Solving Drive Shaft Failure in Electric Vehicles

Inherent capability of electric motors to induce high instantaneous torque & causes high load reversals in electric vehicle drive shafts when subjected to certain road conditions & driving maneuvers, which necessitates specific countermeasures for drive shaft design improvements to achieve optimal sizing of drive shaft joints. This paper discusses systematic approach undertaken for root cause analysis of catastrophic driveshaft failure under specific vehicle testing condition on road with multiple speed breakers, leading to multiple high torque reversals and achieve system robustness with shaft design & process change to increase strength together with software calibration technique to reduce the torque demand upon detection of such operating condition. Vehicle level torque measurement, replication of failure on rig & simulation correlation & process sensitivities are studied before finalizing design & process changes & improvement is confirmed on rig level testing first. New drive shaft design showed 9% increase in ultimate torsional strength on rig level, that led to 6 times increase in life in vehicle level test. Additionally, 4 times life increase achieved via software calibration to minimize actual torque demand in vehicle. Keywords: Drive half shaft, life, torsional strength