An investigation on the vibration transmissibility of the human elbow subjected to hand-transmitted vibration

Abstract

This present study is devoted to investigate the vibration transmissibility of the elbow along the forearm direction as a function of hand grip force. The vibration was from 6 to 500 Hz, which was generated on a single-axis electric shaker. It was transmitted to the elbow from an instrumented handle fixed on the shaker through the hand-arm system. 34 healthy adults participated in the measurement experiment. Each of them applied a constant grip force while maintaining the forearm in horizontal direction with a 90° elbow angle. The grip force was controlled in terms of the percent maximum voluntary contraction and three levels (20%, 30% and 40%) most frequently observed at workplaces were used in the experiment. A laser vibrometer was used to measure the vibration on the bony surface of the elbow along the forearm direction. The measured vibration transmissibility spectrum was expressed in an equal frequency band with a resolution of less than 1 Hz. This study found that increasing the grip force did not significantly change the first resonant peak at 8 Hz but it increased the second resonant frequency and the vibration transmissibility at higher frequencies. Relevance to industryThe effect of the grip force on the elbow vibration transmissibility can be used to enhance the understanding of the vibration-induced disorders. The force-specific transmissibility can also be used as a frequency-weighting factor to quantify the exposure. They may help improve the method for the risk assessment of vibration-induced elbow injuries and disorders.