Aerospace Material and Component Testing Techniques - Assignment Example

Aerospace Material & Component Testing: Material Testing Techniques Part a: Component testing. Response to question Component an approach of testing that aims towards empirical testing of the usability of the component of interaction. In this respect, a component requires an independent, controllable and perceivable state. Component testing is divided into hardness testing, Tensile testing and Impact testing. Hardness testing. Hardness involves a material property, which enables it to have resistance to plastic deformation, normally through penetration. This term can also refer to the abrasion, bending, cutting and scratching resistance. The material’s hardness can be assessed by measuring the scratching or cutting resistance. In minerals, relative hardness can be assessed using a reference to the Mohs Scale that ranks the potential of a material to have resistance to the scratching of another material. Other methods that can be used to assess relative hardness include the file test, in which a tempered file to the desired hardness is rubbed on the material surface of a test. If this file slides with no biting, or marks the surface, the test material is said to be extremely harder than that file. If the file marks or bites the surface, the material test is said to be softer than that file. Other methods of achieving a value of hardness involves measuring the area or depth of a left indentation by an indenter or a shape that is specific with a particular force applied for a particular time. In this case, the three standard methods used in giving out the relationship between the impression size and hardness include Vickers, Brinell, and Rockwell. Each of the test method is categorised into scale ranges that are defined by an applied combination of indenter and load geometry. Tensile testing. Tensile testing can also be referred to as tension testing. This is a basic material science test, whereby a sample is set into a controlled tension up to when a failure is obtained. The test results are mostly used in selecting a material for a quality control application and in predicting how a material reacts under other different categories of forces. Some of the traits that are measured using tensile testing include ultimate tensile strength, area reduction, and maximum elongation. These measurements can determine properties like the Poisson’s ratio, Young’s modulus, Yield strength, and hardening strain. In Isotropic materials, unaxial tensile testing is mostly used in the determination of the mechanical traits. Impact testing. Impact testing involves the testing of the ability of an object to offer resistance to a high-rate loading. It is a test that is used in determining the absorbed energy when a test piece is fractured at an increased velocity. This test is vital because it is an important trait of a part designer, yet extremely difficult to be quantified. The part impact resistance is a measure that is critical in service life. This implies that it involves problem perplexing of a product liability and safety. For any impact test to be done, one needs to determine, the part’s impact energies that are expected to be seen in a lifetime, the category of the impact that will give out the energy, and select materials that would have resistance to such assaults in a given lifespan. Response to question 2. A lab report on Hardness testing. Aim. The key aims of this experiment are; to establish the hardness measurements of aluminium, brass, steel, and iron, and to compare and contrast the hardness of aluminium, brass, 1018 steel, and cast iron using the Rockwell hardness test. Apparatus. The materials used in this experiment include brass, aluminium, steel, iron, and the Rockwell Scale. Procedure. Using the Rockwell scale, the measurements of hardness of brass, aluminium, steel, and iron were determined and recorded. The same process was repeated five times and an average for the measurements determined. Results. All the data collected in the experiment were recorded in the table 1. Table 1. Material Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 AVg Brass 74.2 76.6 64.0 70.3 72.3 71.5 Aluminum 43.5 52.7 51.3 49.7 46.7 48.8 1018 steel 93.6 90.5 93.4 91.7 92.3 92.3 Cast iron 97.9 98.4 97.2 98.5 97.7 97.9 Table 2. Material Experimental Published % Difference (+/-) Brass 71.5 69.4 2.1 Aluminum 48.8 40 8.8 1018 steel 92.3 98.7 -6.4 Cast Iron 97.9 100.8 -2.9 Graph: Average hardness values of four metals ordered like in table 1. Graph 2: average values versus published values of hardness. Discussion. The obtained data is consistent to the hardness tester calibrations. The experiment was done through performing the different tests on metals having hardness that is known. There was a close similarity between the experimental values and the published values of hardness. From the results, it is evidenced that cast iron was the hardest material followed by 1018 steel, brass and lastly aluminium. Aluminium is considered to be relatively durable, soft, lightweight, malleable and ductile metal having an appearance that range from silver towards dull gray. Its appearance is dependent on the roughness surface. Aluminium is nonmagnetic and has a low potential for ignition (Chow, 2008). An aluminium fresh field acts as a good visible light reflector and a delightful reflector of far and medium infrared radiations. Pure aluminum has yield strength of 7 to 11 MPa where as its alloy has a yield strength of about 200MPa-600MPa (Chow, 2008). Studies conducted on the hardness of aluminium found out that aluminium ’s hardness is one third that of steel. This research argued out that aluminium was less hard than steel. The hardness of cast iron was close to that of 1018 steel. On the other hand, the hardness of brass changes according to its treatment and preparation and treatment. The hardness will be high in the presence of cold work like swaging, rolling, and bending. The hardness may reduce whenever the annealation is done at temperatures that are elevated. The acoustic and malleability characteristics of brass makes the metal be extremely useful in musical instruments such as trumpets. The strips of brass are used in organic pipes as reeds that beat over the shallot. Brass is considered to be a highly malleable component. It has a melting point that is relatively law. It also has a property of flow which makes it relatively easy to be casted. Since the metal is an alloy of copper and zinc, varying the proportion of its components alters the properties of brass giving room for soft and hard brass. It is a component that is not ferromagnetic hence could be separated from a scrap that is ferrous through passing the scrap close to a powerful magnet (Chow, 2008). The addition of aluminium on brass makes it increase its hardness