scholarly journals Evaluating the Effect of Wheel Polygons on Dynamic Track Performance in High-Speed Railway Systems Using Co-Simulation Analysis

2019 ◽  
Vol 9 (19) ◽  
pp. 4165 ◽  
Author(s):  
Song ◽  
Du ◽  
Zhang ◽  
Sun
Keyword(s):  
High Speed ◽  
Ride Comfort ◽  
Concrete Slab ◽  
Equivalent Stress ◽  
Dynamic Responses ◽  
Traffic Density ◽  
Harmonic Order ◽  
High Speed Railway ◽  
Von Mises Equivalent Stress ◽  
Von Mises

With increases in train speed and traffic density, problems due to wheel polygons and those caused by wheel–rail impacts will increase accordingly, which will affect train operational safety and passenger ride comfort. This paper investigates the effects of polygonal wheels on the dynamic performance of the track in a high-speed railway system. The wheel–rail interaction forces caused by wheel polygons are determined using a dynamic vehicle–track model, and the results are entered into a slab track finite element model. The influence of the harmonic order and out-of-roundness (OOR) amplitude of wheel polygons on the transient dynamic characteristics of the track(von Mises equivalent stress, displacement, and acceleration) is examined under high-speed conditions. The results indicate that the vibration acceleration and von Mises equivalent stress of the rail increase in proportion to the harmonic order and the OOR amplitude and velocity of a polygonized wheel. The vibration displacement of the rail first increases and then decreases with a change in the harmonic order, and reaches a maximum at the ninth order. The dynamic responses of the concrete slab layer, cement-asphalt layer, and support layer increase linearly with the harmonic order and amplitude of wheel polygons and decrease from top to bottom. Through a combination of numerical simulations and real-time monitoring of rail vibrations, this study provides guidance on potential sensor locations to identify polygonized wheels before they fail.

Mechanical Properties and Experimental Study of a Composite Polishing Plate during Super-High Polishing

2010 ◽  
Vol 135 ◽  
pp. 337-342
Author(s):  
Li Zhou ◽  
Shu Tao Huang ◽  
Li Fu Xu
Keyword(s):  
Chemical Reaction ◽  
High Speed ◽  
Equivalent Stress ◽  
Stress Distributions ◽  
Centrifugal Forces ◽  
X Ray ◽  
High Speed Rotation ◽  
Speed Rotation ◽  
Von Mises Equivalent Stress ◽  
Von Mises

A new composite polishing plate for polishing of CVD diamond films has been designed. The displacement and stress distributions of the high speed rotation polishing plate have been investigated due to centrifugal forces, and the polishing mechanism of super-high polishing has been analyzed by using X-ray photo-electron spectroscopy. The results showed that the displacements both in axial and radial increase with the increasing of the rotational speed. When the rotation speed reached to 1200 rad/s, the von Mises equivalent stress is about 242 MPa, which is safe for the composite polishing plate. Additional, the polishing mechanism is mainly the chemical reaction between carbon and titanium during the super-high speed polishing. At elevated temperature, the chemical reaction between oxygen and titanium, oxygen and carbon can also occur.

Finite element analysis of the wheel–rail impact behavior induced by a wheel flat for high-speed trains: The influence of strain rate

2017 ◽  
Vol 232 (4) ◽  
pp. 990-1004 ◽  
Author(s):  
Liangliang Han ◽  
Lin Jing ◽  
Longmao Zhao
Keyword(s):  
Shear Stress ◽  
Plastic Strain ◽  
Strain Rate ◽  
High Speed ◽  
Equivalent Stress ◽  
Equivalent Plastic Strain ◽  
Impact Behavior ◽  
Wheel Flat ◽  
Von Mises Equivalent Stress ◽  
Von Mises

