scholarly journals Analysis of the Vibration Mitigation Characteristics of the Ballasted Ladder Track with Elastic Elements

2019 ◽  
Vol 11 (23) ◽  
pp. 6780 ◽  
Author(s):  
Xiangyu Qu ◽  
Meng Ma ◽  
Minghang Li ◽  
Yanmei Cao ◽  
Weining Liu
Keyword(s):  
Fem Analysis ◽  
Vibration Mitigation ◽  
Low Frequencies ◽  
Environmental Consequence ◽  
Ballasted Track ◽  
Body Dynamics ◽  
Vibration Attenuation ◽  
Multi Body ◽  
Moving Train ◽  
Elastic Elements

Despite the fact railways are seen as an environmentally friendly and sustainable form of transport, however, the train-induced vibration has been seen as a negative environmental consequence. The ballasted ladder track is one type of ballasted track with longitudinal sleepers. The elastic elements can not only protect the track structure but also control the vibration. To investigate the vibration mitigation effects of ballasted ladder track with elastic elements, a finite element - infinite element (FE-IFE) model was built considering the elastic elements of under-sleeper pads (USPs) and under-ballast mats (UBMs). This model was validated by a laboratory test. Then, the moving train load was obtained based on the multi-body dynamics (MBD)-finite elements method (FEM) analysis. The vibration mitigation effects of the ballasted ladder track with different types of elastic elements were calculated compared with the ballasted tracks without elastic elements. The results indicate that: (1) the ballasted ladder track has the advantage of vibration reduction at low frequencies, with a maximum vibration attenuation of 25.2 dB and an averaged vibration attenuation of 19.0 dB between 5 and 20 Hz through the ballast. (2) The ballasted ladder track with USPs or UBMs can provide better vibration attenuation between 30 and 100 Hz, but it induces a vibration amplification between 5 and 30 Hz. (3) The ballasted ladder track with elastic elements in different cases can provide different vibration mitigation effects. The ballasted ladder track with both USPs and UBMs can provide the best mitigation effect with an average vibration mitigation of approximately 15 dB and a maximum vibration mitigation of 30 dB between 30 and 100 Hz.

Safety of a high-speed train passing by a windbreak breach under different wind speeds

2021 ◽  
pp. 095440972110460
Author(s):  
Zhuang Sun ◽  
Syeda Anam Hashmi ◽  
Huanyun Dai ◽  
Guiyu Li
Keyword(s):  
High Speed ◽  
Navier Stokes ◽  
Windward Side ◽  
High Speed Train ◽  
Wind Speeds ◽  
Pressure Fields ◽  
Body Dynamics ◽  
Multi Body ◽  
Yaw Angle ◽  
Moving Train

A derailment phenomenon could take place on the windward side of a 120 km/h high-speed train when it runs by a breach, between two windbreak walls, subjected to a normal wind speed of 32 m/s. To study the safety of a high-speed train under different normal speeds of crosswind, six wind speeds are investigated; 32 m/s, 28 m/s, 25 m/s, 20 m/s, 15 m/s, and 10 m/s. The wind forces and moments of the moving train are calculated using the Unsteady Reynolds-averaged Navier-Stokes (URANS) model, which are then applied to the train multi-body dynamics. The pressure fields around the train passing by the breach are analysed, which gives a reasonable explanation for the fluctuation of the wind loads. After an analysis on the response of the train, it is apparent that the risk of derailment on the windward side is much greater than the risk of overturning. The lateral distance of the first wheelset increases towards the windward side as along with the yaw angle of the wheelset, which increases as well with wind speeds of higher than 20 m/s.

Locomotive Underactuated Implement Guided via Elastic Elements (L.U.I.G.E.E): A Preliminary Design

2015 ◽  
Author(s):  
Thomas Reilly ◽  
Jerome K. O’Rourke ◽  
Daniel Steudler ◽  
Davide Piovesan ◽  
Roberto Bortoletto
Keyword(s):  
Human Body ◽  
Equilibrium Position ◽  
Simulation Software ◽  
Dynamics Simulation ◽  
Original Position ◽  
Preliminary Design ◽  
Top Down ◽  
Body Dynamics ◽  
Multi Body ◽  
Elastic Elements

