The vibration transmissibility and driving-point biodynamic response of the hand exposed to vibration normal to the palm.
Xu XS; Welcome DE; McDowell TW; Wu JZ; Wimer B; Warren C; Dong RG
Int J Ind Ergon 2011 Sep; 41(5):418-427
Prolonged, intensive exposure to vibrations from palm and orbital sanders could cause finger disorders. They are likely to be associated with the biodynamic responses of the fingers. Although the biodynamic responses of the hand-arm system have been studied by many researchers, the detailed biodynamic responses distributed in the hand substructures have not been sufficiently understood. To advance the knowledge in this aspect and to aid in the development of improved finite element models of the substructures, this study simultaneously measured the overall driving-point biodynamic response and the distribution of vibration transmissibility at the fingers and back of the hand exposed to a flat plate vibration (as an approximate simulation of the operations of the palm and orbital sanders) and examined the relationship between these two measures of biodynamic responses. Ten subjects (five males and five females) participated in the experiment. A scanning laser vibrometer was used to measure the distributed vibration. This study confirmed that the distributed hand responses generally varied with locations on each finger, vibration frequencies, and applied hand force. Two major resonances were observed in the vibration transmissibility. At the first resonance, the transmitted vibrations at different locations were more or less in phase; hence, this resonance was also observed in the driving-point biodynamic response that measures the overall biodynamic response of the system. The second resonance was observed at the fingers. Because this resonant frequency varied greatly among the fingers and the specific segments of each finger, it is difficult to identify this resonance in the driving-point biodynamic response. The implications of the findings for further model developments and applications are discussed. Relevance to industry: This study enhanced the understanding of the biodynamic responses of the fingers and hand exposed to vibrations on a contact surface with a large effective radius such as that found on palm and orbital sanders. The results can also be used to develop and/or validate models of the substructures of the hand-arm system, which can be further used to help design and analyze these tools and associated anti-vibration devices. The results may also be applicable to help develop location-specific frequency weightings to assess the risks of the finger vibration exposure. Highlights: 1. Simultaneously measured transmissibility and driving-point biodynamic response. 2. The driving-point response is correlated with the transmissibility. 3. Results are useful for developing hand and finger models. 4. Models are required for the designs and analyses of tools and anti-vibration devices. 5. Models are required for quantifying vibration exposure and frequency weighting.
Vibration; Vibration-effects; Vibration-exposure; Hand-injuries; Exposure-levels; Exposure-limits; Humans; Men; Women; Power-tools;
Author Keywords: Hand-arm vibration; Hand-transmitted vibration; Driving-point biodynamic response; Hand vibration transmissibility; Palm sander; Orbital sander
Xueyan S. Xu, Engineering & Control Technology Branch, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505
International Journal of Industrial Ergonomics