UNIVERSITI TUN HUSSEIN ONN MALAYSIA Faculty of Mechanical and Manufacturing Engineeringauthor.uthm.edu.my/uthm/www/content/lessons/165/BDA27101... · 2012-09-14 · Faculty of Mechanical

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

Faculty of Mechanical and Manufacturing Engineering __________________________________________________________________

COURSE INFORMATION

COURSE TITLE: ENGINEERING LABORATORY III (BDA 27101)

TOPIC 1: TENSILE TEST

1. INTRODUCTION

The tensile experiment is the most common mechanical test that reveals several

important mechanical properties, such as: modulus of elasticity, yield strength,

ultimate tensile strength, ductility, and toughness. The material to be tested is

formed into a shape suitable for gripping in the testing machine, and then pulled at

constant rate until it fractures. The tensile instrument elongates the specimen at a

constant rate and has devices to continuously measure and record the applied load

and elongation of the specimen. During the stretching of the specimen, changes

occur in its physical dimensions and its mechanical properties. The ability to

predict the loads that will cause a part to fail depends upon both material

properties and the part geometry. This experiment involves testing to determine

the relative properties.

2. OBJECTIVES

1. To understand the principles of tensile testing machine.

2. To observe the stress-strain relationship for several standard materials by

performing a tensile test.

3. To obtain approximate values from stress-stain curve such as percentage of

elongation, Yield Strength; Tensile Strength and Modulus of Elasticity, E.

3. LEARNING OUTCOMES

At the end of this experiment, students should be able to:

1. Conduct experiment and identify the dependent and independent variables.

2. Record, tabulate and analyze the raw data.

3. Indicate the important parameters such as yield strength, elastic, plastic

region, maximum load, failure load and explain each parameter.

4. Determine the modulus of elasticity for each specimen.

5. Understand the stress-strain relationship for several standard materials by

performing a tensile test and tensile properties from a stress strain curve.



BDA27101-Edition III/2011

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4. THEORY

A tensile test, also known as tension test, is probably the most fundamental type of

mechanical test that can be performed on material. Tensile tests are simple,

relatively inexpensive, and fully standardized. By pulling on something, you will

very quickly determine how the material will react to forces being applied in

tension. As the material is being pulled, you will find its strength along with how

much it will elongate.

You can learn a lot about a material from tensile testing. As you continue to pull

on the material until it breaks, a good, complete tensile profile will be obtained. A

curve showing how it reacted to the forces being applied is produced. The point of

failure is typically called its "Ultimate Strength" or UTS on the chart.

For most tensile testing of materials, you will notice that in the initial portion of

the test, the relationship between the applied force, and load, and the elongation

the specimen exhibits is linear. In this linear region, the line obeys the relationship

defined as "Hooke's Law" where the ratio of stress to strain is a constant, or E =

δ/ε. E is the slope of the line in this region where stress (σ) is proportional to

strain (ε) and is called the "Modulus of Elasticity" or "Young's Modulus".




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5. ADDITIONAL THEORY

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6. APPARATUS

Figure 1: Universal Testing Machine GT-7001-LS10, Tensile Specimen &

Vernier Caliper

7. PROCEDURES

In order to obtain uniform and accurate results, it is important that all tests have to

be conducted under standard conditions. The American Standard for Testing and

Materials (ASTM) has set up standards, which should be followed. The standard

method of mechanical testing is specified by ASTM E-8M for metals. Identify the

material of each specimen used.

1. Record and measure the specimen parameter such as: diameter; and the

gauge length. Fill up Table 1 as d1 and l1.




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2. Mount the specimen in the testing machine, figure 1 and test the specimen

to fracture (the lab technician and/or your lab instructor will help with the

right procedure).

3. Test data will be saved in readable file format and given to your instructor.

Arrange with your instructor to get these test data files.

4. When the specimen is removed from the instrument determine all

parameters that you have measured earlier and Fill up Table 2 as d2 and

l2.

