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Project 2 Tensile Test of Materials Laboratory Manual Prepared for 1502ENG Engineering Materials Outline Students should work in groups of 5 to complete this assessment item. The aim is to investigate...

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Project 2
Tensile Test of Materials
Laboratory Manual
Prepared for 1502ENG Engineering Materials


Outline
Students should work in groups of 5 to complete this assessment item. The aim is to investigate
the tensile properties of the various classes of materials, and relate these properties to real-world
applications, i.e., a bicycle frame.
1502ENG Engineering Materials Griffith College
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CONTENTS
1 Mechanical Properties of Materials 1
1.1 Aim ........................................................................................................................ XXXXXXXXXX1
1.2 Introduction ........................................................................................................... XXXXXXXXXX1
1.3 Scenario ................................................................................................................. XXXXXXXXXX3
1.4 Equipment ............................................................................................................. XXXXXXXXXX3
1.5 Testing Procedure .................................................................................................. XXXXXXXXXX3
1.6 Results ................................................................................................................... XXXXXXXXXX5
References 10
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m2

1 MECHANICAL PROPERTIES OF MATERIALS
1.1 AIM
The of this part is to characterise various specimens by means of the tensile test.



1.2 INTRODUCTION
There are various tests to characterise the properties of a material and they are classified in two main cat-
egories: destructive and non-destructive tests. The latter are mainly utilized to check for defects whereas
the former are used to obtain the material strength and stiffness. Amongst the destructive material tests,
the uniaxial tensile test is the most important of them all (see Fig. 1).
Figure 1: Schematic depiction of a sample under tensile loading, (a) before deformation, and (b) after
deformation. Adapted from (Öchsner 2016, p. 3, Fig. 1.2)

A tensile test is conducted by means of a specialised machine, called the tensile testing machine. In such
machines, a controlled loading of the sample is possible. The deformation of the sample is its response
to the applied load. During the test, the values of the force and deformation are continuously recorded.
Engineering stress (σ ) can be calculated using the recorded forces:
F
σ = , (1)
A0
where F is the instantaneous load applied perpendicular to the specimen cross section in units of newtons
(N), A0 is the original cross-sectional area before any load is applied (m2). The units of engineering stress
is pascal (Pa) which is equivalent to newton per square meter ( N ).
Engineering strain (ε) is the change in the dimension per unit length. Engineering strain can be calculated
y knowing the deformation at every instance:

l − l0
l0
∆l
= , (2)
l0
⑧ Write down the hypothesis of this experiment using the mentioned aim. What was the research
question?
1502ENG Engineering Materials Griffith College
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where l0 is the original length, i.e., the gauge length, before any loading, l is the the instantaneous
length, l − l0 is the deformation elongation or change in length at some instant, as referenced to the
original length. The percentage of strain is the engineering strain times 100.
During the test, the applied force and the displacement, which is the response of the sample to the applied
load, is constantly measured. The tensile testing machine to be used is depicted in Fig. 2.
(a) General view (b) Components of the testing equipment
Figure 2: Tensile testing apparatus.

A tensile sample, or sometimes called a coupon, has a plain geometry (see Fig. 3). It consist of clamping
areas at the two ends of the sample and a prismatic section in the middle. The prismatic section is the area
of interest which incorporates the gauge length. This is the same area in which failure will happen. The
two ends serve the sole purpose of fixating the sample in the apparatus with a better grip. Nevertheless,
other geometries are also possible for the sample.




Figure 3: Flat tensile sample and fixation equipment.
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1.3 SCENARIO
In this activity, your group should conduct some tensile tests and provide the answer for the following
scenario:


