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Journal articles on the topic 'Track dynamics'
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1
Zeng, Yong. "Effects of Track Elasticity on Wheel-Rail Dynamic Performance of Heavy Haul Railway." Applied Mechanics and Materials 744-746 (March 2015): 1249–52. http://dx.doi.org/10.4028/www.scientific.net/amm.744-746.1249.
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Two vehicle-track dynamics models on heavy haul railway are established in two conditions of rigid track and elastic track. And the impact of track elasticity on the wheel-rail dynamics performance was analyzed using models. The results show that the critical speed of heavy vehicles and wheel-rail dynamic indexes, such as wheel-rail lateral force and wheel-rail vertical force decreased on elastic track compared with rigid track. However, other dynamic indexes, including derailment coefficient and lateral displacement of wheelsets increased on elastic track. And the wheel-rail wear indexes are some differences on two tracks.
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Kaewunruen, Sakdirat, Chayut Ngamkhanong, and Xin Liu. "Spectro-Temporal Responses of Curved Railway Tracks with Variable Radii of Arc Curves." International Journal of Structural Stability and Dynamics 19, no. 04 (2019): 1950044. http://dx.doi.org/10.1142/s0219455419500445.
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On curved railway tracks, wheel/rail interface can usually cause a traveling source of sound and vibration, which constitutes high-pitch or tonal noise pollution causing considerable concern to rail asset owners, commuters and people living or working along the railway corridor. The sound and vibration can be in various forms and spectra. The undesirable tonal sound on curves caused by excessive lateral wheel/rail dynamics in resonance with falling friction states are often called ‘squeal noises’. This paper evaluates the transient effect of curve radii on the possible occurrence of lateral track resonances, which is a principal cause of dynamic wheel/rail mode coupling that could trigger ‘curve squeal’. This study is devoted to systems thinking approach and better insight into dynamic phenomena of railway tracks that could resolve the railway curve noise problems. Curved track models in three-dimensional space have been developed using a finite element package, STRAND7. The dynamic responses of curved track have been simulated by applying a moving train load. The transient loading model of a common wheel/rail slip has been adopted. The simulations of railway tracks with different curve radii have been carried out to develop state-of-the-art understanding of lateral track dynamics, including rail dynamics, cant dynamics and overall track responses. Parametric studies have been conducted to evaluate lateral displacements, velocities and accelerations of rail over sleeper and rail at midspan, both in static and dynamic conditions. The study firstly reveals that the lateral resonance of tangent tracks is relatively rare and the mode coupling behavior is unlikely to occur on moderately curved tracks. The lateral vibration responses have been presented in terms of time histories and spectro-temporal responses (also called “Spectogram”). The dynamic lateral responses of the track are found to be sensitive to the change of curved radii. The resonance peak in the lateral direction is related to the agreement of corresponding natural frequencies of rail and the vibration excitation frequencies under an individual rolling velocity. The outcome of this study establishes new insight into the dominant influences of different track parameters to track lateral dynamic behaviors.
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Hubbard, Mont, Michael Kallay, and Payam Rowhani. "Three-Dimensional Bobsled Turning Dynamics." International Journal of Sport Biomechanics 5, no. 2 (1989): 222–37. http://dx.doi.org/10.1123/ijsb.5.2.222.
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We have developed a mathematical model and computer simulation of three-dimensional bobsled turning. It is based on accurate descriptions of existing or hypothetical tracks and on dynamic equations of motion including gravitational, normal, lift, drag, ice friction, and steering forces. The three-dimensional track surface model uses cubic spline geometric modeling and approximation techniques. The position of the sled on the track is specified by the two variables α and β in the along-track and cross-track directions, differential equations for which govern the possible motions of the sled. The model can be used for studies involving (a) track design, (b) calculation of optimal driver control strategies, and (c) as the basis for a real-time bobsled simulator. It can provide detailed quantitative information (e.g., splits for individual turns) that is not available in runs at actual tracks. The model also allows for comparison of driver performance with the numerically computed optimum performance, and for safe experimentation with risky driving strategies.
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SADEGHI, J., and M. FESHARAKI. "IMPORTANCE OF NONLINEARITY OF TRACK SUPPORT SYSTEM IN MODELING OF RAILWAY TRACK DYNAMICS." International Journal of Structural Stability and Dynamics 13, no. 01 (2013): 1350008. http://dx.doi.org/10.1142/s0219455413500089.
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Attention is drawn to the fact that the recent increase in axle loads, speed and traffic volume in railway tracks, as well as concerns over passengers' riding comfort and safety have resulted in fresh challenges that are needed to be addressed. These challenges can only be successfully tackled with a more accurate modeling of the dynamic behavior of railway tracks. Although a significant amount of research involving mathematical modeling of railway track dynamics has been conducted in the last two decades, the nonlinearity of track support systems has not been given sufficient attention. This paper is concerned with the effect of nonlinearity of the support sub-layers on the dynamic responses of the railway track. To this end, a railway track model that considers the nonlinear properties of the track sub-layers is developed. Then, a field investigation into the dynamic responses of the railway track system under moving trains is conducted. The effect of the nonlinearity properties of the track support system on the track responses is investigated by comparing the results obtained by the numerical model, with or without consideration of track support nonlinearity, with those from the field tests. It is illustrated that consideration of the nonlinear properties of the track support system improves the accuracy of the calculated responses by a factor of three. It is also shown that the train axle loads and track accumulative loading have a significant effect on the nonlinearity of the track support system and, as a result, on the modeling of track responses.
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Chang, Edmund K. M., Sukyoung Lee, and Kyle L. Swanson. "Storm Track Dynamics." Journal of Climate 15, no. 16 (2002): 2163–83. http://dx.doi.org/10.1175/1520-0442(2002)015<02163:std>2.0.co;2.
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Xu, Qingyuan, Hao Sun, Lexuan Wang, Lei Xu, Wei Chen, and Ping Lou. "Influence of Vehicle Number on the Dynamic Characteristics of High-Speed Train-CRTS III Slab Track-Subgrade Coupled System." Materials 14, no. 13 (2021): 3662. http://dx.doi.org/10.3390/ma14133662.