The wheel–rail impact response induced by a wheel flat for high-speed trains is simulated numerically, based on the strain rate-dependent constitutive parameters of wheel–rail materials, using the finite element software LS-DYNA explicit algorithm. Influences of the speed of the train, the length of the wheel flat, and axle load on the wheel–rail impact behavior are discussed over a wide range, in terms of the vertical impact force, von Mises equivalent stress, shear stress, and equivalent plastic strain. The maximum wheel–rail impact forces are 2.6–4.4 times greater than the corresponding static axle loads due to the presence of a wheel flat. The maximum von Mises equivalent stress and equivalent plastic strain have occurred on the wheel–rail contact surface, while the maximum xy shear stress has often occurred on the subsurface of 4–6 mm below the contact surface. The wheel–rail impact responses induced by a wheel flat are sensitive to the speed of trains, flat length, and axle load. Besides, the strain rate effect of wheel–rail materials has a significant influence on the maximum von Mises equivalent stress, shear stress, and equivalent plastic strain, while it has no influence on the maximum vertical impact force. These findings are very helpful to guide the maintenance and repair of wheel–rail components in rail transport.

Exact Solution of Radial Displacement and Stress of Rotating Elastic Interference Fits

2013 ◽  
Author(s):  
Sheng Feng ◽  
Haipeng Geng ◽  
Baisong Yang ◽  
Lie Yu ◽  
Lihua Yang ◽  
...  
Keyword(s):  
Exact Solution ◽  
High Speed ◽  
Radial Displacement ◽  
Equivalent Stress ◽  
Elastic Plane ◽  
Stress Theory ◽  
Temperature Changes ◽  
Rotating Speed ◽  
Von Mises Equivalent Stress ◽  
Von Mises

Interference fits, which are widely used in flexible couplings, can transfer large torques while avoiding unbalance. Using the classic elastic plane stress theory, the equations of the rotating interference fits taking into account of the temperature changes are derived, and the exact solution of radial displacement and radial stress, hoop stress and tangential stress of the rotating interference fits are obtained, then taking the interference fits of the coupling for a high speed microturbomachinery as an example, the above solutions are plotted using the numerical method, and also Von Mises equivalent stress is calculated. It is found that there are significantly different for the radial displacements between the two cases of with/without taking into account the change of temperature under two kinds of parameters, one is rotating speed chosen as a parameter and other parameters keeps constant, the other is the inner radius of the shaft and rotating speed chosen as parameters.

An Analysis of Filament Overwound Toroidal Pressure Vessels and Optimum Design of Such Structures

2002 ◽  
Vol 124 (2) ◽  
pp. 215-222 ◽  
Author(s):  
Shuguang Li ◽  
John Cook
Keyword(s):  
Optimum Design ◽  
Equivalent Stress ◽  
Mechanical Damage ◽  
Stress Rupture ◽  
Optimization Procedure ◽  
Pressure Vessels ◽  
Thickness Variation ◽  
Von Mises Equivalent Stress ◽  
Metal Liner ◽  
Von Mises

This paper is concerned with the membrane shell analysis of filament overwound toroidal pressure vessels and optimum design of such pressure vessels using the results of the analysis by means of mathematical nonlinear programming. The nature of the coupling between overwind and linear has been considered based on two extreme idealizations. In the first, the overwind is rigidly coupled with the liner, so that the two deform together in the meridional direction as the vessel dilates. In the second, the overwind is free to slide relative to the linear, but the overall elongations of the two around a meridian are identical. Optimized designs with the two idealizations show only minor differences, and it is concluded that either approximation is satisfactory for the purposes of vessel design. Aspects taken into account are the intrinsic overwind thickness variation arising from the winding process and the effects of fiber pre-tension. Pre-tension can be used not only to defer the onset of yielding, but also to achieve a favorable in-plane stress ratio which minimizes the von Mises equivalent stress in the metal liner. Aramid fibers are the most appropriate fibers to be used for the overwind in this type of application. The quantity of fiber required is determined by both its short-term strength and its long-term stress rupture characteristics. An optimization procedure for the design of such vessels, taking all these factors into account, has been established. The stress distributions in the vessels designed in this way have been examined and discussed through the examples. A design which gives due consideration of possible mechanical damage to the surface of the overwind has also been addressed.