5. Once you have completed the test on all specimens, calculate the

percentage of elongation and area of reduction

6. Draw the stress versus strain curve for each specimen and determine the

ultimate tensile strength, yield strength and the Young’s Modulus for each

specimen.

In all cases, be sure to write your observations for each test. You need to include

these observations in your report. The general stress strain curve for a typical

metal is shown in Figure 2 with all the important properties that can be directly

measured.

Figure 2: A schematic stress strain curve for a metallic alloy

8. RESULTS

Measure and fill up Table 1 and Table 2

Table 1: Parameter of specimen before testing

Shaft

Diameter, d1

(mm) Average

Gauge length, l1

(mm) Average

1 2 3 1 2 3

Aluminium

Mild Steel




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Table 2: Parameter of specimen after testing

Shaft

Diameter, d1

(mm) Average

Gauge length, l1

(mm) Average

1 2 3 1 2 3

Aluminium

Mild Steel

9. OBSERVATIONS

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10. CALCULATIONS

Calculate Young’s modulus, percentage reduction of area (RA) and

elongation (EL).




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11. DISCUSSIONS

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1. Explain the advantages of mild steel in comparison with aluminum in

terms of Young’s modulus, yield strength and ultimate tensile strength?

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2. List of all possible source of errors include errors in load cell, cross-

sectional dimensions and gauge measurements. How does this error affect

the obtained results?

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12. CONCLUSION

Write your observations and comments whenever possible in your discussion in

term of achievement, problems facing throughout the experiment and

recommendation for improvement.

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13. REFERENCES

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COURSE INFORMATION


TOPIC 2: TORSION TEST

1. INTRODUCTION

Torsion tests allow direct measurement of the shear modulus (G) of a material.

This ability makes torsion testing, although not as common, a useful partner for

tensile testing in determining the mechanical properties of a material.

There are two kinds of torsion experiments: torque control and angular speed

control. Torque control experiments apply a uniformly increasing torque to the

specimen and the amount of strain is measured as an angle through which the

specimen has turned. Angular speed control turns the specimen at a specific

angular speed while the torque is measured.

Angular speed control is the type of experiment we will be doing, thus the directly

measured quantity in this experiment will be torque.

Young's modulus (E) is related to the shear modulus and finding E with the

experimentally obtained G reinforces this relationship; they are dependent upon

one another according to the equation:

Where, v is Poisson's ratio.

2. OBJECTIVES

The main objective of this experiment is to determine the elastic and yield

behavior of material when subjected by torque load.



1. Conduct experiment, record, tabulate and analyze the raw data.

2. Plot the graph of Twisting angle versus Load torque (N.m).

3. Determine the modulus of rigidity for each specimen

4. Compare the value of modulus of rigidity form experiment with the theory

5. Produce good conclusion from the experiment conducted.




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4. THEORY

When a circular shaft is twisted at either end, with no other forces acting upon it,

the bar is said to be in pure torsion. If we let the left-hand end of the shaft remain

fixed, then the right-hand end the bar will rotate through an angle ( ) with respect

to the left end .See Figure 1

Figure 1

Simultaneously, a longitudinal line on the surface of the bar, such as line nn, will

rotate through a small angle with respect to the position nn'. Because of this

rotation, a rectangular element on the surface of the bar, such as the element

shown in the figure between two cross sections distance dx apart, is distorted. This

element is shown again in Figure 2, isolated from the remainder of the bar.

Figure 2

During torsion, the right-hand cross section of the original configuration of the

element (abdc) rotates with respect to the opposite face and points b and d move

to b' and d', respectively. The lengths of the sides of the element do not change

during this rotation, but the angles at the corners are no longer 90°. Thus, the

element is undergoing pure shear and the magnitude of the shear strain is equal

to the decrease in the angle bac.




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This angle is

Note: tan is approximately equal to because under pure torsion the angle (

) is small.

The distance bb' is the length of a small arc of radius r subtended by the angle ,

which is the angle of rotation of one cross section with respect to the other. Thus,

bb' = r . Also, the distance ab is equal to the length of the element, dx.

