Study of Wearing EVA Foam Slippers for Reducing Whole Body Vibrations of Bus Passengers

Effectiveness of using thicker ethylene vinyl acetate (EVA) foam based slippers to reduce the whole body vibrations(WBV) of passengers travelling in Sri Lankan public transport buses is presented. It was observed that wearing regular slippers cannot bring the WBV to safer levels according to the ISO 2631 standard, primarily due to the thickness limitations. The vibration radiation exposure was estimated by measuring the vibration dosage value (VDV) levels. Also experimented the effect of the bus speed on the VDV. Tri-axial accelerations readings on the floor, between the slipper and the foot and top of the foot were measured by using tri axial accelerometers at a particular steady bus speed and a selected slipper thickness. Nonlinear finite element based static deformations and dynamic forced acceleration models were developed for obtaining the pre-acceleration deformed state and estimating accelerations of the slipper and the foot with respect to the forced accelerations on the bus floor. Nonlinear effects of hyperelastic and viscoelastic nature of EVA foam and human tissues were used.