Course and ductility. For the tensile test the

 

 

Course

BEng
Hons Mechanical Manufacturing Engineering

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Module

TM614
Applied Mechanics

Lead
Tutor

Geoffrey
Newcomb

Student
Name

Lal
Kima

Student
ID

1236081

Submitted
in

19
January 2018

 

List of Contents

 

Abstract ……………………………………………………………………………………1

Introduction ………………………………………………………………………………. 1

1.0 Materials Testing (Destructive) ……………………………………………………. 1

1.1 Tensile Test
……………………………………………………………………… 1

1.2 Bend Test
………………………………………………………………………… 4

1.3 Hardness Test
…………………………………………………………………… 5

2.0 Materials Testing (Non-Destructive) ……………………………………………….
6

2.1 Visual Test
……………………………………………………………………….. 7

2.2 Liquid Penetrant Inspection
…………………………………………………….. 8

2.3 Ultrasonic Test
…………………………………………………………………… 9

3.0 Discussion …………………………………………………………………………….10

Conclusion …………………………………………………………………………………10

Appendices ………………………………………………………………………………..11

References ……………………………………………………………………………….. 11

 

 

 

 

 

 

 

 

 

 

Abstract

This report covers both practical and research aspects of
material test methods. Material testing is imperative to ensure that a different
types of material testing are used to prove their strength, ability, ductility and
quality of product.”For suppliers, the mechanical properties are an important measure
of product quality, and buyers often require certification of the value” (ADMET,
2015).

 

Introduction

The paper is based on both of destructive and
non-destructive material testing. The metal testing is vitally imperative for
ensuring its strength and ductility. For the tensile test the materials of the
specimen can be different, however the test procedure is the same.

 

 

 

 

1.0  Material Testing (Destructive)

According to the Business Dictionary (2018) the purpose of
destructive testing is to determine service life and to detect design
weaknesses that may not show up under normal working conditions. In destructive
testing the specimen cannot be reused more than once.

1.1  Tensile Test

A website (Laboratory Testing Inc., 2017) explains that the
tensile test is a destructive test method that provides information about its
strength, yield strength and its ductility of the material. Tensile testing is
imperative for ensuring a safe, high quality material and avoiding the major
liabilities associated with providing non-compliant products (ADMET, 2017). Tensile
test is one of the most fundamental types of material test which can be
performed on materials such as plastics, metals, composites, paper, rubbers,
elastomers, fabrics, films, adhesives, etc. The test is simple, relatively cheap,
and fully standardized. The tensile test is a must for ensuring the specimen
not to be loosed before the test is applied. Otherwise the test result can be
different or cannot produce the right answer. The test sample is securely held
by top and bottom grips attached to the tensile or universal testing machine
(Laboratory Testing Inc. 2017). This is proved by the test where it had been
carried out in the Newcastle Aviation Academy. During the tension test, the
grips are moved apart at a constant rate to stretch the specimen. The force on
the specimen and its displacement is continuously monitored and plotted on a
stress-strain curve until failure.

Tensile strength in a material is obtained by measuring the
maximum load.

 

This
diagram represents a brittle material (glass)

 

The
diagram shows that a material with some elasticity and limited plasticity
(high-carbon steel)

 

The
figure represents a material with some elasticity and good plasticity (e.g.
soft aluminium).

 

 

 

The above diagram shows the test result of the Ultimate
Tensile Strength

 

Tensile testing results can be included stiffness, maximum
load, and deflection of maximum load, work at maximum load, load of break, work
at break, stress, strain, Young Modulus, and chord slope. The process is
carried out by placing the test specimen in the test machine and extending it
until it breaks.

 

Advantages

Disadvantages

ü 
Allowing even materials are ductile

ü 
Providing no information about the material at different
temperatures

 

 

 

 

 

1.2
Bend Test

“The bend test is often used as a measure of the ductility
of a material” (Philip and Bolton, 2002). This test is a simple and inexpensive
test that can be used to evaluate both soundness and ductility of a material. The
bend test, also known as bending test, is used for the materials such as
ceramics or glass, wood or plastic, and concrete or stone. The TWI (2018)
proves that the test can be carried out on the shop floor, needing no expensive
test equipment and test specimens are easily prepared (TWI, 2018). This bending
test may be guided or free formed. The bend test method can be various such as
mandrel test, bending on a vee block, bending on a block of soft material and
the angle of bend. According to the author of Materials for engineering
(Bolton, 2000, p. 44) other methods can also be used, e.g. bending round a
mandrel, free bending and pressure bending. The author has been further
discussed that the angle of bend can be withstood without breaking or cracking.

The mandrel form of test is the simplest method test. This
test is suitable for medium and thin thickness sheet for angles of bend up to
120° while the medium thickness sheet with bend angles up to 90° is suitable
for bending on a vee block.