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In this paper, a high-speed train–CRTS III slab track–subgrade coupled dynamic model is established. With the model, the influence of vehicle number on the dynamic characteristics of a train–CRTS III slab track–subgrade coupled system with smooth and random track irregularity conditions for conventional and vibration-reduction CRTS III slab tracks are theoretically studied and analyzed. Some conclusions are drawn from the results: (1) the largest dynamic responses of the coupled system for all items and cases are no longer changed when the vehicle number exceeds three, and three vehicles are adequate to guarantee the simulation precision to investigate the dynamic responses of the coupled system. (2) The acceleration of the car body has almost no relation with the vehicle number, and only one vehicle is needed to study the vehicle dynamics using the train–CRTS III slab track–subgrade coupled dynamic model. (3) For the conventional CRTS III slab track on a subgrade, the vehicle number has a negligible influence on the accelerations of the rail, slab, and concrete base, the positive and negative bending moments of the rail, the compressive force of the fastener, and the positive bending stress of slab, but it has a large influence on the tension force of the fastener, and the negative bending stresses of the slab and concrete base. Only one vehicle is needed to study track dynamics without considering the tension force of the fastener, the negative bending stresses of the slab and concrete base, otherwise, two or more vehicles are required. (4) For vibration reduction of the CRTS III slab track on a subgrade, the number of vehicles has some influence on the dynamic responses of all track components, and at least two vehicles are required to investigate the track dynamics.
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Chapman, Christopher C., Andrew McC Hogg, Andrew E. Kiss, and Stephen R. Rintoul. "The Dynamics of Southern Ocean Storm Tracks." Journal of Physical Oceanography 45, no. 3 (2015): 884–903. http://dx.doi.org/10.1175/jpo-d-14-0075.1.
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AbstractThe mechanisms that initiate and maintain oceanic “storm tracks” (regions of anomalously high eddy kinetic energy) are studied in a wind-driven, isopycnal, primitive equation model with idealized bottom topography. Storm tracks are found downstream of the topography in regions strongly influenced by a large-scale stationary meander that is generated by the interaction between the background mean flow and the topography. In oceanic storm tracks the length scale of the stationary meander differs from that of the transient eddies, a point of distinction from the atmospheric storm tracks. When the zonal length and height of the topography are varied, the storm-track intensity is largely unchanged and the downstream storm-track length varies only weakly. The dynamics of the storm track in this idealized configuration are investigated using a wave activity flux (related to the Eliassen–Palm flux and eddy energy budgets). It is found that vertical fluxes of wave activity (which correspond to eddy growth by baroclinic conversion) are localized to the region influenced by the standing meander. Farther downstream, organized horizontal wave activity fluxes (which indicate eddy energy fluxes) are found. A mechanism for the development of oceanic storm tracks is proposed: the standing meander initiates localized conversion of energy from the mean field to the eddy field, while the storm track develops downstream of the initial baroclinic growth through the ageostrophic flux of Montgomery potential. Finally, the implications of this analysis for the parameterization and prediction of storm tracks in ocean models are discussed.
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Yuan, Xuancheng, Shengyang Zhu, Lei Xu, Wanming Zhai, and Huailong Li. "Investigation of the vibration isolation performance of floating slab track with rubber bearings using a stochastic fractional derivative model." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, no. 9 (2019): 992–1004. http://dx.doi.org/10.1177/0954409719883552.
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Floating slab track is an effective countermeasure to mitigate undesirable vibrations caused by metro trains. In this work, a stochastic fractional derivative model is proposed for simulating the dynamic behavior of rubber bearings in floating slab tracks. The stochastic fractional derivative model is based on the Grünwald representation of fractional calculus, the number theoretical method, and the probability density evolution method (PDEM). It considers the viscoelastic characteristics of the rubber bearings, as well as randomness in mechanical behavior due to manufacturing tolerances, aging, and fatigue. The stochastic fractional derivative model is then implemented into a vehicle–floating slab track coupled dynamics model to investigate the vibration isolation performance of the floating slab track with rubber bearings. The characteristics and advantages of the stochastic fractional derivative model with deterministic parameters are illustrated by comparing the results with the conventional Kelvin model. Finally, stochastic analyses of the dynamic response and the vibration isolation performance of the floating slab track are carried out using the coupled vehicle–floating slab track system dynamics model. Results show that the stochastic simulation of the vehicle–floating slab track system using PDEM is efficient and reliable compared with the Monte Carlo method. Thus, the proposed model is effective and useful for evaluating the vibration levels in floating slab tracks with uncertain parameters, and for predicting the reliability of the vibration isolation performance.
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Zhu, Shengyang, Jun Luo, Mingze Wang, and Chengbiao Cai. "Mechanical characteristic variation of ballastless track in high-speed railway: effect of train–track interaction and environment loads." Railway Engineering Science 28, no. 4 (2020): 408–23. http://dx.doi.org/10.1007/s40534-020-00227-6.
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AbstractDue to the fact that ballastless tracks in high-speed railways are not only subjected to repeated train–track dynamic interaction loads, but also suffer from complex environmental loads, the fundamental understanding of mechanical performance of ballastless tracks under sophisticated service conditions is an increasingly demanding and challenging issue in high-speed railway networks. This work aims to reveal the effect of train–track interaction and environment loads on the mechanical characteristic variation of ballastless tracks in high-speed railways, particularly focusing on the typical interface damage evolution between track layers. To this end, a finite element model of a double-block ballastless track involving the cohesive zone model for the track interface is first established to analyze the mechanical properties of the track interface under the loading–unloading processes of the negative temperature gradient load (TGL) followed by the same cycle of the positive TGL. Subsequently, the effect of wheel–rail longitudinal interactions on the nonlinear dynamic characteristics of the track interface is investigated by using a vehicle-slab track vertical-longitudinal coupled dynamics model. Finally, the influence of dynamic water pressure induced by vehicle dynamic load on the mechanical characteristics and damage evolution of the track interface is elucidated using a fluid–solid coupling method. Results show that the loading history of the positive and negative TGLs has a great impact on the nonlinear development and distribution of the track interface stress and damage; the interface damage could be induced by the wheel–rail longitudinal vibrations at a high vehicle running speed owing to the dynamic amplification effect caused by short wave irregularities; the vehicle dynamic load could produce considerable water pressure that presents nonlinear spatial–temporal characteristics at the track interface, which would lead to the interface failure under a certain condition due to the coupled dynamic effect of vehicle load and water pressure.
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Клубничкин, Evgeniy Klubnichkin, Клубничкин, Vladislav Klubnichkin, Бухтояров, and Leonid Bukhtoyarov. "Investigation of the kinematics and dynamics of propulsor of track harvester." Forestry Engineering Journal 4, no. 4 (2015): 179–90. http://dx.doi.org/10.12737/8471.
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The research of multilink mechanism on the example of propulsor track harvester ЛЗ-5 was made. Propulsor of track harvester (CH) is a multilink mechanism, as it consists of track tracks, including a large number of tracks hingedly connected to each other. For research, we selected the program UM Tracked Vehicles, as it is most appropriate for the task. At the stage of development of the design documentation, such virtual testing in economic terms is more favorable than the natural prototype testing.
