Lightweight materials are essential for boosting the fuel economy of modern automobiles while maintaining safety and performance. A 10-percent reduction in vehicle weight can improve fuel economy by 6 to 8 percent.
Roozbeh Dargazany, assistant professor of civil engineering at Michigan State University, will use $1.5 million to help in the weight-reduction effort by building a one-of-a-kind database to better understand one of the challenges – the corrosion of polymeric adhesives, the “glue” for lightweight materials.
“The auto industry is focused on replacing cast iron and traditional steel components with composites, electrification and miniaturization as major steps toward reducing weight of vehicles,” Dargazany said. “Polymeric adhesives also play a major role.”
Reliability of adhesives in corrosive environments is specifically important in the design of electronics, electro-mechanical modules and structural components. Polymer adhesives include such things as epoxy, polyurethane or UV acrylates.
Past research used physical experiments to better understand the short-term reliability of those adhesives but understanding the long-term reliability remains a major challenge, Dargazany said.
His team will predict the service life of degrading adhesives by creating computational software to describe damage accumulation.
He says the research is extremely relevant in electronics since the tools of daily life are increasingly made by materials held together by polymer adhesives.
“Most electronics, including your cellphone, laptop or even your car CPU, may stop functioning due to unexpected corrosion-induced failure of adhesives used in their electrical or structural components,” Dargazany said. “In many systems, early failures can have major consequences.”
Dargazany is collaborating with experts from Bosch Germany and Bosch U.S. to build the database focused on corrosion and reliability analysis of adhesive joints.
The team has proposed a new hybrid modeling technique that could help engineers monitor the aging of specialized adhesives as they are exposed to corrosion due to water, heat and sunlight.
Dargazany said the observed corrosion is a sign of continuous degradation at the atomic and molecular levels. In modeling degradation it’s important to understand how different factors such as UV, temperature or moisture change the rate of degradation at the micro-scale.
“In extreme conditions, adding these factors to fatigue loading can reduce the service-life of the samples from decades to days,” he said. “Our data-driven approach will allow models of different corrosion and fatigue mechanisms to be integrated into one platform. We hope to predict the service life of degrading adhesives to begin solving this issue.”
Emad Poshtan from Bosch’s Division of Automotive Electronics said, “corrosion of polymeric adhesives in joints is a menace to electronics and structural components of vehicles. Damage accumulates from heat, oxidation, radiation, moisture and other sources. Combined with progressive aging and fatigue it becomes a reliability issue.”
Endurica President William Mars noted that one of the key challenges in “vehicle lightweighting”, especially for polymeric adhesive interfaces, is achieving adequate durability.
“The ability to accurately test and simulate the performance of such adhesive interfaces under realistic conditions will drive many new opportunities for these materials in demanding applications,” Mars said.
Dargazany’s research is supported by a 2018 Energy Efficiency and Renewable Energy Award from the U.S. Department of Energy, Robert Bosch LLC and Endurica.