Substituting these expressions into the preceding equation, we have

Under pure torsion, the rate of change /dx of the angle of twist are constant

along the length of the bar. This constant is equal to the angle of twist per unit

length. Thus, = / L, where L is the length of the shaft. Then, we have

Now, observe that for linear elastic material, the magnitude of the shear stress,

(shown in Figure 1) is.

From here we can establish the relationship between the applied torque T and the

angle of twist which it produces. The resultant of the shear stresses shown in

Figure 3, below, must be statically equivalent to the total torque T. The shear

force acting on an element of area dA (shown shaded in the figure) is dA, and the

moment of this force is also equal to dAG 2 . The total torque T is the summation

over the entire cross-sectional area of these elemental moments;

Thus, where J is equal to the polar moment of inertia of the circular cross section

GrG




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Thus, we have

(Note that GJ is called the torsional rigidity of the shaft.) Finally, since the total

angle of twist is equal to L, we have that

This is the result we want. The experiment you are about to perform will yield

data on the torque T and the angle from which we can calculate G, the shear

modulus, given the dimensions of the shaft. Important to note that for a solid

circular shaft of uniform radius:


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Figure 3




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6. APPARATUS

Figure: Torsion Testing Machine, Torsion Specimen & Vernier Caliper.




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7. PROCEDURES

1. Record and measure the Specimen length and diameter at three different

locations and calculate the average length and diameter. Also measure

pully length. Fill up Table 1.

2. Mount the Specimen in the testing machine and test the Specimen (the lab

technician and/or your lab instructor will help with the right

procedure).Make sure pulley is in Horizontal position.

3. Attach the angle indicator and zero the readings.

4. Measure the angle of twist when load (W) is added from 0 to 200N and

when load is removed from 200N to 0N for both specimens. Fill up Table

2 and Table 3.

8. RESULTS

Table 1: Diameter of specimen

Shaft Diameter, D (mm)

Average Length, L (mm)

Average 1 2 3 1 2 3

Brass

Mild Steel

Pulley Length

Table 2: Torsion test result for Brass Shaft

Load, W (N) 0 50 100 150 200

Angle of

twist during

additional of

load

Angle of

twist during

removal of

load




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Table 3: Torsion test result for Mild Steel Shaft

Load, W (N) 0 50 100 150 200

Angle of

twist during

additional of

load

Angle of

twist during

removal of

load

9. OBSERVATIONS

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10. CALCULATIONS

Calculate torsion constant and shear modulus for the brass and mild steel

specimens. Determine the shear stress and strain for both specimens.




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11. DISCUSSIONS

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1. If the cross section of shaft is not cylinder, explain how to perform the

torsion analysis.

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2. Briefly explain some of the important factors in designing a high-quality

shaft.

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12. CONCLUSIONS




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13. REFERENCES

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COURSE INFORMATION


TOPIC 3: SHEAR FORCE OF A BEAM

1. INTRODUCTION

This guides describes how to set up and perform Shear Force in a Beam

experiments. It clearly demonstrates the principles involved and gives practical

support to your studies.

Figure 1 shows the Shear Force in a Beam experiment. It consists of a beam

which is ‘cut’. To stop the beam collapsing a mechanism, (which allows

movement in the shear direction only) bridges the cut on to a load cell thus

reacting (and measuring) the shear force. A digital display shows the force from

the load cell.

A diagram on the left-hand support of the beam shows the beam geometry and

hanger positions. Hanger supports are 20mm apart, and have a central groove

which positions the hangers.

Figure 1: Shear Force In A Beam Experiments.




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2. OBJECTIVES

The objectives of this experiment are as follows:



1. Conduct experiment and identify the dependent and independent variables.

2. Record, tabulate and analyze the raw data.

3. To draw shear diagram.

4. Compare the theoretical and experimental result

5. Produce good conclusion from the experiment conducted.

4. THEORY

Beams are defined as structural members supporting loads at various points along

the member. Transverse loadings of beams are classified as concentrated loads or

distributed loads. One of the main concerns that should be put into consideration

when designing beams for strength is how the material and the cross section of a

beam of a given selected span should be selected if the beam is not to fail under a

given loading.