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Guo, Yi Shi, Zu Jun Yu, and Hong Mei Shi. "Natural Vibration Analysis of High-Speed Railway Slab Tracks under Rail Longitudinal Force." Advanced Materials Research 706-708 (June 2013): 1443–49. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.1443.
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The slab track is the main structure of the high-speed railway track, the Inherent dynamic characteristics of which is of great significance to the research on the Vehicle-Track Coupling Dynamics. The assumptions of the modal function describing the natural vibration of the track is a necessary theoretical basis in analytic and numerical calculations for dynamics problems, which is more in accordance with the real situation, the more likely characteristic estimation are to be accurate. In this paper, with the method of combine matrix, the system characteristic equation of slab-track model is deduced, and the exact analytic formulas of frequency equation and modal function are obtained. Meanwhile the specific effects of the Rail longitudinal force on the vibration performance of the tracks are analyzed through instances. The results show that this approach is an effective analytic method, the solution of which is accurate. And the track parameters can be flexibly initialized, which is especially applicable for the condition of track parameters varying and longitudinal strain with distribution.
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Lau, Albert, and Inge Hoff. "Simulation of Train-Turnout Coupled Dynamics Using a Multibody Simulation Software." Modelling and Simulation in Engineering 2018 (July 22, 2018): 1–10. http://dx.doi.org/10.1155/2018/8578272.
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With the advancements of computing power, multibody simulation (MBS) tool is used to study not only train dynamics but also more realistic phenomena such as train-track coupled dynamics. However, train-turnout coupled dynamics within MBS is still hard to be found. In this paper, a train-turnout coupled model methodology using a MBS tool GENSYS is presented. Dynamic track properties of a railway track are identified through numerical receptance test on a simple straight track model. After that, the identified dynamic track properties are adopted in a switch and crossing (turnout) to simulate train-turnout coupled dynamic interaction including parameters such as rail bending stiffness and sleeper mass variation along the turnout. The train-turnout coupled dynamic interaction is compared to the dynamic interaction simulated from a widely accepted moving mass train-turnout model. It is observed that the vertical and lateral normal forces for the new train-turnout coupled model and the conventional moving mass train-turnout model are in good agreement. In addition, the new train-turnout coupled model can provide additional track dynamics results. It is concluded that the train-turnout coupled model can provide a more realistic train-turnout dynamic interaction compared to the moving mass train-turnout model.
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Wilson, Chris, Bablu Sinha, and Richard G. Williams. "The Effect of Ocean Dynamics and Orography on Atmospheric Storm Tracks." Journal of Climate 22, no. 13 (2009): 3689–702. http://dx.doi.org/10.1175/2009jcli2651.1.
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Abstract The control of atmospheric storm tracks by ocean dynamics, orography, and their interaction is investigated using idealized experiments with a simplified coupled atmosphere–ocean climate model. The study focuses on the quasi–steady state for the storm tracks in the Northern Hemisphere winter mean. The experiments start with a background state without mountains and ocean dynamics, and in separate stages include orography and a dynamic ocean to obtain a more realistic control simulation. The separate effects of ocean dynamics, orography, and their nonlinear interaction are identified for the storm tracks and the surface thermodynamic forcing over the ocean. The model study suggests that atmospheric storm tracks are a robust feature of the climate system, occurring at midlatitudes even if there is no orographic forcing or ocean heat transport. Ocean dynamics generally lead to a poleward shift in both the storm track and the maximum in atmospheric northward heat transport and induce a northeastward tilt over the Atlantic. This poleward shift is linked to the extra heat transport by the ocean and the tightening of sea surface temperature gradients on the western side of ocean basins. Orographic forcing causes along-track variability with a weakening of the storm track over the continents and induces a northeastward tilt over the western Pacific, which is associated with a stationary planetary wave train generated by the Tibetan Plateau. The interaction between ocean dynamics and orographic forcing plays a localized role, enhancing the contrast between the Atlantic and Pacific. Much of the response to the forcing is eddy mediated and transient eddies help to spread the influence of orographic and ocean forcing.
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Mori, Shozo, W. H. Barker, Chee-Yee Chong, and Kuo-Chu Chang. "Track association and track fusion with nondeterministic target dynamics." IEEE Transactions on Aerospace and Electronic Systems 38, no. 2 (2002): 659–68. http://dx.doi.org/10.1109/taes.2002.1008994.
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Sun, Wen Jing, Dao Gong, and Jin Song Zhou. "Study on Wheel-Rail Coupled Vibration of Metro with Co-Simulation of Finite Element Analysis and Multi-Body Dynamics Simulation." Applied Mechanics and Materials 752-753 (April 2015): 636–41. http://dx.doi.org/10.4028/www.scientific.net/amm.752-753.636.
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Based on the multi-body dynamics theory and modal-reduction analysis, finite element method and multi-body dynamics were combined to establish the flexible track model. The rigid-flexible coupled dynamics model can reflect the features of coupled vibration accurately. When the flexibility of the rail, damping and stiffness of support layers under the rail are taken into consideration, the whole track structure acted as a buffer while wheel and rail is interacting with each other. Compared with rigid track model, the wheel-rail vibration is less in the flexible track model. The proposed method in this paper is simple and effective, which makes the calculation of vehicle-track dynamic response more convenient and quick.
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Ma, Hong Wei, and Chuan Wei Wang. "Studying and Simulation Analysis for Rubber Track of Rescue Robot." Applied Mechanics and Materials 457-458 (October 2013): 643–48. http://dx.doi.org/10.4028/www.scientific.net/amm.457-458.643.
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Rubber track of Rescue Robot was dispersed into limited number of track blocks by the method of finite segment method used in flexible multibody dynamics. The two neighbor track blocks were connected by springs and dampers, then the moldel was become a multi-rigid-body system with flexible joint. Rubber track was modeled with the help of macro command used in the secondary development of virtual prototype technique software named ADAMS. Flexible connection was realized by the method of adding Bushing, and then a new method was proposed to build rubber track model. The obstacle-surmounting simulation of climbing the barrier of single step was carried out. It intuitively reflected the stress and deformation under the condition of climbing barrier. The method mentioned above laid good foundation for studying obstacle-surmounting abilities of the rubber-tracked robots and dynamic characteristic of the tracks.
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Li, Li, and Yan Yun Luo. "Stable Analysis of CWR Track by its Vibration Characteristics." Advanced Materials Research 446-449 (January 2012): 2624–32. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.2624.
