As part of the vehicle qualification process, the Federal Railroad Administration (FRA) currently requires in its track and passenger equipment safety standards that a validated vehicle model be used to demonstrate safe dynamic vehicle response to allowable track geometry variations. Transportation Technology Center, Inc. (TTCI) was contracted by FRA to characterize, model, and analyze a high speed passenger vehicle in order to provide guidance related to the vehicle qualification process. The overall objective of the project was to evaluate methods required to demonstrate the validity of a vehicle dynamics model project and investigate how different input parameters affect the accuracy of the model. The project consisted of four main tasks: (1) characterize a high speed passenger vehicle; (2) develop a mathematical model of the vehicle using measured parameters; (3) validate the mathematical model using on-track tests; and (4) conduct a sensitivity analysis of the vehicle model to determine the critical parameters. FRA tasked TTCI with applying the testing and modeling methodology to FRA’s DOTX 216 geometry car. Specific parameters were identified that needed to be measured in order to develop a dynamic vehicle model of the car. A characterization test regime was outlined and performed to determine the necessary mass, stiffness, and damping characteristics, and the measured parameter values were used to create a mathematical model of the vehicle using TTCI’s NUCARS ®* dynamic modeling software. A series of on-track validation tests were performed on different tracks at the Transportation Technology Center (TTC) using the DOTX 216 car to facilitate model validation efforts. The model was then used to simulate the on-track testing regime conducted at TTC. Model validation was evaluated using displacement, acceleration, and wheel/rail force measurements. Results from the simulations and test data were compared using multiple methods to demonstrate the validation of the DOTX 216 model. TTCI also conducted a parameter sensitivity analysis using the validated model to assess its sensitivity to changes in different parameter values and to identify the most critical parameters for simulating passenger vehicles. The testing, modeling, and model validation methodology described in this work provide a practical example of developing a validated vehicle model for use in the vehicle qualification process.

Thermoplastic elastomers (TPE’s) are increasingly being used in rail service in load damping applications. They are superior to traditional elastomers primarily in their ease of fabrication. Like traditional elastomers they offer benefits including reduction in noise emissions and improved wear resistance in metal components that are in contact with such parts in the railcar suspension system. However, viscoelastic materials, such as the railroad bearing thermoplastic elastomer suspension element (or elastomeric pad), are known to develop self-heating (hysteresis) under cyclic loading, which can lead to undesirable consequences. Quantifying the hysteresis heating of the pad during operation is therefore essential to predict its dynamic response and structural integrity, as well as, to predict and understand the heat transfer paths from bearings into the truck assembly and other contacting components. This study investigates the internal heat generation in the suspension pad and its impact on the complete bearing assembly dynamics and thermal profile. Specifically, this paper presents an experimentally validated finite element thermal model of the elastomeric pad and its internal heat generation. The steady-state and transient-state temperature profiles produced by hysteresis heating of the elastomer pad are developed through a series of experiments and finite element analysis. The hysteresis heating is induced by the internal heat generation, which is a function of the loss modulus, strain, and frequency. Based on previous experimental studies, estimations of internally generated heat were obtained. The calculations show that the internal heat generation is impacted by temperature and frequency. At higher frequencies, the internally generated heat is significantly greater compared to lower frequencies, and at higher temperatures, the internally generated heat is significantly less compared to lower temperatures. However, during service operation, exposure of the suspension pad to higher loading frequencies above 10 Hz is less likely to occur. Therefore, internal heat generation values that have a significant impact on the suspension pad steady-state temperature are less likely to be reached. The commercial software package ALGOR 20.3TM is used to conduct the thermal finite element analysis. Different internal heating scenarios are simulated with the purpose of obtaining the bearing suspension element temperature distribution during normal and abnormal conditions. The results presented in this paper can be used in the future to acquire temperature distribution maps of complete bearing assemblies in service conditions and enable a refined model for the evolution of bearing temperature during operation.

