College of Engineering
Mechanical Engineering Department
BS in Mechanical Engineering
This document details the collaborative Mechanical Engineering Senior Project with Cal Poly PROVE Lab on PROVE Lab’s Project 2; an electric vehicle designed to travel 1000 miles on a single charge. Logan Simon, Justine Kwan, and Lauren Williams are given the challenge of designing an innovative proof of concept front suspension suspension for this vehicle.
After detailed research of new suspension systems, it was determined that the innovative nature could be in the form of unique manufacturing methods, materials use, or mechanical design. At this point in time, this vehicle is a purely conceptual design with no concrete requirements. Therefore engineering specifications were generated based on vehicles of similar size and function, such as PROVE Lab Project 1, Tesla’s Roadster, and the BMW z4. These specification included vehicle weight, speed, vertical travel, system weight, travel speed, and track width.
Since this car is aimed to travel 1000 miles on one charge, efficiency is a big concern for the design. From ideation, the three suspension configurations of interest were MacPherson, double wishbone, and multi-link. A decision matrix was created to evaluate these designs based on design requirements, resulting in the selection of the multi-link configuration. However, after further investigation it was decided that a double wishbone configuration would provide nearly equal performance and be much more manageable of a task on the senior project time frame, compared to multi-link.
The focus of the project then shifted to innovative manufacturing methods. Carbon fiber was chosen as the material to be used due to its lightweight nature, its accessibility through PROVE lab, and its lack of usage in a suspension system thus far. The upright would provide the most weight savings, so it was designed as a carbon fiber sandwich panel. Computer analysis of the system included SolidWorks FEA, Tsai Wu Failure Analysis, and ANSYS composite analysis to verify Tsai Wu. Four destructive tests were performed to validate the analysis and to determine the number of plies to be used for the final part. With all four tests passing the minimum load requirements with a factor of safety above 1, 16 plies per laminate was chosen and with an additional 8 plies around the edges.
The final system proves that a carbon fiber suspension that is structurally sound for maximum loading cases and that cuts weight down to 4.3 pounds is possible. The full non-destructive test will be performed by the PROVE Project 2 team in the future, unassociated with this senior project.