Investigation of Motorcycle Handle Vibration Attenuation using a Suspended Handlebar with Different Rubber Mount Characteristics

Motorcycle riders are exposed to prolonged hand-transmitted vibration that can lead to hand numbness and trembling and, in extreme cases, disorders such as the Hand-arm Vibration syndrome (HAVs). The vibration of a motorcycle handle is the result of two major excitation forces, namely the engine vibration and the road-tire vibration. Operating the engine throttle control requires the rider to grip and twist the throttle handle which in turn provides a good vibration transmission path from the handle to the hand. The on-road measurement of hand-arm vibration (HAV) in a rider of an underbone single-cylinder motorcycle show a relatively high value of HAV, with a_hv of 8.28m/s^2. One feasible solution is to attenuate the handlebar vibration transmissibility, by using rubber mounts to create a suspended handlebar. In this study, based on Experimental Modal Analysis (EMA), a hand gripped modal model of the handlebar is developed, and the evaluation is done on the frequency responses of different handlebar designs. The selection criterion is based on the frequency response function (FRF) synthesis index (area under curve) and in this work the area under FRF curve is taken for frequency range of 0 ? 200Hz based on the HAV system. Order analysis of the handle vibration showed higher acceleration level in the z-axis (vertical) compared to the y-axis (horizontal) and for the on-road testing produces, much higher vibration level is determined compared to engine-related vibration due to the tire-road interaction. The suspended handlebar with the best performance is selected for actual on-the-road test, and the result shows a lower a_hv value of 4.08m/s^2 (51% reduction), which significantly increases the vibration exposure limit value (EAV) time from 44 minutes to 3 hours.