This paper presents the simulation and fabrication of a bipedal humanoid system actuated with linear springs to produce a standing equilibrium position. The humanoid system is comprised of two leg assemblies connected by a hip bracket. Eleven pairs of springs were attached to the system in locations designed to simulate the muscles and tendons in a human body. The assembly was modeled in the multi-body dynamics simulation software SimWise 4D. Simulations were performed to determine the springs’ stiffness and natural lengths using a top-down heuristic approach. After a set of springs were found to produce a good simulated stable position, they were cross referenced to standard commercially-available parts. A final simulation was then performed to verify that the real-world spring values produced a stable system. Working in tandem with SimWise 4D, the humanoid assembly was fabricated using PLA plastic via an extrusion-type rapid prototyping machine. From the results of the simulation, the set of working springs were implemented onto the plastic model. After final modifications, the assembly then produced a standing equilibrium position. Finally, the assembly was perturbed in several directions to ensure that after the system experienced a displacement it would then return to its original position.

scholarly journals An investigation of sleeper voids using a flexible track model integrated with railway multi-body dynamics

2009 ◽  
Vol 223 (6) ◽  
pp. 597-607 ◽  
Author(s):  
Y Bezin ◽  
S D Iwnicki ◽  
M Cavalletti ◽  
E de Vries ◽  
F Shahzad ◽  
...  
Keyword(s):  
Vehicle Dynamics ◽  
Railway Vehicle ◽  
Detailed Calculation ◽  
Track System ◽  
Ballasted Track ◽  
Body Dynamics ◽  
Flexible Track ◽  
The Uk ◽  
Multi Body ◽  
The Impact

This article describes a flexible track system model (FTSM) that represents the track structure for a typical ballasted track, taking into account the flexibility of the rails, the sleeper mass and the resilience of the pad/fastening elements, as well as the ballast support stiffness condition. The detailed track model is integrated into a commercial railway vehicle dynamics software, thus allowing for any vehicle to be simulated onto the flexible track while at the same time taking into account the detailed calculation of the non-linear wheel—rail contact interaction. As an example, the application of the FTSM to the study of hanging sleepers, with respect to the UK Railway Group Standard limits, is presented. This example shows the impact of forces because of hanging sleepers on the vehicle and on the track, and attempts at quantifying the damage made to the track components for the specific conditions simulated.

scholarly journals Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics

2012 ◽  
Vol 8 (4) ◽  
pp. 660-664 ◽  
Author(s):  
K. T. Bates ◽  
P. L. Falkingham
Keyword(s):  
Body Size ◽  
Feeding Behaviour ◽  
Ontogenetic Change ◽  
Positive Allometry ◽  
Musculoskeletal Models ◽  
Terrestrial Animal ◽  
Body Dynamics ◽  
Mode Of Life ◽  
Scaling Analyses ◽  
Multi Body

Bite mechanics and feeding behaviour in Tyrannosaurus rex are controversial. Some contend that a modest bite mechanically limited T. rex to scavenging, while others argue that high bite forces facilitated a predatory mode of life. We use dynamic musculoskeletal models to simulate maximal biting in T. rex . Models predict that adult T. rex generated sustained bite forces of 35 000–57 000 N at a single posterior tooth, by far the highest bite forces estimated for any terrestrial animal. Scaling analyses suggest that adult T. rex had a strong bite for its body size, and that bite performance increased allometrically during ontogeny. Positive allometry in bite performance during growth may have facilitated an ontogenetic change in feeding behaviour in T. rex , associated with an expansion of prey range in adults to include the largest contemporaneous animals.

Sir Robert Stawell Ball and methodologies of modern screw theory

2002 ◽  
Vol 216 (1) ◽  
pp. 1-11 ◽  
Author(s):  
H Lipkin ◽  
J Duffy
Keyword(s):  
Computational Geometry ◽  
Rigid Body ◽  
Lie Algebra ◽  
Screw Theory ◽  
Mechanical Design ◽  
Ball Screw ◽  
Dual Numbers ◽  
Body Dynamics ◽  
Rigid Body Mechanics ◽  
Multi Body

The theory of screws was largely developed by Sir Robert Stawell Ball over 100 years ago to investigate general problems in rigid body mechanics. Nowadays, screw theory is applied in many different but related forms including dual numbers, Plilcker coordinates and Lie algebra. An overview of these methodologies is presented along with a perspective on Ball. Screw theory has re-emerged after a hiatus to become an important tool in robot mechanics, mechanical design, computational geometry and multi-body dynamics.

Tanker Truck Sloshing Simulation Using Bi-Directionally Coupled CFD and Multi-Body Dynamics Solvers

2014 ◽  
Author(s):  
Michael S. Barton ◽  
David Corson ◽  
John Quigley ◽  
Babak Emami ◽  
Tanuj Kush
Keyword(s):  
Body Dynamics ◽  
Tanker Truck ◽  
Multi Body
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