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Stress contained in rails, mainly due to thermally-induced expansion and contraction, results in large longitudinal loads which lead to broken rails and track buckling. According to the beam bending theory of structural dynamics with a consideration of the influence of axial load, a CWR track model is developed in the present study to be used for extensive buckling analysis of CWR tracks. The model discusses CWR track vibration characteristics with a length of unsupported rail subjected to the longitudinal force due to fluctuation of temperature. From the result, it can be gotten that the critical point of the temperature which may cause the rail have the danger of unstable. This model would help to evaluated and measure the real temperature in rail by analyzing the dynamic response of CWR track.
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Sun, Y. Q., and C. Cole. "Comprehensive wagon-track modelling for simulation of three-piece bogie suspension dynamics." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 221, no. 8 (2007): 905–17. http://dx.doi.org/10.1243/09544062jmes434.
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A wagon-track dynamics interaction model has been developed to investigate the dynamics of suspensions with friction wedge dampers that are widely used in three-piece bogie wagons in Australia. The wagon is modelled using 66 degrees-of-freedom, accounting for the three-dimensional movements of all wagon components. The mass of the wedge has also been modelled. The track is modelled with rails as Timoshenko beams and discretely supported by the spring and damper elements representing the elasticity of pads, fasteners, and ballast. An assumed track geometry irregularity, i.e. top surface profile, is used for the analysis of suspension dynamics. The simulation results of the wagon-track dynamics interaction model have been compared with those from a VAMPIRE model. The VAMPIRE model uses the normal user level approaches without special subroutine development. Effects of the wedge friction conditions and the effect of track geometry irregularity have been investigated for the better understanding of dynamic performance of three-piece bogie suspensions.
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Zhang, Jiaming, Maik Lang, Rodney C. Ewing, Ram Devanathan, William J. Weber, and Marcel Toulemonde. "Nanoscale phase transitions under extreme conditions within an ion track." Journal of Materials Research 25, no. 7 (2010): 1344–51. http://dx.doi.org/10.1557/jmr.2010.0180.
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The dynamics of track development due to the passage of relativistic heavy ions through solids is a long-standing issue relevant to nuclear materials, age dating of minerals, space exploration, and nanoscale fabrication of novel devices. We have integrated experimental and simulation approaches to investigate nanoscale phase transitions under the extreme conditions created within single tracks of relativistic ions in Gd2O3(TiO2)x and Gd2Zr2–xTixO7. Track size and internal structure depend on energy density deposition, irradiation temperature, and material composition. Based on the inelastic thermal spike model, molecular dynamics simulations follow the time evolution of individual tracks and reveal the phase transition pathways to the concentric track structures observed experimentally. Individual ion tracks have nanoscale core-shell structures that provide a unique record of the phase transition pathways under extreme conditions.
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Greenwood, Royston, and C. R. Hinings. "Organizational Design Types, Tracks and the Dynamics of Strategic Change." Organization Studies 9, no. 3 (1988): 293–316. http://dx.doi.org/10.1177/017084068800900301.
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Change and stability in organizations is to be understood through the twin concepts of design archetypes and tracks. Organizations operate with structural designs which are given meaning and coherence by underlying interpretive schemes. Particular interpre tive schemes coupled with associated structural arrangements constitute a design archetype. The temporal relationship between an organization and one or more archetypes defines an organization's track. Prototypical tracks include inertia, aborted excursions, re-orientations and unresolved excursions. The particular track followed by an organization will be a function of the degree of alignment or compatibility between structures and contingency constraints, the pattern of commitment to prevailing and alternative interpretive schemes and the incidence of interest dissatisfaction of powerful groups.
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Peng, Dong Hui, Zi Sen Wei, and Jue Fei Liu. "The Exploration and Research of CRTS I Slab Ballastless Track Used in the Freight Lines." Applied Mechanics and Materials 253-255 (December 2012): 2031–34. http://dx.doi.org/10.4028/www.scientific.net/amm.253-255.2031.
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The CRTSⅠslab ballastless track structure was the research object of this thesis and the truck vehicle-track dynamics coupled model had established in this thesis. Germany track interference spectrum was used as the track irregularity. The study analyzed the force conditions of the CRTSⅠslab ballastless track under the action of heavy freight trains in 110km/h, as well as the wheel-rail vertical force, vertical displacement and acceleration of the rail and rail board changes with time. The results show that the CRTSⅠslab ballastless track can meet the basic requirements of freight line.
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Xu, Zhouzhou, Zixue Du, Zhen Yang, and Junchao Zhou. "Research on Vehicle-Bridge Vertical Coupling Dynamics of Monorail based on Multiple Road Excitations." Mechanics 26, no. 4 (2020): 301–10. http://dx.doi.org/10.5755/j01.mech.26.4.24399.
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In order to study the vertical dynamic behavior of the monorail-bridge system, the vehicle-bridge coupling dynamic equation and train simulation model are established based on the principle of dynamics; the train simulation model is established based on the multi-body dynamics; the track model is established based on the finite element theory, and the compression deformation of PC beam and the effect of finger band on train are equivalent to load spectrum on train axle by means of dynamic equivalence principle, and finally, the train-track interaction model is established; the vertical vibration of the train before and after adding the influence of the compressive deformation of the track beam is simulated and calculated respectively, the results show that the influence of the compressive deformation of the track beam on the vertical vibration of the train is significant, and the simulation data under multiple road excitations are very close to the real value.
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Xie, Haoran, Bin Yan, and Jie Huang. "Vertical Dynamic Analysis of Ballastless Tracks on Train-Track- Bridge System." MATEC Web of Conferences 306 (2020): 02003. http://dx.doi.org/10.1051/matecconf/202030602003.
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In order to investigate the vertical dynamic response characteristics of train-track-bridge system on CWR (Continunously Welded Rail) under dynamic load of train on HSR (High-Speed Railway) bridge. Based on the principle of vehicle train-track-bridge coupling dynamics, taking the 32m simply supported bridge of a section of Zhengzhou-Xuzhou Passenger Dedicated Line as an example, the finite element software ANSYS and the dynamic analysis software SIMPACK are used for co-simulation, and bridge model of the steel spring floating slab track and the CRTSIII ballastless track (China Railway Track System) considering the shock absorbing steel spring, the limit barricade and the contact characteristics of track structure layers are established. On this basis, in order to study the dynamic response laws of the design of ballastless track structure parameters to the system when the train crosses the bridge and provide the basis for the design and construction, by studying the influence of the speed of train on the bridge, the damage of fasteners and the parameters of track structure on the train-track-bridge system, the displacement of rail, vertical vibration acceleration and wheel-rail force response performance are analyzed. Studies have shown that: At the train speed of 40 km/h, the displacement and acceleration of the rail and track slab in the CRTSIII ballastless track are smaller than the floating slab track structure, but the floating slab track structure has better vibration reduction performance for bridges. The acceleration of rail, track slab and bridge increases obviously with the increase of train speed, the rail structure has the largest increasement. Reducing the stiffness of fasteners could decrease the vertical acceleration response of the steel spring floating slab track system, the ability to absorb shock can be enhanceed by reducing the stiffness of the fastener appropriately. Increasing the density of the floating slab can increase the vertical acceleration of the floating slab and the bridge, thereby decreasing the vibration amplitude of the system.