 

Advantages

Disadvantages

ü 
Ease of the specimen preparation and testing

ü 
Testing methods are sensitive to specimen

ü 
Test is simple and cheap

 

 

 

 

 

 

1.3 Hardness Test

The hardness test is defined as the ability of a material
to withstand scratching (abrasion) or indentation by another hard body. It is
an indication of the wear resistance of the material (Timings, 1998). The
hardness of materials is started by measuring their resistance to indentation.
Various methods are used, but the most common methods are Brinell, Rockwell and
Vickers hardness tests. This test is measured by pressing a hardened steel ball
or diamond point into the metal’s surface.

Five major hardness
scales are used in hardness testing such as Brinell-HB, Rockwell-HR, Knoop-HK,
Vickers-HV and Leeb hardness test. The Brinell test is the oldest hardness test
method but still in common use today, determining the hardness of castings and
forgings. The Brinell hardness test uses a carbide ball indenter and methods
are defined by ASTM E10 and 9SO 6506 standards.

Rockwell hardness test
is one the destructive testing of the hardness test. The Rockwell hardness test
is inexpensive, fast and no requirement of a highly skilled operator as the
machine has provided the added advantage. This test is generally easier to do,
and more accurate than other types of hardness test methods. The Rockwell
values are based upon the depth of the indentation while Brinell and Vickers
are based upon the area of indentation.

 

Figure: Rockwell
Hardness Test

 

Vickers hardness test
is similar to the Brinell test, but Vickers uses a squared-based diamond
pyramid indenter. This test is called microhardness test and is used for thin
sections and small parts, or case depth work. The Knoop hardness test is done
at test forces from 10g to 1000g and the test needs a high-powered microscope
to measure the indent size (Instron).

Leeb test is one of the
hardness tests to use for the materials. Leeb test is also known as Equotip
which uses a modern electronic version of Scleroscope. Leeb test uses a carbide
ball hammer that is spring rather than gravity powered (Instron).

 

 

Advantages

Disadvantages

ü 
Taking heavy loads for testing

ü 
Consisting of several short

ü 
It’s easy to perform

ü 
Overlapping scales

ü 
Big materials can be tested

ü 
Only surfaces can be tested

ü 
One indenter is used for all types of metals

ü 
Taking time for experiment

ü 
It’s quick to test (1-30 sec)

 

ü 
Inexpensive

 

 

 

 

2.0  Material Testing
(Non-Destructive)

A website called American Society for Nondestructive
Testing (ASNT, 2017) states that Non-Destructive Testing (NDT) is a test of
material which can still be used the part when the test or inspection is
completed. The NDT involves inspection, evaluation of materials, assemblies or
components for discontinuities, or differences in characteristics without
destroying the serviceability of the part or system. This statement agrees
Prakash (2009) that NDT may be defined as those testing methods in which the
material under test is not destroyed or to say that the future usefulness of
the material under test is not impaired. Various test methods can be used on
NDT Testing such as Ultrasonic Testing (UT), Leak Testing (LT), Visual Testing
(VT), Acoustic Emission Testing (AE), Eddy-Current Testing (ECT), Laser Testing
Methods (LM), Ground Penetrating Radar (GPR), etc.

 

2.1  Visual Test

Visual Test is the most common test Non-Destructive Testing
(NDT) techniques. It is the oldest test for Non-Destructive Testing (NDT) Techniques
as well. Visual Test is easy to apply and the test simple with low cost.

Many defects can be detected by applying direct visual
inspection. Boroscopes, Magnifying glasses, Micrometres, UV Lights, and Mirrors
are mechanical and optical aids used in visual testing (Tech Service Products,
2018).

According to a report from the British Institute of
Non-Destructive Testing (2013) “Much of the success of visual inspection
depends on the surface condition and the lighting arrangements.”

 

The below picture is useful tools for visual testing

 

Advantages

Disadvantages

ü 
Minimum training

ü 
Misinterpretation of scratches

ü 
Minimum part preparation

 

 

 

 

2.2  Liquid Penetrant Inspection

Liquid Penetrant Inspection, also known as dye penetrant
test, is one of the simplest way to test for non-destructive testing technique.
It is also widely used and can detect only surface flaws in every materials. A
dye or fluorescent liquid is used as penetrating medium which technique is
called either dye-penetrant technique or fluorescent-penetrant technique
(Prakash, 2009).

 

These spraying have been used for a dye penetrant testing

 

There are six steps can be carried out when doing the dye
penetrant testing as follows;

1.    Pre-clean
part.

The surface needs to be cleaned from dirt, dust, rust, oil,
etc.

2.    Apply
penetrant.

This step is done by spraying penetrant from the aerosol
can. This normally takes 5-30 minutes but should never be long to dry. The
written procedure on the aerosol can should be followed (NBBI, 2018).

