Different Kinds of Engineering Material - Assignment Example

1. Failure Mode and Scientific Principles a) Ductile Fracture -Ductile fracture is an important mode of fracture in engineering materials. Ductile fracture occurs on ductile materials and the cracks works slowly and a large amount of plastic deformation is depicted. However, the crack will extend further only if certain amount of stress is applied on the material. According to (O’Brien,2002,pg -291 ) “When brittle materials fracture, they shatter. However, ductile materials demonstrate a much wider range of fracture behaviors. This wider range of behaviors arises due to the interaction of plastic energy absorption with the fracture process”. Fig 1 ; Ductile Fracture b) Brittel Fracture – Brittle fracture basically is a fracture where there is a rapid run of cracks within the stressed material . In this case, the crack works much faster and it is difficult to undestand the fracture before failure occurs. The scientific principle in brittle fracture is that the crack moves close to the perependicular where the stress is applied. becuase of this actio, there remains a perpendicular fracture which leaves a flat surface at the broken area. Apart from havinga flat fracture surface , brittle material more or less showcase a pattern on their fractured surface. Fig 2 ; Brittle Fracture c) Fatigue – Fatigue is the most common material failures found in engineering field. Fatigue is a kind of failure mode where the material tend to fracture by means of progressive brittle cracking with regard to repeated cycle of stress. Here, the stress implied on the material is of lesser intensity which means below the average strength. Eventhough the fracture is more kind of brittle , it would take some time to propogate as the frequency and intensity of the stress applied is in cycles. Fig 3; Fatigue d) Creep – Creep is a failure mode which occurs on engineering materials at an elevated speed. Basically it is seen on stainless steel when there is constant stress on the material with exposure to high temperatures. According to ( Total Materia,2010) “The stress that produces a specified minimum creep rate of an alloy or a specified amount of creep deformation in a given time (for example, 1% of total 100,000 h) is referred to as the limiting creep strength, or limiting stress”. Fig 4 : Creep 2. Destructive and one Non-Destructive Test Method a) Destructive Test -The destructive test method is performed to understand the strength, hardness and toughness of a material. The test utilized here is the stress test and for this purpose the material chosen was aluminum crank arm. The specimen was obtained and different loads and stresses were applied on the same. The destructive testing which is also known as mechanical testing displayed some results when stress was put on the iron with the help of hammer. The specimen was hammered until it showed breakage .The transition in the iron was noticed at a typical stress around 13 GPa and it was seen that there was an evident brittle fracture. Fig 5: Brittle fracture on aluminum crank arm. b) Non – Destructive test method - In this test method, the concrete is taken as a specimen for the experiment. Concrete differ from other materials and the stress test on this material is expected to give out distinctive result. The instrument used to apply stress on the steel was a schimdt rebound hammer and it was dropped from fixed height to understand the breaking tendency of the steel specimen. According to ( Carino, 1997,pg .1 - 68) “Owing to its simplicity and low cost, the Schmidt rebound hammer is, by far, the most widely used nondestructive test device for concrete. While the test appears simple, there is no simple relationship between the rebound number and the strength of concrete. During the process, 2 rebound numbers were taken into consideration and the penetration resistance of the concrete was observed. The strength and hardness of the concrete was able to be assessed with this test. Here, the average rebound number observed was between 30 and 40 which recommend that the material is of good layer. Fig 6 : Non – Destructive Test on Concrete 3. Degradation Process of Metals, Polymers and Ceramics. a) Degradation of Metals (Corrosion) – Corrosion is a degradation process of metals and this happens due to the exposure of metal with the environment. Corrosion mainly occurs on metals like iron and it can rust the metal and decrease its durability and strength. Corrosion is also of different kind like localized corrosion, general attack corrosion and Galvanic corrosion. Corrosion comes in many different forms and can be classified by the cause of the chemical deterioration of a metal (Bell , 2015) Fig 7 ; Corrosion of iron b) Degradation of Polymers (Plastic degradation) - The degradation of plastic is a process where the polymer is synthesized and then molding begins. This degradation happens when the plastic is exposed to oxygen, humidity, heat, bacteria and stress. Plastic is a polymer that can be contaminated by other plastic. Fig 8 : Degradation of Plastic c) Degradation of Ceramics – The degradation in ceramics can occur in many ways as they can warp within time .The degradation of ceramics can happen when the material is exposed to high temperatures. Apart from this, degradation of ceramics can come in the form of cracks which is also known as ‘dozlers’. By this way, the ceramic crack or even shatter and constant breaking can result in expansion of the material which causes internal fracture. Fig 9; Degradation of Ceramics 4. Destructive and one Non-Destructive Test Procedure a) Destructive Test (Stress Test) Stress test is one of the destructive methods which is useful as it helps the construction field in understanding the efficiency of engineering materials. With the stress test, it is possible to gauge the state of a material and its performance capability .In construction; the engineering materials are the core substance which aid structure formation. If the materials like iron, steel, ceramic and concrete are exposed to stress test then the durability and toughness of the same can be measured effectively. The engineering materials used in construction are exposed to atmosphere, heat and water and they durability need to be measured well ahead in time in order to test their potency. For example, if iron is exposed to stress test, it is possible to understand its performance when used for engineering purpose. b) Non Destructive Test ( Wield Verification) In the same way , among non destructive test method, wield verification is a high beneficial aspect in engineering as it is the most effective way to understand the workability of a any engineering material iron, steel or metal alloys. For example the compressive strength of steel product can be assessed with wield verification test. The caliber of a material is gauged solely with the help of this test and if the sample of steel has undergone this non destructive test then the structure of a building can remain functional. 