Applied loads result in internal forces consisting of a shear force (from the shear

stress distribution) and a bending moment (from the normal stress distribution).

For prismatic beam, that is straight beam with a uniform cross section; their

design depends primarily upon the determination of the largest value of the

bending moment and shear force created in the beam by a given loading. The

determination of these values and of the critical sections of the beam in which

they occur is greatly facilitated by drawing a shear force diagram and bending

moment diagram. The variation of the shear force V (N) and the bending moment

M (Nm) along the beam may be investigated from these diagrams. The values of

V and M at various points may be obtained either by drawing free body diagram

of successive portions of the beam or from relationship that involves the applied

load, shear force and bending moment.

Determination of the maximum normal stress (σmax) and maximum shearing

stress (τ max) requires identification of maximum internal shear force and bending

moment. Shear force and bending moment at a point are determined by passing a

section through the beam and applying an equilibrium analysis on the beam

portions on either side of the section as shown in Figure 2 and 3. Sign

conventions for shear forces V and V’ and bending couples M and M’

1. To comprehend the action of shear in a beam.

2. To measure the shearing force at a normal section of a loaded beam and to

check its agreement with theory.




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Figure 2: Beam section at point C (at distance x from left end A)

Figure 3: Internal forces (positive shear and positive bending moment)


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6. APPARATUS

Figure 4: Shearing force of a beam experiment in the structures frame.




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Before setting up and using the equipment, always:

Visually inspect all parts, including electrical leads, for damage or wear.

Check electrical connections are correct and secure.

Check all components are secured correctly and fastenings are sufficiently

tight.

Position the Test Frame safely. Make sure it is mounted on a solid, level

surface, is steady, and easily accessible.

Note: Never apply excessive loads to any part of the equipments. If the meter

is only 0.1 N, lightly tap the frame (there may be a little ‘stiction’ and this

should overcome it).

7. PROCEDURES

6.1 Experiments 1: Shear Force Variation with an Increasing Point Load

Figure 5: Force Diagram.

The equation we will use in this experiment is:

Shear force at cut, =

Where a is the distance to the load (not the cut)

Distance a = 260mm

You may find the following table useful in converting the masses used in the

experiment to loads.

Table 1: Grams to Newton’s Conversion Table

Mass (Grams) Load (Newton)

100 0.98

200 1.96

300 2.94

400 3.92

500 4.90




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Step 1 to 4 of the following instructions may already have been completed for

you.

1. Place an assembled Test Frame (refer to the separate instructions supplied

with the Test Frame if necessary) on a workbench. Make sure the

‘window’ of the Test Frame is easily accessible.

2. There are four securing nuts in the top member of the frame. Slide them to

approximately the positions shown in figure 5.

3. With the right-hand end of the experiment resting on the bottom member

of the Test Frame, fit the left- hand support to the top member of the

frame. Push the support on to the frame to ensure that the internal bars are

sitting on the frame squarely. Tighten the support in position by screwing

two of the thumbscrews provided into the securing nuts (on the front of the

support only).

4. Lift the right-hand support into a position and locate the two remaining

thumbscrews into the securing nuts. Push the support on to the frame to

ensure the internal bars are sitting on the frame squarely. Position the

support horizontally so the rolling pivot is in the middle of its travel.

Tighten the thumbscrews.

5. Make sure the Digital Force Display is ‘on’. Connect the mini DIN lead

from ‘Force Input 1’ on the Digital Force display to the socket marked

‘Force Output’ on the left- hand support of the experiment. Ensure the lead

does not touch the beam.

6. Carefully zero the force meter using the dial on the left-hand beam of the

experiments. Gently apply a small load with a finger to the centre of the

beam and release. Zero the meter again if necessary. Repeat to ensure the

meter returns to zero.

