Modeling differences in the vibration response characteristics of the human body

Mathematical models may provide a useful tool for the development and evaluation of seating systems for vibration mitigation. A five-degree-of-freedom (DOF) model was formulated based on the measured driving-point impedance and transmissibilities of major anatomical structures contributing to the observed resonance behaviors. The model was limited in its ability to simulate differences observed in the resonance behaviors of a broader population and was unable to simulate the multiple resonances observed in the thigh. This paper describes the effectiveness of a modified five DOF model in simulating the major resonance behaviors observed in the population using representative data from a 56 kg female and 75 kg male. In addition, the model was also evaluated for its ability to predict the effects of selected seat cushions. The modified lumped-parameter model improved the peak chest and spine transmissibility simulations. The model was effective in simulating both the lower impedance peak observed in the primary resonance region (4-8 Hz) and the prevalent impedance peak observed in the second resonance region (7-10 Hz) in the smaller subjects. However, the model was not effective in predicting the dampening observed in the second resonance peak with the use of cushions. Redistribution of the model coefficients for the legs and the consideration of coupling between the legs and other anatomical structures may further improve the ability of the lumped-parameter model to predict the effects of seating systems on vibration transmission in the human body.