Article,
Dynamic properties of the biomechanical model of the human body-influence of posture and direction of vibration stress
Journal of low frequency noise, vibration and active control, (2005)
Abstract
Previous studies have shown that exposure to whole-body vibration
can interfere with comfort, activities, and health. In analogy to
materials handling it is assumed that the elevated spinal forces
are a crucial component in the pathogenesis of the health impairment.
To estimate the forces a biomechanical model was developed. In the
model the human trunk, neck and head, the legs, and the arms are
represented by 27 rigid bodies. An additional body simulates the
vibrating vehicle or machinery. The bodies are connected by visco-elastic
joint elements. In total 106 force elements imitate the trunk, neck,
and leg muscles. The motion equations were derived by means of the
dynamics of systems of rigid bodies. Motions were simulated in different
standing and sitting postures and in three vibration directions.
The transfer functions between the accelerations of the surface or
the seat and the spinal forces were computed. By means of these functions
it can be shown that under the conditions investigated the compressive
forces seem to be the dominant stressor between the forces transmitted
in the lumbar spine. However, it cannot be stated that under horizontal
vibration the health risk is only dependent from the compressive
forces. Here the relationship with the shear strength of the spine
being much lower than the compressive strength must be regarded.
