Search Results

This paper describes the development of an analytical method to assess and optimize halfshaft joint angles to avoid excessive 3rd halfshaft order vibrations during wide-open-throttle (WOT) and light drive-away events. The objective was to develop a test-correlated analytical model to assess and optimize driveline working angles during the virtual design phase of a vehicle program when packaging tradeoffs are decided. A twelve degree-of-freedom (12DOF) system model was constructed that comprehends halfshaft dynamic angle change, axle torque, powertrain (P/T) mount rate progression and axial forces generated by tripot type constant velocity (CV) joints. Note: “tripot” and “tripod” are alternate nomenclatures for the same type of joint. Simple lumped parameter models have historically been used for P/T mount optimization; however, this paper describes a method for using a lumped parameter model to also optimize driveline working angles.

The continued push for faster automotive design cycles while maintaining high product quality requires increasing fidelity in virtual analysis. One vibration disturbance load case that has been targeted for virtual analysis improvement is launch shudder, particularly in electric vehicle (EV) applications. Launch shudder can be caused by halfshaft constant velocity joint (CVJ) excitation of a powertrain mounting resonance. It is heavily dependent on the CVJ friction characteristics, axle torque, dynamic operating angles of the halfshafts, the mounting system of the powertrain and the transfer path of vibration to the occupant’s seat. The need to model these parameters accurately makes a full vehicle, multi body dynamics model a great candidate for this load case. This study introduces an approach to modeling, analysis and applications of launch shudder simulation at General Motors.