Modeling of Automotive Gear Rattle Phenomenon: State of the Art

The sources of gear rattle in automotive transmission and other components are clearance non-linearities, which include backlashes, multi-valued springs, hysteresis, etc. Periodic vibro-impacts are generated because of the single sided or double sided impacts. It is obviously desirable to develop an appropriate computer simulation model which can aid in the control of transient noise and vibration signatures. Such models can also be used to design experiments and to interpret measured data. Several approaches have been attempted in the past, but most common is the digital simulation of the governing differential equations describing the non-linear, torsional dynamics of the drivetrain. Some progress has been made in understanding the basic rattle phenomenon and in developing suitable mathematical models. This article intends to be a status report on the mathematical or computer models including pre- and post-processing considerations. Various topics that will be briefly discussed include dimensionality and reduced order models, numerical difficulties encountered by solution algorithms, design analysis and optimization, etc. Two specific case histories are analyzed in this paper. The first deals with a reverse-idler gear pair rattle problem, and the second case examines flywheel-clutch-hub spline subassembly.