A Study of Body Posture on Human Comfort Under the Influence of Whole-Body Vibrations for the Rail Passengers

Abstract

When traveling by train, passengers are exposed to vibration. A well designed seat will attenuate the vibration path to the person in the frequency region where it is the most perceptible, between 3 and 10 Hz. This paper studies the relationship between posture and the human response to vibration. The pressure on the spinal discs has been measured for different postures and it has been found that sitting in a relaxed posture results in a lower intervertebral discs pressure than standing; however, sitting in a upright posture without a suitable back support causes the greatest loading on the spine. Experiments have been performed to examine the perceived discomfort of sitting in a seat with varying backrest angles. Generally, as the backrest is reclined, the discomfort decreases. It has been found that for a tense posture, both the magnitude and frequency of the resonant peak increase comparated to a relaxed posture. This paper concluded that the seat has a great influence on the posture adopted by the passenger, and that a seat with mechanical damping in the 3 to 10 Hz range and a design that encourages a relaxed posture with a slightly reclined backrest will minimize discomfort.