Analysis and optimization of clutch judder based on a hybrid uncertain model with random and interval variables

Abstract

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.

Investigation on friction-induced judder of vehicle driveline based on a nonlinear friction model

“…After the engagement of the flywheel and the clutch driven disc is completed, the relative speed between the two is almost zero, and the torque transmitted by the two is equal. Therefore, assuming € u f = € u c , the shear torque T s can be obtained from Equation (21):…”

“…When the gradient of the friction coefficient with relative speed is negative, the system's comprehensive damping effect is negative, which can easily cause the system to be unstable and then cause the self-excited judder. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Based on the conclusion, many scholars have concentrated on the influencing factors of clutch friction coefficient. Li et al 23 analyzed the influence of friction materials on clutch judder through the comparative analysis of 18 kinds of frictional lining specimens.…”

“…In addition, when analyzing the judder caused by friction, most scholars use the Karnopp friction model for the friction torque analysis, 7,11,12,15,[19][20][21][22]34 but the Karnopp friction model does not include the stribeck effect and cannot accurately reflect nonlinear characteristics of the friction. The Gaussian friction model includes the stribeck effect, but it assumes that the friction torque is zero simultaneously when the relative speed is zero, 8,24 which is inconsistent with the reality.…”

“…Through a 4DOF equivalent dynamic model, Li et al 20 analyzed the influence of factors such as the axial stiffness of the clutch waveform cushion, the inertia and damping of the clutch driven disc on the self-excited judder. Hao et al 21 also established a similar 4DOF equivalent model, and analyzed the influence of factors such as the friction coefficient, the damping of the torsional vibration absorber and clutch driven disc on system stability.…”

Mechanism-oriented control for suppressing start-up judder of vehicle with automatic dry clutch: Experiment and simulation analysis

“…Under start-up condition, judder and shuffle may occur in driveline. 1 In the process of synchronizing clutch and engine, severe torsional vibration sometimes may occur due to unstable sliding friction, and meanwhile the tactile sensation perceived by drivers is the longitudinal vibration of vehicle body, which is referred to as the vehicle start-up judder phenomenon, 2–4 especially for manual transmission (MT). After the synchronization, the shuffle phenomenon may occur because of sudden changes from sliding friction to static friction in torque.…”