SURNAME AND INITIALS: MBUTHUMA.N
STUDENT NO : 217110177
SEMESTER AND YEAR: S2 2019
SUBJECT: STRENTH OF MATERIALS III
PROJECT ASSIGNMENT: ONE
LECTURER : Z MKOKO
DUE DATE : 09 MAY 2019
TABLE OF CONTENTS
Material testing is often the last phase in the production cycle. Yet, both the process and the material result in quality. If the material entering the product is defective, the product may be defective. After the fact, quality can not be put into it. Understanding the properties of the material can help to better predict the manufacturing outcome by forming materials. (Types, 2019)
A material profile will assist identify differences in components from providers for stamping and forming activities and for many goods. In reality, many of the most frequently used metals and many plastics, polymers, fabrics and composites display Hookean conduct, meaning that the pressure in a fabric is equal to the strain it generated. For manufacturers, it is of the utmost significance to recognize the mechanical residences of materials that exhibit some Hookean behavior throughout loading. It is necessary because the overall performance of a structure is frequently determined via the quantity of deformation permitted. A deflection of a few thousandths of an inch in an optical grinding machine will produce scrap lenses, whereas a bridge truss or joist would possibly deflect various inches.
Tensile testing, also recognized as stress testing, is a damaging engineering and electronics scientific experiment that either applies regulated stress to a sample as a load for evidence testing or until it falls completely. This is one of the most popular mechanical test methods and is used to figure out how powerful a fabric is before it splits and how much it can be extended. This experiment technique is used to determine output capacity, maximum tensile capacity, ductility, stress hardening features, the Youngs modulus and Poissons ratio. (Twi-global.com, 2019)
PURPOSE OF TENSILE TESTING
Tensile testing provides details of a material’s mechanical tensile properties. These properties can be plotted as a stress / strain curve on a graph to show details such as the point where the material failed as well as details of properties such as the elasticity, strain and yield strength module. (Limited, 2019)
ADVANTAGES OF TENSILE TESTING
Tensile offers statistics on the integrity and protection of materials, elements yet products, assistingmanufacturers ensure to that amount their completed merchandise are fit-for-purpose then constructed in accordance with the perfect quality. (Limited, 2019) said.
The data produced in a tensile test can be used in many ways including:
To determine batch quality
To determine consistency in manufacture
To aid in the design process
To reduce material costs and achieve lean manufacturing goals
To ensure compliance with international and industry standards
APPLICATION OF TENSILE TESTING
Tensile testing is used in a broad spectrum of sectors to ensure the performance of parts, equipment and completed goods. Typical tensile inspection requests are mentioned. (Limited, 2019)
Electrical and Electronics Industry
Medical Device Industry
An impact test is used to observe the mechanics that a material will exhibit when it experiences a shock load that causes the specimen to completely deform, fracture or rupture immediately. The sample is put in a holding shed with the design and direction determined by the sort of experiment used and then a defined weight is usually removed from a recognized height but not always in the form of a pendulum so that it collides with the specimen with a sudden force. This collision between the weight and the sample usually results in the sample being destroyed, but the power transfer between the two is used to determine the material’s deformation structure. (Types, 2019)
PUPORSE IMPACT TESTING
An impact test is intended to determine the material’s ability to absorb energy during a collision. Depending on the test performed and the characteristic to be determined, this energy can be used to determine the material’s toughness, impact strength, fracture resistance, impact resistance or fracture resistance. These values are important for the selection of materials to be used in applications requiring the material to undergo very rapid loading processes such as collisions with vehicles. (Types, 2019)
Types of Impact Test
The Charpy V-notch test, the Izod test and the Tensile Impact test are the three most common sample kinds for a single effect exam. All of these three experiments mainly determine the same material features but vary in the test sample direction, which allows the sample to be squeezed in distinct ways and involves a known weight produced from a recognized height that collides with the specimen in its test shed. All these experiments are helpful in determining the sample specimen’s effect dynamics. (Types, 2019)
(Izod test equipment)
(Schaulsohn, 2019) said a fatigue test helps to determine the ability of a material to withstand conditions of cyclic fatigue load. By design, a material is selected to meet or exceed service loads anticipated in fatigue testing applications. Cyclic fatigue tests produce repeated loading and unloading of these stresses in tension, compression, bending, torsion, or combinations. Fatigue experiments are frequently packed into compression and inverted in tensiontension, pressurepressure and strain.
A specimen is packed into a fatigue testing device or fatigue testing device to conduct a fatigue experiment and weighed using the pre-determined experiment pressure, then unloaded to either null or an inverse load. This charging and unloading process will then be continued until the exam ends. The experiment can be conducted to a predetermined amount of periods or until the sample fails depending on the test parameters. (Schaulsohn, 2019)
PURPOSE OF FATIGUE TESTING
Usually the aim of a fatigue test is to determine the lifetime that can be anticipated from a product subject to continuous loading, however the values frequently requested are fatigue strength and crack resistance. A material’s fatigue life is the total number of cycles under a single loading scheme that a material can undergo. A fatigue test is also used to determine the peak load for a defined amount of cycles that a sample can resist. In any sector where a material is subject to fluctuating rather than steady pressures, all these features are highly crucial. (Schaulsohn, 2019)
Hardness is a material feature, not a basic physical property. It is described as the indentation strength and is determined by evaluating the indentation’s continuous width. Simply put, the smaller the indentation, the harder the material when using a fixed force (load) and a given indenter. (Hardnesstesters.com, 2019)
(Hardnesstesters.com, 2019) said that the Rockwell technique estimates the continuous indentation depth generated on an indenter by a force / load. First, using a diamond or ball indenter, a preliminary test force (frequently referred to as preload or low load) is introduced to a sample. This preload breaks through the surface to decrease ground finishing impacts. The baseline depth of indentation is evaluated after keeping the preliminary sample force for a designated dwelling moment.
