torsion test machine design

Higher Colleges of Technology, Abu Dhabi

Design Torsion Machine

June 5

2011

Torsion Test for MTRX322 Engineering design

By

Waleed Alyafee Khaled Alhosani Mohed Khalfan Darweish Ali

Mechanical engineering students.

for contacts: [email protected]

Design Torsion Machine 2011

MTRX-322 | HTC, Abu Dhabi

2

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

8.4 Operating a Machine ................................................................. 25

9 Machine summary .............................................................................. 26



3

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



4

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.

rL

G

J

T

Where,

T = Applied Torque ……………………………………… Nm or lbf in



5

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

G = Modulus of rigidity ………………………………….2mm

N or

2in

lbf

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

= Shear stress at radius „r‟…………………………… 2mm

N or

2in

lbf

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

2 Morphological charts of torsion testing machine

Torsion Test Machine Concepts

Function Possible Solutions

Torque

Application

Motor Moment Arm Torque Wrench Socket Extension

Torque

measurements

Main shaft Specimen grip

holders

Torque cell Friction

Angel of Twist

Application

Crank angle

sensor

Boom angle

sensor

Rack and pinion

gear with laser

distance sensor

Absolute position

angel sensor

Angel of Twist

Measurement

Pinion gear laser distance

sensor

Rack gear Distance used

Polar second

moment of area

measurements

Body resistance to

torsion

shape Mass Reference axis



6

2.1 Brain storming



7

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

switched on, the calibrated power of the light source will be displayed on its display.

Step 2



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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:

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.

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



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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

angle

sensor

2 5 4 1 11

protractor 2 2 2 2 8

Use rack

and pinion

with laser

sensor

5 3 4 4 16

Method used for measuring the torque Total

selection of group member with score of 5

Khaled Darweish Mohamed Waleed

Torque

wrench

3 5 5 5 18

Strain gauge 4 2 2 2 12

Pulley and

weight

3 3 3 2 11

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.



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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

= 981.7477mm

4

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/m

3

for cooper is

=8.4 N/m

3

for aluminum is

=6 N/m

3

by having the value of

=that will give us angle of twist

= 0.102 rad

=0.1326 rad=7.59 degree

=0.0381 rad

=0.199644 rad=11.439 degree



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=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 m

4

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 m

4= 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



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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

ANG ultimate * SF

127.299 N.m

Max Torque =94.829 * 3

T ultimate * SF

284.5 N.m



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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

http://www.google.ae/imgres?imgurl=http://www.js-hybridlife.com/content/images/products/aluminum-frame/solar-aluminum-frame-kc9i0382.jpg&imgrefurl=http://www.js-hybridlife.com/products/solar-aluminum-frame.html&usg=__FCmAHWBWgFOKUQt8KM4iAP2ND24=&h=427&w=640&sz=32&hl=ar&start=18&zoom=1&tbnid=u5I9ZZ3L9X_vQM:&tbnh=141&tbnw=189&ei=Q_HjTYvOO4rCvgP6y-TNBg&prev=/search?q=aluminum+frame&um=1&hl=ar&biw=1259&bih=615&tbm=isch&um=1&itbs=1&iact=rc&dur=0&page=2&ndsp=18&ved=1t:429,r:15,s:18&tx=76&ty=89



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Drill chock To hold the

specimen in both

the moving end and

fixed end

Rack and pinion

gear

To change the

rotary motion of the

shaft in to linear

motion to measure

the angle of twist

Laser distance

sensor

To measure the

displacement of the

rack gear to

represent the angle

of twist



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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.



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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



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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



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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

Then the number of teeth is equal length/ pitch = 314/ 0.98 =320 teeth.



19

The following is an example shows example of calculation



20

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.



21

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



22

7 Material selection

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.

Name

Material

size

Estimated cost

Guiding rod Polished stainless 1.25m*Ð10mm

4 pieces

80 Dhs

Rock and pinion Nylon Pinion Ð=20mm

Rack length≥70mm

pinion20 Dhs

Rackk 40Dhs

Laser sensor Plastic Should measure more

than 70mm

200 Dhs

Frame Aluminum ,10 mm

sheet

1500mm long ,100 mm

height and 100mm

width

2f by 8ft

165Dhs

Drill chock steel 5mm to 25mm 70 Dhs

Digital torque

wrench

Steel 0-300 N.m torque

rating

730Dhs



23

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

metal can be used for application used higher load than in composite



24

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

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.



25

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.



26

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



27

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

http://www.ehow.com/list_7159565_safe-operating-procedures-machinery.html

http://www.ehow.com/search.html?q=Calibrating+a+Torque+Wrench%3A&skin=health&t=all

http://www.ehow.com/search.html?q=Calibrating+a+Torque+Wrench%3A&skin=health&t=all

http://www.ehow.com/search.html?q=Calibrating+a+laser+distance+sensor&skin=health&t=all

http://www.ehow.com/search.html?q=Calibrating+a+laser+distance+sensor&skin=health&t=all

http://www.roymech.co.uk/Useful_Tables/.../Gears.html

http://www.econobelt.com/Q460/PDF/Pg_4-005.pdf

http://www-g.eng.cam.ac.uk/125/now/mfs/tutorial/non_IE/charts.html

http://abduh137.wordpress.com/category/material-selection/

http://news.thomasnet.com/news/portable-tools/fastening-tools/wrenches/manual-torque-wrenches/40

http://news.thomasnet.com/news/portable-tools/fastening-tools/wrenches/manual-torque-wrenches/40

http://www.ferret.com.au/c/Rockwell-Automation/Laser-distance-measurement-sensors-from-Rockwell-Automation-n735657

http://www.ferret.com.au/c/Rockwell-Automation/Laser-distance-measurement-sensors-from-Rockwell-Automation-n735657

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