Study on clutch engagement judder during launch process for dual clutch transmissions

Clutch engagement judder, as part of vehicle noise, vibration and harshness (NVH), is an important vehicle attribute in the design of dual clutch transmissions (DCTs). This paper presents a system analytical model for clutch engagement judder during launch for DCT vehicles. Influencing factors on clutch judder, including internal factors (friction characteristic, damping, backlash) and external factors (engine torque fluctuation, applied oil pressure fluctuation), are studied analytically and numerically through system stability analysis and free vibration analysis. The results of the simulations show that clutch judder is dependent on the slope of the friction coefficient, static friction coefficient, system damping, applied oil pressure and engine torque fluctuation. Sensitivity analysis and sensitivity functions are presented to find the most sensitive elements in mass matrix and stiffness matrix to shift the undesirable system natural frequencies. The research provides a basis for refinement and optimisation of vehicle design.

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