Selection of Material in the Design of Torsion Bar - Coursework Example

Title Name Name of instructor Subject Institution Date Selection of material in the design of Torsion Bar Introduction Torsion bar is a form of suspension that is mainly used in wheeled vehicles such as cars and trucks. It is a vital factor in a vehicle construction as they enable the tires to be in contact with the ground, provide support to the chassis and absorbs forces created by movement of the vehicle. Sharna, C. and Purchin, K (2005.p367) their mode of functioning is on the principle of a spring. One end is fixed to the fame of the vehicle while the other end may be connected to the axle, suspension arm or spindle depending on the specifications of the vehicle construction. During the motion of the vehicle, the forces generated by the motion of the vehicle create a torque which bends the bar along its axis. Opposing the torque is achieved by the fact that the bar automatically tends to oppose the twisting cause and assume its original form. In so behaving, the suspension resists the forces created by the movement of the vehicle. Kalluri, S and Bonacus, P., (2000 .p120). This is basically the principle on how the suspension system works. The choice of material relies on its performance characteristics. Alloyed steal are strong, stiff and cheap. This paper gives a detailed analysis of factors that determine the choice of the best quality torsion bar during design. Discussion The design of a torsion bar with optimum characteristics majorly relies on these characteristics. Safety The cross coupling air linking should be prepared switch able by solenoid air valves to enable it to be activated in only off road conditions and in usual highway the right and left spring should not have a connection. Activation on the highway can result in daunting handling troubles. Heibing. B and Ersoy, M. (2010.p60) Furthermore if you are trying any form of cross linking, you need to leave the sway bar linked. Otherwise, the vehicle is likely to fall on its side. The air suspension ECU is used to determine when to activate cross-coupling by monitoring wheel articulation and switching on the cross-linking when it senses the vehicle in uneven off road landscape. Performance Attainment of high functionality is achieved by use of alloy steel. The steel undergo heat treatment process to improve its characteristics, and performance. Coupling is reinforced on either end by use of a spline end.. The finished bar should be fibred coated to keep away rust and oxidization. The spring should be designed to increase spring rate reducing suspension bottom out. The application of high performance torsion bars also boost roll stiffness, minimize weight transfer and improve handling of highly sports vehicles. Cost The materials used in the manufacture of torsion bars should be of low cost and easily available. The materials should be easy to cast into the finished product and the method of casting should be less laborious. The stabilizer bars should be properly designed for the new vehicle design. Protrusion would be the best way of casting because it is cost effective. Furthermore, the method of fixing the torsion bar to the vehicle should not be expensive. Also the overall weight of the torsion bar should not contribute to a greater increase in the weight of the car. The bar should take up les of the vehicle’s volume to allow room for creation of passenger areas. The overall cost of designing, fixing and testing the torsion bar should not contribute significantly to the cost of the car. Regulation The spring rate of the bar should be determined as a function of its diameter, length and material. While the height of riding may be adjusted by rotating the adjuster bolts on the stock torsion key, adjusting the stock key too far can cause the bending of the rotating bolt and place the shock piston below the standard of the stock standard of travel. Over-rotating of the torsion bar should be minimized as it can also result in the suspension hitting the bump stops ahead of time, causing a harsh travel. Changing torsion bars for bar systems which are adjusted using bolts which connect the torsion bars to the knuckles can be achieved using the spring rate of the bar as the determining factor. A proposal for a testing regime The testing of the material would be carried out in a bad terrain environment such as a hilly place, rocky ground or using mechanical tools to test the qualities of the chosen material. The safety analysis would involve determining the spring rate of the torsion bar. If the spring rate does not correspond with the weight and model of the car, the torsion bar would not be selected and an alternative material sought. The maximum bending moment of the bar can be determined by trying the car in a bad terrain environment like a rocky ground. If the material breaks