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EXPERIMENT 1

TENSILE TESTING (UNIVERSAL TESTER)

MATERIALS LABORATORY

MEMB221

UNIVERSITI TENAGA NASIONAL

SEMESTER 1, 2014/2015

DATE PERFORMED: 19 June 2014

DATE SUBMITTED: 26 June 2014

NAME:RANJANI VASU

ID: ME091074

SECTION : 4

GROUP NUMBER : A

GROUP MEMBERS:

1. NOOR FAHMEEDA KUSYAIRI (ME091169)

2. MALIK AINUDDIN AZMON (ME091149)

3. MUHAMAD ADIB HALIM (ME091160)

4. AHMAD HAZIZI ZULKIFILI (ME091148)

LAB INSTRUCTOR:

Pn. Siti Zubaidah Othman

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SUMMARY

This analysis is called as Tensile Test (Universal Tester). It's to verify the Stress-Strain

cooperation of materials in this way to figure some mechanical terrains of the materials.

The supplies used are WP 300 and the illustrations are Aluminium and Metal. The grounds of the

supplies are first thought about and the cases' determinations are noted down. Certain

mathematical statements for modulus of adaptability, designing anxiety, fabricating strain and

protracting at break are exhibited here.

The test routines are then went hand in hand with. Readings of prolongation and its examining

life are taken and tabulated. The stress and strain values are then figured using the

aforementioned values. Graphs of trouble in resistance to extending are drawn and also the

anxiety-strain graphs for both samples. It's from the aforementioned outlines that the mechanical

terrains case in point E modulus, prolongation at split, tensile and yield capacity are obtained.

Qualities got indicated a considerable vast rate slips from the speculative qualities. This may be

because of some mistakes as talked over further underneath.

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of the material. The charged tensile value, RM is processed from the most utmost test force, FB

and the starting cross-fragment zone, A0 of the example:-

0 A

F R B

M

The most fundamental route to of guaranteeing the most extreme test compel is by method of the

most maximum pointer on the force showcase. In the tensile test itself, the cross-fragment of the

illustration is diminished its gagged and the precise pesters are quite higher.

The development at break, An indicates the acclimatization in length of the case differentiated

and its introductory length, L0 and is figured using the length, LU of the illustration taking after

break :-

%100

0

0

L

L L A U

To measure the lengths, a few measuring checks are had a cooperation with the test bar.

Accompanying split, numerous conclusions of the case are situated as one unit perfectly at the

break show and the division between the some measuring stamps is measured.

b) Fundamental Principles of Stress-Strain Diagram

The stress-strain graph (Figure 1) indicates the offbeat behaviour of the distinct materials

absolutely plainly. Every material has a their own characteristic pattern of stress and strain.

Important material information could be perused from the stress-strain graph. Notwithstanding

tensile quality, RM, the point of confinement proportionality, RP is especially fascinating.

Beneath this point of confinement, the material submits to Hooke's Law with the Modulus of

Flexibility, E: Strain, is corresponding to stress , : -

E

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When this stress is passed, bending is no longer relative to the trouble.

One specific imperative parameter from specialized outlook is the yield indicate, RE. From this

center onwards, the material winds up being enduringly plastically deformed. Deformation

remains when load is assuaged. To guard the function of the section, it may simultaneously not

be stacked any further.

With certain materials, for instance reinforced sensitive steel, kept up creeping happens from the

yield onwards. The case is broadened without the trouble being broadened push. In materials

without avowed creeping, the affirmation stress Rp0.2 is specified. In entirely an awesome case,

the material has a unending amplification of 0.2% which remains accompanying accommodate

of the burden.

The hardened steel blasts virtually without plastic miss happening but has an actually upliftedtensile value. The tempered steel is far tougher but still has a towering capacity. The fragile

reinforced steel has an especially increased prolongation but a level tensile capability. In this

case, there is indicated slithering in the transition to plastic behaviour. In the aluminium mix, the

antsiness-strain bow risings less steeply in the adaptable zone than the distinctive steel materials

in light of the compliment modulus of adaptability.

The anxiety-strain graph is processed from the qualities for strength and the stretching recorded

the same time as the tensile test.

0 A

F and

0

0

L

L LU

Pois sons Ration

Pois sons ration is defined as z

x

Where x = the strain perpendicular to the tensile axis

z = the longitudinal strain

In general increases during the run, starting about 0.3 in the elastic region and about 0.5 after

the material begins to deform plastically.

