Out-of-roundness in railway wheels, in particular polygonal wear resulting in regular, multi-lobed, out-of-round wheels, has become a significant problem in recent years. It is of concern to railway ...operators due to the increased noise and vibration it can cause. This polygonisation is caused by cyclic wear but the exact mechanism leading to this type of wear is not fully understood. It appears to be the result of dynamic linking between a resonance or other periodic excitation in the coupled vehicle-track system and the existing wear at the wheel. This paper reviews the developing body of research being carried out in many countries by research groups, manufacturers and operators. Some examples of polygonisation on different types of railway vehicles are reported including feight trains, urban transit trains and high-speed trains. The main theories for the formation mechanisms are presented and the current measurement methods, computer simulation techniques and the effects and potential mitigation methods are reviewed. In parallel, the mechanisms and consequences of discrete wheel tread irregularities, such as wheel flats and material fall-out due to rolling contact fatigue cracking, are addressed.
Serious wheel polygonal wear usually causes drastic wheel/rail interactions, which threats the running safety of railway vehicles. This paper presents an investigation into the effect of polygonal ...wear of heavy-haul locomotive wheels on the dynamic performance and wheel/rail interactions through extensive on-site tests and numerical simulations, in which a special attention is paid to locomotive vibrations and dynamic wheel/rail tangential forces. The measured results conducted on two objective locomotives were firstly compared, including the characteristics of wheel polygonal wear and locomotive vibrations in vertical, longitudinal and lateral directions. A 3D heavy-haul train-track coupled dynamic model was then formulated to investigate wheel/rail dynamic interaction induced by polygonal wear of locomotive wheels. A low adhesion zone (LAZ) and a PI-based anti-slip control algorithm were embedded into the dynamic model to analyse the effects of wheel polygonal wear on wheel/rail longitudinal and lateral interactions under normal and low adhesion conditions. The results show that the severe wheel polygonal wear affects not only the vertical but also the longitudinal performance of the wheel/rail system notably. The wheel high-order polygonal wear has a conspicuous effect on longitudinal, lateral and vertical vibrations of locomotive system components.
With over thirty years of experience in the design, development, and patenting of some products in the field of wheel alignment, the author shares his knowledge on the importance of wheel maintenance ...to the overall performance of a vehicle.
From the ancient bullock carts to chariots to automobiles, wheels have undergone many changes to serve the purpose of mankind's mobility. Mobility is inevitable in today's life. A world without wheels is unimaginable. Every vehicle owner expects his tires to last longer and perform better. But improper wheel alignment and wheel balancing can drastically impact the wear and tear on a tire.
This book walks the readers through the basics to techniques for wheel alignment on light vehicles, commercial vehicles, and trailers. In addition, illustrations present various types of tire wear and the cause of each. Finally, the author delves into tire safety from understanding how air pressure effects a tire to the importance of tire rotation.
The Wheel-rail adhesion is essential for safe and stable vehicle operation. Since the beginning of railway construction, many railway researchers and engineers have been actively involved in the ...study of this railway-specific issue. Most studies to date have focused on the various factors influencing the adhesion characteristics and quantifying the extent of their influence. This paper gives an overview of experimental and theoretical studies on evaluating wheel-rail adhesion characteristics under conditions where different third-body materials are interposed between wheel and rail and describes further challenges and research directions in the field of adhesion for the future.
•The influences of various contaminations between wheel and rail have been assessed.•Third-body material has a significant influence on the wheel/rail adhesion coefficient.•The adhesion coefficient decreases in the order of dry, wet, oil, wet leaf, and dry leaf.•Alumina particles, sand, and traction gel have the effect of increasing adhesion.
This paper aims to detect railway vehicle wheel flats and polygonized wheels using an envelope spectrum analysis. First, a brief explanation of railway vehicle wheel problems is presented, focusing ...particularly on wheel flats and polygonal wheels. Then, three types of wheel flat profiles and three periodic out-of-roundness (OOR) harmonic order ranges for the polygonal wheels are evaluated in the simulations, along with analyses implemented using only healthy wheels for comparison. Moreover, the simulation implements track irregularity profiles modelled based on the US Federal Railroad Administration (FRA). From the numerical calculations, the dynamic responses of several strain gauges (SGs) and accelerometer sensors located on the rail between sleepers are evaluated. Regarding defective wheels, only the right wheel of the first wheelset is considered as a defective wheel, but the detection methodology works for various damaged wheels located in any position. The results from the application of the methodology show that the envelope spectrum analysis successfully distinguishes a healthy wheel from a defective one.
Polygonisation is a common nonuniform wear phenomenon occurring in railway vehicle wheels and has a severe impact on the vehicle–track system, ride comfort, and lineside residents. This paper first ...summarizes periodic defects of the wheels, including wheel polygonisation and wheel corrugation, occurring in railways worldwide. Thereafter, the effects of wheel polygonisation on the wheel–rail interaction, noise and vibration, and fatigue failure of the vehicle and track components are reviewed. Based on the different causes, the formation mechanisms of periodic wheel defects are classified into three categories: (1) initial defects of wheels, (2) natural vibration of the vehicle–track system, and (3) thermoelastic instability. In addition, the simulation methods of wheel polygonisation evolution and countermeasures to mitigate wheel polygonisation are presented. Emphasis is given to the characteristics, effects, causes, and solutions of wheel polygonisation in metro vehicles, locomotives, and high-speed trains in China. Finally, the guidance is provided on further understanding the formation mechanisms, monitoring technology, and maintenance criterion of wheel polygonisation.
