Pelvis Rotation during Whole-Body Vibration: Modeling & Validation Experiments

It is generally recognized that long-term whole-body vibrations can induce degeneration of the lumbar spine, but it remains unclear what the exact mechanism behind this degeneration is. The problem is complex due to the incompletely understood dynamic responses of the body and influence of many variables. Several researchers have indicated the importance of the rocking movement of the pelvis in the response of the spinal system, but only few data is available to support this hypothesis.

A 3D finite element (FE) model of the human buttocks is developed. The model contains a detailed geometric description of the pelvis and thighs and realistic material properties, seated on a rigid chair. The model’s response was verified with the chair moving according to a multisine signal comprising frequencies from 0.7 to 20Hz. The model reveals considerable pelvic rotation during the vibration. The predicted movements of the pelvis are compared to passive and active marker measurements and to measurements made with an advanced imaging technique called dynamic white light raster line triangulation (WLRT).