An Investigation on High Impact Torque of BEV and Driveshaft Robustness Improvements

The inherent capacity of electric motors to generate substantial instant torque can lead to significant load reversals in electric vehicle driveshafts under specific road conditions and driving maneuvers, highlighting the need for targeted improvements in driveshaft design, particularly in optimizing joint sizing. This paper presents a systematic approach to investigate the root causes of a catastrophic driveshaft failure that occurred during specific vehicle tests on a road with multiple speed bumps, resulting in numerous high torque reversals. The objective was to enhance system robustness through changes in driveshaft design and the manufacturing process, coupled with a software calibration technique to reduce torque demands under such operating conditions. The process encompassed torque measurements at the vehicle level, failure replication on a test rig, and correlation with simulations. Sensitivity analyses of the manufacturing process preceded the finalization of design and process modifications, initially validated through rig-level testing. The new driveshaft design exhibited an impressive 9% increase in ultimate torsional strength during rig-level testing, resulting in a substantial sixfold lifespan increase during vehicle-level testing. Furthermore, an additional fourfold increase in lifespan was attained through software calibration, effectively minimizing actual torque demands on the vehicle.