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DESCRIPTION OF EXPERIMENTAL

APPARATUS/EQUIPMENT

Technical description of the Equipment

The WP 300 material testing mechanism is a compelling unit laid out specifically for specific

guideline and is one of the time honored materials testing device in materials science. The

adjustable diagram of the unit permits an inconceivable run of uncommon tests requiring tensile

or compressive drive. Due to its clear, fundamental layout, the

unit is ideally suited for both researchers' examinations and for

showings. Its decreased degrees and nearly simple weight permit

flexible use and erection on all standard research focus seats.

In its essential shape, the unit does not require any outside

acquaintanceships. The test oblige is prepared through a manuallyincited water driven schema and indicated by method of an

extensive, easily dapper presentation instrument with a trailing

pointer. Extending of the illustration is recorded by method of a

dial measure. All ornament are screwed to the cross-parts. This signifies

that the test unit may be immediately refitted for contrasting tests.

The fundamental unit is basically comprises of the accompanying components:

- Machine base (1) with handgrip (2)

- Support with cross-head (2)

- Load frame with upper (3) and lower cross-member (4)

- Hydraulic system consisting of a main cylinder (5) and a master cylinder with hand wheel (6)

- Force display (7)

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- Elongation display via a dial gauge (8)

- Gripping heads (9) with sample (10)

Machine Base

The unbending machine base made of flings press structures the

gathering and assurances stability of the test unit in affiliation with 4

flexible feet. The machine base underpins the force through force

and the packaging.

Load Frame

The burden casing comprises of the upper (1) and flatter cross-part (2) and the guide pole (3).The burden edge transmits the test drive from the pressure driven primary chamber to the

correlated specimen. The burden edge is slide-mounted in the cross-head of the backing. Tensile

examples are braced between the upper cross-part and the cross-head, whilst compressive

examples are cinched between the flatter cross-part and the cross-head.

Hydraulic System

The test compel is created by hydraulic means. A cylinder in the expert barrel (2) incited through

the hand wheel (1) and the strung axle makes a hydrostatic force which prompts the test

constrains in the principle chamber (3). The hydraulic means transmission proportion is 2.77:1,

whilst the mechanical transmission proportion hand wheel/spindle is 503:1. Avoiding erosion

misfortunes, this could relate to a manual constrain of 1 N for every 1.3 kN test constrain. The

full stroke of the fundamental barrel of 45 mm needs 83 unrests of the hand wheel.

Force Display & Elongation Measurement

The power measuring gadget works consistent with the manometer guideline. It measures the

hydrostatic force in the water driven framework. The substantial showcase with a width of 160

mm helps exact perusing. A greatest pointer stores the greatest constrain. The stretching is

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measured through an alterable mounted dial measure. The dial check shows the relative

displacement between the upper cross-part and the cross-head.

Gripping Heads

The grasping heads are intended for tensile tests with a M10 strung head. What's more, level

clamping cushions can effectively be embedded in the cross-head and cross-part and are kept by

nut.

Note: Examples utilized are Aluminium and Metal. The speculative Modulus of Flexibility for

Aluminium is 70 GPa and Metal is 105 GPa.

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Procedure

1. To set up the test device the hand wheel on the master cylinder was untwisted. Then, the

gripping heads were screwed with the short bolt at the bottom and long bolt at the top.

2. Insertion of the required tensile sample was done. The test length L o of the sample

between two marks were measured and noted. The sample was screwed into the lower

gripping head followed by the upper gripping head until the end stopped.

3. The nut on the upper gripping head was tighten until the gripping head was seated

without slack in the upper cross-member.

4. Adjustment of the dial gauge was done by pushing the dial gauge upwards on the support

bar until the tracer pin touches the drive.

5. The rotating scale on the dial gauge and the maximum pointer on the force display were

set to zero. The specimen was slowly and constantly loaded by rotating the hand wheel.

The force was applied over a time interval of 5-10 seconds.

6. The force was read from the force display every 0.1mm and noted with the corresponding

extension. The reading interval was extended to 0.2mm from 1mm extension onwards.

The maximum test force was read and noted.

7. The sample was removed from the gripping heads. The hand wheel was twisted back and

the experiment was repeated with another different specimen.