7. This experiment examines how shear force varies with an increasing point

load. Figure 5 shows the force diagram for the beam.

8. Check the Digital Force Display meter reads zero with no load. Place a

hanger with a 100 g mass to the left of the ‘cut’ (40mm away).Record the

Digital Force Display reading in table as in Table 2. Repeat using masses

of 200g, 300g and 500g. Convert the mass into a load (in N).

9. Remember, Shear force at the cut = Displayed force.

10. Calculate the theoretical shear force at the cut and complete the Table 2.

6.2 Experiment 2: Shear Force Variation for Various Loading Conditions

This experiment examines how shear forces varies at the cut position of the beam

for various loading conditions. Figure 6, Figure 7 and Figure 8 show the force

diagrams.




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We will use the statement: “The Shear Force at the ‘cut’ is equal to the

algebraic sum of the forces acting to the left or right of the cut”

1. Check the Digital Force Display meter reads zero with no load.

2. Carefully load the beam with the hangers in the positions shown in Figure 6,

using the loads indicated in Table 1.

3. Record the Digital Force Display reading as in Table 3. Remember, Shear

force at the cut (N) = Displayed Force.

4. Calculate the support reactions (RA and RB) and calculate the theoretical shear

force at the cut.

5. Repeat the procedure with the beam loaded as in Figure 7 and Figure 8.




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8. RESULTS

7.1 Fill up Table 2 for part 1 experiment and Table 3 for Part 2 experiment.

Experiments 1

Table 2: Results for Experiment 1

Mass (g) Load (N) Experimental

Shear Force (N)

Theoretical

Shear Force (N)

0

100

200

300

400

500

Experiment 2

Table 3: Results for Experiment 2.

Figure W1

(N)

W2

(N)

Experimental

Shear Force

(N)

RA

(N)

RB

(N)

Theoretical

Shear Force

(N)

6 3.92 0

7 1.96 3.92

8 4.91 3.92

9. OBSERVATIONS

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10. CALCULATIONS

Plot a graph for shear force vs. load for both experimental and theoretical

results in experiment 1. Calculate support reactions (RA and RB) and

theoretical shear force at the cut.




32

11. DISCUSSIONS

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1. Comment on the shape of the graph. What does it tell us about how shear

force varies due to an increased load? Does the equation we used

accurately predict the behavior of the beam?

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2. Comment on how the results of the results of the experiments compare

with those calculated using the theoretical.

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12. CONCLUSION.




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13. REFERENCES

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36

COURSE INFORMATION


TOPIC 4: BENDING STRESS IN A BEAM

1. INTRODUCTION

The Bending Stress in a Beam experiment introduces students to stress and strain,

bending moment, section properties and the bending equation. It allows students

to investigate the stresses and strains within a structure in relation to bending

loads. The experiments are quick, clear, and accurate and clearly demonstrate the

principles involved and gives practical support to subject studied.

2. OBJECTIVES.

The main objective of this experiment is to study the stress distribution (bending

force and strains) across the section of a beam.


At the end of this experiment, students should be able to understand the

relationship between stresses and strains within a structure in relation to bending

loads and the relationship between bending moment and the strain at the various

positions.

4. THEORY

Figure 1: Beam set-up and schematic




37

As well as the information given on the unit you will need the following formulae

(The bending equation):

Where,

And

Where,


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6. APPARATUS

Figure 2 shows the Bending Stress in a Beam experiment, while Figure 3 shows

the Bending Stress in a Beam experiment in the structures frame. It consists of an

inverted Aluminum T-beam, with strain gauges fixed on the section. The panel

assembly and Load Cell apply load to the top of the beam at two positions each

side of the strain gauges. Strain gauges are sensors that experience a change in

electrical resistance when stretched or compressed. T-beam has strain gauges

bonded to it. These stretch and compress the same amount as the beam, thus it

measure strain in the beam. The Digital Strain Display converts the change in

electrical resistance of the strain gauges to show it as displacement (strain). It

shows all the strains sensed by the strain gauges, reading in micro strain (με).




