A decisive factor in achieving the climate targets of the German government is the reduction of CO2 through the gradual electrification of transport. In battery-electric vehicles, the energy storage system is typically positioned close to the ground under the passenger cell. Thus, the passage of ground level obstacles or typical load scenarios affecting the underbody are crucial for vehicle safety. Currently, such battery protection structures usually consist of thick-walled aluminum, steel or titanium constructions, which are associated with increased weight and manufacturing costs [1]. Larger moving masses in battery electric vehicles lead to high resource consumption during the usage cycle. Therefore, the battery protection structure represents a lightweight structure.

This paper addresses the development of a functionally integrative lightweight battery protection structure made of glass fiber reinforced plastic (GRP). In addition to the purely mechanical protection of the energy storage unit, this structure should be able to detect and classify any damage occurring to the battery module above during operation. A structure-integrated sensor system allows to automatically determine the extent of damage, which means that downtimes caused by service operations or component replacements are limited to cases of reliably detected damages and are not necessary within defined maintenance intervals or on suspicion.

Based on a detailed requirement profile for the structure, a comparison of selected sensor concepts is carried out. For further investigations, three sensor types (pressure sensor, strain sensor, inductive sensors) are examined in more detail and analyzed with regard to their positioning in the composite as well as their suitability for detecting different load cases. A further issue is the clarification of possible integration options in terms of production technology. For this purpose, the so-called e-preforming technology is used, which enables an automated application of functional elements. In this context, different types of conductor track manufacturing and contacting of electronic components within the sandwich structure is demonstrated.

References

[1] Zhu, J., Zhang, X., Wierzbicki, T., Xia, Y., & Chen, G. (2018). Structural Designs for Electric Vehicle Battery Pack against Ground Impact (No. 2018-01-1438). SAE Technical Paper.