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Data and Observation

Aluminium

Diameter = 6.1 mm

LO = 32.0 mm

LU = 32.0+4.8 =36.8 mm

Elongation, L=L U-L O (mm) Force (kN)

0.1 1.3

0.2 3.1

0.3 5.00.4 7.5

0.5 8.8

0.6 9.1

0.7 9.2

0.8 9.2

0.9 9.3

1.0 9.31.2 9.3

1.4 9.4

1.6 9.45

1.8 9.5

2.0 9.55

2.2 9.6

2.4 9.6

2.6 9.6

2.8 9.5

3.0 9.3

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Table 1: Elongations and corresponding forces for Aluminium

BrassDiameter = 6.1 mm

L0 = 32.1 mm

LU = 32.1+6.2 = 38.1 mm

Elongation, L=L U -LO (mm) Force (kN)

0.1 0.5

0.2 1.5

0.3 3.2

0.4 5.6

0.5 8.2

0.6 10.1

0.7 11.6

0.8 12.5

0.9 13.0

1.0 13.2

1.2 13.5

1.4 13.7

1.6 13.9

1.8 14.0

3.2 9.2

3.4 8.8

3.6 8.7

3.8 8.2

4.0 7.8

4.2 7.5

4.4 6.7

4.6 6.3

4.8 6.3

5.0 Fracture

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2.0 14.1

2.2 14.2

2.4 14.3

2.6 14.3

2.8 14.4

3.0 14.5

3.2 14.5

3.4 14.5

3.6 14.6

3.8 14.6

4.0 14.7

4.2 14.8

4.4 14.8

4.6 14.7

4.8 14.7

5.0 14.7

5.2 14.6

5.4 14.8

5.6 14.8

5.8 14.76.0 14.5

6.2 14.3

6.4 Fracture

Table 2: Elongations and corresponding forces for Brass

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Observation

While conducting this experiment, we can observe that there are not much difference or

the changes that occurs on both the specimens. Then as greater force is applied to the specimen,

they start to elongate uniformly. A significant pattern of necking is observed with the aluminium

specimen, whereas the brass specimen doesnt show any significant signs of necking.

Aluminium elongates until it factures at 4.8mm elongation. On the other hand, brass

elongates until it fractures with a loud sound after elongation of 3.0mm.

The fracture for the brass specimen occurs at the edge of the specimen, whereas the

aluminium fractures at the middle of the specimen.

Analysis and ResultsI. Aluminium

Graph 1

Sample calculation :-

i) Stress, : -

0

2

4

6

8

10

12

0 1 2 3 4 5 6

E l o n g a t i o n

( m m

)

Force, F (kN)

Aluminium

Force

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= where = = 2.92x 10 -5

=

At = 0.1 mm, F = 0.1 kN

= = 3.536776513 MPa

ii) Strain, :-

= = = 0.003125

Elongation, L=LU -LO(mm)

Force (kN) Stress(Mpa) Strain

0.1 1.3 44520.54795 0.003125

0.2 3.1 106164.3836 0.00625

0.3 5 171232.8767 0.009375

0.4 7.5 256849.3151 0.0125

0.5 8.8 301369.863 0.015625

0.6 9.1 311643.8356 0.018750.7 9.2 315068.4932 0.021875

0.8 9.2 315068.4932 0.025

0.9 9.3 318493.1507 0.028125

1 9.3 318493.1507 0.03125

1.2 9.3 318493.1507 0.0375

1.4 9.4 321917.8082 0.04375

1.6 9.45 323630.137 0.05

1.8 9.5 325342.4658 0.05625

2 9.55 327054.7945 0.0625

2.2 9.6 328767.1233 0.06875

2.4 9.6 328767.1233 0.075

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2.6 9.6 328767.1233 0.08125

2.8 9.5 325342.4658 0.0875

3 9.3 318493.1507 0.09375

3.2 9.2 315068.4932 0.1

3.4 8.8 301369.863 0.10625

3.6 8.7 297945.2055 0.1125

3.8 8.2 280821.9178 0.11875

4 7.8 267123.2877 0.125

4.2 7.5 256849.3151 0.13125

4.4 6.7 229452.0548 0.1375

4.6 6.3 215753.4247 0.14375

4.8 6.3 215753.4247 0.15

5.0 Fracture - -

Table 1: Stress Strain for Aluminium

Graph 2

0

50000

100000

150000

200000

250000

300000

350000

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16

stress (MPa)

Strain (mm/mm)

