Investigation on train dynamic derailment in railway turnouts caused by track failure

ABSTRACT The carbody shaking phenomenon (CSP) can greatly reduce the ride comfort of high-speed trains. To investigate the abnormal vibration feature and causes of the CSP, extensive field measurements and numerical simulations were conducted. A three-dimensional rigid-flexible coupled dynamic model of a high-speed vehicle is constructed to reproduce the CSP and reveal the key influence factors, in which the finite element model of the carbody is updated based on the experimental modal data. The field test show that the main vibration frequency of the carbody accelerations appear around 7.90 Hz, which is close to the natural frequency of the carbody diamond mode. The simulation results demonstrate that the CSP is caused by the carbody resonance vibrations induced by bogie hunting motion, which is triggered by the deterioration of wheel-rail contact geometry. When the train passes through turnouts at high speed, wheel-rail impact will further aggravate the CSPs.

https://www.tandfonline.com/doi/pdf/10.1080/23248378.2022.2077850?needAccess=true

Mechanism of high-speed train carbody shaking due to degradation of wheel-rail contact geometry

The problems of safety and reliability of rail vehicles movement is constantly being developed in scientific research [41]. Processes aiming at increasing the level of operational reliability and safety are taken into consideration as early as their design. World trends in this issue require using theories of safety reliability and such vehicles’ operational safety [29, 34, 39]. The theory of safety evolved in the 90s so as to counteract risks of failures or accidents which could lead not only to the disruption of a particular technical system functioning but the loss of health, human life or other damage as well [21]. As far as rail vehicles are concerned derailment is the most common kind of accident which causes at the same time the risk of infrastructure degradation, rolling stock or transported cargo damage, disruption of services and environmental damage (the transportation of hazardous materials) [16, 18]. Therefore the risk determination of such an event occurrence is vital during rail vehicles’ tests. Theoretical analyses and tests are carried out while designing of such vehicles in order to forecast the impact of vehicle parameters on a test track [1, 9, 28] as well as running safety and reliability connected with derailment during movement and monitoring [6, 7]. Then they are continued experimentally in acceptance tests during qualifications to place them in service or after extensive maintenance/modernization of rail vehicles in operation [11, 35]. Safety against derailment is one of primary criteria for assessing the reliability of rail vehicle operation. Many researchers still deal with the topic of rail vehicle safety [10, 48, 49]. In many cases, the main mechanism causing train derailment is the loss of lateral stability of a railway vehicle [6, 24, 43]. This is caused by a rise in the lateral force value in the wheel-rail contact KonowrocKi r, chojnAcKi A. Analysis of rail vehicles’ operational reliability in the aspect of safety against derailment based on various methods of determining the assessment criterion. Eksploatacja i niezawodnosc – Maintenance and reliability 2020; 22 (1): 73–85, http://dx.doi.org/10.17531/ein.2020.1.9.

/pdf/analysis-of-rail-vehicles-operational-reliability-in-the-4zsm5uqkaf.pdf

Analysis of rail vehicles’ operational reliability in the aspect of safety against derailment based on various methods of determining the assessment criterion

Coupler jack-knifing and derailment of slave control locomotives in 20,000-tonne heavy-haul trains usually occur due to the combinations of large in-train forces with poor track conditions. This pa...

Experimental assessment of the dynamic performance of slave control locomotive couplers in 20,000-tonne heavy-haul trains:

As the operating speed of a train increases, there is a growing interest in reducing damage caused by derailment and collision accidents. Since a collision with the surrounding structure after a derailment accident causes a great damage, protective facilities like a barrier wall or derailment containment provision (DCP) are installed to reduce the damage due to the secondary collision accident. However, the criteria to design a protective facility such as locations and design loads are not clear because of difficulties in predicting post-derailment behaviors. In this paper, we derived a simplified frame model that can predict post derailment behaviors in the design phase of the protective facilities. The proposed vehicle model can simplify for various frames to reduce the computation time. Also, the actual derailment tests were conducted on a real test track to verify the reliability of the model. The simulation results of the proposed model showed reasonable agreement to the test results.

