Static and dynamic stiffness optimization on the body structure of an electric quadricycle

Abstract

Reducing vehicle vibrations is of particular importance due to the adverse effect of vibrations on the ride comfort of passengers. Electric quadricycles are growing rapidly because they are quieter and less polluting than fossil-fuelled vehicles, and these reasons make them a green alternative to personal transportation, and their popularity increases day by day. In this article, the optimization of the body structure of EQ10, an electric quadricycle under development, is discussed to reduce the weight and vibrations transmitted to the passengers with the constraints of bending stiffness and torsional stiffness and yield stress of the elements. The vibrations transmitted to the occupants are measured beneath the driver’s seat by reading the acceleration resulting from the EQ10 excitation sources vibrations. First, a finite element model of the body structure was designed. Then, for optimization, the EQ10 body structure is divided into 29 modules, and in the optimization process, the thickness of these 29 modules is considered as a design variable. The BIGOPT gradient-based method was chosen to solve the optimization problem due to its superior performance to other numerical solution algorithms. To calculate static and dynamic stiffness, modal analyses, and frequency transfer function are conducted to evaluate its general behavior under various functional conditions. Following optimization, results show that the bending and torsional stiffness increased by 45% and 31%, respectively; such fascinating results could not have been obtained without the methods employed in this investigation.