Crashworthiness of C-SMC: a Structural Battery Case for Automotive Application

Abstract

The drive towards electrification has brought a new series of challenges in the automotive world. The need of supporting and protecting the battery modules requires the fulfillment of contrasting objectives. Those are to provide sufficient robustness and stiffness at a low weight while at the same time keeping the costs low. One class of material that promises to meet such requirements is C-SMC (carbon fibre sheet moulding compound). These consists of chips of prepreg fibers that are randomly laid onto a plane and initially compacted into mats. These mats can be cut to side to match the geometry needed. Stiff, light and with the possibility to be formed through pressing, if used in an industrial (automated) environment, it can be a viable alternative to steel and aluminum solutions. With C-SMC the battery case could be designed to incorporate multiple functions such as the thermal management and crash protection with integration into the structure. The simulation of the whole battery system enhanced the design process with the prediction of the mechanical behavior under normal operating conditions and in crash events. Material tests were performed to assess the dynamic response of the material implemented. Advanced non-linear material models and damage evolution methods based on experimental data were used. The collaboration with our industrial partners and the expertise in the process simulation ensured the feasibility of the design as well as its production optimization. The positive outcome of the simulations exposed the full potential of adopting the C-SMC material as a choice for structural parts in EV, resulting in a lightweight although mechanically sound battery casing. Innovative value of the work C-SMC material use in the automotive world has been limited to rather simple and non-structural applications due to the lack of knowledge of advanced mechanical response. Thanks to the expertise and data gathered using laboratory tests (static and dynamic crash tests), as well as the experience coming from industrial partners, an innovative modelling strategy was devised. Modelling, simulation and production of the whole battery case took place. This work resulted in the creation of one of the biggest structural C-SMC component of its kind. After manufacturing, the whole battery case was tested for fire safety as well as crash protection.