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Yang, Chang Wei, Jian Jing Zhang, and Chuan Bin Zhu. "Analysis of Dynamic Responses of Bridge-Subgrade Transition of High-Speed Railway." Applied Mechanics and Materials 90-93 (September 2011): 189–96. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.189.
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Referred the vehicle-track coupling dynamics theory [1] and the vertical dynamic analysis models of Bridge-Subgrade transition developed by Zhai [2] ，Wang [3] and others [4]. This article takes account of the interaction between different structural layers in the subgrade system further by using the dynamic ballastless track model and finally establishes a space dynamic numerical model of the vehicle-track-subgrade coupled system. The dynamic response of the coupled system is analyzed when the speed of the train is 350km/h and the transition is filled with graded broken stones mixed with cement of 3%. Results show that the setting forms of Bridge-Subgrade transition have little effect on the dynamic responses, so designers can choose it on account of the practical situation. Due to the location away from abutment about 5m has greater deformation; the stiffness within 5m should be designed alone. Based on the study from vehicle-track dynamics, we suggest that the maximum allowable track deflection angle is 0.9‰ and K30190Mpa within 5m behind the abutment.
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McCullough, M. K., and E. J. Haug. "Dynamics of High Mobility Track Vehicles." Journal of Mechanisms, Transmissions, and Automation in Design 108, no. 2 (1986): 189–96. http://dx.doi.org/10.1115/1.3260801.
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A mechanical system superelement that represents spatial dynamics of high mobility track vehicle suspension systems is derived. Using results from a companion paper [1], the equations of motion for a suspension system with an arbitrary number of road wheels are systematically derived. Track is represented as a complex internal force element that acts between ground, wheels, and the chassis of the vehicle. Track tension is computed from a relaxed catenary relationship and track bridging effects are modeled. Numerical results for driver acceleration and absorbed power, as well as track tension are presented. A factor of 90 decrease in compute time is achieved over a comparable multibody model of the same vehicle.
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Lundqvist, A., and T. Dahlberg. "Load impact on railway track due to unsupported sleepers." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 219, no. 2 (2005): 67–77. http://dx.doi.org/10.1243/095440905x8790.
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Ballasted railway tracks will settle as a result of permanent deformations in the ballast and in the underlying material layers. The settlement is caused by the repeated traffic loading and the severity of the settlement depends on the quality and the behaviour of the ballast, the sub-ballast, and the subgrade. As the behaviour of the material is not exactly the same under all sleepers, and since the loading of the track is irregular, the amount of settlement will differ from one sleeper to another. A result of this is that the sleepers are not always fully supported, and some sleepers may even become completely unsupported (voided). A gap appears between the sleeper and the ballast bed. As soon as the track geometry starts to deteriorate, the variations of the train/track interaction force increase, and this speeds up the track deterioration rate. This paper presents a computer model by which the dynamic train/track interaction can be simulated. The influence of one or several voided sleepers on the train/track interaction force and on the track dynamics is investigated. Track settlement due to hanging sleeper(s) is discussed.
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Kumar, Vivek, Vikas Rastogi, and PM Pathak. "Dynamic analysis of vehicle–track interaction due to wheel flat using bond graph." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 232, no. 3 (2017): 398–412. http://dx.doi.org/10.1177/1464419317739754.
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The dynamic response of a railway track under a moving train in the presence of a wheel with flat has been studied over many years. The force at the wheel–rail interface is mainly responsible for vehicle and track components deterioration and adds to the maintenance cost. So, reliable predictions of wheel–rail interaction forces are of prime concern to get the key factors responsible for damage of vehicle and track components. In most of the studies, a symmetrical vehicle–track model with linearity in track components behavior is assumed for simplification. This may lead to incorrect results in some situation. In this paper, wheel–rail impact dynamics is investigated by considering an asymmetrical vehicle–track model with due consideration to nonlinear behavior of track. Some nonlinear factors such as loss of wheel–rail contact, nonlinearity in pad, and ballast behavior are taken into consideration. A combined vehicle–track bond graph model is developed to study the wheel–track interaction dynamics. The rail is modeled as a flexible Euler Bernoulli beam resting on discrete support. The nonlinear Hertzian contact theory is used to accomplish the dynamic interactions between the vehicle and the track. Time response of forces, displacements, velocities, and accelerations of the related components of the vehicle and the track are obtained. It has been found that, though the wheel flat exists on leading right wheels, its effect has also been transferred to other components of the vehicle. The obtained results further lead to provide a better understanding of the interaction dynamics at the wheel–track interface with attention to the nonlinear behavior of pad and ballast.
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True, Hans. "Dynamics of a Rolling Wheelset." Applied Mechanics Reviews 46, no. 7 (1993): 438–44. http://dx.doi.org/10.1115/1.3120372.
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We discuss the kinematics and dynamics of a wheelset rolling on a railway track. The mathematical model of a suspended wheelset rolling with constant speed on a straight track is set up and its dynamics is investigated numerically. The results are presented mainly on bifurcation diagrams. Several kinds of dynamical behavior is identified within the investigated speed range. We find a stationary equilibrium point at low speeds and at higher speeds symmetric and asymmetric oscillations are found and ranges with chaotic motion are identified. The bifurcations are described.
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AUERSCH, Lutz. "VEHICLE-TRACK-INTERACTION AND SOIL DYNAMICS." Vehicle System Dynamics 29, sup1 (1998): 553–58. http://dx.doi.org/10.1080/00423119808969586.
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Zhai, Wanming, Kaiyun Wang, and Chengbiao Cai. "Fundamentals of vehicle–track coupled dynamics." Vehicle System Dynamics 47, no. 11 (2009): 1349–76. http://dx.doi.org/10.1080/00423110802621561.
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Dai, Li, Yun Gong Li, Yu Liu, and Jian Wang. "The Dynamic Analysis of Concrete Pump Truck Arm in Civil Engineering." Advanced Materials Research 568 (September 2012): 138–41. http://dx.doi.org/10.4028/www.scientific.net/amr.568.138.
