scholarly journals Analytical model of skip motion taking into account influence of head and balancing ropes

2021 ◽  
pp. 105-113
Author(s):  
Mikhail A. Zhuravkov ◽  
Vladimir P. Savchuk ◽  
Michael A. Nikolaitchik
Keyword(s):  
Analytical Model ◽  
Vertical Acceleration ◽  
Principal Moment ◽  
Natural Vibrations ◽  
Principal Vector ◽  
Vertical Speed ◽  
Vertical Vibrations

The article describes an analytical model of mine skip dynamics taking into account the presence of the head and balancing ropes and the existing curvilinearity of the guides. Expressions for the forces acting on the skip from the side of the guides have been constructed. It is shown, that the frequencies of natural vibrations of skip depend on the vertical acceleration and the distance traveled during its lifting. A graph (diagram) of skips vertical speed which observance does not lead to the appearance of skips vertical vibrations due to elasticity of the ropes is developed. An algorithm for finding the forces principal vector and the forces principal moment acting on the skip based on the reading of three accelerometers recording horizontal accelerations of skip during its movement is presented.

scholarly journals The coupled effects of bending and torsional flexural modes of a high-speed train car body on its vertical ride quality

2019 ◽  
Vol 233 (4) ◽  
pp. 979-993 ◽  
Author(s):  
Vahid Bokaeian ◽  
Mohammad A Rezvani ◽  
Robert Arcos
Keyword(s):  
Analytical Model ◽  
Quality Index ◽  
High Speed ◽  
Ride Quality ◽  
Vertical Acceleration ◽  
Beam Model ◽  
High Speed Train ◽  
Flexural Mode ◽  
Car Body ◽  
Rail Irregularities

This study is focused on the effects of bending and torsional flexural modes of the car body on the ride quality index of a high-speed train vehicle. The Euler–Bernoulli beam model is used to extract an analytical model for a high-speed train vehicle car body in order to investigate its bending and torsional flexural vibrations. The rigid model includes a car body, two bogie frames, and four wheelsets such that, each mass has three degrees of freedom including vertical displacement, pitch motion, and roll motion. The results obtained with the proposed analytical model are compared with experimental measurements of the car body response of a Shinkansen high-speed train. Moreover, it is determined that the bending and torsional flexural modes have significant effects on the vertical acceleration of the car body, particularly in the 9–15 Hz frequency range. Furthermore, the ride quality index is calculated according to the EN 12299 standard and it is shown that the faster the train the more affected is the ride quality by the flexural modes. In addition, the effect of coherence between two rail irregularities (the right and the left rails) on the results of the simulation is investigated. The results conclude that if the irregularities are completely correlated the torsional flexural mode of the car body does not appear in the response. Also, the first bending flexural mode in such cases is more excited compared with the partially correlated or uncorrelated rail irregularities. Therefore, the ride quality index in completely correlated cases is higher than other cases.

scholarly journals Effect of the Anti-Yaw Damper on Carbody Vertical Vibration and Ride Comfort of Railway Vehicle

2020 ◽  
Vol 10 (22) ◽  
pp. 8167
Author(s):  
Mădălina Dumitriu ◽  
Dragoș Ionuț Stănică
Keyword(s):  
Ride Comfort ◽  
Vertical Vibration ◽  
Theoretical Research ◽  
Railway Vehicle ◽  
Vertical Acceleration ◽  
Damping Force ◽  
Comfort Index ◽  
Lateral Vibrations ◽  
Power Spectral ◽  
Vertical Vibrations

The theoretical research on means to reduce the vertical vibrations and improve the ride comfort of the railway vehicle relies on a mechanical model obtained from the simplified representation of the vehicle, while considering the important factors and elements affecting the vibration behaviour of the carbody. One of these elements is the anti-yaw damper, mounted longitudinally, between the bogie and the vehicle carbody. The anti-yaw damper reduces the lateral vibrations and inhibits the yaw motion of the vehicle, a reason for which this element is not usually introduced in the vehicle model when studying the vertical vibrations. Nevertheless, due to the position of the clamping points of the anti-yaw damper onto the carbody and the bogie, the damping force is generated not only in the yawing direction but also in the vertical and longitudinal directions. These forces act upon the vehicle carbody, impacting its vertical vibration behaviour. The paper analyzes the effect of the anti-winding damper on the vertical vibrations of the railway vehicle carbody and the ride comfort, based on the results derived from the numerical simulations. They highlight the influence of the damping, stiffness and the damper mounting angle on the power spectral density of the carbody vertical acceleration and the ride comfort index.

