An improved degraded adhesion model for wheel–rail under braking conditions

Abstract

Purpose The purpose of this paper is to develop an improved adhesion model to better reproduce the low adhesion condition of the anti-skid control for rail vehicles under braking condition. Design/methodology/approach In view of the low adhesion characteristics for rail vehicles under braking conditions, the Polach adhesion model was improved based on the sliding power and sliding energy. The wheel–rail low adhesion model suitable for braking condition was given. The analysis of braking anti-skid control under emergency braking condition was carried out through the co-simulation, and compared with the test data; the effectiveness and practicability of the improved low adhesion model were verified. Findings The results showed that the improved adhesion model is simple and efficient and the parameters involved are less, and it can be directly applied to the real-time simulation of anti-skid control in the process of train braking. Originality/value This paper can provide a theoretical reference for the reasons of change and improvement of adhesion between wheel and rail caused by the adjustment of braking force under anti-skid control, which can fulfill a need to the study of sliding energy on the contact surface, the removal effect of pollutants on the wheel–rail surface and the improvement and recovery of adhesion caused. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0244/

Research on train braking model by improved Polach model considering wheel‐rail adhesion characteristics

“…However, the Polach model does not consider that the periodic action of the anti-skid device of the train under lowadhesion conditions will have a cleaning effect on the rail surface to a certain extent. Therefore, this paper uses the improved Polach model [17] to establish an adhesion model, which considers adhesion improvement caused by sliding power and energy. The two are calculated by Equations ( 8) and ( 9), respectively, and 𝜏 is calculated by sliding power as shown in Equation (10).…”

“…The primary suspension and the secondary suspension can be simplified as springs and dampers. The output force of the suspension part can be calculated by Equation (17).…”

“…Hamid Alturbe [13,14] used MAT-LAB/Simulink to establish a dynamic simulation platform for train braking under low-adhesion conditions, which can predict the train brake system performance and support decisionmaking in the design and optimization of the braking system including wheel slide protection, sanders and the blending and control of friction and dynamic brakes in low adhesion conditions. WengLiang Zhu [15][16][17] established a co-simulation platform for the brake anti-skid control system for the current micro-computer controlled direct electric air brake system, and also proposed an improved Polach model. Nicola Bosso et al [18] build a numerical model that allows to evaluate the dynamics of the vehicle during the braking operation and to correlate the pressures to the brake cylinder, which are related to the braking forces, and the angular velocities measured on the axles of the vehicle, with the adhesion coefficient.…”

“…Hamid Alturbe [13, 14] used MATLAB/Simulink to establish a dynamic simulation platform for train braking under low‐adhesion conditions, which can predict the train brake system performance and support decision‐making in the design and optimization of the braking system including wheel slide protection, sanders and the blending and control of friction and dynamic brakes in low adhesion conditions. WengLiang Zhu [15–17] established a co‐simulation platform for the brake anti‐skid control system for the current micro‐computer controlled direct electric air brake system, and also proposed an improved Polach model. Nicola Bosso et al.…”

Design and validation of a wheel-rail adhesion simulator in PLS-Circulator

“…Under the condition of low adhesion caused by water and oil at wheel-rail interface, rail vehicles may have safety problems such as exceeding safe braking distance [1]. It has been found that the large slip between wheel and rail can recover the low adhesion caused by the fluids [2,3], from line tests [4] as well as rollers [5][6][7] both in China and abroad. However, in these studies, the fluid distribution between wheel and rail is different from the reality.…”