Drivetrain Gear Rattle Simulation Methodology & Optimization: Simulation and Testing Correlation

This paper describes a simulation methodology developed for gear rattle severity evaluation and drivetrain architecture optimization. The noise generated by gear rattle is one of the main contributors towards customer’s overall NVH perception. This study adopts a model-based design approach to simulate the tendency of gear rattle in neutral and drive conditions. Gear rattle simulation model for Tractor driveline developed in 1-D environment and correlated with test data acquired on tractor drivelines for multiple field applications. This analytical physics-based model includes engine torsional signature, clutch damper torsional characteristic and dynamics of traction and PTO driveline. This dynamic simulation model helps to understand and predict the gear rattle severity of various drivetrain architecture early in the product development cycle and assess & Optimize driveline NVH performance. The simulation model predicts the mesh force variation between the gear pairs based on engine excitation & driveline system dynamic response. The standard deviation of this gear mesh force is used as a gear rattle metric to quantify the rattle tendency and correlated with NVH subjective assessment. DOE conducted to assess the impact of the various driveline parameters i.e., Flywheel inertia, damper stiffness & hysteresis, gear backlash etc. on gear rattle metric. This virtual methodology was deployed for multiple drivetrain architecture evaluation & based on the analysis optimal drivetrain architecture adopted for better customer NVH perception. This methodology helped in developing new predictive simulation workflows to resolve design issues analytically and effectively within a relatively shorter time with significant reduction of product development time and cost.