Vibration/shock/impact injuries

Knowledge of tolerable limits for human exposure to vibration, shock, and impact is essential for maintaining health and performance in the many environments in which man is subjected to dynamic forces and accelerations. As already noted, humans cannot be subjected to injurious stimuli for etbical reasons, and so little direct information is available fixim this source. In these circumstances, the simulation of human response to potentially life-threatening dynamic forces and accelerations is desirable, and is commonly undertaken using biodynamic models, and anthropometric or anthropomorphic manikins. They are also used in the development of vehicle seats and, in the case of hand-arm models, of powered hand-held tools. 

There is extensive literature on the occurrence of health effects and injury from exposure to vibration, shock, and impact, which has been reviewed recently (von Gierke et al 2002) and serves as the basis for the present discussion. Estimates of exposures necessary for common human responses and health effects are summarized in Table 10.2 for healthy adults the interested reader is directed to the references given in the table for more complete information, or to the recent review article cited. Included in Table 10.2 are the metric used for assessing the exposure, the frequency weighting of the stimidus, and a representative value for the response or health effect under consideration. As already noted, there are large variations between individuals in response, and susceptibility, to vi-bratirHi, shock, and impact. 

Ityury from Shock and Impact. Physiological responses to shocks and objects impacting the body include those discussed for whole-body vibration. For small contact areas, the injuries are often related to the elastic and tensile limits of tissue (Haut, 1993 von Gierke et al., 2002). The respcmses are critically dependent on the magnitude, direction, and time history of the acceleration and forces entering the body, the posture, and on the nature of any body supports or restraints (e.g., seat belt or helmet). 

Balandin, D. V, Bolotnik, N. N., Crandall, J. R., Pilkey, W. D., Purtsezov, S. V. Optimal impact isolation for injury prevention evaluated by the head injury criterion. Shock and Vibration 2007 14 355-70. 

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