Torsion TEST lab 3 strenght lab PDF

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UNIVERSITI TEKNOLOGI MARA FAKULTI KEJURUTERAAN MEKANIKAL Program : Bachelor of Engineering (Hons) Mechanical (EM220/EM221) Course : Applied Mechanics Lab Code : MEC 424 Lecturer : DR Anizah Kalam Group : EMD4M6B MEC 424 - LABORATORY REPORTTITLE : TORSION TESTNo NAME STUDENT ID SIGNATURE1 MUHAMMAD HE...

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UNIVERSITI TEKNOLOGI MARA FAKULTI KEJURUTERAAN MEKANIKAL ___________________________________________________________________________ Program : Bachelor of Engineering (Hons) Mechanical (EM220/EM221) Course : Applied Mechanics Lab Code : MEC 424 Lecturer : DR Anizah Kalam Group : EMD4M6B2 ___________________________________________________________________________

MEC 424 - LABORATORY REPORT TITLE :

TORSION TEST

No

NAME

STUDENT ID

1

MUHAMMAD HELMI AMINULLAH BIN JELISUN

2019415632

NUR IZZAH SYAKIRAH BINTI SHAH FENNER KHAN

2019416466

3

NUR SABRINA BINTI ZULKIFLI

2019253066

4

NUR SYAFIQAH BINTI JAAFAR

2

LABORATORY SESSION

:

SIGNATURE

2019405402

16/4/2021

*By signing above you attest that you have contributed to this submission and confirm that all work you have REPORT SUBMISSION : 30/4/2021 contributed to this submission is your own work. Any suspicion of copying or plagiarism in this work will result in an investigation of academic misconduct and may result in a “0” on the work, an “F” in the course, or possibly more severe penalties.

Marking Scheme No

1

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Total

Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014

1. ABSTRACT A torsion test has been done is to determine the behaviour of a particular material when been under torsional forces because of applied moments causing shear stress about the axis. This experiment will be performed by applying a rotational motion or applying both axial forces until the material break. From that, we can determine some mechanical properties which are stress, strain, and Modulus of Rigidity. In this experiment, we use mild steel as the specimen to demonstrate how it behaves due to the torsional force that we exert on it. By measuring the relationship of torque and the angle of twist, we can determine the shear modulus, shear stress and failure types. We can conclude that not all deformation is elongational nor compressive. Stress and strain can be extended to inclined shearing or distortional effects. In the strength of the material, torsion is the twisting of an object due to applied torque.

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Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014

2. TABLE OF CONTENT

1.

ABSTRACT.......................................................................................................................................................1

2.

TABLE OF CONTENT......................................................................................................................................2

3.

LIST OF TABLES..............................................................................................................................................3

4.

LIST OF FIGURES............................................................................................................................................4

5.

INTRODUCTION..............................................................................................................................................5

6.

THEORY............................................................................................................................................................5

7.

EXPERIMENTAL PROCEDURES...................................................................................................................7 7.1.

Apparatus...................................................................................................................................................7

7.2.

Procedure...................................................................................................................................................7

8.

RESULTS...........................................................................................................................................................8

9.

DISCUSSIONS................................................................................................................................................15

10.

CONCLUSIONS..........................................................................................................................................18

REFERENCES..........................................................................................................................................................19 APPENDICES AND RAW DATA............................................................................................................................20

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Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014

3. LIST OF TABLES

Table 1 Data Given.......................................................................................................................9 Table 2 Raw Data........................................................................................................................21

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Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014

4. LIST OF FIGURES Figure 1 Applied Torque...............................................................................................................5 Figure 2 Torsion Test Machine.....................................................................................................7 Figure 3 Torque (Nm) vs Angle of Twist (Rad)............................................................................9 Figure 4 Shear Stress (MPa) Vs Shear Strain (Pa).....................................................................10

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Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014

5. INTRODUCTION

Torsion test is a type of mechanical testing that put the material under stress from angular displacement to test the properties of materials. The act of twisting or wrenching a body of material by exertion of forces tending to turn one end or part about the longitudinal axis while the other is held or turned in the opposite direction is called torsion. In many areas of engineering applications, materials are sometimes subjected to torsion in services, for example, driveshafts, axles and twisted drills. Moreover, structural applications such as bridges, springs, car bodies, aeroplane fuselages and boat hulls are randomly subjected to torsion. The materials used in this case should require not only adequate strength but also be able to withstand torque in operation. In torsion testing, twisting the longitudinal sample is placed in the torsion machine and been twisted until the long axis failure. The purpose of this test is to determine the properties of the material when put under torsional force by the applied moment that causes shear stress to the axis. The modulus of elasticity in shear, yield shear strength, and maximum shear stress is measured and calculated to prove the properties of the material.

6. THEORY

The most notable test that demonstrates the effects of shearing forces and resulting

Figure 1 Applied Torque

5

Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014

stresses are the torsion test of a solid circular bar or rod. This test generates a state of pure shear stress in the torsional loaded rod. Such a test is used to ascertain all the major shear properties of metal materials, i.e., the ultimate shear stress, the yield shear stress and the modulus of rigidity or shear modulus.