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The concrete pump truck integrates transportation with pouring process ，which is characterized with flexibility, facility and celerity in civil engineering. As for the concrete pump truck, the arm system is the most important because the rationality of the arm directly influences the performance and pouring position of the truck in its application in civil engineering. For the arm system of the concrete pump truck, the movement of the arm system and the hydraulic cylinder are analyzed respectively with multi-body dynamic theory. By using numerical arithmetic to resolve the dynamic equation, the terminal track of the arms is analyzed. It shows that the kinetic equation built by multi-body dynamics can describe the dynamic characteristics of pump truck exactly.
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Balamurugan, S., and R. Srinivasan. "Tracked Vehicle Performance Evaluation using Multi Body Dynamics." Defence Science Journal 67, no. 4 (2017): 476. http://dx.doi.org/10.14429/dsj.67.11534.
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The objective of the study was to shorten the design cycle and evaluate the performance of infantry fighting vehicle using advanced multi body dynamics (MBD) environment before physical prototypes built. The MBD model is built with tracked vehicle module consisting of tracks (Links), sprocket, Support rollers, and hydro pneumatic suspension with suitable connections. Hull, turret are characterised by mass and inertial properties. The dynamic analysis was carried out for different field conditions i.e. trench crossing, step and ramp climbing, etc., to extract the hull forces at joints, power required to manuever, track tension forces to determine overall vehicle stability and look for possible design modifications. Recommendations were then suggested for power train, number of track segments, tensioner force, etc to ensure proper behavior during different manuevers. The MBD results are used in FEA to determine structural response in terms of stress, deformation, fatigue etc., and reflects in design modification before physical prototype made and are validated with base level analytical results.
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Shamanov, V. I. "Alternating traction current dynamics in track lines of double-track hauls." Russian Electrical Engineering 87, no. 10 (2016): 566–71. http://dx.doi.org/10.3103/s1068371216100060.
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Kouroussis, G., G. Gazetas, I. Anastasopoulos, C. Conti, and O. Verlinden. "Discrete modelling of vertical track–soil coupling for vehicle–track dynamics." Soil Dynamics and Earthquake Engineering 31, no. 12 (2011): 1711–23. http://dx.doi.org/10.1016/j.soildyn.2011.07.007.
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Hu, Yong, and David B. Bogy. "Dynamic Stability and Spacing Modulation of Sub-25 nm Fly Height Sliders." Journal of Tribology 119, no. 4 (1997): 646–52. http://dx.doi.org/10.1115/1.2833864.
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Designing a reliable sub-25 nm spacing head/disk interface for today’s magnetic hard disk drives demands a greater dynamic stability and a smaller spacing modulation. An air bearing dynamic simulator with multiple features is developed to investigate the dynamic characteristics of three shaped-rail negative pressure sub-25 nm fly height sliders. Various simulations including air bearing stiffness, impulse response, surface roughness induced spacing modulation, bump response, and track seeking dynamics are performed. The results indicate that the roughness induced spacing modulation decreases with the increase of the air bearing stiffness and the decrease of the slider size. The suspension dynamics is integrated into the air bearing dynamics simulation for the track accessing motion by modal analysis. It is concluded that the fly height modulation during a track accessing event is attributed to many factors such as the effective skew angle, the seeking velocity, and the roll motion caused by the inertia of the moving head. The extent of the roll motion effect depends on the air bearing roll stiffness and the level of the inertia force of the moving head. Larger roll stiffness and smaller inertia force produce a smoother track accessing performance.
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Mbengue, Cheikh, and Tapio Schneider. "Storm Track Shifts under Climate Change: What Can Be Learned from Large-Scale Dry Dynamics." Journal of Climate 26, no. 24 (2013): 9923–30. http://dx.doi.org/10.1175/jcli-d-13-00404.1.
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Abstract Earth’s storm tracks are instrumental for transporting heat, momentum, and moisture and thus strongly influence the surface climate. Climate models, supported by a growing body of observational data, have demonstrated that storm tracks shift poleward as the climate warms. But the dynamical mechanisms responsible for this shift remain unclear. To isolate what portion of the storm track shift may be accounted for by large-scale dry dynamics alone, disregarding the latent heat released in phase changes of water, this study investigates the storm track shift under various kinds of climate change in an idealized dry general circulation model (GCM) with an adjustable but constant convective stability. It is found that increasing the mean surface temperature or the convective stability leads to poleward shifts of storm tracks, even if the convective stability is increased only in a narrow band around the equator. Under warming and convective stability changes roughly corresponding to a doubling of CO2 concentrations from a present-day Earthlike climate, storm tracks shift about 0.8° poleward, somewhat less than but in qualitative agreement with studies using moist GCMs. About 63% (0.5°) of the poleward shift is shown to be caused by tropical convective stability variations. This demonstrates that tropical processes alone (the increased dry static stability of a warmer moist adiabat) can account for part of the poleward shift of storm tracks under global warming. This poleward shift generally occurs in tandem with a poleward expansion of the Hadley circulation; however, the Hadley circulation expansion does not always parallel the storm track shift.
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Yang, Jianjin, Shengyang Zhu, and Wanming Zhai. "Modeling Slab Track for Vehicle –Track-Coupled Dynamics Analysis Using Spline Function Method." International Journal of Structural Stability and Dynamics 20, no. 02 (2020): 2050026. http://dx.doi.org/10.1142/s0219455420500261.
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This paper presents a new approach for modeling the slab tracks by using the spline function to derive an element that is capable of describing the vertical motions of the entire slab. The accuracy and advantages of the method are verified through comparison with the finite element method (FEM) by the frequency response analysis for the CRTS-III slab track system. With this, a three-dimensional train–slab track-coupled dynamic (TSTCD) model is developed and solved by a hybrid explicit–implicit time integration method. Finally, the characteristics and feasibility of the developed TSTCD model are demonstrated through two typical case studies together with the comparison made for verifications. The results indicate that the proposed method provides an alternative approach for modeling the slabs, by simplifying the modeling process and decreasing the computational time without losing accuracy, with respect to the FEM. Besides, the modes of the slab appear many dips and peaks above the first resonant frequency, leading to complicated frequency responses of the CRTS-III slab. Moreover, the developed TSTCD model is not only feasible, but also capable of describing the slab vibrations at medium-high frequencies.
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ElMaraghy, W. H., and R. V. Dukkipati. "LATERAL STABILITY ANALYSIS OF A RAILWAY TRUCK ON ROLLER RIG." Transactions of the Canadian Society for Mechanical Engineering 21, no. 3 (1997): 317–26. http://dx.doi.org/10.1139/tcsme-1997-0015.
