The clutch judder has serious impacts on the NVH (noise, vibration and harshness) performance. In this paper, a simplified four-degree-of-freedom dynamic model with nonlinear friction torque and engine torque excitation is developed to simulate the clutch judder, and the stability and dynamic response of the clutch is analyzed based on the simplified model. In addition, the real part of judder modal frequency, the moment when the clutch enters the stick state, and the fluctuation level of the driving part of clutch are treated as the evaluation indexes of the judder performance. An uncertain hybrid model with random and interval variables is used to described the uncertainty of parameters and a hybrid perturbation vertex method is formulated to compute the uncertainty of the clutch judder. Furthermore, the parameters with high sensitivities are used as design variables and the uncertainty-based optimization are conducted to reduce the clutch judder.The optimization results have strongly validated that the proposed method is very effective to improve the robustness of the clutch judder performance.
The driveline torsional vibration issue is one of the most significant NVH (Noise, Vibration and Harshness) problems, especially in a rear wheel drive vehicle with a manual transmission. In this paper, a new driveline and rear axle coupled torsional vibration model (DRCTVM) is developed, which considers the relationship between the driveline and the rear axle. The experiments have shown that the DRCTVM can provide much better results compared with the traditional model. In addition, for the first time, the uncertainty theory is introduced to the analysis and optimization of driveline torsional vibration based on DRCTVM. A truncated normal distribution is used to describe the uncertainty of DRCTVM, which considers both the probability distribution and bounds of uncertain variables. Furthermore, the robustness of the driveline torsional vibration is analyzed by Monte Carlo process and optimized by Multi-Island Genetic Algorithm. The optimization results have strongly validated that the proposed model and method are very effective to improve the robustness of driveline torsional vibration performance.
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