A Comprehensive Study on Long-Term Durability of Protective Epoxy Coatings for Wireless Power Transmission Systems in Electrified Roadways

Underground wireless power transmission (WPT) systems are susceptible to environmental threats such as high temperatures, water ingression, and mechanical impact from above-ground objects. Typical WPT systems are safeguarded with civil-grade epoxy coating, thus it is imperative to assess the coating’s durability in these extreme conditions. Among various environmental threats, this study is primarily focused on both experimental and numerical investigations of water diffusion effects on civil-grade epoxy materials. A series of water diffusion tests were performed on the specimens made from two commercially available electronics casting epoxy materials at room (23°C) and high (50°C) temperatures. A sequentially coupled, multi-physics finite element (FE) model was developed to predict long-term water diffusion induced hydrothermal and mechanical damage in the epoxy materials. The FE model consisted of three sequentially coupled analyses: (1) heat transfer analysis, (2) swelling analysis form long-term mass diffusion, and (3) low velocity impact (LVI) analysis. The numerical results show good agreement with in-house experimental findings, indicating that the framework can serve as a baseline for predicting epoxy coating performance on WPT systems.