BRINELL HARDNESS TEST
In 1900, Dr. J. A. Brinell created the Swedish Brinell test. The eldest of today’s commonly used hardness analysis techniques, the Brinell test is often used to determine the strength of forgings and castings that have a sheet composition that is too course for Rockwell or Vickers testing. Brinell experiments are therefore often performed on big components. Almost all plastics can be screened using a Brinell test by adjusting the sample strength and cap size. Brinell values are considered independent of test force as long as the relationship between ball size and test force is the same, said (Instron.us, 2019)
Developed in England in 1925, the Vickers (HV) test was formally known as the Diamond Pyramid Hardness (DPH) test. The Vickers test has two distinct ranges of force, micro (10 g to 1000 g) and macro (1 kg to 100 kg) to address all experimental criteria. For both ranges, the indenter is the same, so Vickers hardness values are continuous over the total range of metal hardness (typically HV100 to HV1000). Vickers values are generally regarded as independent test force with the exception of test forces below 200 g. In other words, if the material being tested is uniform, if tested using a 500 g force or a 50 kg force, the Vickers scores will be the same. Caution should be used when attempting to compare results below 200 g.
NON-DESTRUCTIVE TESTING METHODS
Non-Destructive Testing (NDT) is the examination of a technology-based item or substance that does not influence its potential utility. NDT can be used without any item or content being destroyed or damaged. NDT offers an outstanding equilibrium of quality control and cost-effectiveness as it enables inspection without intervening with the ultimate use of a product.
The word “NDT” involves a number of possible techniques:
Detect imperfections internally or externally
Determine characteristics of structure, composition or content
Measure geometric properties
In any stage of the design and manufacturing process of a product, NDT can and should be used, including material choice, study and growth, performance assurance and production.
TYPES OF NON-DESTRUCTIVE TESTING METHODS
Liquid Penetrant Testing
One of the easier techniques used to identify material flaws is liquid penetrating testing. When applied to a surface, a liquid dye penetrant is drawn into any surface cracks or voids, highlighting visible breaks in the structure. (Twi-global.com, 2019)
Advantages of the penetrant method of Non-Destructive Examination are
It is a technique that is very delicate and can find incredibly good faults.
It can be used with some plastics and glass on natural and non-magnetic materials.
It is possible to inspect small items with unpleasant forms.
For some penetrating testing techniques, an energy supply is not required.
The technique does not require excellent ability and can be easily understood.
Many tiny items can be examined in batches using automated processes.
Disadvantages of the penetrant method of Non-Destructive Examination are:
Only faults accessible to the ground can be detected.
Preparation can be time-consuming and expensive before testing.
The technique requires time and in less than 30 minutes can rarely be finished.
Normally, the method cannot be used for coloured items.
It is sometimes hard to interpret the outcomes.
Contaminated cleaning and penetrating liquids may have a trouble disposal.
Dry, smooth circumstances are crucial, just as the surfaces to be examined are carefully cleaned.
The method is often abused and skimped, or not fully understood.
There can be a fume exposure problem, particularly in confined spaces.
Magnetic Particle Testing
Magnetic particle analysis is commonly used in ferromagnetic products to detect surface and near-surface defects. The fabric is magnetized to be screened. The air gaps caused by any faults on or near the ground trigger magnetic flux leakage. To outline each fracture and promote detection, iron ions distributed on the ground will be drawn. (Twi-global.com, 2019)
Advantages of the Magnetic Particle method of Non-Destructive Examination are:
It’s fast and comparatively straightforward.
It provides instant signs of faults.
It demonstrates surface and close surface flaws, and as they focus pressures, these are the most severe ones.
You can adapt the technique to use the location or laboratory.
Compared to radiography, it is cheap.
It is possible to examine large or tiny items.
There is no need for pre-cleaning.
Disadvantages of the Magnetic Particle method of Non-Destructive Examination are:
It is limited to ferromagnetic materials-usually iron and steel, and can not be used on stainless steel austenitic.
Most techniques require energy availability.
Whether the magnetic field is powerful enough to offer useful signs is sometimes uncertain.
If there is a thick paint coating, the method can not be used.
Spurious or irrelevant signs are likely, and understanding is therefore a qualified job.
Some of the suspended liquids of the paints and particles can cause a fume or fire issue, especially in a confined room.
Materials are chosen for use on the basis of several factors, the most significant of which are the material characteristics. The properties of a substance, under different circumstances, describe its personality or conduct. In metalworking, mechanical characteristics are the most crucial to consider. Strength, hardness, elasticity, plasticity, ductility, and toughness are the desirable characteristics. Brittleness is an undesirable metal property. Material testing is required to determine a material’s capacity to perform a specific task. The metals selected for use in a venture must be sustainable, reliable and secure.
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