Variation Reduction of Axle System NVH

This paper presents a study of axle system NVH (noise, vibration and harshness) performance using DFSS (Design for Six Sigma) methods with the focus on the system robustness to typical product variations (tolerances / manufacturing based). Instead of using finite element as the simulation tool, a lumped parameter system dynamics model developed in Matlab/Simulink is used in the study, which provides an efficient way in conducting large size analytical DOE (Design of Experiment) and stochastic studies. The model's capability to predict both nominal and variance performance is validated with vehicle test data using statistical hypothesis test methods. Major driveline system variables that contribute to axle gear noise are identified and their variation distributions in production are obtained through sampling techniques. Through analytical DOE and ANOVA analyses, the critical design parameters that control the system NVH variations with respect to both product variations and variations due to operating conditions are obtained and given in the paper. Design criteria of axle systems with respect to robust NVH performance are discussed.