Tolerance allocation for multiphysical system – Application to an electric vehicle battery module

The growing interest in electrical vehicles as a solution to decrease gas emission in the transport sector is accompanied by the need to develop lithium-ion batteries technology. This type of complex multiphysical system requires consideration of system behaviors and the interactions between various physical domains when defining the geometry of constitutive parts. The main goal is to ensure the system performance and safety by managing dimensional stability and geometric tolerance compliance throughout the battery’s lifecycle. In the case of an electrical vehicle battery module with prismatic cells, geometric deviations caused by thermo-mechanical stresses directly impact functional requirements such as the system integrity in the vehicle’s battery pack. For this type of module, the cells are generally maintained by metallic plates welded together to secure the assembly and limit movement. In this article we propose to investigate the behavior of a battery module and its impact on casing geometry across different life phases through scenario-based studies. We first examine the vehicle integration phase by verifying that there are no assembly geometrical interferences between the system and fastening screws. We then explore the impact of cells swelling phenomenon during operation. This work introduces iterative tolerance analysis based on the polyhedral model. It focused on the operational life of the system to analyze the impact of the cells swelling phenomenon on a local clearance value through the evolution of the resulting polytope hypervolume. Through these scenarios, we identify the influence of mechanical constraints on the overall behavior of the system, ensuring its correct positioning in the battery pack architecture and its overall structural integrity.