Wheeled mobile robots (WMR) have been deployed in Mars/Lunar exploration, military missions, and geological investigations, and they must handle rough and deformable terrains. The dynamics at the ...wheel-soil interface, including the wheel-terrain contact angle, wheel sinkage, and wheel-soil interaction forces and torque, are major factors in the entrapment of NASA SPIRIT MER and the subsequent mission failure. This paper presents an experimental apparatus that is developed to measure the wheel-terrain contact angle, wheel sinkage, and wheel-soil interaction forces and torque in real time to improve our understanding of the WMR mobility on soft and deformable terrains. A method for wheel sinkage evaluation is presented based on measuring the wheel-terrain contact angle. The wheel-soil interaction forces and torque are measured by installing a force/torque sensor along the axle of the apparatus. The proposed approach is implemented on a testbed, and the experimental results are used to evaluate it; they demonstrate the reliable detection of the wheel-terrain contact angle, wheel sinkage, and wheel-soil interaction forces and torque. Moreover, based on the measured wheel-terrain contact angle, the relative errors in the predicted wheel-soil interaction forces and torque are less than 8% compared with the experimental data.
This paper reports on fundamental research to investigate the influence of wheelset flexibility on the development of wheel polygonization of a locomotive. After preparing a flexible wheelset model ...by importing a FE (Finite Element) model into the MBS (Multi-Body System) environment, the investigation work proceeded in 3 steps. Firstly, FRF (Frequency Response Function) of the contact responses against the track irregularity is analysed for a free wheelset and an on-track wheelset, with consideration of rotation effect. Secondly, the influence of the wheelset flexibility on the contact responses excited by white noise is investigated for straight and curved tracks. The final step is to check the influence of the wheelset flexibility on the development of wheel polygonization based on a developed prediction program for railway wheel polygonization. 6 scenarios are investigated with comparison between rigid and flexible wheelsets. Results show that, the wheelset flexibility cannot dominate the railway wheel polygonization in a general sense, unless some prerequisites are fulfilled to provide a suitable environment for the wheelset flexibility to be effectively and continually excited to fluctuate the contact responses, and thereby initiate wheel polygonization. The torsional mode of the wheelset can be effectively excited by stick-slip vibration due to saturated contact adhesion that can occur on track with small curve radii or by large traction torque. In this case, the developed wheel polygonization order will be exactly determined by the wheelset torsional modal frequency and the vehicle speed.
•The influence of wheelset flexibility on wheel polygonal wear is identified based on a prediction program.•All the investigated wheelset flexible modes can be excited to influence the contact responses, but in very different way.•The wheelset flexibility cannot dominate the wheel polygonization unless some prerequisites are fulfilled.•The torsional mode of wheelset can be excited by stick-slip vibration to initiate the wheel polygonization.
As a common condition in train operation, the out‐of‐roundness (OOR) of wheels may have a great influence on the life of cracked wheels. In this study, the I–II mixed‐mode crack growth rate of ...different angles was tested, finite element analysis was carried out by using the test results, and the influence of different wheel roundness conditions on the life of cracked wheels was revealed. The results show that the mode II stress intensity factor of mixed‐mode cracks is the main driving force for crack propagation in the process of wheel rim crack growth. With an increase in the wheel scar length and the order of the wheel polygon, the crack propagation life decreases significantly.
Highlights
Fracture mechanical properties are obtained for different crack deflection angles.
The wheel‐rail contact model for out‐of‐round wheel with crack submodel is constructed.
The remaining life of the wheel decreases as the crack angle and flat scar length increase.
The polygon phenomenon of the wheel will greatly reduce the remaining life of the wheel.
This paper provides an overview of different theories to analyse unsteady rolling contact phenomena between wheel and rail: the exact formulation by Kalker, the simplified model based on the Winkler ...approximation, and the recent two-regime model. The classic solution to the transient problem derived by Kalker using the complete theory of elasticity is first recalled. The more involved situation of combined creepages and spin is analysed using Kalker’s simplified model. Analytical solutions are reported in integral form concerning the time-varying and constant creepages. Qualitative results are additionally provided for the case of a time-varying contact patch. Finally, a novel theory, which describes the transient evolution of the force-creepage characteristics using a system of ordinary differential equations (ODEs), is introduced.
•Three theories concerning transient wheel–rail rolling contact are discussed.•The two-regime theory is adapted to the transient wheel–rail rolling contact.•The case of a time-varying contact patch is analysed using the simplified theory.•An analytical transient model for combined creepage conditions is developed.•The comparison between the presented theories shows good theoretical agreement.
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