Effect of passenger uncertainty on the inertial property and stability of a railway vehicle

There are a lot of uncertainties in railway vehicle system, and these uncertainties can have a non-negligible effect on vehicle dynamics, so it should be prudently considered in practical use. In the paper, the effect of passenger uncertainty is focused on the inertial property and stability of a railway vehicle. The rotation transformation matrix and translation transformation matrix are derived, and they are combined to quantify the inertial property and stability of a railway vehicle with random passengers. A dynamical CRH2 (China Railway High-speed) vehicle model is established, and the CRH motor coach and inertial properties of passengers in statistical terms are illustrated. After that, a simplified simulation model is given for validation of theoretical results. The Monte-Carlo method is used to quantify the statistical characteristics of the vehicle system with different passengers. It is indicated that CG (center of gravity) positions and moments of inertia are all close to linear variation with passenger numbers but at different slopes near the full-load condition. It is also found that yaw moment of inertia and pitch moment of inertia are highly correlated. The mass has a larger correlation on CG z than CG x and CG y, and a larger correlation on roll moment of inertia than yaw and pitch moment of inertia. The mean values of the critical speeds with passengers are larger than those of the empty coach; moreover, the distribution is close from lognormal to normal distribution with increasing passenger numbers. It may offer some instructions for a more realistic simulation of railway vehicle dynamics with passengers and reference for measure experiments.