Gear rattle modelling and analysis for automotive manual transmissions

 · Abstract: Manual transmission gear rattle is an NVH (noise, vibration, and harshness) concern in the automotive industry. It is induced by repetitive impacts on loose (unselected) gear wheelEstimated Reading Time: 6 mins. Modeling and Analysis of Gear Rattle in Automotive Transmissions. Weijie Zhao, Doctor of Philosophy, Dissertation directed by: Professor Yu M. Wang Department of Mechanical Engineering. In recent years, attainment of high quality in automotive vibration and sound has become a major effort in automotive vehicle refinement programs.  · AbstractIn this paper a non-linear one-degree-of-freedom model for analysis of gear rattle vibrations in automotive manual transmissions is presented. In order .

Layshaft transmission gear rattle and development of gear rattle noise metrics Corvette racing team (C6R) drivetrain dynamic modeling and analysis Present General Motors-Michigan Tech University Relations Team Lead for educational and research partnerships Facilitate and mentor various projects related to advanced propulsion. Highlights We characterize the rattle noise of an actual automotive gearbox. We measure drag torque, restitution coefficient, rattle threshold, loose gear dynamics. A non linear model of the loose gear dynamics is built. Dimensionless parameter describing the rattle excitation level is validated. Real life gear rattle can be characterized for any loose gear and operating conditions. 1. Model complex parametric transmissions 2. Capture all relevant effects correctly and efficiently 3. Update and validate their models Solution: Transmission Builder Up to 5x faster Model creation process Simcenter Transmission Builder Gear train specification based on Industry standards Multibody simulation model.

Previous studies have indicated that temperature plays a key role in transmission rattle (see Tangasawi et al., , and Chapter 26). It is suggested that at higher temperatures loose gear pairs are more prone to rattle due to reduction in resistive (drag) torque. It has also been shown that at some ideal temperature values gear rattle is attenuated. It may be surmised that lubricant viscosity variation in different conjunctions, described above, may be the cause of this. A representative model is developed for a FWD manual transmission, as operated in a dynamometer test cell. Once validated by experimental data, the model is used to investigate the influence on gear rattle of parameters not readily modified or controlled during hardware evaluations. A sinusoidal torque is used to excite the system, and a signal processing technique similar to that derived in Part I of this two part paper is used to identify the inception of gear rattle. Based on the flexible MBD method, a numerical model is used to study and optimize the gear rattle phenomenon of the manual transmission driveline system. This model simulates the gear meshing influenced by driveline torsional vibration, gear clearance, oil drag damping, friction and other nonlinear factors. The mechanism of these influences on gear rattle noise is summarized through parametric study for the purpose of reducing the transmission rattle noise.