100 ft-lb / 145 N-m - 1/2" Drive
DTW-250f - 250 ft-lb / 340 N-m - 1/2" Drive

The new Check-Line DTW Electronic Torque
Wrenches are designed for simple and precise
measurement of industrial, automotive, aerospace and
many other applications. The DTW displays
Real-Time and Peak torque on a large LCD
display in ft-lb, in-lb or N-m, user selectable.

The DTW features a target set point that
indicates a desired torque value with a bright
LED and audible beep.

15



6.2 Measuring the angle.
By converting the rotating motion of
twist to linear motion, we can
measure the angle of twist. This done
by calculation how much will be
resulted in linear motion when full
turn of twist is there.
To do so rack and pinion gear is
used. the size of pinion diameter is
50mm then the movement of one
rotation is π×D 157mm. and we need
at least to make 5 rotation. Therefore,
the diameter should be less than 50.
we can find other pinion gear with
diameter of 20 mm then the
movement of one rotation is π×D
=62.8mm . from that we can notes
each 1 mm movement rack gear
mean that the pinion rotate 5.73 degree. On other hand. To
read 0.5 degree rotation of twist, the rack should move 0.09
mm which is close to 0.1mm. the total linear motion will be
62.8×6 =376.8. the device used to measure the rotation can
be laser sensor.

The following picture show the idea of using laser sensor to
know the angle of twist

16



The diametric pitch is number of teeth divided by the pitch diameter.
The pitch diameter we have is 20mm
From table 8-3 standard modules we find the following

17



We selected module 0.3 mm because it has fine tooth for precise operation. Our diameter is 20
mm 0.8 inch then the number IS 80/inch *0.8 = 64 teeth.
Pitch size equal circular/ number of teeth 62/ 64 =0.98 mm
The length for the rack is circular * number of turn.
= 62.8 * 5 = 314 mm
18
Then the number of teeth is equal length/ pitch = 314/ 0.98 =320 teeth.



The following is an example shows example of calculation

19



6.3 Specification of laser sensor

The MRL-ML1 is a short range laser measurement sensor from
Metrology Resource Co. with an accuracy of ± 3.0mm @ 2
SIGMA and a range of 0.05m to 30m.

The MRL-ML1 Laser Distance Sensors are the new generation of
MRC devices that are compact and robust distance measuring
modules designed to meet the demands of the industrial
measurement market.

Principles of Operation

The MRL3 device is a phase shift laser measurement device that
compares the outgoing and returning wave signals to determine the distance to a target. These
frequency waves are timed to an internal clock to measure the time it takes for the laser light to
go out and return to the sensor. This phase shift is often calibrated based on ambient lighting
conditions and temperature.

6.4 Griping device to hold specimen
A drill chock can be used for this purpose. Of drill
chock will be fixed to the rotating shaft with pinion
gear and torque wrench. The other one will be not
rotating fixed on the other side on the frame.

20



The following diagram shows the assembly of identified part on the top

Assume that the rack gear has moved 10 mm linearly what is the angle of twist. by knowing that
the circumference of the pinion is 62.8 mm. That represent 3600 then the 10mm displacement is
0

21



7 Material selection

Name Material size Estimated cost
Guiding rod Polished stainless 1.25m*Ð10mm 80 Dhs
4 pieces

Rock and pinion Nylon Pinion Ð=20mm pinion20 Dhs
Rack length≥70mm Rackk 40Dhs

Laser sensor Plastic Should measure more 200 Dhs
than 70mm

Frame Aluminum ,10 mm 1500mm long ,100 mm 2f by 8ft
sheet height and 100mm 165Dhs
width
Drill chock steel 5mm to 25mm 70 Dhs

Digital torque Steel 0-300 N.m torque 730Dhs
wrench rating

The following graph shows a comparison between the young‟s modulus with the density. The
material with higher density the higher mass .Although the wood and polymers are in the low
density area, they have low young‟s modulus value. Therefore composite and metal can be used
as strong material compare with the density.

22



The following graph illustrates property of material comparing the strength of material with its
price.

The graph indicated that the composites materials are more expensive than metal. Moreover 23
metal can be used for application used higher load than in composite



The following graph show the strength of metal and alloy Vs the cost.

As it can be seen from metal and alloy, high allow steel has maximum strength of 3000 MPa
with cost of 8 euro per kilogram. However mild steel has strength of more than 100 Mpa with
cost of 0.5 euro per kilogram.

8 Ease of safe operation
8.1 Equipment and Clothing
Avoid wearing long flowing clothes. Tie up long hair. Wear protective equipment such as a dust
mask, gloves, eye protection, ear mufflers, jacket and boots that provide good grip on the floor.

8.2 Surrounding Area
Make sure the area around the machine is free of clutter and you have sufficient space to work.
Do not work in poorly lit conditions or in positions that are uncomfortable to you. Notify a
supervisor of such problems promptly. The machine must be positioned on a stable surface and
must be a suitable distance away from you. Position yourself in a comfortable manner so that
you do not have to reach out or bend.

8.3 Starting a Machine
Before starting a machine, check the machine guards and ensure they all fit and are in place.
Ensure that any keys or wrenches are removed so they do not fly out and hit you or another 24
person nearby. Never operate a machine if you notice loose parts, unusual sounds or vibrations.
To avoid electric shocks, you must ensure that the machine is properly grounded.



8.4 Operating a Machine
Never let yourself be distracted from the task at hand. If somebody interrupts you, turn off the
machine before you start a conversation. Never interrupt or startle a co-worker who is handling a
machine. Always use feeding and holding tools to push objects toward the machine or to clamp
them in place. Never attempt to remove a blockage or stalled part without first turning the
machine off and putting the safety locks in place. You must never leave a machine unattended
without turning it off.

25



9 Machine summary

Parameter Value
Max torque 300 N.m
Max angle of twist 18000 equal to 5 turn
Specimen diameter 10 mm diameter.
Specimen length 200 mm
Machine shape Vertical
Method of measuring angle of twist Rack and pinion with laser distance sensor
Number of teeth for pinion gear 64 teeth
Number of teeth on rack gear 329 teeth
Pitch size 0.98mm
Pitch diameter 20 mm
Method of measuring torque Using digital torque wrench

26



10 References

1. http://www.ehow.com/list_7159565_safe-operating-procedures-machinery.html
2. http://www.ehow.com/search.html?q=Calibrating+a+Torque+Wrench%3A&skin=health
&t=all
3. http://www.ehow.com/search.html?q=Calibrating+a+laser+distance+sensor&skin=health
&t=all
4. Book: Machine Elements in Mechanical Design , Fourth Edition , Writer, Robert L. Mott
5. www.roymech.co.uk/Useful_Tables/.../Gears.html
6. www.econobelt.com/Q460/PDF/Pg_4-005.pdf
7. http://www-g.eng.cam.ac.uk/125/now/mfs/tutorial/non_IE/charts.html
8. http://abduh137.wordpress.com/category/material-selection/
9. http://news.thomasnet.com/news/portable-tools/fastening-tools/wrenches/manual-torque-
wrenches/40
10. http://www.ferret.com.au/c/Rockwell-Automation/Laser-distance-measurement-sensors-
from-Rockwell-Automation-n735657

27


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