Optimization Of Suspension Characteristic Of A Pushrod Actuated Suspension System Of An FSAE Car

Since ages, we are trying to find out how things behave. In this process, we started to design the mechanical system based on our knowledge of physics and mathematics. Here is an approach to relate physics and mathematics in engineering problems- of how to optimise the suspension characteristics of a FSAE car. Whenever the suspension geometry is under consideration, the spring and damper acts as the major systems and undergoes fatigue loading which includes many variables. All these variables are reduced to 3 main variables; Factor of safety, diameter of spring wire and motion ratio. Study shows that the ultimate strength of the wire and carbon content is related to the diameter of the spring wire. FOS is related to spring index in turn to the diameter of spring wire and the diameter of the spring is related to the number of coils. Spring rate and motion ratio defines the geometry of the suspension system. A surface fit is obtained between motion ratio, diameter of the wire and FOS by collecting the sampling points. By using Bi-variate interpolation methods, the 3D surface is obtained for the above parameters in x, y and z axis. The obtained surface is chopped off for any value of x, y, z in that particular plane. Mathematically, the intersection of two planes is always a line. This line will be the direct relation between the other two parameters excluding the cut/intersecting plane. Thus all the points in this line satisfy all the design consideration and thus an optimum solution is obtained. Keywords- Bi-variate interpolation, carbon content, diameter of spring wire, Factor of safety, motion ratio, stiffness, Spring index, ultimate strength, Wheel travel, Wahl stress factor.