Mechanical models can be used to virtually predict a mechanically induced short circuit. All types of battery cells – cylindrical or prismatic hard case and pouch – can be modeled.

In principle, two different types of modeling can be distinguished:

• In the meso-mechanical modelling approach, each cell layer is modelled separately but homogenized. This means, for example, that an electrode is made up of three layers (active material, metal current collector and active material). Due to the small element size, the time step is very small and the computing time very high, so this model is not suitable for simulating a complete vehicle crash. It allows detailed analysis at layer level.
• In the macro-mechanical approach, all layers are modelled together by a homogenized material with sum properties. This approach provides a fast calculation option with acceptable time steps, which can also be used in vehicle and pack models.

In combination with coordinated virtual detection, both models provide precise short-circuit predictions and enable the crash-proof vehicle integration of batteries. In future vehicle concepts, the so-called structural battery is expected to be part of the load path and a load-bearing component in normal operation and in the event of a crash. For this reason, exact reproduction of the mechanical behavior in a virtual environment under quasi-static and dynamic loads will become even more important.

In addition to model development – including test design and management – current research topics deal with multiphysics coupling and the substitution of mechanical models by AI/ROM.

The multiphysics model kit SIMBAT (Simulation Battery Toolkit) developed by VIRTUAL VEHICLE supports the mechanical and thermal development of batteries from the cell level to battery integration in vehicles and enables a holistic evaluation at an early stage of development.

AI/ROM models can be created from the load cases of the meso-mechanical model and provide information about the mechanical behavior and short-circuit risk. These can replace the macro-mechanical model in the future and can also be integrated into higher levels. This means that the level of detail of the meso-mechanical model is available at all manufacturing levels.