Finite element calculations of rail vibration countermeasures

Elastic waves may constitute a nuisance for people living close to high-speed lines. In order to decrease the spread of vibrations, it is common to reinforce the ground with lime cement columns. This article presents the results of simulations of three different ways to install the columns. The calculations have been done with an integrated rigid body—finite element model. Equations from various physical domains are merged into one big system. The results indicate that the straight configuration works best to protect the track. When attention is focused on preventing vibrations from the soil, the leaning column method is more effective. The chosen technique would depend on the aims of the countermeasure.     

轻轨列车通过高架桥引起地面振动有限元分析

采用移动荷载列过桥原理,建立车辆一桥梁动力分析模型,并计算移动荷载列下桥墩支座的反力时程。通过建立三种人工边界条件下桥墩一土体的三维动力分析模型,利用ANSYS求解弹性状态下地面的动力响应。分别比较了三种人工边界和相邻桥墩对计算结果的影响,结果表明地面衰减规律与实测一致。     

高频振动筛受迫振动有限元分析

通过高频脱水筛几何模型及力学模型的建立,得出了任意时刻筛箱整体结构的响应,找出了其易产生共振的频段,为振动筛的结构设计提供依据。     

Modelling,simulation and evaluation of ground vibration caused by rail vehicles*

ABSTRACT

There is a great need to develop rail networks over long distances and within cities as more sustainable transport options. However, noise and vibration are seen as a negative environmental consequence. Compared with airborne noise, the related problem of ground vibration is much more complex. The properties of the ground vary significantly from one location to another. There is no common assessment criterion or measurement quantity and no equivalent to the noise maps. Ground-borne vibration is transmitted into buildings and perceived either as feelable whole-body vibration or as low frequency noise; it can also affect sensitive equipment but it is generally at a level that is too low to cause structural or cosmetic damage to buildings. A review is given of evaluation criteria for both feelable vibration and ground-borne noise, empirical and numerical prediction methods, the main vehicle and track parameters that can affect the vibration levels and a range of possible mitigation methods.     

Multiphysic modelling of railway vehicles equipped with pneumatic suspensions

This article presents a multidisciplinary approach of railway pneumatic suspension modelling: both multibody and pneumatic aspects are taken into account. The work aims at obtaining a realistic model of the secondary suspension and coupling it with a multibody model of a train. Various components of the pneumatic circuit such as bellows, tanks, pipes and valves are taken into account. The article focuses on the bellow–pipe–tank subsystem for which several modelling approaches are presented and compared. Differences between differential and algebraic models are highlighted, and an application-dependent choice between them is suggested. A complete model of the pneumatic circuit is then obtained and coupled with a multibody model of the train. As a result, the behaviour of a suburban train equipped with a pneumatic secondary suspension is analysed, in particular undesired oscillating motions which affect the comfort. Topological modifications and improvements of the suspension are also investigated and discussed.     

Multiphysic modelling of railway vehicles equipped with pneumatic suspensions

This article presents a multidisciplinary approach of railway pneumatic suspension modelling: both multibody and pneumatic aspects are taken into account. The work aims at obtaining a realistic model of the secondary suspension and coupling it with a multibody model of a train. Various components of the pneumatic circuit such as bellows, tanks, pipes and valves are taken into account. The article focuses on the bellow-pipe-tank subsystem for which several modelling approaches are presented and compared. Differences between differential and algebraic models are highlighted, and an application-dependent choice between them is suggested. A complete model of the pneumatic circuit is then obtained and coupled with a multibody model of the train. As a result, the behaviour of a suburban train equipped with a pneumatic secondary suspension is analysed, in particular undesired oscillating motions which affect the comfort. Topological modifications and improvements of the suspension are also investigated and discussed.     

75 k/m钢轨12号高锰钢辙叉受力有限元分析

针对重载铁路上75 kg/m钢轨12号高锰钢辙叉出现水平裂纹、竖直裂纹及垂磨等病害问题,分别建立既有线上、中铁山桥改进型、中铁宝桥改进型高锰钢辙叉的有限元受力分析模型,计算分析三种辙叉在极限荷载和疲劳荷载作用下的受力性能,并对高锰钢辙叉改进前后力学性能进行对比分析,为重载铁路高锰钢辙叉结构设计提供参考.     

Investigating the influence of rail grinding on stability,vibration, and ride comfort of high-speed EMUs using multi-body dynamics modelling

ABSTRACT

High-speed electric multiple units (EMUs) have been popularised rapidly all around the world and have become a major transportation method. Increases in running velocity and wheel-rail deterioration lead to excessive vibration and reduced ride comfort, which are common issues encountered in the operation of high-speed EMUs. While built-in sensors on a car body are able to detect abnormal vibrations in the car body itself, they cannot effectively reflect the ride comfort of passengers. Wheel-rail profile matching can improve the wheel-rail interaction, and rail grinding has thus been introduced as a practical solution to alleviating the aforementioned problems. Nonetheless, the working mechanism of rail grinding has not been investigated theoretically. This study develops flexible car body and human body models based on the rigid-flexible coupled method to systematically study the effects of wheel-rail wear and rail grinding on passenger ride comfort. Case studies show that the proposed models can predict the ride comfort of passengers accurately. It is also demonstrated that rail grinding can significantly alleviate excessive vibration and improve passenger ride comfort in the long term. A long-term investigation reveals that rail grinding can improve the smoothness of the rail surface and reduce the damage to the rail.     

