Publication: Vibration attenuation of the small scale boat engine handle using dynamic vibration absorber
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Date
2022-01-01
Authors
Md Isa, Mohamad Syazwan
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Abstract
A small-type motorboat engine used by fisherman in the rural area has a direct handle-engine mounting mechanism which can exposed them to the high level of vibration and lead to the Hand-arm Vibration syndrome (HAVs). This study investigates the vibration transmissibility of 3.3 Hp motorboat engine and the application of Dynamic Vibration Absorbers (DVA) at two critical points of motorboat handle to attenuate the vibration in specific direction and frequency ranges. A lab-scale experimental rig is constructed to represent the actual operation of the motorboat engine. Natural frequencies of the handle are determined before and after the DVA implementation to study the resonance effect that may excites the handle vibration.Two types of parameters are taken into consideration for the vibration measurement which is the engine speed (Speed 1: 3000 rpm and Speed 2: 6000 rpm) and gear condition (neutral gear and forward gear) in all three axis directions. From this study, the first and second natural frequencies of the handle are determined in the frequency
ranges of 70-78 Hz and 92-95 Hz, respectively, and the values been shifted closed to the targeted frequency ranges when the DVAs are applied. From the vibration measurement, the handle resulted in high vibration at y axis direction within 45-50 Hz for Speed 1, and 95-100 Hz for Speed 2 in both neutral and forward gear conditions. Two set of DVAs are fabricated and attached at two critical points (point 1 and 3) for each relative engine speed. As a result, the DVAs are capable to reduce the handle vibration in y axis by 42.08% for neutral gear condition at Speed 1, while 53.56% of vibration reduction is obtained in y axis for Speed 2 at forward gear condition. The vibration transmissibility of the handle shows a significant result (above than 1) in frequency range of 0-100Hz and the application of DVAs have improved the vibration transmissibility of the handle. The vibration data is then filtered based on ISO 5349 and the result shows that by applying the DVA, the vibration transmissibility of the handle is significantly reduced by 57.14% for neutral gear condition at Speed 2 and 38.46% vibration reduction is achieved for forward gear condition at Speed 1. Thiscan subsequently reduce the risk of getting HAVs among the motorboat engine operators.