The applied torque (T) as shown in Figure 1, to the specimen and resulting deformation (angle of twist,) are measured during the torsion test. These results are converted to shear stress ( ) and shear strain( ) by the following respective equations:

= where c is the radius of the solid circular rod, Lo is the length over which the relative angle of twist is measured (this angle must be in radians) and J is the polar moment of inertia defined as follows: The shear modulus of elasticity is defined as the linear slope, of the shear stressshear strain relation, between zero shear stress and the proportional limit shear stress (defined below), i.e.,

This equation clearly states that the shear modulus, like Young’s modulus, is only valid for the linear elastic range of the material.

7. EXPERIMENTAL PROCEDURES 6

Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014

7.1. Apparatus

Figure 2 Torsion Test Machine

1. Torsion test machine 2. Torque meter 3. Vernier Caliper

7.2. Procedure 1. Measure the specimen size at several points and calculate the average diameter. Measure the overall length. 2. Fixed the specimen’s ends on the machine chuck and set all readings on the gauge to zero. Make sure that the specimen is not initially loaded. 3. Turn the handwheel clockwise to provide the applied load. The torque will be measured by a reference torsion rod and strain gauges and read from the torque meter. 4. For the first rotation choose an increment of a quarter rotation (90°), for the second and third rotation of a half rotation (180°) and the fourth And to 10 rotation of one rotation (360°).i.e (1 rotation 10 reading, 2 rotations 10 reading, 3 rotation until specimen break). 5. To calculate the angle of twist at the specimen divides the rotation at the input by the reduction of 62. Usually, a fracture will occur (for mild steel specimen) between 100 to 200 rotations. 6. Note that for each rotation of the handwheel, compensate the deformation on the specimen by turning the handwheel of the compensation unit, until the dial gauge returns to its initial value (zero) and then read the torque from the display. 8. RESULTS Type of Material: Mild Steel 7

Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014

Radians = Radius: 0.003 m Length: 0.084 m

Table 1 Data Given Angle of Rotation (Deg)

Revolutio n

Torque (Nm)

Angle of twist (Deg)

Angle of twist (Rad)

Shear Stress (MPa)

Shear Strain (Pa)

0 90 90 90 90 180 180 180 180 360 360 360 360 360 360 360 360 360 360 360 360 360 360 360 360 360 360 360 360 360 720

0 0.25 0.25 0.25 0.25 0.5 0.5 0.5 0.5 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2

0.00 0.20 0.95 2.60 5.05 10.35 15.40 18.65 20.45 22.00 22.80 22.95 22.65 22.70 22.80 22.85 22.75 22.75 22.60 22.70 22.70 22.75 22.80 22.80 22.80 22.80 22.80 22.80 22.80 22.80 22.75

0 1.45107 1.45107 1.45107 1.45107 2.90214 2.90214 2.90214 2.90214 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 5.80428 11.60856

0 0.025393725 0.025393725 0.025393725 0.025393725 0.05078745 0.05078745 0.05078745 0.05078745 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.1015749 0.2031498

0 4.715868899 22.40037727 61.30629568 119.0756897 244.0462155 363.1219052 439.7547748 482.1975949 518.7455789 537.6090545 541.1459561 534.0721528 535.25112 537.6090545 538.7880217 536.4300872 536.4300872 532.8931856 535.25112 535.25112 536.4300872 537.6090545 537.6090545 537.6090545 537.6090545 537.6090545 537.6090545 537.6090545 537.6090545 536.4300872

0 0.000906919 0.000906919 0.000906919 0.000906919 0.001813837 0.001813837 0.001813837 0.001813837 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.003627675 0.00725535

Polar Moment of Inertia, J

= 8

Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014

= 1.272

Sample Calculations

=

= 1.571 rad = = 0.02534 rad

Torque (Nm) vs Angle of Twist (Rad) 25

Torque (Nm)

20 15 10 5 0

0

3 3 5 5 .1 0.0 0.0 0.0 0.0 0

0.1 0.1 0.1

0.1 0.1

0.1 0.1 0.1

0.1 0.1

angle of twist (Rad)

Figure 3 Torque (Nm) vs Angle of Twist (Rad)

9

0.1 0.1

0.1

Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014

Shear Stress (Mpa) vs Shear Strain (Pa) 600

Shear stress (Mpa)

500 400 300 200 100 0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Shear Strain (Pa)

Figure 4 Shear Stress (MPa) Vs Shear Strain (Pa)

(Muhammad Helmi Aminullah Bin Jelisun/2019415632) G = 210 GPa r = 0.003 m

Shear Stress : shear stress T: torque at 0.2 Nm r: radius (0.003 m) J: polar moment of inertia ()