Rotational vibration absorber for the mitigation of rail rutting corrugation

Torsional vibrations of metro wheel sets are known to be involved in the wavelength-fixing mechanism of the rutting-type rail corrugation. In the first part of this paper, the basic conditions for this type of wear to appear are established using a theory developed in the frequency domain. The efficiency of a dynamic vibration absorber tuned to the first torsional resonance of the wheel set to mitigate rutting corrugation is evaluated numerically. In the second part, the phenomenon is studied on a quarter-scale test bench. The scaling laws for wheel–roller wear predictions are established. The efficiency of the dynamic vibration absorber is evaluated on the scaled bench. The results are compared with theoretical predictions from a linear model. Additionally, the measurements are compared with numerical results from a multi-body model portraying the experiment.     

横梁总成的有限元分析

利用三维软件SolidWorks中自带的COSMOSWorks软件对横梁总成进行有限元分析,找出受力最大区域,对该区域进行加强,解决横梁总成加强筋开裂问题。     

Crash analysis and dynamical behaviour of light road and rail vehicles

The main goal of crashworthiness is to ensure that vehicles are safer for occupants, cargo and other road or rail users. The crash analysis of vehicles involves structural impact and occupant biomechanics. The traditional approaches to crashworthiness not only do not take into account the full vehicle dynamics, but also uncouple the structural impact and the occupant biomechanics in the crash study. The most common strategy is to obtain an acceleration pulse from a vehicle structural impact analysis or experimental test, very often without taking into account the effect of suspensions in its dynamics, and afterwards feed this pulse into a rigid occupant compartment that contains models of passengers. Multibody dynamics is the most common methodology to build and analyse vehicle models for occupant biomechanics, vehicle dynamics and, with ever increasing popularity, structural crash analysis. In this work, the aspects of multibody modelling relevant to road and rail vehicles and to occupant biomechanical modelling are revised. Afterwards, it is shown how multibody models of vehicles and occupants are used in crash analysis. The more traditional aspects of vehicle dynamics are then introduced in the vehicle models in order to appraise their importance in the treatment of certain types of impact scenarios for which the crash outcome is sensitive to the relative orientation and alignment between vehicles. Through applications to the crashworthiness of road and of rail vehicles, selected problems are discussed and the need for coupled models of vehicle structures, suspension subsystems and occupants is emphasized.     

Experimental and numerical investigation of the effect of rail corrugation on the behaviour of rail fastenings

This paper presents the results of a detailed investigation of the effects of rail corrugation on the dynamic behaviour of metro rail fastenings, obtained from extensive experiments conducted on site and from simulations of train–track dynamics. The results of tests conducted with a metro train operating on corrugated tracks are presented and discussed first. A three-dimensional (3D) model of the metro train and a slab track was developed using multi-body dynamics modelling and the finite element method to simulate the effect of rail corrugation on the dynamic behaviour of rail fastenings. In the model, the metro train is modelled as a multi-rigid body system, and the slab track is modelled as a discrete elastic support system consisting of two Timoshenko beams for the rails, a 3D solid finite element (FE) model for the slabs, periodic discrete viscoelastic elements for the rail fastenings that connect the rails to the slabs, and uniformly viscoelastic elements for the subgrade beneath the slabs. The proposed train–track model was used to investigate the effects of rail corrugation on the dynamic behaviour of the metro track system and fastenings. An FE model for the rail fastenings was also developed and was used to calculate the stresses in the clips, some of which rupture under the excitation of rail corrugation. The results of the field experiments and dynamics simulations provide an insight into the root causes of the fracture of the clips, and several remedies are suggested for mitigating strong vibrations and failure of metro rail fastening systems.     