With the development of high-speed rail technology, the interaction between wheel and track becomes more serious, which threatens the running stability, riding quality and safety of the vehicle. Due to the selected stiffness and damping parameters, conventional passive suspensions cannot fit in with the diverse conditions of the railway. Additionally, among these vibrations contains a large amount of energy, if this vibrational energy can be recycled and used for the active suspension to control, it will be a good solution compared to the conventional passive suspensions. Many energy-harvesting shock absorbers have been proposed in recent years, the most popular design is the electromagnetic harvester including linear electromagnetic shock absorbers, rotational electromagnetic shock absorbers, the mechanical motion rectifier (MMR), and the hydraulic electromagnetic energy-regenerative shock absorber (HESA). With different energy converting mechanisms, the complicated effects of the inertia and nonlinear damping behaviors will severely impact the vehicle dynamic performance such as the ride comfort and road handling. In the past few years, engineers and researchers have done relevant researches on HESA which have shown that it has good effects and proposed several suspension energy regeneration solutions for applying to car. This paper presents a novel application of HESA into a bogie system for railway vehicles comparing to the conventional suspension systems. HESA is composed of hydraulic cylinder, check valves, accumulators, hydraulic motor, generator, pipelines and so on. In HESA, the high-pressure oil which is produced by shock absorber reciprocation could be exported to drive the hydraulic motor, so as to drive the generator to generate electricity. In this way, HESA regenerate the mechanical vibrational energy that is otherwise dissipated by the traditional shock absorber as heat energy. Because the bogie has two sets of suspension systems, a dynamic model of bogie based on AMESim is established in order to clarify the influence of the dynamic characteristics effect and the energy harvesting efficiency when installing the HESA into different sets of the bogie. Then, set the HESA model into each suspension system of the bogie and input with the corresponding characteristic excitation, the influence of the dynamic characteristics and the energy harvesting efficiency are analyzed and compared. The simulation results show that the system can effectively reduce the vibration of the carriage, while maintaining good potential to recycle vibratory energy. Based on the results of the simulation, the relationships as well as differences between the first suspension system and second suspension system have been concluded, which are useful for the design of HESA-Bogie. Moreover, comparing the energy harvesting efficiency discrepancy between the two suspension systems, the potential of energy harvesting of a novel railway vehicle bogie system with HESA has been evaluated and then the best application department has been found, which indicates the theoretical feasibilities of the HESA-bogie to improve the fuel economy.

With the increasing of the train load, the wheel-rail wear is worsening, the maintaining and replacing cycle is shortened enormously, the problem of replacing steel rail and wheel prematurely not only make the railway transportation cost increasing, but also affect the railway normal transportation. This paper proposes a novel type of active energy self-supply radial steering technology — the parallel interconnection hydraulic-electric energy-harvesting active radial steering bogie system. This system is a typical “machine – electric – hydraulic” coupling system, which includes parallel interconnection hydraulic-electric energy-harvesting suspension and active radial steering bogie, consisting of mechanical, electronic, hydraulic and control subsystems internally. In this system, the radial steering bogie is equipped with four HESA, and HESA can reuse the mechanical vibration energy which used to be transformed into waste heat by the shock absorber. In this system, the mechanical vibration energy is now used to drive power module of active radial steering bogie, so as to implement the train’s active radial steering without external power supply. This paper discusses the evolution of radial steering bogie in general, and introduces the structure and basic principle of the parallel interconnection electro-hydraulic energy-harvesting active radial steering bogie system. The system establishes a model of the parallel interconnection hydraulic-electric energy-harvesting shock absorber. The typical vertical irregularity of American track is established. In the paper, we research on the system’s damping performance and energy recovery performance through stimulation. Simulation results show that the maximum vertical acceleration of train body is reduced from 42.9% to 62.3%, and the average energy recovery power from the system increases from 217W to 1835W when the system works at the six levels of track irregularities.

Railway transitions like bridge approaches experience differential movements related to differences in track system stiffness, track damping characteristics, foundation type, ballast settlement from fouling and/or degradation, as well as fill and subgrade settlement. A recent research study at the University of Illinois has used advanced geotechnical instrumentation to identify and quantify different factors contributing to recurrent differential movement problems at three different bridge approaches along Amtrak’s Northeast Corridor (NEC) near Chester, Pennsylvania. Field instrumentation data have indicated excessive ballast movement to be the primary factor contributing to the “bump” development at these bridge approaches. Among the different remedial measures applied to mitigate the recurrent track geometry issues were: (1) Chemical Grouting, (2) Stone Blowing, and (3) Under-Tie Pads. This paper will discuss the implementation methods using track geometry records and instrumentation data, and highlight the effectiveness of chemical grouting and stone blowing to mitigate the differential movement problem at railroad bridge approaches. According to the trends in the transient ballast deformation data collected under train loading, both remedial measures were effective in significantly reducing excessive ballast deformation, which was the primary mechanism behind the bump development at these locations. Ballast degradation and presence of excessive fine particles in the ballast layer adversely affected the ability of the grout to bond with aggregate particles. A “clean” ballast layer, on the other hand, facilitated adequate bonding between the grout and ballast particles leading to significantly improved long-term track performance.

