Energy absorption and transmission in the hand and arm during high frequency vibration and impact
Abstract: There has been discussion in international literature as to whether vibration containing impact and high frequencies, i.e. above 1000 Hz could make a special contribution to injuries in the hand and arm. The aim of this thesis was to investigate the effect of impact and high frequency vibration on the absorption and transmission of energy to the hand and arm system. The results show that the transmission of acceleration magnitude or energy to different parts of the hand and arm decreases with the distance from the source and are highly dependent in the vibration frequency. There are also differences in the energy transmission due to different types of exposure, random or sinusoidal vibrations. Furthermore, the results show that a great amount of energy was absorbed in the human hand and arm within the freequency range 20 to 5000 Hz. Moreover, was found that there were also differences in energy absorption due to gender; females absorbed less energy than males. Vibration containing impact had a significant influence on both the energy absorption and the hand forces compared to vibration without impact. There were differences in the amount of absorbed energy in the hand and arm between the four investigated vibrating tools. The vibration level also has a strong effect on the quantity of absorbed energy in present studies. If the assumption that higher amount of absorbed energy in the hand and arm represent and increased risk for injury, it can be concluded from the results in this thesis that high frequency vibration and impacts increase the risk for injury.
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