Transportation Material - Term Paper Example

Transportation Material A disc break is an important aerospace component whose function is to slow down or stop the rotation of a wheel when it is in motion through conversion of kinetic energy into heat energy. The disc break is found connected to the wheel and/or the axle. Disc brakes are usually made of cast iron especially lamellar graphite grey cast iron. Characteristics that make cast iron a good material in the manufacture of disc brakes include high shock resistance, thermal conductivity, machinability, tensile strength, and wear resistance. Cast iron has good surface finish and hardness. Graphite acts as a lubricant hence improving resistance to wear (Heeck et al 1996). Cast iron has a tendency to ‘damp’ mechanical vibrations including sound. Cast iron is able to withstand frictional heat generated during rubbing optimizes due to its high heat capacity and thermal resistance characteristics. Cast iron is also used due to its low cost and ease of production. Its disadvantage is high density leading to heavy weight. Such a weight reduces the initial acceleration and cause increased fuel consumption. Another material that can be sued to manufacture disc brakes is ceramics, for example Porsche Composite Ceramic (PCC). Ceramic has some advantages over cast iron. It is light compared to cast iron hence the weight of ceramic discs is half that of conventional. This results to good fuel efficiency and reduced dust generation. Ceramic functions well in wet conditions compared to cast iron. It has good frictional values hence highly utilized in racing cars. Its characteristics of shock absorption, resistance to friction, thermal conductivity and temperature capability are improved compared to cast iron. PCC brakes can withstand temperature that can make iron cast brakes bendable. Its durability in corrosive environments is enhanced with long maintenance intervals. The disadvantage of ceramics as a disc brake material is its cost. It is higher compared to the price of cast iron (Anderson 1990). Published academic papers relevant to disc brakes ‘Tribological investigation of titanium-based materials for breaks.’ is an academic paper that has published investigation reports concerning break systems. It was published by Blau Peter, Jolly Brian, Qu Jun, Peter William and Blue Craig in 2006. The main aim of the research was to come up with light weight materials that can be use to make effective breaking systems and contribute to fuel efficiency. The objective was to investigate the thermal heating, wear and friction characteristic of Titanium alloys in different forms compare the outcome with cast iron under similar treatment. Basically, the research investigated the tribological characteristics of various titanium-based materials. Materials used in the investigation were seven titanium based materials. These consisted of thermally sprayed coating on titanium, commercial alloys and matrix composites of experimental hand-particle metal. The results useful in determining the potentiality of titanium alloys and their components to reduce the weight of truck disc components and increase their resistance to road-salt corrosion. A research that promises to reduce the cost of titanium had been conducted. This motivated this research because of the ‘promised’ potential low cost and efficiently that titanium break systems. According to Kraft, H. (2002), Titanium alloys have high resistance to salt-corrosion, light weight, high stiffness. The results of this investigation revealed that titanium alloys will need some particulate additions, coating and surface modifications so as to be able to become satisfactory rotor materials. This is because they have some disadvantages. The truck industry is less familiar with the material hence it might not get a good reception Titanium alloys have low thermal conductivity compared too cast iron. This characteristic is crucial in the breaking system because its main purpose is conversion of kinetic energy to heat energy. It has a large thermal conductivity to other parts (Blau et al 2004). Titanium parts cost more than those of other materials. This is due to high cost of raw materials, processing, surface treatment, fabrication and machining. Non-coated titanium discs are more prone to wear compared to cast iron discs. Its positive aspect is that it provides improvements in fade resistance over cast iron. However, it needs a more enhanced wheel well cooling. Thermally sprayed titanium has high thermal values than cast iron but no the other types. The second paper academic paper is a research on self boosting disc brakes for commercial brakes done by Treatsiak Dzmitry and Kliauzovich Siarhei. The purpose of the research was to demonstrate the working capacity of a disc break with self-boosting and its efficiency. The study had three goals: First was to get the decision for the realization of self-boosting in the mechanism of disc brakes which can be distributed to various drives and kinds of vehicles. Secondly, the research was aimed at coming up with an imitation model for loading in ADAMS and estimation of its reliability. Thirdly, to use simulation in AMESim so as to estimate the functional working capacity of disc brakes with self-boosting. Components used for the research were engine for a car on runaway, brake mechanism of a wheel, imitation of the influence of a driver on a brake pedal. The new design has some advantages like minimal alterations of the serial brake design and reduced power run-off from engine at braking and reliability in all working range. The design has maintained all quality brake dynamics at an equal driving effort and at identical break mechanism parameters. Its disadvantages include a complex design due to presence of balls, coupling springs and inclined surfaces of flutes. The design has a complicated heat removal and wear products from surfaces under friction/rubbing because mechanisms of breaking settle inside brake drums. This has negative effects on its maintainability and operational qualities (Roberts et al 2004). In 20 years’ time, investigation of titanium as a material for brake discs will have come up with ways of improving the thermal conductivity of titanium disc breaks. This is because the failure to deal with this issue will continue to disadvantage innovation. Thermal conductivity is crucial characteristics in relation to the role of a disc break. In 20 years time, research on self boosting disc brakes for commercial brakes will have encompassed its usability in private vehicles as well. Mechanisms of how to overcome its complicated heat removal, complex design and wear products will have been covered to enable good utilization its good qualities like reliability. References Anderson, E. et al. (1990), “Hot spotting in automotive friction systems”. Online: http://www.docstoc.com/docs/68697055/Ceramic-Materials-and-Components-for-Engines. Retrieved. 11th March, 2011. Blau. P. et al (2004). “Research on Non-Traditional Materials for Friction Surfaces in Heavy vehicle Disc Breaks” Oak Ridge national laboratory report ORNL/TM 2004/265. Tennessee. Oak Ridge Office of science and technology. Kraft, H. (2002). “The opportunities of low cost Titanium is reduced fuel consumption, improved emissions, and enhanced durability: Heavy truck vehicles.” Oak Ridge national laboratory report. ORNL/TM 4000013062/1. Tennessee. Oak Ridge Office of science and technology. Heeck, I. Diawiddie, R. Ponter, W. and Wong H. (1996). “Thermal transport properties of Grey cast iron.” Society of automotive engineers, paper number 962126. Roberts, R. Gombert, B. Hartman, H. Lange, D and Schautt, M. (2004). Testing the Mechanotronic Wedge Brake”. SAE Technical Paper Series, paper no 2004-01-2766 Read More