Novel Methodology to Compute Halfshaft Joint Forces and Virtually Simulate Powertrain Wiggle

Vibrations affect vehicle occupants and should be prevented early in design process. Powertrain (PT) wiggle is one of the well-known issues. It is the 3rd order lateral vibration, forced by half shaft inner LH/RH plunging tripod joints [1,2]. Lateral PT resonance (7-15Hz) occurs at certain vehicle speed during acceleration and may excite lateral, pitch and roll PT modes. Typically, PT wiggle occurs in speed range of 5-25kph. Vibration is noticeable on driver and passenger seats mostly in lateral direction. The inner half shaft joints are the major source of vibration. Unfortunately, existing MBD tools like Adams [3] are missing detailed tripod joint representation because of complex mechanical interactions inside the joint. At least three sliding contacts between tripod rollers and joint housing, lubricant inside the can and combination of rotation and plunging make the modeling too complicated.

This paper is dedicated to provide a novel methodology in tripod joint modeling which combines a wide range of MBD tools capabilities in ADAMS [3] along with Matlab based simplified tripod joint model and identification process in order to generate tripod joint forces based on experimentally measured Generated Axial Forces (GAF), provided by halfshaft suppliers. The paper also illustrates the procedure using these forces to perform PT wiggle simulation in ADAMS and correlate the trends of seat track velocities as observed in tests. This process can be used as a directional tool early in design to simulate PT wiggle and drive design improvements.