Modeling and Simulation of Collision-Causing Derailment to Design the Derailment Containment Provision Using a Simplified Vehicle Model

The derailments of empty wagons of long freight trains frequently occurred around the world, which caused tremendous losses every year Aiming at an actual derailment of empty wagons on straight line during dynamic braking, the field investigation was conducted to find the reasons of the accident According to the investigation results, the large coupler yaw angle and coupler force, the special connection mode by drawbars, as well as the poor conditions of wheel treads and flanges were supposed to be responsible for the accident The simulaiton model composed of 3 C80-type gondolas, and two RFC-type drawbars is established, the accuracy of which is validated by the field experimental test When the wheel-rail friction coefficient is set to be 07 and the coupler forces are set to be 350 kN with a coupler yaw angle of 7 degrees, the simulation results are consistent with the field investigation results Simulation results indicate that the coupler yaw angle, coupler force, and wheel-rail friction coefficient have significant influences on the derailment The increasing coupler yaw angle and coupler force will increase the risk of derailment For the wagon units adopting the drawbars, the riskiest wagon changes from the middle wagon to the front one as the lateral components of the coupler forces increase A large wheel-rail friction coefficient can raise the risk of derailment However, an overlarge friction coefficient will decrease the derailment risk According to the field investigation and simulation results, the wheel-rail friction coefficients should be limited below 05 to ensure the running safety of empty wagons Besides, the operations of the train should be optimized to avoid large coupler yaw angle and coupler force

/pdf/investigation-on-derailment-of-empty-wagons-of-long-freight-2cuichn9ov.pdf

Investigation on Derailment of Empty Wagons of Long Freight Train during Dynamic Braking

Abstract Air brake systems are critical equipment for railway trains, which affects the running safety of the trains significantly. To study air braking characteristics of long freight trains , an approach for simulating air brake systems based on fluid dynamics theory was proposed. The structures and working mechanisms of locomotive and wagon air brakes are introduced, and mathematical models of the pipes, brake valves, reservoirs or chambers, cylinders, etc., are presented. Besides, the dynamic motions of parts in the main valve are considered. The simulation model of the whole air brake system is then formulated, and the solving method based on the finite-difference method is used. New efficient pipe boundary conditions without iterations are developed for brake pipes and branch pipes, which can achieve higher computational efficiency. The proposed approach for simulating the air brake system is validated by comparing with published measured data. Simulation results of different train formations indicate that models that consider the dynamic behavior of brake pipes are recommended for predicting the characteristics of long trains under service braking conditions. 

/pdf/an-approach-for-simulating-the-air-brake-system-of-long-rg30o1pl.pdf

An approach for simulating the air brake system of long freight trains based on fluid dynamics

The derailment of railway vehicles in the turnout area is a worldwide concerned issue. Previous studies mainly concentrate on the derailment at the switch area, and the risk at the frog area is seldom concerned. Based on a specific derailment case of the remote locomotive in a 20,000-tonne heavy-haul train, a study on the derailment of the locomotive at the turnout frog area is presented. The conditions of the derailed locomotive and turnout track are introduced, and the potential influence factors are screened according to the field investigation results. A detailed simulation model that considers the complex wheel-frog/guard rail contact relationship and the interaction between adjacent vehicles is established. Through numerical simulation, the derailment process of the locomotive at the turnout frog area is reproduced, and the derailment mechanism is revealed, followed by the influence analysis of the potential factors. The results indicate that the combined effect of the compressive coupler force and the coupler jack-knifing promotes the derailment remarkably. Moreover, the derailment at the turnout frog area is more likely to occur under low-speed conditions, and the possibility of derailment can be reduced by decreasing the compressive coupler force and the friction coefficients between the wheel and stock/frog/guard rail. 

Study on the derailment of the remote locomotive in a heavy-haul train with distributed power at the turnout frog area: field investigation and numerical simulation

Measurement of Vehicle Speed Based on the GCC Algorithm and its Application in Anti-Slip Control

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