hence become resistant to corrosion. Aluminium establishes a hard layer (aluminium oxide) that is self healing, transparent, thin and beneficial on the surface of brass. Steel is an alloy that is obtained from the combination of iron and other elements like carbon. In this respect, carbon and other elements in steel have a function of hardening the component hence preventing the crystal lattice of the iron atom from dislocating and sliding past another. The extent of hardness of steel is controlled by varying the quantities of the alloying elements and their present form inside steel. Steel that has a high amount of carbon content is harder than iron, but it may have less ductility than iron. In this respect, cast iron is an alloy having a carbon content that is higher than 2.1% (Chow, 2008). In this experiment, cast iron was found to be harder than the other 1018 steel, aluminium and brass because of its amount of carbon. The quantity of carbon in cast iron made it have a high hardness score in the Rockwell Scale test. This implies than the content of carbon in cast iron was higher than that in 1018 steel. Conclusion. The experiment established that cast iron had the highest harness score compared to the other metals. All the objectives of the experiment were achieved. Aluminium was found to have a minimum score of hardness compared to the other metals. The experimental values were found to be different to the published values due the errors during the experiment. Some of the experimental errors came about due to air resistance, the heterogeneous trait of the calibration plate, faultiness of the Rockwell scale, and wrong calculation. The experimental errors due to parallax were minimised by conducting the experiment five times. The other errors could be reduced by conducting the experiment in a room that has vacuum conditions, and ensuring that the testing scale is accurate before beginning the experiment. The merit of using this method in testing hardness is that it has a direct number of Rockwell hardness and a fast time of testing. Its demerits are that the method has arbitrary scales that are nonrated and specimen influence may support anvil. Part b : Non destructive testing. Response to question 1. NDT or non destructive testing is a technique of analysis that is used in the industry and science fields to evaluate the material properties, system or component with no resulting damage (Hugo, 2001). In this technique, the material properties are evaluated through different techniques of analysis. NDT does not change the article or material that is being inspected, and testing is known to be economical and time saving (Brian, 2005). In aerospace, NDT has a wide range of application because it uses the methods that rely on the utility of electromagnetic radiation, material inherent properties, and sound to examine the different samples. It uses microscopy in examining the external surfaces in detail (Lord, 2006). Response to question 2. Application of electromagnetic testing. ET or electromagnetic testing as one category of NDT involves induction of magnetic fields or electric currents inside an object test and the response of electromagnetism is observed. This type of NDT is crucial because whenever a test is prepared well, a defect within the object test creates a response that is measurable (Brian, 2005). There are different types of electromagnetic testing methods. This include eddy current testing, remote field test, magnetic flux test, wire rope test, and alternating current measurement field among others (Lord, 2006). Advantages of electromagnetic testing. The devices of testing are portable, give out prompt feedback, and does not need the contact of the questioned item. For instance, in eddy current testing, a direct contact with the object to be tested is not needed. This means that the measurements would be done by use of coatings, corrosion products, weather sheeting, and materials of insulation. This gives an allowance of a high inspection of temperature. Disadvantage of electromagnetic testing. Eddy current testing as a form of ET has a number of limitations. Firstly, this testing can only be applied to the materials that are conductive. Secondly, the material surface needs to be accessible (Chow, 2008). Thirdly, the test may result into a material finish that has terrible readings. Fourthly, the penetration depth inside the materials has a limitation to the conductivity of the materials. Lastly, those flows positioned parallel towards the probe might not be detected (Hugo, 2001). Part c : Metrology. Response to question 1. Metrology involves a measurement science. It includes all the practical and theoretical measurements aspects. Metrology as field can be categorised into definiting measurement unit that is internationally accepted, realisating the measurement units in practice, and chain application of tracability measurements links in standards of reference. This can further be divided into fundamental or scientific metrology, technical, industrial or applied metrology, and legal metrology (Baber, 2006). Scientific metrology is used in making quantity systems, unit of measurements, unit systems, new measurement development methods, standard measurements realisation, and the traceability transfers from the standards to society users. Industrial metrology deals with manufacturing science measurements and utility in the society, enhance measurement instrument suitability, the calibration, and the measurement quality control. Additionally, legal metrology involves activities resulting from statutory requirements. Response to question 2. One gauge in metrology that is used in the lab is the error. An error may occur due to mistakes which make counts or measurements incorrect. Generally, all measurements are known as being incorrect. This inexactness in measurements during experiments is referred to as error or measurements uncertainty. In this case, the different measurements needs to be left for chance or observed for correctness. Metrology is useful in making the specific situation measurements correctness. This is performed through allowing and anticipating for both the error and the mistake. For example, one method that is common is the study of the ANOVA gauge R & R (Chow, 2008). References. Baber, Z., 2006. Science of Empire: Civilization, Colonial Rule, and Scientific Knowledge in India. New York: State University Press. Brian, A., 2005. Computer Programming Language. New York: Prentice-Hall Software Series. Chow, T.,2008. Test Softwares Designs Models by Finite-States Machine, IEEE Transaction on the Software Engineering. New York: Oxford publishers. Hugo, L., 2001. Electromagnetic Nondestructive Tests Method. New York : Wiley-Interscience. Lord, W., 2006. Electromagnetics NDT Techniques Retrospective. Materials Evaluation, 12(4) 547- 550. Read More