Optimized Modelling and Fabrication of a Parabolic Leaf Spring with Finite Element Analysis

A leaf spring is a simple form of spring commonly used for suspension system of vehicles which is originally called laminated or carriage spring. They perform isolation task in transferring vibration due to road irregularities to driver's body. To improve the suspension system, many modifications have taken place overtime but recent innovations imply parabolic leaf spring and application of composite materials for these springs. The conventional flat profile of the leaf spring has been transformed into parabolic leaf spring which facilitates lighter, cheaper, better fatigue life and isolating more noise. This project basically includes designing a leaf spring with a conventional flat profile design following the standard dimension (SAE Manual) with acceptable tolerance and regard it as the base model for the project. To obtain the deformation, stress and fatigue life of the base model; a Computer Aided Simulation has been carried out in ANSYS Workbench considering the Structural Steel as the base material. Afterwards, the conventional flat profile design has been changed to parabolic shape consisting 1 Master leaf and 3 graduated leaves. In this case, initially the structural steel has been selected as the base material and later on SAE 5160 steel has been implemented to carry out the simulation. As only spring steel is the material widely used for parabolic leaf spring and many research has been carried out with spring steel, therefore different materials with combination of different spring design has been carried out in this project to get a better life cycle compared to the widely used one. After first modification, number of leaves has been increased to 5 but analysis has been carried out with the same two materials considered for initial simulation. Due to time constraint, the final optimized design has been selected among the analysis finished with the combination of leaves and materials which incorporate the better fatigue life, reduced deformation, reduced weight of the spring and increased factor of safety and later on following the final design (analyzed from CAE results) the parabolic leaf spring has been built with the assistance of a spring shop.