Validation of railway vehicle dynamic models in training simulators

Training simulators play an important role for sustaining safety, efficiency and cost effective railway transportation. Dynamic modelling of train systems is one of the main modules of training simulators. Validation of the dynamic models with collected real data ensures the fidelity of the simulator utilising the respective models. In this study, a validation process (Dynamic Modelling Validation Process (DyMVaP)) which is developed to support the validation of railway dynamic models is introduced. However, the proposed process can also be used in validating other dynamic models as well. The developed process is based on five steps including the preparation of validation scenarios, sensor deployment, real data collection, data preparation, and comparison of simulated and measured data. Note that the proposed DyMVaP was used for the validation of a full-mission training simulator so called TRENSIM, which was developed for Turkish State Railways. During the study it is realised that the current speed, travelled distance, acceleration (in x, y, z directions), rotation angles (around x, y, z axes), air pressure, in-train pressure/tension forces, traction motor currents, catenary voltage, positions of controllers must be collected synchronously by using proper sensors in order to ensure simulation validation. The required data was collected from locomotive body, bogies, wheel sets and connection of railway cars. The data (～200?GB) collected from the field by applying 27 different scenarios and transformed into appropriate data for utilising the generated dynamic models within the simulator. The measured and simulated data were also compared visually using graphical representation of the parameters as well as performing computations regarding the magnitude, phase and comprehensive error factors.     

汽车发动机连杆有限元分析

连杆是汽车发动机的重要构件，其结构、形状和受载状况均很复杂。这里应用有限元分析技术对某汽车发动机的连杆组件进行了三维非线性分析，分析涉及接触问题。从变形、应力和安全系数三个方面对计算结果进行分析，得出的计算结果与实际情况吻合。     

客车骨架有限元建模的研究

介绍了有限元理论在客车结构设计中的啦用,提出了三维几何模型的简化原则及在建模过程中存在的问题,并以某6127型客车为研究对象,对通过CATIA和UG建立的三维儿何模型导入到有限元分析软件中的过程及出现的问题进行了系统地阐述,得出了相关的建模技巧。     

汽车挡风玻璃除霜性能数值模拟

利用CFD方法建立汽车除霜性能动态模型,并量化了除霜器在挡风玻璃附近的气流速度场,对挡风玻璃除霜时间及效果进行了探讨,为汽车挡风玻璃除霜效果模拟工程提供了参考。     

Optimization of curving performance of rail vehicles

The curving performance of a transit rail vehicle model with 21 degrees of freedom is optimized using a combination of multibody dynamics and a genetic algorithm (GA). The design optimization is to search for optimal design variables so that the noise or wear, arising from misalignment of the wheelsets with the track, is reduced to a minimum level during curve negotiations with flange contact forces guiding the rail vehicle. The objective function is a weighted combination of angle of attack on wheelsets and ratios of lateral to vertical forces on wheels. Using the combination of the GA and a multibody dynamics modelling program, A’GEM, the generation of governing equations of motion for complex nonlinear dynamic rail vehicle models and the search for global optimal design variables can be carried out automatically. To demonstrate the feasibility and efficacy of the proposed approach of using the combination of multibody dynamics and GAs, the numerical simulation results of the optimization are offered, the selected objective function is justified, and the sensitivity analysis of different design parameters and different design parameter sets on curving performance is performed. Numerical results show that compared with suspension and inertial parameter sets, the geometric parameter set has the most significant effect on curving performance.     

Optimization of curving performance of rail vehicles

The curving performance of a transit rail vehicle model with 21 degrees of freedom is optimized using a combination of multibody dynamics and a genetic algorithm (GA). The design optimization is to search for optimal design variables so that the noise or wear, arising from misalignment of the wheelsets with the track, is reduced to a minimum level during curve negotiations with flange contact forces guiding the rail vehicle. The objective function is a weighted combination of angle of attack on wheelsets and ratios of lateral to vertical forces on wheels. Using the combination of the GA and a multibody dynamics modelling program, A'GEM, the generation of governing equations of motion for complex nonlinear dynamic rail vehicle models and the search for global optimal design variables can be carried out automatically. To demonstrate the feasibility and efficacy of the proposed approach of using the combination of multibody dynamics and GAs, the numerical simulation results of the optimization are offered, the selected objective function is justified, and the sensitivity analysis of different design parameters and different design parameter sets on curving performance is performed. Numerical results show that compared with suspension and inertial parameter sets, the geometric parameter set has the most significant effect on curving performance.     

液压挖掘机动臂的有限元分析

用Pro/E软件建立了液压挖掘机动臂的三维模型,对铰销间接触载荷的处理时采用经典弹性力学方法,选用板壳单元建立了动臂的有限元模型。对动臂的两种工况进行了计算,结合工作装置的静强度试验结果,进行对比分析,对现行设计提出了改进建议。     

Condition monitoring of rail vehicle suspensions based on changes in system dynamic interactions

A novel scheme for the fault detection and condition monitoring of vehicle suspensions is presented in this study. The new technique exploits the dynamic interactions between different vehicle modes caused by component failures in the system, leading to a simple but effective solution. Compared with many model-based fault detection techniques, the proposed technique does not require complex mathematical models of the system and it overcomes potential difficulties associated with nonlinearities and parameter variations in the system. The use of inexpensive inertial sensors and ease of tuning make the practical implementation of the proposed scheme straightforward. A conventional railway vehicle is used in the study to illustrate the basic ideas as well as the effectiveness of the novel fault detection method, although the general principle is applicable to other systems.