Optimization of the high-frequency torsional vibration of vehicle driveline systems using genetic algorithms

Vehicle drivelines with manual transmissions are exposed to different dynamic engine torques under driving conditions. Engine torque can dramatically vary with throttle demand from coast to drive condition and, conversely, with throttle release from drive to coast. Abrupt application or release of throttle in slow moving traffic or rapid engagement of the clutch can be followed by an audible response, referred to in industry as the clonk noise. This paper presents a complete dynamic model of a vehicle driveline for the optimization of high-frequency torsional vibration by the distributed-lumped (hybrid) modelling technique (DLMT). The model used is first validated against experimental tests. Parameter sensitivity studies have been carried out using the model to identify the important components affecting clonk. Three key parameters have been chosen from the parameter study. To optimize these key factors, genetic algorithms (GAs) have been used in this multi-parameter optimization problem. The GAs show significant reduction in the driveline noise, vibration and harshness (NVH)

Combined Experimental and Flexible Multibody Dynamic Investigation of High Energy Impact Induced Driveline Vibration

Lightly damped non-linear dynamic driveline components are subjected to excitation with rapid application of clutch and/or throttle. Modern thin-walled driveshaft tubes respond with a plethora of structural-acoustic modes under such impulsive conditions, which are onomatopoeically referred to as clonk in the vehicle industry. The underlying mechanisms for the occurrence of this phenomenon are investigated, using combined experimentation and flexible multi-body dynamics under impulsive impact conditions. The coincidence of high-frequency structural modes, coupled with acoustic response is highlighted for the broad-band spectral response of the hollow driveshaft tubes. The cyclic relationship of clonk with the shuffle response of the driveline system is also established for transient decay of the clonk phenomenon. In particular, the multi-body model is used to ascertain the effect of vehicle laden state on the propensity of driveline clonk, an approach not hitherto reported in literature

Longitudinal vibrations analysis of vehicular clutch

This paper investigates the dynamic nature of clutch pedal in-cycle vibration as a powertrain NVH concern. The concern, referred to as "whoop" in industry, occurs during the clutch engagement and disengagement processes. The MATLAB and ADAMS as powerful programs for simulating dynamic systems to model clutch actuation system as a series of multi-bodies between the flywheel and the clutch pedal are used. Finally, the results are compared to experimental evidence and other models which were provided before