4.72 MPa

Shear Strain : shear strain : angle of twist at 0.000629921rad 10

0

0

0

0

Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014

r: radius (0.003 m) L: length (0.084 m)

2.24872

Modulus of rigidity : shear strain : shear stress G: Modulus of rigidity

210.097 GPa

Percentage of error

0.04%

(Nur Sabrina Binti Zulkifli/ 2019253066)

Modulus rigidity of mild steel (Theoretical)

78 GPa

Shear Stress,

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Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014

Shear Strain, = = = 0.000906919 Pa

Modulus of Rigidity, G

Percentage Error

(Nur Syafiqah Binti Jaafar/2019405402)

=

= 53.77

=

= 9.05

Modulus of rigidity, G 12

Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014

=

= 32.58 GPa The slope of Stress Vs Strain graph that has been plotted indicates the Theoretical Modulus of Rigidity of the mild steel.

Percentage Error

= = 58.23 %

The percentage error is above half percent which is quite high. They might have some errors occur when handling this experiment.

(Nur Izzah Syakirah Binti Shah Fenner Khan/ 2019416466) Shear Stress,

Shear Strain,

Modulus of Rigidity,

13

Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014 Percentage of error = = = 38%

9. DISCUSSIONS (Muhammad Helmi Aminullah Bin Jelisun/2019415632) In the experiment, the first revolution is 90 result in the angle of twist (0.000629921) and load torque(0.2Nm) respectively. Graph load Torque against the angle of twist was plotted to show the data graphically. The graph is increasing linearly until load torque reaches 22.5Nm with 720 revolution and the angle of twist is 0.071653543. The graph obeys Hooke’s Law as the graph is increasing linearly.

The experimental modulus of rigidity for mild steel is . Calculating the percentage error.

= 0.04%

The percentage error is 0.04% which not exceed 10% conclude that the experiment was successfully conducted. Torsion test fracture is divided into two which are the cup and cone surface and the brittle surface. The cup and cone surface indicates the ductile fracture has occurred at the specimen. For brittle surface, the specimen of material will have a flat fracture surface.

(Nur Sabrina Binti Zulkifli/2019253066) 14

Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014

The theoretical value for mild steel is 78 GPa. By torsional test, the rigidity modulus of the materials can be obtained. Modulus rigidity is also known as a shear modulus. The ratio of shear stress to the corresponding shear strain within the proportional limit of a material is the modulus of rigidity (G), the modulus rigidity is the elastic coefficient when a shear force is applied resulting in lateral deformation. In this experiment, the type of specimen used is mild steel. From the experiment, the value for modulus of rigidity obtained is 37.57 GPa.

The percentage of error for this experiment is 51.83% which is higher than it should be. This is because when conduction the experiment we may do some error. The error is the causes of the difference in experimental value compared to the theoretical value. The error happened in measured values that are consistently too high or consistently too low. For example, observational error, parallax in reading a meter scale and instrumental errors when the instrument is having some troubleshoot. Next, random error. We might not twist the specimen to the exact angle as the state in the procedure. While the meter is not stable, we might already take the reading from the torsion meter. The error might lead to inaccurate data recorded and will affect the calculation in the result section.

The magnitude of the torque exerted on the specimen must be equal to the forces exerted on any cross-section of the shaft. At this phase, the entire shaft will be assumed to be inelastic range until it fractured. In this experiment, the graph of torque (T) against the angle of twist obeys Hooke’s Law. As the revolution increase, the torque also increases and started to obtain constant value until the specimen fractured.

The fracture of Mild Steel is ductile. The Mild Steel had been twisted by using a torsion test machine until it breaks. In a ductile fracture, there is the absorption of massive amounts of energy and cause progressive degradation of material stiffness when plastic deformation reaches a certain limit.

(Nur Syafiqah Binti Jaafar/2019405402) 15

Applied Mechanics Lab – MEC 424/AHA/MCM Rev. 01-2014

The outcome of this experiment is that it shows us how important the torsion test in the production of the material. This torsion test is to determine the behaviour of the mild steel when been twisted or under a torsional force. The implication of this experiment will help the production of the material to produce high-quality material that passes the strength criteria and satisfied the client demand.

Throughout the experiment, we can analyze the relationship between shear stress and shear strain. As the shear strain increases, the shear stress increases as well. Due to this torsion experiment, we can see the relationship between torque and angle of twist too. The higher the angle of twist, the higher the torque will be. The twist angle starts at 0 and increases linearly as a function of x.

The theoretical modulus of rigidity of mild steel is 78GPa. The percentage error of mild steel in this experiment passes 50% which is quite high. Possible errors that might occur is a human error where we could have made an error during scale reading. The eyes probably did not perpendicular to the scale of the torsion test machine. This will cause those errors in data recorded that effecting the result after that. Hence, causes the difference between the value of modulus rigidity in term of theoretical and experimental.

The results are expected as it obeys the theory stated above. The magnitude of the torque exerted on the specimen must be equal to the forces exerted on any cross-section of the shaft. At this pha...