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Generic linear models were developed of a freight car (with a characteristic North American three-piece truck) on tangent track. The models were developed using the generalized multi-body dynamics software MEDYNA. Predictions were made of the theoretical linear model hunting (lateral stability) characteristics of the freight car, i.e., the critical speeds and frequencies, for five different configurations: (a) freight car on track, (b) the freight car’s front truck on the roller stand and its rear truck on track, (c) freight car on the roller rig, (d) a single truck on track and (e) single truck on the roller stand. These were compared with the Association of American Railroads’ field test data for an 80-ton hopper car equipped with A-3 ride control trucks. Agreement was reached among all the analytical models, with all models indicating a range of hunting speeds of 2% from the highest to lowest. The largest discrepancy, approximately 8%, was indicated between the models and the field test data.
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Balekwa, Bingo Masiza, and Daramy Vandi Von Kallon. "Correlation of Short Pitch Rail Corrugation with Railway Wheel-Track Resonance at Low Frequencies of Excitation." Vibration 3, no. 4 (2020): 491–520. http://dx.doi.org/10.3390/vibration3040031.
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As much as there has been a significant increase in the development of railway systems in recent years, one of the significant drawbacks on this mode of transport is ground-borne vibrations and noise emanating from vehicle-track interaction in service. This greatly affects the ecology and physical surroundings of the railway track. Experimental tests and Finite Element modal and complex eigenvalue analysis are conducted to investigate the dynamics of a traction wheelset and rail track. This is done to establish the correlation between the short pitch rail corrugation in the Belfast to Steelpoort railway line, in the Limpopo Province of South Africa, with railway wheel-tract resonance at low frequencies of excitation. A 3D Finite Element Method (FEM) and complex eigenvalue analysis are used to validate the resonance modes of the wheelset and rail track obtained through experimental modal analysis. Mode shapes are determined for natural frequencies that match the excitation frequency induced by short pitch rail corrugation. The results show that based on average train speeds around track curves, the excitation frequency induced by corrugation matches (quite reasonably) natural frequencies of the wheelset. Whilst the wheelset FEM results are in better agreement, they rather prove the correlation to occur at 100 Hz. In a previous study by the authors, at the average speeds per track curve, the corrugation excitation frequency was found to be 108 Hz. The current study goes further by investigating natural frequencies of rail tracks. Moreover, mode shapes of a traction wheelset and rail tracks are also investigated, and the results are presented herein.
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Zhi-Chen, Wang, Song Ying, and Wang Jian-Xi. "Relation Between Track Irregularity of Speed-Increased Railway and Dynamic Speed Limits Through Simulation." Open Mechanical Engineering Journal 8, no. 1 (2014): 197–200. http://dx.doi.org/10.2174/1874155x01408010197.
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Based on the vehicle-track coupled dynamics theory and the corresponding simulation software ADAMS/Rail software package, a vehicle-track coupling system model is established, and the track irregularity is introduced to the coupling system model as an excitation source. Firstly, the dynamic responses of speed-increased railway vehicle and track components due to different types of track irregularity are obtained. Secondly, the sensitive wavelength of different track irregularities in high-speed operation is discussed. Finally, suggestions about the maximum operation speed to meet the standards value of daily maintenance target, comfortable value, emergency repair and speed management target are put forward.
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Sankar, S., A. Dhir, and V. S. Shankhla. "Simulation and Field Testing of Tracked Vehicle Suspension Dynamics." Journal of Dynamic Systems, Measurement, and Control 116, no. 4 (1994): 764–73. http://dx.doi.org/10.1115/1.2899276.
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A nonlinear, in-plane ride dynamic simulation model of a typical off-road tracked vehicle is developed assuming constant forward vehicle speed and nondeformable terrain surface. The ride model includes nonlinear suspension characteristics, wheel/track-terrain interactions, and dynamic track loads. An equivalent damper and continuous radial spring formulation is employed to model wheel/track-terrain interactions, whereas dynamic track loads are modeled in view of track belt stretching and initial track tension. Typical simulation results are presented for a conventional armoured personnel carrier traversing discrete half round obstacles, and a random course, and are validated against field measurements. The predicted ride responses exhibit generally good agreement with field test data.
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Zhou, Ming Xing, Yun Peng Ren, Long Ye, Yu Zhou, and Guo Qiang Wang. "Discussion of Track Tension for Heavy Tracked Vehicles." Advanced Materials Research 813 (September 2013): 30–33. http://dx.doi.org/10.4028/www.scientific.net/amr.813.30.
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This paper aims at getting a way to obtain the suitable track tension by analyzing a heavy tracked vehicles driving prototype which is consisted of the sprocket and the meshing tracks. First, by analyzing the force state in the driving part in the multi-body dynamics simulation tool: RecurDyn, a critical condition to judge the peel-off of tracks in heavy tracked vehicle is proposed. Second, by comparing the different models built in RecurDyn, an ideal track distribution around the sprocket is obtained and also the relationship between the driving torque and the track tension under that ideal situation is concluded. Third, basing on the data from the simulation, the force state of each track meshed with the sprocket is analyzed, and an assumption about the proportion between each tracks upper and bottom pulling force is proposed.
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Wang, Ping, Hao Xu, and Rong Chen. "Effect of Cement Asphalt Mortar Debonding on Dynamic Properties of CRTS II Slab Ballastless Track." Advances in Materials Science and Engineering 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/193128.
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The debonding of cement emulsified asphalt mortar (CA mortar) is one of the main damage types in China railway track system II slab ballastless track. In order to analyze the influence of mortar debonding on the dynamic properties of CRTS II slab ballastless track, a vertical coupling vibration model for a vehicle-track-subgrade system was established on the base of wheel/rail coupling dynamics theory. The effects of different debonding lengths on dynamic response of vehicle and track system were analyzed by using the finite element software. The results show that the debonding of CA mortar layer will increase the dynamic response of track. If the length of debonding exceeds 1.95 m, the inflection point will appear on the vertical displacement curve of track. The vertical vibration acceleration of slab increases 4.95 times and the vertical dynamic compressive stress of CA mortar near the debonding region increases 15 times when the debonding length reaches 3.9 m. Considering the durability of ballastless track, once the length of debonding reaches 1.95 m, the mortar debonding should be repaired.
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Ungermann, J., L. Hoffmann, P. Preusse, M. Kaufmann, and M. Riese. "Tomographic retrieval approach for mesoscale gravity wave observations by the PREMIER Infrared Limb-Sounder." Atmospheric Measurement Techniques Discussions 2, no. 5 (2009): 2809–50. http://dx.doi.org/10.5194/amtd-2-2809-2009.