3.    Remove
penetrant.

The third step is to remove penetrant. This penetrant
should be removed with dry, clean, lint-free rags until thoroughly clean. The
material should be cleaned until there is no penetrant visible on the surface.

4.    Apply
developer.

 A thin, light
coating of developer should be sprayed on the part being examined. A dwell time
needs to be observed to allow time for the dye to exit the flaws and create an
indication (flaw) in the developer (NBBI, 2018). A developer takes an hour.

5.    Evaluate
indications.

Evaluation is measured by length of indications, not length
of the flaw. The defects of the linear indications are rejectable, but the
round indication is norelevant.

6.    Post-clean
part.

This is the last part of the dye penetrant test which needs
to be cleaned and removed all developer after the material has been evaluated.

 

 

The figure shows how to inspect the depth of damage by
using dye penetrant inspection

 

Advantages

Disadvantages

ü  It is easy to inspect

ü  Multiple process
steps must be performed

ü  Few material
limitations

ü  Detects only surface
flaws

ü  High sensitivity to
small surface discontinuities

ü  Fumes can be
hazardous

 

 

2.3  Ultrasonic Test

Ultrasonic testing is one of the most popular
non-destructive testing techniques for the detection of internal flaws. This
testing is based upon the interaction of sound waves with the internal
structure of the material (Prakash, 2009). This testing is often performed on
steel and alloys and other metals.

 

Advantages

Disadvantages

ü  The test does not
cause any health hazard to the operator to the persons standing nearby

ü  High degree of
operator skill is needed

ü  It’s sensitive to the
surface

ü  Surface must be
accessible to probe

ü  Only single sided is
needed

ü  Couplant required

 

In the ultrasonic testing the transducer generates high
frequency ultrasonic energy. The high- frequency sound waves are transmitted
into a material to detect imperfections or to locate changes in material
properties. The sound energy is introduced and propagates through the materials
in form of waves. When there is a discontinuity in the wave path, part of the
energy will be reflected back from the flaw surface (NDT Resource Centre).

Pulse echo is the most commonly used in ultrasonic testing
technique. The sound is introduced into a test object and echoes from internal
imperfections are returned to a receiver (NDT Resource Centre). Ultrasonic
testing techniques are not only used for quality control but also used in
industry for inspection of incoming materials (Prakash, 2009).

 

 

 

3.0
 Discussion

As different components there can be different methods for
both destructive and non-destructive testing. Some testing like X-ray testing
are more expensive and slow process while some have good value and simple with
low cost.

 

Conclusion

Despite the advance in both Destructive Testing (DT) and
Non-Destructing Testing (NDT) technology, some testing will continue to be a
technique which many industries rely on for ensuring their quality examination.

 

( ) :

 

Appendices

 

 

 

 

 

 

References

 

ADMET (2017). Why
Tensile Testing is Imperative for Metals Manufacturers Internet.
Available at:
Accessed: 16 January 2018.

ADMET (2015). The Importance
of Materials Testing Internet. Available at; http://info.admet.com/blog/bid/49922/The-Importance-of-Materials-Testing
Accessed; 18 January 2018.

 

ASNT (2017). Introduction
to Nondestructive Testing Internet. Available at; https://www.asnt.org/MinorSiteSections/AboutASNT/Intro-to-NDT  Accessed; 18 January 2018.

 

BINDT (2013). Visual Inspection Internet. Available at:
< http://www.bindt.org/What-is-NDT/Visual-inspection/ >
Accessed: 18 January 2018.

 

Bolton, W (2000). Materials for Engineering. 2nd
ed. Oxford: Newnes.

Instron. Knoop Test
Internet. Available at; http://www.instron.us/en-us/our-company/library/test-types/hardness-test/knoop-test  Accessed; 17 January 2018.

 

Business Dictionary (2018). Destructive Testing Internet. Available at: Accessed;
18 January 2018.

 

NBBI (2018). Liquid
Penetrant Examination Internet. Available at:
Accessed: 18 January 2018.

 

Philip, M; Bolton, W (2002). Technology of Engineering Materials. Oxford: Butterworth-Heinemann.

 

Prakash, R (2009). Non-Destructive Testing Techniques.
Kent: New Age Science.

 

Timings, R.L (1998). Engineering Materials. 2nd
ed. London: Longman.

 

Laboratory Testing Inc. (2017). Tensile Testing Specimens, Fasteners, Tubing, Rebar, Welds &
Castings Internet. Available at:
Accessed: 16 January 2018.

 

Tech Service Products (2018). Visual Testing is Oldest and Most Common NDT Technique Internet.
Available at: < http://tspndt.com/non-destructive-testing-industrial-supplies-blog/visual-testing-is-oldest-and-most-common-ndt-technique >
Accessed: 18 January 2018.

TWI (2018). Bending
Testing Job Knowledge 73 Internet. Available at:
Accessed: 16 January 2018.