Effect of Coupled Mechanical and Thermal Loading on Adhesively Bonded Joints between Metal and Composites in Automotive Structures

With the increased motivation for high fuel efficiency, most automotive research and development efforts are being directed at reducing the weight of an automobile without sacrificing the performance related to safety, durability and NVH. Body structure is one of the viable components for weight reduction. Therefore, use of composites, in particular fiber reinforced plastics are seen as a viable alternative to metals to reduce body weight with the lowest penalty on performance and cost. One could expect future vehicles to be a combination of light weight metals and non metals involving a lot of adhesively bonded interfaces. Structural analysis of these bonded joints subjected to mechanical loads is essential. However, since fiber reinforced plastics are subject to temperature effects, an analysis of structure involving such adhesively bonded materials should account not only for mechanical loading effects but also for the thermal loading effects. In particular since geometric and material discontinuities pose the problem of stress concentration, a coupled thermo-mechanical analysis of the bonded joints become critical from a durability perspective. This paper provides a methodology and results from an ongoing work on the stress analysis at adhesively bonded joint interfaces between metals and plastics subjected to coupled mechanical and thermal loading.