| Popis: |
It has been generally hypothesized that the biodynamic responses to vibration such as vibration stress, strain, and power absorption density of the human finger tissues are among the major stimuli that cause vibration health effects, because mechanics regulates biological processes. Furthermore, the finger contact pressure can affect these effects. It is difficult to test these hypotheses using human subjects or existing animal models. Therefore, the objective of this study was to develop a new rat-tail exposure system and its related analytical method to investigate the combined effects of vibration and contact pressure and to identify their relationships with the biodynamic responses. Physically, the new exposure system was developed based on the existing NIOSH rat-tail model by adding a loading device to it. An analytical model of the rat-tail exposure system was also proposed and used to formulate the methods for quantifying the tail biodynamic responses required to test the hypotheses. A series of experiments with a tail dissected from a rat cadaver were conducted to test and evaluate the new tail model. The experimental and modeling results demonstrate that the new model behaves as designed. Unlike the previous model, the vibration strain and stress of the rat tail do not depend primarily on the vibration response of the tail itself but on that of the loading plate. This makes it possible to quantify and control the biodynamic responses conveniently and reliably by measuring the plate response. Examples of the quantified tail biodynamic responses are demonstrated and discussed. |