The transition zones especially railroad bridge transitions are one the weakest track sections that need more maintenance in order to keep a good track performance. These locations are also commonly create noise and vibration pollution which is unpleasant specifically in urban parts of the city. A new product known as Resiliently Bound Ballast (RBB) is a new engineered material composed of Ballast, tire derived aggregate (TDA) and proprietary elastomeric epoxy binder which can be manufactured with different mixtures to meet various engineering properties. In order to study the workability of this material in railroad bridges, in this research a one dimensional (1D) two degree of freedom (2DOF) composite RBB-Ballast track on concrete deck bridge has been modeled with different RBB thicknesses from 0.01 in. (0.025 cm) to 23.99 in. (60.94 cm) and material damping of 2.5, 5 and 10 %. The range of properties for RBB are based upon values obtained from static and dynamic testing. The results show that the most peak amplitude reduction occurs between 2.5% to 5% damping, RBB has the ability to dissipate energy over a broader range of frequencies and as the damping increases, the RBB thickness becomes more effective in track dynamic performance.

Two different remedies to reduce track stiffness and increase track damping for the track on the bridges were implemented for two separate ballast deck bridges with standard concrete ties located on a high tonnage heavy haul revenue service route. One remedy used concrete ties fitted with rubber pads on the bottom surface and the other used ballast mats between the ballast layer and bridge deck. The ballast sections were increased to a minimum depth of 12 inches below the bottom of the ties, and drainage improvement was made to ensure that water would not accumulate on the bridges or in the approaches. The two bridge locations were selected in September 2007 and June 2009, for remediation and long-term monitoring of performance as part of the heavy axle load revenue service mega site testing program conducted by Transportation Technology Center, Inc. and Union Pacific Railroad. Before remediation, these two locations experienced excessive track geometry degradation, mud pumping, and track component failure that required localized maintenance work on a quarterly basis (approximately 63 MGT). After remediation, no localized maintenance (except yearly surfacing operations for the entire line) has been required for more than 1,000 MGT. The main root causes of these problems were determined to be high track stiffness and low track damping for the track on the bridges, which adversely affected dynamic vehicle-track interaction when differential track settlement started to occur at the bridge approaches. Some of these ballast deck bridges with concrete ties had track modulus measured at 12,000 lb/in/in, which is considered too high to accommodate dynamic vehicle-track interaction. Long-term performance of these remedies has been excellent, resulting in significant benefits from reduction of slow orders, train delays, and major track maintenance activities.

General purpose railway tank cars similar to road tankers are known to transport liquid cargo in partial-fill state due to variations in liquid cargo density and governing axle load limits. It is widely reported that the cargo movements constitute additional forces and moments that could strongly affect the wheel-rail interactions and coupling forces, and thereby the directional dynamics of the wagon. In this study, the linear slosh theory is used to describe the liquid cargo movement in the roll plane by a simple pendulum, which is integrated into a comprehensive nonlinear multi-body model of a three-piece truck to study the effects of liquid cargo slosh on lateral dynamics of the tank car. The model also incorporates the nonlinear secondary suspension restoring and damping forces, attributed to friction of the wedges, using the non-smooth contact method in addition to the geometric constraints of various components. The wheel/rail contact forces are simulated considering non-elliptical wheel-rail contact using the FASTSIM algorithm. The lateral dynamic responses of the multi-body model of a freight car with partially filled liquid load and an equivalent rigid cargo are evaluated to study the effect of cargo movement on the critical speed and the wheelset hunting oscillations frequency. The results obtained considering different fill ratios of the liquid cargo suggest that the fluid slosh yields additional damping effect on the lateral dynamics of the car. Liquid cargo movement within partly-filled tank car could thus yield a beneficial influence on the wheelset hunting. This was evidenced from the phase relationship between the lateral oscillations of the pendulum and the bogie/wheelset. Consequently, a partially filled tanker resulted in relatively higher critical hunting velocity compared to that of the wagon with equivalent rigid cargo.