Biomechanical Behavior of All-Ceramic Crowns with Variable Thicknesses of Zirconia Frameworks

2016 ◽  
Vol 835 ◽  
pp. 97-102
Author(s):  
Liliana Porojan ◽  
Florin Topală ◽  
Sorin Porojan
Keyword(s):  
Mechanical Behavior ◽  
Equivalent Stress ◽  
The Finite Element Method ◽  
Static Loads ◽  
Biomechanical Behavior ◽  
All Ceramic ◽  
Ceramic Crowns ◽  
Von Mises Equivalent Stress ◽  
Von Mises ◽  
Posterior Restorations

Zirconia is an extremely successful material for prosthetic restorations, offering attractive mechanical and optical properties. It offers several advantages for posterior restorations because it can withstand physiological posterior forces. The aim of the study was to achieve the influence of zirconia framework thickness on the mechanical behavior of all-ceramic crowns using numerical simulation. For the study a premolar was chosen in order to simulate the mechanical behavior in the components of all-ceramic crowns and teeth structures regarding to the zirconia framework thickness. Maximal Von Mises equivalent stress values were recorded in teeth and restorations. Due to the registered maximal stress values it can be concluded that it is indicated to achieve frameworks of at least 0.5 mm thickness in the premolar area. Regarding stress distribution concentration were observed in the veneer around the contact areas with the antagonists, in the framework under the functional cusp and in the oral part overall and in dentin around and under the marginal line, also oral. The biomechanical behavior of all ceramic crowns under static loads can be investigated by the finite element method.

Dynamic Responses of Bridge–Tunnel Overlapping Structure for High-Speed Railway Under Different Seismic Excitations

2018 ◽  
Vol 37 (1) ◽  
pp. 43-60
Author(s):  
Guangchen Sun ◽  
Jiayou Xie ◽  
Shan He ◽  
Helin Fu ◽  
Xueliang Jiang ◽  
...  
Keyword(s):  
High Speed ◽  
Dynamic Responses ◽  
Seismic Excitations ◽  
High Speed Railway

Dynamic Behavior of FGM Doubly Curved Panel due to Mechanical Loading

2019 ◽  
Vol 950 ◽  
pp. 200-204
Author(s):  
Guang Ping Zou ◽  
Nadiia Dergachova
Keyword(s):  
Mechanical Loading ◽  
Volume Fraction ◽  
Equivalent Stress ◽  
Functionally Graded ◽  
Excitation Mode ◽  
Simply Supported ◽  
Curved Panel ◽  
Von Mises Equivalent Stress ◽  
Von Mises ◽  
Doubly Curved

This study presents the dynamic response analyze of a simply supported and isotropic functionally graded (FG) double curved panel under mechanical loading. The aim of the research was to investigate mechanical behavior in a FGM curved panel due to different excitation mode of dynamic loading. The novelty of this research is an investigation of von Mises equivalent stress distribution in double curved panel due to different excitation mode. Computed results are found to agree well with the results reported in the literature. Moreover, influence of volume fraction of the material is studied.

Analysis on the track quality evolution law of polyurethane-reinforced ballasted track in high-speed railway

2020 ◽  
pp. 095440972097557
Author(s):  
Jie-Ling Xiao ◽  
Pu Jing ◽  
Si-Xin Yu ◽  
Ping Wang
Keyword(s):  
Standard Deviation ◽  
Test Section ◽  
High Speed ◽  
Ride Comfort ◽  
Normal Operation ◽  
High Speed Railway ◽  
Evolution Law ◽  
Ballasted Track ◽  
One Year ◽  
Track Quality

Polyurethane-reinforced ballasted track (PRBT) can improve the integrity of ballasted track structures and satisfy the high-stability requirements of high-speed railways. In this study, the quality evolution law of PRBT structures after being launched into train service was analyzed, and a reference for structural optimization and maintenance operation was provided. The track geometric state of the PRBT test section of a high-speed railway was measured and monitored for nearly one year after it was launched into operation, and the ballastless track of the adjacent section was selected as a reference. The geometric states of the tracks were evaluated and compared using various parameters, including sliding standard deviation, average standard deviation, and track irregularity spectrum density. Results show that the track quality indexes of the test section, which were in operation for nearly one year, were slightly over the limit. Moreover, the fastener can be finely adjusted for the high-value index sections to further improve the ride comfort. The application effect of PRBT in the subgrade fracture zone was good, which could satisfy the requirements of high-quality transportation as well as the normal operation and maintenance of high-speed railway.

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