39

Figure 2: Bending stress in a beam experiment

Figure 3: Bending stress in a beam experiment in the structures frame

Thumbwheel

Set zero control




40

Figure 4: Bending stress in a beam experiment from the structure software

7. PROCEDURES

1. Ensure the beam and load cell is properly aligned. (Request instructor to

align.)

2. Turn the `Thumbwheel’ (refer to Figure 3) in the structures frame on the

Load Cell to apply a positive (downward) preload to the beam for 100 ±

5N.

3. After preload, turn `set zero control’ knob back to zero load reading.

4. Click `Zero Strain Gauges’ to zero strain signals on the software.

5. Take the readings and fill up Table 1 with force values.

6. Increase the load to 100 N and by clicks the `record data table’ button

and fill up Table 1 with all the strain value. Repeat the procedure 6 in

100N increments up to 500 N. (DO NOT EXCEED LOAD LIMIT)

7 Finally, gradually release the load and preload.

8 Correct the strain reading values by eliminating zero error (be careful with

your signs!) and convert the load to a bending moment then fill up Table

2.

9 From your results, plot a graph of strain against bending moment for all

nine gauges (on the same graph).

10 Calculate the average strains from the pairs of gauges and enter your

results in Table 3 (disregard the zero values). Carefully measure the actual

strain gauge positions and enter the values into Table 3. Plot the strain

against the relative vertical position of the strain gauge pairs on the same

Load reading

Zero strain gauge

Record data table

Strain gauges

values

Bending moment




41

graph for each value of bending moment. Take the top of the beam as the

datum.

11 Calculate the second moment of area and position of the neutral axis for

the section (use a Vernier to measure the exact size of the section) and add

the position of the neutral axis to the plot.

*Never apply excessive loads to any part of the equipment.

8. RESULTS

Table 1: Results for Experiment 1 (uncorrected)

Gauge

Number

Load (N)

0 100 200 300 400 500

1

2

3

4

5

6

7

8

9

Table 2: Results for Experiment 1 (corrected)

Gauge

Number

Bending Moment (Nm)

0 17.5 35 52.5 70 87.5

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

9 0




42

Table 3: Averaged strain readings for Experiment 1

Gauge

Number

Vertical

Position

(mm)

Bending Moment (Nm)

0 17.5 35 52.5 70 87.5

1 0

2,3 6.4

4,5 23

6,7 31.7

8,9 38.1

9. OBSERVATIONS

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10. CALCULATIONS

Plot a graph for strain vs. bending moment and strain vs. position.

Calculate bending moment. Determine experimental and theoretical

maximum stress.




43

11. DISCUSSIONS

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1. What is the relationship between the bending moment and the strain at the

various positions?

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2. What do you notice about the strain gauge readings on opposite sides of

the section? Should they be identical? If the readings are not identical, give

two reasons why.

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12. CONCLUSION.




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13. REFERENCES

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47

COURSE INFORMATION


TOPIC 5: THIN CYLINDER

1. INTRODUCTION

The analysis of the stress distribution in a thin walled cylinder is of considerable

importance in pressure vessels and gun barrels. Strain gauges mounted on various

radius and at different alignments throughout the cylinder wall provide the

measurement of the strains. Thus stress distribution throughout the wall of a

cylinder subjected to an internal pressure could be analyzed.

2. OBJECTIVES.

The objectives of this experiment are as follows:

1. To enable comprehensive analysis of stresses and strains in a thin cylinder

under internal pressure.

2. To allow investigations with the cylinder in both open-ends and closed-

ends conditions


At the end of this experiment, students should be able to get an appreciation of:

1. A biaxial stress system

2. The use of strain gauges

3. Young’s Modulus

4. Poisson’s ratio

4. THEORY

Consider a thin cylinder of plate thickness t, mean diameter d and length l,

subjected to internal pressure p. Now consider that the cylinder is sectioned by the

x-plane of symmetry and by the two z-planes (of distance z apart) as shown in

Figure 1.




