Review of human perception of whole-body vibration and mechanical shock: the implications of biodynamic nonlinearities and soft tissue

Previous studies have shown that the resonance frequencies apparent in the dynamic response of the human body tend to decrease with increasing excitation magnitude. However, many current standards assume that the human subjective and biodynamic responses to vibration and mechanical shock are the same at substantially different magnitudes of excitation. This paper aims to gather evidence, from human perception and biomechanical studies, that the nonlinear magnitude dependence of human discomfort is related to the nonlinearity in objective measurements primarily caused by soft tissue. Studies are compared in two categories: i) subjective perception studies of whole-body vibration and mechanical shock; ii) experimental and analytical investigations examining the dynamic property of soft human tissue. It was concluded that implementing the nonlinear mechanism of soft tissues into current human body models has the potential to improve the prediction of human physical and subjective responses to vibration. Predictive methods are particularly important for assessing and controlling health risks from high magnitude and high loading rate events such as mechanical shocks and impacts.