Keywords: human body models, standing human body, stiffness distribution, mass distribution, vertical vibrations.

Human body models have been widely studied as an aid to the understanding of human response to vibration. The many models to represent a standing human body may be classified using four types:

1. simple single or two degree of freedom models in which the parameters of the models were determined based on shaking table tests in the study of body biomechanics,
2. high degree of freedom models in which an anthropomorphic model of the average male body in a standing posture was used;
3. continuous body models and
4. human-structural interaction model.

The scope of the work is to develop a new model that can link the four types of model. A continuous standing human body model in vertical vibrations is developed using the anthropomorphic model and the two available natural frequencies in the biomechanics models. A standing human body is considered as a bar with particular mass and stiffness distributions in vertical directions. The mass distribution of a standing body is formed using the mass distribution of fifteen body segments in the anthropomorphic model [1]. The axial stiffness of the model is determined based on the best matching between the first two natural frequencies of the proposed models and the two available natural frequencies [2]. Six similar models are assessed using finite element parametric analysis. The best of the six models has seven uniform mass segments and two uniform stiffness segments. The continuous model is able to show the shapes of vibration modes throughout the height of a standing body. The fundamental mode shows that the upper part of the body has much more significant movement than the lower part of the body while the second mode indicates that the lower torso has the largest movement but the upper torso moves insignificantly. Finally the modal mass and modal stiffness of the continuous model are evaluated, which are related to the human-structure interaction models.

1

S.P. Nigam, M. Malik, "A study on a vibratory Model of a human body", Journal of Biomechanical Engineering, 109, 148-153, 1987. doi:10.1115/1.3138657

2

Y. Matsumoto, M.J. Griffin, "Mathematical Models for the apparent masses of standing subjects exposed to vertical whole-body vibration", Journal of Sound and Vibration, 260, 431-451, 2003. doi:10.1016/S0022-460X(02)00941-0

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