The application of Operational Modal Analysis (OMA) in the railway sector opens a broad field of opportunities. The validation of the numerical model employed in the design phase is usually performed employing data obtained in static tests. The drawback is that some suspension parameters, such as dampers, only have an influence in the dynamic behavior and not in the static behavior. Because of that, the use of the mode shapes identified from track measurements in combination with the static tests leads to a more accurate validation of the numerical model. Apart from that, most passenger comfort and dynamic problems are associated to slightly damped modes. A correct identification of the modal parameters can be used as a continuous design improvement tool to improve the comfort and dynamic characteristics of future designs. Another valuable application of OMA techniques is the identification of the mode shapes corresponding to instabilities, due to the safety impact that they have. In railway vehicles, instabilities are associated to mode shapes that present a damping rate which decreases with the increase of the running speed. Above a certain speed value, the excitation coming from track cannot be damped by the vehicle and it reaches an unstable condition. This unstable condition leads to high acceleration levels experienced by the passengers and high interaction forces between the wheel and the rail that may lead to safety hazards. The speed above which the vehicle is unstable is known as critical speed, and has to be greater than the maximum speed of the vehicle with a reasonable safety margin. The use of OMA techniques allows identifying the mode shape that causes the instability. This paper presents the application of OMA techniques to measurements performed on a passenger vehicle, in which the speed was increased until the vehicle was unstable. The mode shape that caused the instability was identified as well as its corresponding natural frequency and damping rate.

This study uses a nonlinear multibody dynamics model of a railway vehicle with three-piece trucks to perform a parametric study on a wide range of parameters influencing the performance of the truck on tangent track. One of the major disadvantages of the three-piece truck is that its performance can be greatly influenced due to worn parts or contaminants on friction surfaces, such as the friction wedge. The influence of worn parts is modeled as increased gap between bodies, using dead-band springs. The influence of environmental contamination is modeled as change in coefficients of friction. Lateral accelerations, measured at the center of gravity of the leading axle of the leading truck (Axle 1) are used for the hunting performance of the vehicle. For the baseline case, an eigenvalue analysis of a linearized model is used to evaluate the effect of speed on damping ratio and lateral motion frequency. A comparison of the linear model and non-linear time series analysis show that the linear model is less conservative, in that it predicts that the onset of hunting occurs at higher speeds. The results indicate a direct relationship between various coefficients of friction and hunting velocity of the rail vehicle. Increasing the gap between the pedestal legs and bearing housing does not influence hunting velocity, but reduces lateral acceleration magnitudes during hunting. The weights of the carbody and cargo also has a direct relationships with hunting velocity, meaning that hunting occurs at lower speeds for unloaded car and at higher speeds for a loaded car.

This paper provides a detailed dynamic model of the electromechanical system for a scaled roller rig that is under construction at the Railway Technology Laboratory of Virginia Tech (RTL) for accurate study of the mechanics and dynamics at wheel-rail interface in railway vehicles. Roller rigs are critical laboratory test equipment for studying rail vehicle dynamics, either as a full railcar or single component. The controlled laboratory environment will provide a successful path for obtaining data on the mechanics and dynamics of the system, including creepage and creep forces at the wheel-rail interface under various conditions. The single-wheel scaled rig under development at RTL includes a wheel that is placed on a roller with similar profile as a U.S. 136 weight rail. The test setup allows for adjusting the wheel load, the wheel angle of attack, the rail cant, and the lateral position of the wheel with respect to the rail (including flanging). The roller and the wheel are each powered independently by two AC motors that enable controlling their relative speed to a high degree of precision, i.e., 0.1 RPM, in order for precisely controlling and simulating various creep conditions that occur in practice. An essential step for the successful design and development of the test rig is modeling the motors and the roller/wheel drivelines. The model includes the electromagnetic dynamics of the AC motors, the compliances and damping of the drivelines, the inertial properties of the motors, shafts, couplers, and the rotating wheels, in a multi-domain (electrical, magnetic, and mechanical) lumped-parameter model. The model is used to determine the damped natural frequencies of the coupled system. The results of the study indicate that the compliances of the driveline mechanics is the most critical element in maintaining a prescribed speed at the driven wheel, and also controlling the relative creep between the wheel and the simulated (round) rail.

