Carbon Fiber Sheet Moulding Compound (CF-SMC) for Electrical Automotive Applications: Simulative and Experimental Design of a Battery Case

Federico Coren

Research output: ThesisDoctoral Thesis

Abstract

The automotive world has been enriched by a series of new challenges deriving from the need to electrify vehicles. The battery modules are heavy and delicate objects, and to protect them a battery case needs to fulfill a series of contrasting objectives. Major goals are high stiffness, good mechanical resistance, good crash-worthiness, good formability and all of this while having a reasonable manufacturing cost and low weight. Given the sheer size of the battery components, they present some of the biggest weight reduction potential. On top of that, their position low in the car body allows for an increase of the overall rigidity of the vehicle.
For this reason, this research arises from the goal to design, produce and test a battery case made of carbon fiber sheet molding compound (CF-SMC) materials. This material exhibits a high stiffness-to-weight ratio, excellent crash withstanding capabilities and the possibility to be molded into complex shapes. These factors make this material capable of replacing existing metal based solutions.
A new material modeling method for the strength and damage propagation for the CF-SMC has been developed by combining existing theories in a novel way. This method allows for an efficient simulation of CF-SMC structural components by using computationally efficient shell elements. The model is able to capture the complex damage and crack behavior of the material during crash events. In particular the gap between the academic approach, very sophisticated but slow, and the industrial one, very fast but inaccurate, was bridged with this computationally efficient and accurate modeling method. Laboratory tests were performed for both static and dynamic conditions to validate the modeling and simulation method.
Once the modeling was validated, a full scale battery case was designed, simulated and produced. The battery case is 40\% lighter than metal based solutions with similar mechanical performance. The battery case integrates a series of functions such as cooling, structural and crash protection in a single component. Fire protection was investigated and some solutions proposed.
The crush tests confirmed the robustness of the battery case, being able to withstand the crushing force imposed by international standards without damaging the internal components.
The simulation results were compared with the data coming from full scale crush testing of the whole battery case assembly. The simulation predictions are in accordance with the full scale testing, being able to simulate the initial elastic material response as well as capturing the material degradation and cracking.
Original languageEnglish
Awarding Institution
  • Graz University of Technology (90000)
Supervisors/Advisors
  • Fischer, Peter, Supervisor
Publication statusPublished - 2022

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