5. Degradation Process of destructive and non – destructive test a) Oxidation – Among engineering materials, oxidation is an inevitable phenomenon. One of the engineering materials which is exposed to oxidation is ceramics. This is because the ceramics gets reacted with oxygen in the atmosphere and degrades within a time limit. Ceramics and ceramic matrix composites are candidates for numerous applications in high temperature environments with aggressive gases and possible corrosive deposits (Jacobson,2001).Ceramics is basically used in construction for multi purposes like flooring, kitchen tops and bathroom fittings. If the oxidation on ceramic occurs then the appearance of the products can divulge and this can bring fractures and breakage to the fittings or tiles. In the same way another engineering material which is iron also get degraded when exposed to oxygen and water. When the iron gets degraded, then the rusting can be formed and this is a destructive aspect in construction process. Also metal containing iron like certain types of steel are also succumbed to rusting if exposed to air and water for a long time. When engineering materials like ceramics and iron get degraded then their durability and toughness deteriorate and later can damage the building structure or surface. When corroded ceramics exists in a construction then the surfaces using the material can break or give unfinished appearance. In the same way , if the iron used in construction get rusted or corroded then there can be instability in walls, foundation and appliances of the building Iron products are one kind of engineering material which constantly get accustomed to degradation. Fig 10 ; Corroded Ceramic Fig 11 ; Rusted Metal Wall b) Stress Concentration – In construction, stress concentration is a process which is seen ample among engineering materials and it can occur due to many reasons. A stress concentration or stress raisers occurs on the location of the material where the stress exists the maximum. According to (EWP,2010) “To account for the peak in stress near a stress raiser, the stress concentration factor or theoretical stress concentration factor is defined as the ratio of the calculated peak stress to the nominal stress that would exist in the member if the distribution of stress”. Fig 12; Stress Concentration Process Stress concentration can occur to any engineering material like plastic, steel, iron, bricks or concrete. When stress concentration happens to concrete and brick then the surface of the material crack and can bring damage to the structure or surface. In case of stress concentration of iron, the material can show behavior as brittle fracture. Basically, when there is stress concentration on materials it can fail in performance and its cohesive strength can get undermined. The products also can crack and this can cause tension and failure in the construction process. In engineering many product are succumbed to stress concentration and this does have a serious effect on the construction procedure. One of the products that have experienced stress concentration is shaft. This basically can cause fatigue in materials. Fig 13 : Stress Concentration on Shaft Fig 14 : Stress Concentration in Iron Task 6 : Brinell Hardness Testing procedure Brinell Hardness Testing procedure is one of the most popular testing methods when it comes to engineering materials. According to ( Dusharme,1998) “In the United States, the Brinell test typically consists of a 10 mm diameter tungsten carbide or steel ball pressed into a specimen with a force of from 500 kg to 3,000 kg (1,100 lbs. to 6,600 lbs.). The diameter of the indent is measured with a microscope in two perpendicular axes”. In the study, the Brinell Hardness Testing procedure was carried out with the help of perfectly shaped spherical hard steel ball which measures around 10 mm. The test piece chosen for the procedure was iron. This material was cleaned before the experiment so as to remove contamination from oil, grease or paint. The removing of the contamination was done with a sand paper. Before experiment, it was made sure that the surface of the material was flat, hard or thin. Then ball was pressed against the test surface with the help of static force of 3000 kg on a time limit of 10 seconds. Then the indentation left on the surface in diameters was inspected with graduated low power microscope. The equipment used for the procedure is a manually operating hydraulic press which held the test specimen on a table which was sturdy. Then the properly held ball intender was used for applying force but impact was avoided maximum. It was observed that the test method showed meaningful result only when applied correctly. The result of the experiment was that there was a kind of average surface hardness observed because the material was not in uniform shape when looked through the microscope. The Brinell hardness number which was observed f the indentation diameter was around 4 mm .Also the ratio of Force F to the square of BallDiameter D (in mm) was maintained constant. The pair of force and ball diameter for F/D2 was observed equal to 30. Force (Kg) 3000 750 187.5 30 Ball Diameter (mm) 10 5 2.5 1 Fig 15 ; Table of force and ball diameter ratio. Fig 16; Brinell Hardness Testing Procedure Work Cited Bell, T. (2015). Types of Corrosion. In http://metals.about.com. Retrieved May 21, 2015, from http://metals.about.com/od/metallurgy/a/Types-Of-Corrosion.htm Carino, N. I. (1997). Nondestructive Test Methods. Concrete Construction Engineering Handbook, 19(1), 1-68 Dusharme, D. (1998). Hardness Testing: Absolutely Not Absolute. In www.qualitydigest.com. Retrieved May 23, 2015, from http://www.qualitydigest.com/april98/html/hardness.html EWP, (2010). Stress Concentration. EWP, 12(1), 1-50 Jacobson, N. S. (2001). Oxidation and corrosion of ceramics and ceramic matrix composites. NASA, 5(1), 301-309. O'Brien, J. F. (2002). Graphical Modeling and Animation of Ductile Fracture. ACM SIGGRAPH, 15(1), 291-294 Total Material, . (2010). Creep and Stress Rupture Properties. In http://www.totalmateria.com. Retrieved May 21, 2010, fromhttp://www.totalmateria.com/pag e.aspx?ID=CheckAr ticle&site =kts&N M=296 Read More