Rubber damping pad under ballastless slab track can isolate structure vibration and noise so as to reduce stress and wear of railway track components. In order to make scientific evaluation on the influence of rubber damping pad on the dynamic response of the track structure, focusing on the engineering practice of Chengdu-GuanDujiangyan high-speed railway, comparative test of slab track with and without rubber damping pad is carried out by using acceleration sensors, acoustic sensors, and dynamic data acquisition system. Spectrum analysis of vibration acceleration and noise test results shows that rubber damping pad under track slab can greatly isolate the substructure vibration of the track, the bridge vibration and ground vibration; vibration level of the base slab under the pad is reduced by about 20.1dB; the rubber damping pad can reduce some of the structure noise caused by the bridge structure vibration, but it has no significant effect on noise reduction of the whole system due to the influences of EMU pantograph’s arc noise, severe air turbulence noise and field test environment.

As with most highway bridges, railway transitions experience differential movements due to differences in track system stiffness, track damping characteristics, foundation type, ballast settlement from fouling and/or degradation, as well as fill and subgrade settlement. This differential movement is especially problematic for high speed rail infrastructure as the “bump” at the transition is accentuated at high speeds. Identification of different factors contributing towards this differential movement, as well as development of design and maintenance strategies to mitigate the problem is imperative for the safe and economical operation of both freight and passenger rail networks. This paper presents the research framework and preliminary findings from a recently initiated research effort at the University of Illinois at Urbana-Champaign. Aimed at developing design and repair techniques to mitigate differential movement at railway transitions, this research project involves instrumentation, performance monitoring and numerical modeling of new and existing track transitions.

This paper presents a theoretical and experimental study done on an electro-diesel locomotive in order to evaluate the dynamic behavior of the vehicle in terms of safety, running performance and wheel-track interaction. The vibration analysis has been made by means of different experimental methodologies. The first one consists on the acquisition of accelerations at points located at the wheelset, the truck frame and the coach, using piezorresistive accelerometers. The registered signals allow to validate the locomotive in terms of safety against derailment and running behavior, according the UIC 518 leaflet. The second method is based on the modal analysis theory and includes the dynamic properties estimation under vibrational excitation. This procedure takes into account the determination of modal parameters such as natural frequencies, modal damping ratios and mode shapes, by means of a control hydraulic actuator. The third methodology consists on the operational modal analysis done with the experimental measurements acquired on track tests, in order to validate the results obtained by modal analysis and evaluate the dynamic behavior under different speed ranges and cant deficiencies. Several tests have been done by means of the described methods in an electro-diesel locomotive composed by a primary suspension with dampers and a secondary suspension with rigid stiffness. In addition, two types of dampers have been evaluated with the purpose of optimizing the damping properties of the vehicle’s primary suspension. Through these experimental methods, a useful tool for the prediction and analysis of the dynamic behavior is provided. Additionally, the results obtained by means of these methodologies permit examining the influence of different running conditions and vehicle properties on the modal parameters.

Direct fixation fasteners are one of the most important elements in trackwork design. Elastomeric pads are incorporated in the fastener to provide vertical and horizontal flex and they assist in the reduction of noise, vibration and impact. The spring rate in DFF is often adjusted to mitigate ground borne vibration, that adjustment then affects the track modulus. Currently no industry-wide specifications exist for the design, definition or procurement of direct fixation fasteners. A thorough examination of the characteristics and past performance of available fasteners, as well as the characteristics of the proposed transit vehicle should be undertaken prior to fastener selection for any specific application. In this paper a procedure is suggested to calculate the spacing and desirable (vertical) stiffness of DFF that would mitigate noise, vibration and impact. There are two issues to consider enabling proper vibration isolation. The dominant issue is spring rate and the secondary issue is damping constant. Both are considered. Rail can be defined as a beam supported by DFF, directly fixed to a concrete slab. Usually light mass-spring ballast less track systems have a natural frequency varying from 12 Hz up to 18 Hz. Firstly a natural frequency for the direct Fixation Track is chosen. This choice must conform to the fact that exciting frequency such as train passing frequency should not go close to the natural frequency level so as to avoid resonance. Using a load-deflection formula for the track, a formula for natural frequency of a mass-spring system, a DFF passing frequency formula and relation between track modulus and characteristic length, DFF stiffness can be calculated. The design of stiffness and spacing of DFF does not lead to a unique value. There will always be a range of value depending on the choice of frequency ratio, r . It is found that spacing and stiffness are strongly correlated with R 2 = 0.991. At the end a discussion follows on how to choose the value of natural frequency, f n stiffness amplification factor, R and the frequency ratio, r . Finally an application of the proposed design procedure is shown.

