Electric Sports Car Preliminary Design (Performance Envelope)

Abstract

Car design is a complex task because of how highly integrated system of systems it is. Fine designed car models take years of design and optimization and are usually done by specialty teams who are dedicated to each sub-system. This thesis delves into designing a simplified electric race car from scratch with focus on the performance envelope of it. First, a 3D CAD model was done using SolidWorks. That section deals with spatial engineering and strategic placement of major car components for best performance. Having most of the parts in place gives a rough estimate of CoG (Center of Gravity) location, which is needed for vehicle dynamics analysis, which are discussed later in the report. The target for this project car is to have innovative aerodynamics features which might not have been used before because of bulky internal combustion engines restricting available space. One of them is an airfoil-like fascia which makes the center part of the car act as a one big wing. That is believed to give a significant reduction in drag loads on the car. The approach for aerodynamics design and analysis started with a model representing the car’s OML (Outer Mold line) which was simulated separately using Siemens StarCCM+. After understanding the car’s body aero behavior, a rear wing was added to provide extra rear downforce for better handling and stability. The rear wing design was explained in detail. Unfortunately, due to time restrictions as well as software access issues, the aerodynamic analysis of the full car with rear wing is left for future work. After having an estimate about aero loads acting on the car, vehicle dynamics analysis could start. The first subject studied in vehicle dynamics was front-view suspension geometry analysis. Taking the available packaging and geometry into consideration, a 2D model was done in SolidWorks to optimize camber gain. This analysis gave the motion ratio of the front and rear pushrod suspension system which was needed to analyze the performance of the one-eighth car model, ½ car pitch model, and ½ car roll model. These models gave insights into the decision-making process for spring and damping rates to reach a good balance between performance and comfort. This project acts as a hub for further development and studies related to car design.