1.4 EQUIPMENT
The following equipment will be provided:


1.5 TESTING PROCEDURE
You must work in a group of 5 people and obtain the force-deformation data for each sample. Before
starting the test, you should record the required specimen information, e.g., sample number, material
type, cross-sectional area, length, and other required measurements. Additionally, it is required to mark
the gauge length, i.e., 25 cm, on each specimen.
The very first step is to install and clamp the specimen.
Tip
Do not trust the provided measurements, check everything!
➠ Watch the How to use a digital calliper video.
Tip
You need to get the detailed description of the equipment. Refer to Special Issue: Academic Writing.
Equipment
• a digital calliper,
• an extensometer,
• a data acquisition unit,
• the WP300 Universal Material Tester (20 kN), and
• 8 tensile samples:
– Tempered steel (3 samples),
– Annealed steel (1 sample),
– Copper (1 sample),
– PMMA (Acrylic) (1 sample),
– PVC (1 sample), and
– Plywood (1 sample).
Note
The answer to the question must be incorporated in the discussion and be reflected in the conclusion
part of the report. Therefore, it is an individual component of the report.
Scenario The Scrap Metal Co.
You are employed as the designer engineer in Byke Corp. which is a manufacturer of bicycle frames.
There are a few options available for the frames and you need to compare them in terms of their
mechanical properties. The material options are two types of steel, copper, two polymers, and a
composite. Discuss the mechanical properties of the available materials and choose a suitable material
ased on the results of the tensile test.
http:
youtu.be/zBvJDlljvLA
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Figure 4: Mounted tensile sample with attached extensometer






The force is measured by the load cell, located at the lower part of the machine whereas the defor-
mation of the gauge length is measured by an extensometer (see Fig. 2a). Namely, the deformation is
measured along a specific length in
Answered Same DayDec 10, 20191502ENG

Solution

David answered on Dec 24 2019
61 Votes
Testing of tensile strength of materials: A laboratory report
Abstract: The tensile strength test of material is a laboratory based destructive test conducted in order to know the mechanical properties of that material in terms of obtaining their yield strength, yield strain, tensile strength, failure strength, failure strain, resilience, toughness, and percentage elongation, elasticity, stiffness, ductility, plasticity,
ittleness, malleability. The tensile test is a uniaxial test conducted in universal testing machine (UTM) standardized by ASTM in which the standard specimen taken is a solid cylinder of gauge length 2” and diameter 0.5”. This paper is aimed at to test the tensile strength of different materials viz. steel, copper, two polymers, and a composite by making the samples of standard shape and size. The constituted samples are in 8 numbers, 3 of Tempered steel, 1 of Annealed steel, 1 of Copper, 1of PMMA (Acrylic), 1 of PVC, 1of Plywood of standard shape and size. After conducting the test, for each samples, mechanical properties like elastic modulus, yield strength, yield strain, tensile strength, failure strength, failure strain, resilience, toughness, and percentage elongation were calculated then compare the mechanical properties of given tested material and then select the best strength material in order to manufacture of frame of bicycle required by Byke.corp.
Introduction: The mechanical properties of any material are very important in the process of materials selections for any mechanical design otherwise executed design will fail with the passage of time before its life. Hence it is very important to know the mechanical property of material prior to adopt that in any design. Prior to go to mechanical properties, it is very essential to know stress and strain, the terms associated with testing.
Stress is defined as internal resistance of metal offered against deformation which is the force per unit area. Pressure is the external force distributed on unit area of specimen and it’s unit is N/mm2. Stresses are of two types.
a) Engineering or nominal or conventional stress calculation of which is based on initial area of specimen.
) True or actual stress calculation of which is based on actual area and hence varying .
In tension test, actual stress is equal or greater than nominal stress.
In elastic limit, both stresses are equal because change in area is insignificant.
Similarly, strain is the change in length to original length which is again of two types as of stress.
a) Engineering or nominal or conventional strain calculation of which is based on initial length of specimen.
) True or actual strain calculation of which is based on actual length attained during test and hence varying .
Stress-strain curve should be drawn in between the engineering parameter or true parameter.
Stress- strain curve in tension is drawn to know the mechanical properties of material and may include elastic modulus, yield strength, yield strain, tensile strength, failure strength, failure strain, resilience, toughness, and percentage elongation, ductility,
ittleness, elasticity, Malleability, Elasticity, resilience, toughness, hardness etc.
With the help of reading obtained, a plot of stress (σ) versus strain (ε) is constructed during a tensile test experiment. Figure depicted how typical stress-strain curve would look like.
Figure(1):Typical stress- strain curve
The terminology associated with the curve are depicted in curve its self. The associated point is attained with the incremental load on the standard gauge size of specimen. The various required definition are given below
Elastic modulus: It is the slope when the stress- strain curve is drawn. Up to proportional limit, this slope is constant and called as elastic modulus. Hooks law is valid in this zone.
Yield strength and strain: At yield point, in elastic limit, the strength is yield strength and co
esponding strain is yield strain. In Mild...
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