Aluminium - Stress Strain graph

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i) Modulus of Elasticity :-

taking slopes at point 0.2 and 0.5 mm elongation,

E =

=

= = 31477.31097MPa

= 31.47731097 GPa

Pencentage error (Modulus of Elasticity), % :-

as the theoretical Modulus of Elasticity for Aluminium is 69 GPa,

%Error = | | x 100%= | | x 100%= 54.38070874%

ii) Ultimate Tensile Strength (UTS) :-

based on Graph 2 (Stress - Strain Diagram For Aluminium),

Ultimate Tensile Strength = 357.2144278 MPa

iii) Elongation at fracture (Aluminium)

based on Graph 2 (Stress - Strain Diagram For Aluminum), Elongation at fracture : 5.0 mm

A = x100 = x100 = 12.5 %

iv) Yield Strength (offset of 0.2%) :-

based on Graph 2 (Stress - Strain Diagram For Aluminium),

Yield Strength = 353.6776513 MPa

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0.2% Elongation at fracture = = 10 m

Strain, = = 0.00025Yield Strength (offset of 0.2%), = E

= 31.47731097 GPa x 0.00025= 7.869327743 MPa

II. Brass

Graph 3

Sample calculation :-

i) Stress, : -

= where =

=

At = 0.1 mm, F = 2.0 kN

0

2

4

6

8

10

12

14

16

0 1 2 3 4 5 6 7

E l o n g a t i o n

( m m

)

Force, F (kN)

Brass

Force (kN)

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=

= 17.12553026 MPa

ii) Strain, :-

= = = 0.003115

Elongation, L=L U -LO (mm) Force (kN) Stress(Mpa) Strain

0.1 0.5 6849.315068 0.003115

0.2 1.5 51369.86301 0.006231

0.3 3.2 109589.0411 0.009346

0.4 5.6 191780.8219 0.0124610.5 8.2 280821.9178 0.015576

0.6 10.1 345890.411 0.018692

0.7 11.6 397260.274 0.021807

0.8 12.5 428082.1918 0.024922

0.9 13 445205.4795 0.028037

1 13.2 452054.7945 0.031153

1.2 13.5 462328.7671 0.0373831.4 13.7 469178.0822 0.043614

1.6 13.9 476027.3973 0.049844

1.8 14 479452.0548 0.056075

2 14.1 482876.7123 0.062305

2.2 14.2 486301.3699 0.068536

2.4 14.3 489726.0274 0.074766

2.6 14.3 489726.0274 0.080997

2.8 14.4 493150.6849 0.087227

3 14.5 496575.3425 0.093458

3.2 14.5 496575.3425 0.099688

3.4 14.5 496575.3425 0.105919

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3.6 14.6 500000 0.11215

3.8 14.6 500000 0.11838

4 14.7 503424.6575 0.124611

4.2 14.8 506849.3151 0.130841

4.4 14.8 506849.3151 0.137072

4.6 14.7 503424.6575 0.143302

4.8 14.7 503424.6575 0.149533

5 14.7 503424.6575 0.155763

5.2 14.6 500000 0.161994

5.4 14.8 506849.3151 0.168224

5.6 14.8 506849.3151 0.174455

5.8 14.7 503424.6575 0.180685

6 14.5 496575.3425 0.186916

6.2 14.3 489726.0274 0.193146

6.4 Fracture

Table 2: Stress Strain for Brass

Graph 4

0

50000

100000

150000

200000

250000

0 0.05 0.1 0.15 0.2 0.25

S t r e s s

( M P a )

Strain (mm/mm)

Brass- Stress Strain Graph

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iii) Modulus of Elasticity :-

taking slopes at point 0.1 and 0.4 mm elongation,

E = =

= = 37254.04594 MPa

= 37.25404594 GPa

Pencentage error (Modulus of Elasticity), % :-

as the theoretical Modulus of Elasticity for Brass is 105 GPa,

%Error = | | x 100%= | | x 100%= 64.51995625 %

iv) Ultimate Tensile Strength (UTS) :-

based on Graph 4 (Stress - Strain Diagram For Brass),

Ultimate Tensile Strength = 526.9797005 MPa

v) Elongation at fracture (Brass)

based on Graph 4 (Stress - Strain Diagram For Brass),

Elongation at fracture : 2.8 mm

A = x100 = x100 = 6.25 %

vi) Yield Strength (offset of 0.2%) :-

based on Graph 4 (Stress - Strain Diagram For Brass), Yield Strength = 484.5383823 MPa

0.2% Elongation at fracture = = 5.6 m

Strain, = = 0.00014Yield Strength (offset of 0.2%), = E

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= 37.25404594 GPa x 0.00014

= 5.215566.432 MP

DiscussionThe aim of this experiment is to investigate the relationship between stress-strain of material,hence to obtain approximate values of Elongation at fracture, Tensile strength(UTS) and Yield

strength .

