Experimental and Numerical Investigation of the Behavior of Automotive Battery Busbars under Varying Mechanical Loads

Abstract

Automotive high-voltage busbars are critical electrical components in electric vehicle battery systems as they connect individual battery modules and form the connection to the vehicle’s powertrain. Therefore, a vehicle crash can pose a significant risk to safety by compromising busbar insulation, leading to electrical short circuits inside the battery. In turn, these can trigger thermal chain reactions in the cell modules of the battery pack. In order to ensure a safe design in future applications of busbars, this study investigated the mechanical behavior of busbars and their insulation. Our results indicated that crashlike compressive and bending loads lead to complex stress states resulting in failure of busbar insulation. To estimate the safety of busbars in the early development process using finite element simulations, suitable material models were evaluated. Failure of the insulation was included in the simulation using an optimized generalized incremental stress state dependent model (GISSMO). It was shown that sophisticated polymer models do not significantly improve the simulation quality. Finally, on the basis of the experimental and numerical results, we outline some putative approaches for increasing the safety of high-voltage busbars in electric vehicles, such as choosing the insulating layer material according to the range of expected mechanical loads.

On the Dynamic Electro-Mechanical Failure Behavior of Automotive High-Voltage Busbars Using a Split Hopkinson Pressure Bar

“…The SHPB FE model has been validated using standard material (EN AW1050) coupon tests prior to this investigation. The HVB models and the associated material models were derived from the work of Werling et al [ 15 ]. While the insulation materials were modeled using Mat-124 with tension–compression anisotropy, Mat-24 (piecewise linear plasticity) was used for the copper core.…”

“…The contact between the insulation and the copper was treated using a penalty-based non-automatic surface-to-surface tiebreak contact. For PA12, a sliding-only option (contact friction ) allowing only the interfacial sliding of nodes was chosen [ 15 ]. A tiebreak contact with failure option was set for the PA6GF30 insulated busbar.…”

“…A tiebreak contact with failure option was set for the PA6GF30 insulated busbar. Here, failure of the contact occurs when the contact shear stress reaches a critical limit of MPa [ 15 ]. After failure, the contact behaves like a standard surface-to-surface contact.…”

“…Under compression using a sharp indenter geometry, an SC occurred without complete penetration of the insulation. Their subsequent work [ 15 ] treated the development of suitable FE and material models for HVBs. However, the influence of dynamic loading derived from a vehicle crash has not been assessed.…”

“…With the high strain rate data obtained through the SHPB experiments, it is possible to further improve existing HVB FE models. These were derived from previous work [ 15 ] but only include the quasi-static failure behavior of the busbars.…”