48

Consider the equilibrium of forces in the x-direction acting on the sectioned

cylinder shown in Figure 2. It is assumed that the circumferential stress is

constant through the thickness of the cylinder.

Force due to internal pressure p acting on area dz = pdz

Force due to circumferential/Hoop stress ( H ) acting on area 2tz = H. 2tz

Equating: , Therefore:- or

Figure 1

Figure 2

t

prH

t

pdH

2pdztzH 2




49

Now consider the equilibrium of forces in the z-direction acting on the part

cylinder shown in Figure 3.

Force due to internal pressure p acting on area d2/4 = p. d

2/4

Force due to longitudinal stress ( L ) acting on area dt =L. dt

Equating: , Therefore:- or

In the “open” ends condition, there is no obstruction to the end of cylinder.

Therefore,

But . Therefore:-

Hoop Strain,

Longitudinal Strain,

While, in the “closed” ends condition, the force applied onto element are due to

and .

Therefore:-

Hoop Strain,

Longitudinal Strain,

Figure 3

t

prH

t

pdL

4

4

2dpdtL

0L

HHE

1

HLE

1

HL

t

prL

2

HLLE

1

LHHE

1




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6. APPARATUS

Figure 4: The SM1007 Thin Cylinder apparatus.

In the “open” ends condition the hand wheel is fully screwed in. This pushes the

two pistons away from the cylinder end caps so that there is no contact between

them. Therefore, the axial force is transmitted from the pressurized oil into the

frame rather than the cylinder. See Figure 5.

Figure 5: Open Ends Condition

In the “closed” ends condition the hand wheel is wound out. This allows the

pistons to move outward against the cylinder end caps so that there is no contact

with the frame. Therefore the axial force is transmitted from the pressurized oil

into the cylinder itself. See Figure 6.




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Figure 6: Closed Ends Condition

Technical Information

Length 358.8 mm

Wall Thickness 3 mm

Inner diameter, D1 80 mm

Guage factors 2.105

Cylinder material Aluminium alloy 6063

Young’s Modulus 69 GN/m2

Poisson’s ratio 0.33

Maximum allowable test pressure 3.5 MN/m2

Strain gauges Electrical Resistance Type

Figure 7: Orientation of strain gauges




53

7. PROCEDURES

7.1 Experiment 1 – Thin Cylinder with Open Ends

In this experiment we will pressurize the cylinder in the open ends condition and

readings from all six strain gauges are taken, we will then analyze the results in

various ways to establish some important relationships. Examine the cylinder and

the diagram on the front panel to understand the notation and placement of the

strain gauges in relation to the axis of the cylinder. The experimental method

utilizes the SM1007 software to display and take readings

1. CONNECT TO SM1007 from the same menu. The virtual meters on

the screen should now display values of pressure and strain. (If it’s already

running, leave it as it is).

2. Close the pump release valve and zero the readings by selecting ZERO

ALL GAUGES from the EXPERIMENTS menu option. All the virtual

strain meters should now read 0±0.3με, and the pressure meter should read

0±0.01MPa.

3. Take the first set of readings (at zero) into the data table by selecting

RECORD GAUGE READINGS from the EXPERIMENTS menu

option. Display the data table by selecting DATA TABLE in the

RESULTS menu.

4. Pump the handle slowly until a pressure of around 0.5 MPa and record the

readings into the data table again by selecting RECORD GAUGE

READINGS from the EXPERIMENT menu option. Wait a few

seconds between pumps for the gauges to stabilize.

5. Carefully increase the pressure in 0.5 MPa increment, record the readings

into the data table until you have reached a value of 3 MPa (Do not exceed

a maximum cylinder pressure of 3.5 MPa). Record all data in Table 1.