The sample materials that we utilized as specimen in our experiment are Aluminium and

Brass. The values that we obtained from the experiment are tabulated and graphs are drawn. In

Aluminium and Brass, the engineering stress is calculated using the formula0

A

F , while the

engineering strain is obtained by the formula0

0

L

L LU

, the Stress-Strain graph for each

specimen is then drawn. The slope of the graph gained from the graph represent Modulus of

Elasticity. However, the slope is taken at its elastic region which there is an initial straight line

portion. This portion is called as the elastic region in which load is proportional to elongation. As

we known earlier, the material will start to deform permanently beyond this region or the non-

linear portion and is named as plastic deformation. As there is continuity in increment in load

until a maximum value rapture or mostly known as fracture will occur on the material.

Referring to the slope of the two graphs (refer to graph 3 and 4 ), the E modulus for Aluminium is

found to be a 31.47731097 GPa , a percentage error of 54.38070874% from the theoretical value

of 69 GPA. The E modulus for Brass is calculated to be 37.25404594 GPa , thus a deviation of

64.51995625 % from its theoretical value of 105 GPA.

The Elongation of fracture is obtained by the formula %1000

0

L

L L A U .The value of A for

Aluminium is found to be 12.5 GPA and Brass to be 6.25% .From the values gained it is

theorytically proven that Aluminium is more ductile than Brass.Brass get fractured at shorter

elongation than Aluminium.

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From the stress-strain diagram the Ultimate Tensile Strength (UTS) also can be determined.It is

the maximum test force before the specimen get fractured.Hence from the graph drawn the

tensile strength for Aluminium is 357.2144278 MPa and Brass is 526.9797005 MPa .From this

analysis, we are exposed to the fact that Brass comsumed more force before it breaks compared

to Aluminium.

The yield strength is determined by the 0.2% offset on the stress-strain diagram as well.After a

deep research done on stress-strain diagram the yield strength for Aluminium and Brass is

353.6776513 MPa and 484.5383823 MPa respectively.The possible errors that cause defect in

calculation of E modulus are:-

> Specimen error - the specimens used may not be homogeneous material.Therefore

the values obtained did not tally with the actual theoretical values.

> Parallex error - error in positioning eyes when reading the values in dial gauge and

force display.

> The specimen may not be screwed tightly into the gripping heads i.e. insertion is not

uniform.Failure in screwing properly might affect the result as the force applied

would not spread uniformly throughout the specimen and concentrate only at the

specimen s thread instead.

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Question Concrete is strong in compression but relatively very weak in tension. How to improve such

mechanical properties in order to transmit better tensile force?

Answer : To improve such mechanical properties, the concrete material must be mixed with

other type of materials to improve their mechanical properties so that it can transmit better

tensile force.It is because composite material will have both ductile and brittle

properties.Moreover,this mixing will increase strength of the material.

Conclusion

The Principles of Tensile Testing is clearly understood from this experiment.This test is carried

out to clearly understand the mechanical properties of metals and alloys that are widely used in

engineering field.Based on the data obtained from the stress-strain diagram,it has been proven

that elongation at fracture of aluminium is much more higher than brass.This shows that

aluminium is a ductile material.However,the tensile strength,yield strength and modulus of

elasticity of aluminium are lower than brass.This implies that brass is a tougher material

compared to aluminium.

References Ferdinand P.Beer, E.Russell Johnston, Jr., John T.DeWolf. 2004 . Mechanics Of

Materials. 3rd Edition. McGraw Hill. pp 50-60, 746.

Semester 4 2012/2013. MEMB221 Materials Laboratory Manual .COE, Uniten. pp 1-5. Beer, Johnston, DeWolf, Mazurek. 2009. Mechanics of Materials. 5 th Ed. New York:

McGraw-Hill. pp48-56.)

Smith, Hashemi. 2006. Foundations of Materials Science and Engineering. 4 th Ed. New

York: McGraw-Hill. pp213-224)