Effect of direction and arm posture on frequency weightings derived from power absorption of hand exposed to tri-axial random vibration

摘要

The aim of this study is to examine the effects of direction of vibration exposure and arm posture on the frequency weightings derived from vibration power absorption (VPA) of the hand exposed to multi-axial vibration. To calculate the VPA-based frequency weighting factors, the mechanical impedance was measured for twelve male subjects exposed to a tri-axial random vibration. Three combinations of gripping and feed force were considered for three arm posture conditions that consist of two upper-arm postures (horizontally stretched straight and bent by 90 degrees) in combination with two fore-arm postures (pronation and supination). This study showed the VPA-weigh tings under the elbow-bent posture were larger than those under the elbow-stretched posture regardless of vibratory direction. The VPA-weightings in the x and y direction under the elbow-bent posture were quite larger than the ISO-weightings. VPA weightings at the hand were strongly affected by direction of vibration exposure.