This paper describes the results of quasi-static and dynamic tests of a new shock energy absorber (SEA) capable of high energy absorption while limiting peak dynamic force magnitude in the event of an impact or collision. The SEA utilizes the unique reversible phase transition behavior of Ultra High Molecular Weight Poly-Ethylene (UHMWPE) material under pressure. A prototype drop hammer test confirmed the device’s high energy absorption as well as high damping capabilities at a relatively high deformation rate. The results of the test were used to calibrate a finite element (FE) model that enabled scalability of the SEA for practical applications. Preliminary design and FE simulations were made under a Federal Railroad Administration (FRA) sponsored program toward using a set of SEA as a part of a crash energy management (CEM) system to improve locomotive crashworthiness. The main objective of the program was to prevent locomotive override in the event of an inline collision with a hopper car consist at a closing speed of 30 mph. The FE model, without CEM, was validated to a previously performed full-scale locomotive crashworthiness test at Transportation Technology Center, Inc. (TTCI), Pueblo. The FE simulation results with added CEM system showed successful prevention of locomotive override up to 32.1 mph collision speed. Further scope of using suitably tailored SEA units as buffers to the ends of passenger coaches and tank cars with the objective of enhancing their crashworthiness is discussed.

New types of vehicle and track elements are presented, by means of the finite element method, to establish a model for dynamic analysis of vehicle-track-subgrade coupling systems. The associated stiffness matrix, mass matrix and damping matrix for these two types of elements are deduced. Computational software is coded with Matlab. As an application example, dynamic behavior of track transition is investigated by the vehicle and the track elements. The influencing factors for the simulation include train speed, subgrade stiffness, and irregularity angles of track transition as well as the transition pattern. The computational results show that 1) Abrupt changes of the subgrade stiffness influence vertical acceleration of the rail and the wheel/rail contact force, and this influence increases with increases in train speed, 2) Both the irregularity angles of the track transition and the abrupt changes of the subgrade stiffness have significant effects on rail vertical acceleration and the wheel/rail contact force, with the peak value in this situation being greater than that generated by irregularity angles of the track transition or the abrupt changes of the subgrade stiffness, 3) Train speed, abrupt changes of the subgrade stiffness, and track transition irregularity angles have minor influences on the vertical acceleration of the vehicle due to the excellent behavior of vibration isolation resulting from the primary and the secondary suspension systems of the vehicle, 4) Transition pattern for irregularity of track transition has significant influences on the vehicle acceleration and the wheel/rail contact force, and the cosine transition is a much better indicator than the linear transition, and 5) Influences of the directions the train is moving on the dynamic behavior of the vehicle and the track are relatively insignificant.

This paper presents the procedure used for design, fabrication, testing, and numerical modeling of a magnetorheological (MR) damper that is to be applied for vibration control in a 70-ton railcar. MR dampers are semiactive vibration control devices whose damping characteristics can be modified in real time by varying an applied current. Design parameters for the MR damper are estimated from those exhibited by a linear viscous damper that exerts the necessary force required to limit vertical vibrations of the rail truck within acceptable limits. An MR damper is fabricated by modifying the piston of a standard hydraulic damper to function as a solenoid. The assembled MR damper is tested in a uniaxial testing machine by subjecting it to sinusoidal and random displacements while simultaneously varying the current flowing in the solenoid. A variable magnetic field is applied to the MR fluid that fills the damper cavity and the resisting force exerted by the damper is recorded. Data collected in the laboratory are used to train a fuzzy model of the MR damper that characterizes its behavior. Results indicate that a fuzzy model of the MR damper can predict its behavior with a sufficient degree of accuracy while requiring minimal computational time.

The center plate interface is made up of the body plate attached to the car body bolster, the polymer liner, and the bolster bowl, which is a part of the truck bolster. Roll motion of the rail car leads to the car body bolster rolling over the polymer liner on the truck bolster, which may result in partial loss of contact of the body plate with the polymer liner. This nonlinear phenomenon has a deleterious impact on the rail car dynamics. A technique for creating a center plate dynamic model accounting for the polymer liner and the loss of contact condition is presented here. Material tests were performed to model the stress-relaxation of the liner. A stiffness/damping model of the center plate accounting for the nonlinear effects of the lift-off was developed based on a nonlinear Winkler foundation model and was tested for a one-degree-of-freedom dynamic model. This continuous model was adapted into a 16 stiffness-damping element model to enable its usage in a NUCARS™ rail-car dynamic model.