7.2 Experiment 2 – Thin Cylinder with Closed Ends

We will now test the cylinder by taking the same readings as in experiment 1 but

with the cylinder in the closed ends condition to show the effect of the biaxial

stress system.

1. Open the pump release valve and carefully unscrew the hand wheel

enough to set up the closed ends condition. To check that the frame is not

transmitting any load, close the pump release valve and pump the handle

and observe the pressure gauge, you may need to pump a number of times

as the oil pushes the pistons outward.

2. Once a pressure of around 3MPa has been achieved, gently push and pull

the cylinder along its axis, the cylinder should move in the frame




54

indicating that the frame is not transmitting any load. If it doesn’t move,

wind the hand wheel out some and try again.

3. Release the pressure from cylinder by opening the pump release valve.

4. In the SM1007 software choose CLOSED ENDS CONDITION from the

EXPERIMENTS menu option. Then connect the SM1007 unit by selecting

CONNECT TO SM1007 from the same menu. The virtual meters on the

screen should now display values of pressure and strain.

5. Repeat steps 3 to 5 in Experiment 1.

8. RESULTS

Table 1: Thin Cylinder with Open Ends Experiment 1

Pressure Gauge

1 2 3 4 5 6

0.5

1.0

1.5

2.0

2.5

3.0

Table 2: Thin Cylinder with Closed Ends Experiment 2

Pressure Gauge

1 2 3 4 5 6

3.0

9. OBSERVATIONS

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10. CALCULATIONS

Calculate hoop strain and longitudinal strain for open ends and closed ends

conditions.




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11. DISCUSSIONS

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1. Explain the difference between the “Open End” and “Closed End”

conditions?

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2. Which case experiences “uniaxial state of stress” and which case

experiences “biaxial state of stress”?

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12. CONCLUSION.




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13. REFERENCES

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REFERENCES

REFERENCES

SOLID MECHANICS I:

Gere, J.M. and Goodno, B.J., 2009. “Mechanics of Materials”, 7th

Edition,

Cengage Learning.

Beer, F.P., Johnston, E. R. and Deworlf, J.T., 2009. “Mechanics of Materials”, 5th

Edition, Mc Graw Hill.

Hibbeler, R.C., 2008. “Mechanics of Materials”, 7th

Edition, Pearson Prentice

Hall.

Ugural, A.C., 2008. “Mechanics of Materials”, John Wiley & Sons Inc.

Riley, W.F., Sturges, L.D., and Morris, D.H., 2007. “Mechanics of Materials”, 6th

Edition, John Wiley & Sons Inc.



APPENDICES

DEPARTMENT OF ENGINEERING MECHANICS

SOLID MECHANICS I LABORATORY

LAPORAN MAKMAL/LABORATORY REPORT

Kod M/Pelajaran/

Subject Code

ENGINEERING

LABORATORY III BDA 27101

Kod & Tajuk Ujikaji/

Code & Title of Experiment

Kod Kursus/

Course Code

Seksyen /Section

Kumpulan/Group No. K.P / I.C No.

Nama Pelajar/Name of

Student

No. Matrik

Lecturer/Instructor/Tutor’s

Name

1.

2.

Nama Ahli Kumpulan/

Group Members

No.

Matrik Penilaian / Assesment

1.

Teori / Theory 10 %

2.

Keputusan /

Results 15 %

3. Pemerhatian

/Observation 20 %

4. Pengiraan /

Calculation 10 %

5. Perbincangan /

Discussions 25 %

Tarikh Ujikaji /

Date of Experiment

Kesimpulan /

Conclusion 15 %

Tarikh Hantar /

Date of Submission

Rujukan /

References 5 %

JUMLAH /

TOTAL 100%

COP DITERIMA/APPROVED STAMP

ULASAN PEMERIKSA/COMMENTS

Documents

UNIVERSITI TUN HUSSEIN ONN MALAYSIA Faculty of Mechanical and Manufacturing Engineeringauthor.uthm.edu.my/uthm/www/content/lessons/165/BDA27101... · 2012-09-14 · Faculty of Mechanical