Study on the Evaluation Methods of the Vertical Ride Comfort of Railway Vehicle—Mean Comfort Method and Sperling’s Method

Mădălina Dumitriu,Dragoș Ionuț Stănică

doi:10.3390/app11093953

Abstract

The paper herein analyzes the ride comfort at the vertical vibrations of the railway vehicle, evaluated by two methods—mean comfort method and Sperling’s method. The two methods have in common that the estimation of the comfort sensation is conducted with the comfort indices, namely ride comfort index NMVZ and ride comfort index Wz. The values of these indices are derived from numerical simulations. The advantage of using the results of the numerical simulations versus using experimental results, on which most previous research is based, resides in the fact that the ride comfort indices can be examined while taking into account the influence of velocity and certain parameters altering the behavior of vertical vibrations of the carbody, i.e., carbody flexibility and the suspension damping. The numerical simulation applications have been developed based on a theoretical model of the vehicle that considers important factors affecting the behavior of vertical vibrations of the carbody, by means of a ‘flexible carbody’ type model and an original model of the secondary suspension. The results presented mainly show that the two assessment methods lead to significantly different outcomes, in terms of ride comfort, under identical running conditions of the vehicle.

Highlights

During train travel, the passengers’s comfort can be affected by several factors, some due to the movement of the railway vehicle, such as vibrations and noise, while others come from the environment conditions inside the vehicle, e.g., temperature, humidity and air speed, lighting, or the interior fittings and decor [1,2,3,4]
The vibrations of the railway vehicle are considered to be the main factor in determining the ride comfort [1,2,3,9,10]
The ride comfort assessment based on results from numerical simulations involves the representation of the railway vehicle through an equivalent mechanical model, which will consider the important factors affecting the behavior of vibrations of the vehicle in the vertical plan

Summary

Introduction

The passengers’s comfort can be affected by several factors, some due to the movement of the railway vehicle, such as vibrations and noise, while others come from the environment conditions inside the vehicle, e.g., temperature, humidity and air speed, lighting, or the interior fittings and decor (for instance, the shape and placement of chairs) [1,2,3,4]. The ride comfort assessment based on results from numerical simulations involves the representation of the railway vehicle through an equivalent mechanical model, which will consider the important factors affecting the behavior of vibrations of the vehicle in the vertical plan. One of these factors is the structural flexibility of the vehicle carbody. The vehicle carbody is represented by a free-free equivalent beam of constant section and uniformly distributed mass, Euler-Bernoulli type This model gives the possibility to consider the vertical vibration modes of the carbody that are relevant for the ride comfort, namely the rigid modes vibration—bounce zc, pitch θc—and the first vertical bending mode.

Sperling’s Method

Sperling’sMethod