scholarly journals Vertical vibrations of composite bridge/track structure/high-speed train systems. Part 3: Deterministic and random vibrations of exemplary system

2014 ◽  
Vol 62 (2) ◽  
pp. 305-320 ◽  
Author(s):  
M. Podworna ◽  
M. Klasztorny
Keyword(s):  
High Speed ◽  
Extreme Values ◽  
Track Structure ◽  
Vertical Acceleration ◽  
Computer Algorithms ◽  
High Speed Train ◽  
Random Factor ◽  
Static And Dynamic Analysis ◽  
Time Histories ◽  
Vertical Vibrations

Abstract Based on the one-dimensional quasi-exact physical and mathematical modelling of a composite (steel-concrete) bridge/track structure/high-speed train system (BTT), developed in Part 2, advanced computer algorithms for the BTT numerical modelling and simulation as well as a computer programme to simulate vertical vibrations of BTT systems are developed. The exemplary bridge under numerical quasi-static and dynamic analysis, designed according to Polish standards, has a 15.00 m span length and belongs to the SCB series-of-types developed in Part 1. The bridge is loaded by a German ICE-3 high-speed train moving at the resonant and maximum operating speeds. A continuously welded ballasted track structure adapted to high operating velocities is applied. The output quantities include: time-histories of the vertical deflection of the main beams at the midspan, time-histories of the longitudinal normal stress in the bottom fibres of the main beams at the midspan, time-histories of the vertical acceleration of the bridge deck at the midspan, time-histories of the vertical accelerations of the suspension pivots in car-bodies, time-histories of the dynamic pressures of the wheel sets of moving rail-vehicles. The design quantities, understood as the extreme values of the output quantities, are used to verify the design conditions. The basic random factor, i.e. vertical track irregularities of the track, is taken into consideration. Basic statistics of the design quantities treated as random variables are calculated and taken into account in the design conditions.

Numerical Simulation Research on Earthquake Induced Dynamic Responses of Underground Tunnel

2011 ◽  
Vol 90-93 ◽  
pp. 1931-1935
Author(s):  
Shi Tan Gu ◽  
Chun Qiu Wang ◽  
Chun Zhao Xu ◽  
Feng Hai Yu
Keyword(s):  
Vertical Direction ◽  
Time History ◽  
Dynamic Responses ◽  
Vertical Acceleration ◽  
Simulation Research ◽  
Acceleration Time ◽  
Acceleration Time History ◽  
Tunnel Floor ◽  
Vertical Speed ◽  
History Of

A number of nodes at different strata positions of tunnel roof were selected as research objects, the law between the roof deformation and the speed or acceleration time-history of horizontal and vertical direction were simulated on conditions of inputting earthquake wave at particular lacation of deep tunnel floor. With the gradually increasing distance from tunnel top surface, the “high -low-high” law of peak values were performed in speed time-history and acceleration speed time-history curves. One peak value was overally performed on vertical speed time-history curves, but multiple peak fluctuation was indicated in vertical acceleration time-history, horizontal speed and horizontal accelaration time-history curves.

scholarly journals Optimisation of Transition Areas between Ballastless Track and Ballasted Track in the Area of the Tunnel Turecky Vrch

2018 ◽  
Vol 20 (3) ◽  
pp. 67-76
Author(s):  
Libor Izvolt ◽  
Jozef Harusinec ◽  
Michal Smalo
Keyword(s):  
Slovak Republic ◽  
Vertical Displacement ◽  
Vertical Acceleration ◽  
Track Geometry ◽  
Ballastless Track ◽  
Current State ◽  
Railway Infrastructure ◽  
Vertical Speed ◽  
The University ◽  
Transition Areas

The paper follows previously published papers in Communications – Scientific Letters of the University of Zilina No. 4/2014, No. 4/2015 and No. 4/2016, where were presented the results of the diagnostics of the track geometry of the experimental sections surrounding the portals of a new building of the Tunnel Turecky vrch. Based on the data obtained by comprehensive diagnostics, there can be stated that the problematic section in the slab track are the transition areas allowing the transfer of the vehicle between the line structures with a different bending stiffness. The comprehensive diagnostics was realised by the continuous method (measuring trolley KRAB), the results of which were verified by the results of the measuring car of ZSR and by the geodetic monitoring of the layout of the track, as well. Mathematical modelling of the transition areas was realized in the environment of the software ANSYS with the aim to optimise the structural solution of the existing transition areas, as well as of in the future built ones, within the modernization of the railway infrastructure of the Slovak Republic. The model of the existing transition area was structurally optimised –models were realised with application of the stiffening rails and with usage of the under sleeper pads. The model of the current state and the models of the optimised structural solutions of the transition areas were subsequently compared by the values of the vertical displacement, vertical speed and vertical acceleration.

