Masters Theses

Date of Award

5-2025

Degree Type

Thesis

Degree Name

Master of Science

Major

Mechanical Engineering

Major Professor

Uday Vaidya

Committee Members

Uday Vaidya, Krishnan P. Veluswamy, Jeffrey A. Reinbolt

Abstract

As electric vehicles (EVs) grow in popularity for reducing carbon emissions and nonrenewable energy usage, the need arises for automakers to identify ways to further reduce EV energy consumption and increase vehicle range. This can be achieved by lightweighting automotive components to reduce electricity consumption and therefore environmental impact during vehicle operation. Since the EV battery pack (including its enclosure) accounts for 20–30% of total vehicle weight, lightweighting the battery enclosure can lead to significant environmental impact reductions. This thesis utilizes a cradle-to-cradle Life Cycle Assessment (LCA) to evaluate the environmental impact of three battery boxes made from steel, aluminum, and glass fiber sheet molding compound (GFRP-SMC). Six impact categories were considered: carcinogenics, non-carcinogenics, ecotoxicity, eutrophication, fossil fuel depletion, and global warming potential (GWP). A use-phase comparison of GWP vs. driving distance and a sensitivity analysis on SMC resin choice are included. A case study of 10,000 battery boxes is also presented. The results indicate that the GFRP-SMC battery box is the lowest-impact choice in four out of six impact categories and exhibits a 13.2% and 3.9% lower GWP than steel and aluminum respectively. The steel battery box exhibited the highest impact in all categories excluding carcinogenics, where it marginally outperformed aluminum by 0.4%. Aluminum exhibited a 3-11% lower impact than steel in all other categories, but a higher impact than GFRP-SMC in all categories excluding ecotoxicity and non-carcinogenics by a small amount (0.1-0.4%). The use phase comparison highlighted GFRP-SMC as the best option for driving distances greater than 13,000km, with aluminum becoming a lower-emission option than steel for distances beyond 155,000km. Sensitivity analysis results showed that SMC resin type does not significantly affect production-phase emissions. Results of the case study revealed that battery box production-phase GWP could be reduced by up to 65.6% and overall lifecycle GWP reduced by up to 13.2% by switching to GFRP-SMC. Overall, GFRP-SMC was shown to be an excellent choice for EV battery boxes in terms of environmental impact, and further work is recommended to make glass fiber and SMC composite production more economically competitive with traditional metals.

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