easily, then it should not be selected for the torsion bar material. The safest inclination beyond which the bar should not be used should be determined to ensure that the car is not ridden beyond a certain inclination terrain. However, if the safest terrain for the material is lower than the required terrain, the material is not selected. Evans, H. (2003.p79). On the other hand, if the safest working terrain is higher, the better. Determination of the maximum load, to support the material of torsion bar is very. This would involve loading the vehicle with its maximum load. If the bar cannot operate at the maximum load of the car, then the material is not selected for the designing of the torsion bar. The performance of the bar is determined by establishing the tensile strength of the bar. This would involve testing the component made from the material on a rough terrain ground. The higher the tensile strength, the more the suitability of the material for use as torsion bar and the opposite is true. The length of the spline should be determined for the material selected. If the spline length is not able to provide coupling on either end of the bar, then the material is considered unsuitable for the design of the torsion bar. The spring rate of the material can be determined by subjecting the component to a bending moment to determine its ultimate bending moment considering the safety factor. Kalluri, S and Bonacus, P., (2000, pp122-127) If the material snaps easily under bending moments, then it is considered unsuitable for the design of the design of the torsion bar. Cost analysis should also be included in the testing of the suitability of the material for the component. This would involve determining the cost of raw material and the cost of casting the component. It would also involve the analysis of the cost of fixing the component into the vehicle. If the cost of the component contributes significantly to the cost of the car, then the material is considered uneconomical to use while the less the material contributes to the cost of the vehicle, the better. Testing the component for the design of 1. Smart for 2 This is a model of a car that has a rear engine and is not suitable for use in places with rough terrain. Consequently, the testing for the car can only be done in a place of slightly bad terrain such as a pot-holed road to determine the safety of use of its torsion bar. Since the car is designed for use in a slightly good terrain, the spring rate of its torsion bar is not restricted to be high and those materials with low spring rates can be used to make its torsion bar provided they have a spring rate required for the car. The maximum bending moment of the torsion bar for the car can be determined by driving the car in a potholed road at a slightly small angle of inclination. Sharna, C. and Purchin, K, (2005.p259) Alternatively, the component for the torsion bar can be subjected to mechanical forces of slightly low magnitudes to determine its maximum bending moment. Pagani Zonda C9 Pagani Zonda C9 is a model of a sports car; hence its torsion bar is not expected to have very extreme qualities. The testing for the suitability of the torsion bar could involve driving the car in a slightly bad-terrain ground so that the car can be subjected to torsion motion that determines the spring rate of the torsion bar. However, the tensile strength of the bar should be determined by subjecting the sample material to high tensile forces. Campbell, C. (1981.p137). This enables determination of the ultimate tensile stress of the component allows the choice of a suitable factor of safety if the material qualifies to be used as the torsion bar. Graph showing the young modulus vs. the density of the material to be used. The torsion of the material is given as follows  There fore  The maximizing material index becomes Fig 1 ( Picture of land rover discovery) Fig 2 suspension of a land rover discovery. Fig 3 Pagani Zonda suspension system Fig 4 picture of smart for 2 car Fig five suspension system layout Fig 6 suspension system design References Campbell, C. (1981). New directions in suspension design. Making the fast car faster. U.S.A: Library of congress cataloging in publication data.pp129-185 Collins, J, Busby, H and Staab, George. (2010). Mechanical design of machines: U. S. A.: John willey and sons ltd.pp26-65 Evans, H. (2003).The cars of Gran Turismo.U.S.A: Motorbooks internationalpp77-88 Heibing. B and Ersoy, M. (2010).Chasis handbook.Fundamentalsof driving dynamics, components and mechatronics perspectives.Germany: Viewbag and Teuberg publication.pp45-69 Kalluri, S and Bonacus, P., (2000). Multi axial Fatigue and deformation Testing and prediction.U.S.A: America society for testing materials.pp118-130 Sharna, C. and Purchin, K., (2005). Design of machine elements. New Dhelhi: Princetice Hall.pp172-370 Read More