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Abstract. PREMIER is one of three candidates for ESA's 7th Earth Explorer mission that are currently undergoing feasibility studies. The main mission objective is to quantify processes controlling atmospheric composition in the mid/upper troposphere and lower stratosphere, a region of particular importance for climate change. To achieve this objective, PREMIER will employ the first satellite Fourier transform infrared limb-imager combined with a millimetre-wave limb-sounder. The infrared limb-imager can be operated in a high spatial resolution mode ("dynamics mode") for observations of small-scale structures in atmospheric temperatures and trace gas fields with unprecedented 3-D sampling (0.5 km in the vertical direction, 50 km along track, 25 km across track). In this paper, a fast tomographic retrieval scheme is presented, which is designed to fully exploit the high-resolution radiance observations of the dynamics mode. Based on a detailed analysis of the "observational filter", we show that the dynamics mode provides unique information on global distributions of gravity waves (GW). The achievable vertical resolution for GW observations has values between the vertical sampling (0.5 km) of the dynamics mode and the vertical field of view (about 0.75 km). The horizontal across track resolution corresponds to the horizontal across track sampling of 25 km. Since the achievable along track horizontal resolution is about 70 km, the dynamics mode will provide, for the first time, GW limb-observations with a horizontal resolution comparable to nadir sounders. Compared to previous observations, PREMIER will therefore considerably extend the range of detectable GWs in terms of horizontal and vertical wavelength.
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Cai, Xiao-pei, Qi-hao Wang, Da-cheng Li, and Yan-ke Liang. "Theoretical study of long elastic sleeper track to reduce vibrations induced by subway trains." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, no. 5 (2019): 538–49. http://dx.doi.org/10.1177/0954409719848598.
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Long elastic sleeper track (LEST) is a medium vibration reduction track, which is gradually used in urban rail transit in recent years. In order to analyze the structure of LEST used in subways and to study the dynamic effect of the elastic cushion stiffness and vehicle speed, a dynamic model of the vehicle–track–tunnel–soil coupling system was established based on the finite element method and vehicle–track interaction dynamics theory. The results show the following: (1) LEST is more advantageous in vibration reduction performance compared with the common slab track and the low vibration track under the same track stiffness, and LEST also has better integrity and stability than the low vibration track; (2) The lower the cushion stiffness is, the smaller the accelerations of the tunnel wall are, but the dynamic displacements of the track rise in time domain. Considering the dynamic displacements and accelerations, the cushion stiffness is recommended to be 20–30 kN/mm. (3) High vehicle speed has a detrimental effect on the dynamic response, especially the accelerations of track. It is necessary to pay more attention to vibration when the vehicle speed exceeds 100 km/h in the subway if LEST is used.
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Liang, Gao, Ke Ming Yin, and Ge Yan Zhang. "Study on Dynamics Characteristics of Concrete Floating Slab Track in Urban Track." Key Engineering Materials 302-303 (January 2006): 700–705. http://dx.doi.org/10.4028/www.scientific.net/kem.302-303.700.
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In this paper, in order to do research on the characteristics of reducing vibration and declining noise of concrete floating slab track, the vertical dynamic analysis model of vehiclefloating slab track is established with the use of finite element analyses method. By using this model, dynamic responses of floating slab track are studied under different conditions of train’s speed, stiffness and damping of infrastructure, structure size, etc. On the basis of this research, some suggestions for design of floating slab track are put forward.
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Xu, Lei, Wanming Zhai, and Jianmin Gao. "A probabilistic model for track random irregularities in vehicle/track coupled dynamics." Applied Mathematical Modelling 51 (November 2017): 145–58. http://dx.doi.org/10.1016/j.apm.2017.06.027.
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Dhir, A., and S. Sankar. "Dynamics of off-Road Tracked Vehicles Equipped with Trailing Arm Suspension." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 209, no. 3 (1995): 195–215. http://dx.doi.org/10.1243/pime_proc_1995_209_204_02.
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A two-dimensional computer simulation model is developed for dynamic analysis of high-mobility tracked vehicles fitted with a trailing arm suspension system. The simulation model is oriented as a design tool for detailed analysis of vehicle suspension dynamics and ride quality assessment. The Lagrangian model formulation of a tracked vehicle is derived by considering a rigid terrain of an arbitrary profile and constant forward vehicle speed. The model incorporates detailed representations of a vehicle suspension system and dynamic wheel-track-terrain interactions. The wheel forces are evaluated based on an adaptive footprint formulation of a wheel/track-terrain contact patch, and the track forces are modelled based on kinematic considerations. The computer model predictions are validated against field measurements, which were gathered from an extensive field testing of an in-service armoured personnel carrier. The comparison between measured and simulated dynamic responses exhibits a fairly close correlation.
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Lin, Yuh-Lang, Nicholas C. Witcraft, and Ying-Hwa Kuo. "Dynamics of Track Deflection Associated with the Passage of Tropical Cyclones over a Mesoscale Mountain." Monthly Weather Review 134, no. 12 (2006): 3509–38. http://dx.doi.org/10.1175/mwr3263.1.
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Abstract In this study, the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5) was used to simulate Supertyphoon Bilis (in 2000) and Typhoon Toraji (in 2001) in order to investigate the dynamics of track deflection caused by the Central Mountain Range (CMR) of Taiwan. The MM5 predicted the track of each storm reasonably well. Bilis was stronger and had a relatively faster forward motion, which helped make the track continuous as it crossed the CMR. The use of a “bogus” vortex in the initialization process helped produce a storm closer to the observed strength. Bilis is a classic example of a typhoon crossing Taiwan with a continuous track. For comparison, Typhoon Toraji, a typical typhoon having a discontinuous track, was also studied. Toraji was weaker and had a relatively slower forward speed, which prevented the original low center from crossing over the CMR and forced more air parcels to go around the northern tip of the CMR. As a result, it produced a vortex and a secondary low center on the lee. Potential vorticity banners on the north side of the CMR acted to organize the secondary low and the lee vortex. With time, the low-level circulation extended into the upper levels, completing the formation of the secondary center. Remnants of the initial center crossed over the CMR and were entrained into the secondary center. Nondimensional control parameters for track continuity and deflection from idealized studies are calculated for Bilis and Toraji. The results are consistent with the theory proposed in Lin et al. For tropical cyclones (TCs) approaching Taiwan from the southeast, the conceptual model proposed by Lin et al. for continuous and discontinuous tracks was applied. For continuous tracks over the CMR, the blocking effect on the outer circulation of the vortex is weak and the vorticity advection around the northern tip is strong due to an intense TC. Weak TCs tend to be totally blocked by the CMR.
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Auersch, Lutz, and Samir Said. "Track-soil dynamics – Calculation and measurement of damaged and repaired slab tracks." Transportation Geotechnics 12 (September 2017): 1–14. http://dx.doi.org/10.1016/j.trgeo.2017.06.003.
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