Dynamic Modeling of the Three-Dimensional Seated Human Body for High-Speed Train Ride Comfort Analysis

Abstract Typically, seat or floor acceleration is used to evaluate the ride comfort of a high-speed train. However, the dynamic performance of the human body significantly differs from that of the floor. Therefore, using the car body floor and seat accelerations to calculate the ride comfort index of a high-speed train may not reflect the true feelings of passengers. In this study, a 3D human-seat-vehicle-track coupling model was established to investigate the ride comfort of high-speed train passengers. The seated human model, which considers the longitudinal, lateral, vertical, pitching, yawing, and rolling motions, comprises the head, upper torso, lower torso, pelvis, thighs, and shanks. The model parameters were determined using multi-axis excitation measurement data based on a genetic algorithm. Subsequently, the applicability of the small-angle assumption and natural modes of the human model is analyzed. Using the coupling system model, the vibration characteristics of the human-seat interaction surface were analyzed. The ride comfort of the high-speed train and human body dynamic performance were analyzed under normal conditions, track geometric irregularities and train meeting conditions. The results showed that the passenger seats in the front and rear rows adjacent to the window had a higher acceleration value than the others. The human backrest and seat pad connection points have higher vibration amplitudes than the car body floor in the human-sensitive frequency range, indicating that using the acceleration values on the floor may underestimate the discomfort of passengers. The ride comfort of high-speed trains diminishes in the presence of track geometric irregularities and when trains pass each other. When the excitation frequency of track geometry irregularities approached the natural frequency of the human-seat-vehicle system, ride comfort in high-speed trains decreased significantly. Moreover, using seat acceleration to evaluate passenger ride comfort overlooks the vibration characteristics of the human body. The transient aerodynamic force generated when the train meets can cause a larger car body roll and lateral motion at 2 Hz, which, in turn, decreases the passenger ride comfort. This study presents a detailed human-seat-vehicle-track coupling system that can reflect a passenger’s dynamic performance under complex operating conditions.