scholarly journals Analytical and numerical investigation of nonlinear internal gravity waves

2001 ◽  
Vol 8 (1/2) ◽  
pp. 37-53 ◽  
Author(s):  
S. P. Kshevetskii
Keyword(s):  
Internal Wave ◽  
Analytical Model ◽  
Internal Waves ◽  
Numerical Models ◽  
Wave Mode ◽  
Vertical Acceleration ◽  
Quasistatic Problem ◽  
Wave Simulation ◽  
Non Linear

Abstract. The propagation of long, weakly nonlinear internal waves in a stratified gas is studied. Hydrodynamic equations for an ideal fluid with the perfect gas law describe the atmospheric gas behaviour. If we neglect the term Ͽ dw/dt (product of the density and vertical acceleration), we come to a so-called quasistatic model, while we name the full hydro-dynamic model as a nonquasistatic one. Both quasistatic and nonquasistatic models are used for wave simulation and the models are compared among themselves. It is shown that a smooth classical solution of a nonlinear quasistatic problem does not exist for all t because a gradient catastrophe of non-linear internal waves occurs. To overcome this difficulty, we search for the solution of the quasistatic problem in terms of a generalised function theory as a limit of special regularised equations containing some additional dissipation term when the dissipation factor vanishes. It is shown that such solutions of the quasistatic problem qualitatively differ from solutions of a nonquasistatic nature. It is explained by the fact that in a nonquasistatic model the vertical acceleration term plays the role of a regularizator with respect to a quasistatic model, while the solution qualitatively depends on the regularizator used. The numerical models are compared with some analytical results. Within the framework of the analytical model, any internal wave is described as a system of wave modes; each wave mode interacts with others due to equation non-linearity. In the principal order of a perturbation theory, each wave mode is described by some equation of a KdV type. The analytical model reveals that, in a nonquasistatic model, an internal wave should disintegrate into solitons. The time of wave disintegration into solitons, the scales and amount of solitons generated are important characteristics of the non-linear process; they are found with the help of analytical and numerical investigations. Satisfactory coincidence of simulation outcomes with analytical ones is revealed and some examples of numerical simulations illustrating wave disintegration into solitons are given. The phenomenon of internal wave mixing is considered and is explained from the point of view of the results obtained. The numerical methods for internal wave simulation are examined. In particular, the influence of difference interval finiteness on a numerical solution is investigated. It is revealed that a numerical viscosity and numerical dispersion can play the role of regularizators to a nonlinear quasistatic problem. To avoid this effect, the grid steps should be taken less than some threshold values found theoretically.

scholarly journals Influence of Bending Vibration on the Vertical Vibration Behaviour of Railway Vehicles Carbody

2021 ◽  
Vol 11 (18) ◽  
pp. 8502
Author(s):  
Mădălina Dumitriu ◽  
Ioana Izabela Dihoru
Keyword(s):  
Ride Comfort ◽  
Reference Points ◽  
Structural Vibration ◽  
Railway Vehicle ◽  
Type Model ◽  
Vertical Acceleration ◽  
Bending Vibration ◽  
Railway Vehicles ◽  
Bending Mode ◽  
Vertical Vibrations

The topic of reducing structural vibrations in the case of flexible carbodies of railway vehicles has been intensively studied, but it is still an active research topic thanks to the importance of the perspective of improving the ride comfort. However, no study has been identified in the specialty literature to feature the contribution of the vibration structural modes upon the vibration behaviour of the railway vehicle carbody. The structural vibration modes of the flexible carbodies are particularly complex; however, the first vertical bending mode holds great significance in terms of the ride comfort. This paper analyses the influence of the first vertical bending mode on the vibration behaviour in three reference points of the railway vehicle carbody in correlation with the carbody flexibility, the vehicle velocity and the suspension damping. This study relies on comparisons between the results of the numerical simulations obtained for a ‘flexible carbody’ type model of the vehicle and the ones obtained for a ‘rigid carbody’ type model. The first part of this study analyses the characteristics of the vertical vibrations behaviour of the flexible carbody based on the dynamic response of the vehicle and expressed as the acceleration power spectral density. In the second part, the influence of the vertical bending on the vertical vibrations level of the carbody is analysed using the root mean square of the vertical acceleration.

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