Cumulative deformation characteristic and shakedown limit of railway ballast under cyclic loading

2017 ◽  
pp. 1899-1904
Author(s):  
J.H. Xiao ◽  
D. Zhang ◽  
Y.H. Wang ◽  
Z. Luo
Keyword(s):  
Cyclic Loading ◽  
Deformation Characteristic ◽  
Railway Ballast ◽  
Cumulative Deformation ◽  
Shakedown Limit

scholarly journals Micro-mechanical investigation of railway ballast behavior under cyclic loading in a box test using DEM: effects of elastic layers and ballast types

2019 ◽  
Vol 21 (4) ◽  
Author(s):  
Nishant Kumar ◽  
Bettina Suhr ◽  
Stefan Marschnig ◽  
Peter Dietmaier ◽  
Christof Marte ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Early Stage ◽  
Damage Model ◽  
Simulation Models ◽  
Railway Track ◽  
Maintenance Cost ◽  
Particle Movement ◽  
Railway Ballast ◽  
Elastic Layers ◽  
The Impact

Abstract Ballasted tracks are the commonly used railway track systems with constant demands for reducing maintenance cost and improved performance. Elastic layers are increasingly used for improving ballasted tracks. In order to better understand the effects of elastic layers, physical understanding at the ballast particle level is crucial. Here, discrete element method (DEM) is used to investigate the effects of elastic layers – under sleeper pad ($$\text {USP}$$USP) at the sleeper/ballast interface and under ballast mat ($$\text {UBM}$$UBM) at the ballast/bottom interface – on micro-mechanical behavior of railway ballast. In the DEM model, the Conical Damage Model (CDM) is used for contact modelling. This model was calibrated in Suhr et al. (Granul Matter 20(4):70, 2018) for the simulation of two different types of ballast. The CDM model accounts for particle edge breakage, which is an important phenomenon especially at the early stage of a tamping cycle, and thus essential, when investigating the impact of elastic layers in the ballast bed. DEM results confirm that during cyclic loading, $$\text {USP}$$USP reduces the edge breakage at the sleeper/ballast interface. On the other hand, $$\text {UBM}$$UBM shows higher particle movement throughout the ballast bed. Both the edge breakage and particle movement in the ballast bed are found to influence the sleeper settlement. Micro-mechanical investigations show that the force chain in deeper regions of the ballast bed is less affected by $$\text {USP}$$USP for the two types of ballast. Conversely, dense lateral forces near to the box bottom were seen with $$\text {UBM}$$UBM. The findings are in good (qualitative) agreement with the experimental observations. Thus, DEM simulations can aid to better understand the micro-macro phenomena for railway ballast. This can help to improve the track components and track design based on simulation models taking into account the physical behavior of ballast. Graphical Abstract

Study on the Cyclic Loading Effects to the Railway Ballast

2013 ◽  
Vol 724-725 ◽  
pp. 1736-1739
Author(s):  
Xue Jun Wang ◽  
Bin Hua ◽  
Yi Lin Chi ◽  
Xue Yu Zhao ◽  
Fu Yu Li
Keyword(s):  
Cyclic Loading ◽  
Research Method ◽  
Flow Simulation ◽  
Railway Ballast ◽  
Compaction Rate ◽  
Simulation Process ◽  
Loading Effects ◽  
Simulation Results ◽  
Frequency Changes ◽  
Particle Flow Simulation

When ballast materials are subjected to cyclic loading, as a result, the change of particles micromechanical properties will lead to ballast degradation, permanent deformations on the railways step by step. In this paper, it presented a coupling discrete particle-flow simulation model of the railway ballast for cyclic tamping loading. Tamping frequency changes from 25HZ to 60HZ in numerical simulation process. Simulation results that the ballast compaction rate increases linearly with frequency up to a characteristic frequency 35HZ and then it declines in inverse proportion to tamping frequency. The aim of this paper is to study on the effects on the railway ballast under cyclic loading. The study shows that the discrete element method is a valid method for investigation of the microscopic properties of railway ballast now, while we have no other better research method.

Improving Damping Properties of Railway Ballast by Addition of Tire-Derived Aggregate

2019 ◽  
Vol 2673 (5) ◽  
pp. 299-307 ◽  
Author(s):  
Weimin Song ◽  
Baoshan Huang ◽  
Xiang Shu ◽  
Hao Wu ◽  
Hongren Gong ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Damping Ratio ◽  
Shear Stiffness ◽  
Damping Properties ◽  
Railway Ballast ◽  
Loading Test ◽  
Interface Shear ◽  
Peak Shear Stress ◽  
Dilation Effect ◽  
Tire Derived Aggregate

The damping properties of railway ballast are critical to the safe operation of trains. This study aimed to improve the damping properties of railway ballast through the addition of tire-derived aggregate (TDA) and to evaluate the effect of TDA on other properties of ballast. The damping property and other mechanical properties of ballast mixed with different contents of TDA were tested utilizing a large direct shear test (DST) under static and cyclic loading conditions. The cyclic loading test was performed in accordance with ASTM D 7499, from which the resilient interface shear stiffness and damping ratio were obtained. The results showed that TDA significantly increased the damping ratio of railway ballast, but decreased the resilient interface shear stiffness. The stress-strain behavior of the ballast-TDA mixes was obtained from the static loading test, showing that TDA significantly decreased the peak shear stress and the dilation effect. According to the Mohr-Coulomb failure criterion, TDA also decreased the cohesion strength and the internal friction angle of the ballast. Based on the test results from this study, 5% rubber is recommended for use in railway ballast.

Computation of Ratchet Limits for Structures Subjected to Cyclic Loading and Temperature

2002 ◽  
Author(s):  
A. R. S. Ponter ◽  
H. Chen ◽  
M. Habibullah
Keyword(s):  
Finite Element ◽  
Cyclic Loading ◽  
Mechanical Loading ◽  
Limit Theorems ◽  
Thermal Loading ◽  
Loading History ◽  
Cyclic Thermal Loading ◽  
Elastic Plastic ◽  
Plastic Structure ◽  
Shakedown Limit

The paper discusses methods of evaluating the ratchet limit for an elastic/plastic structure subjected to cyclic thermal and mechanical loading. A recently developed minimization theorems by Ponter and Chen [2] provides a generalization of the shakedown limit theorems for histories of load in excess of shakedown. This allows the development of programming methods that locate the ratchet boundary in excess of shakedown. Examples of applications are provided including the performance of a cracked body subjected to cyclic thermal loading. Finally, the theory is used to discuss Kalnins’ [4] proposal that short cut finite element solutions may be used to assess whether a particular loading history lies within a ratchet limit.

Shakedown behaviors of railway ballast under cyclic loading

2017 ◽  
Vol 155 ◽  
pp. 1206-1214 ◽  
Author(s):  
Junhua Xiao ◽  
De Zhang ◽  
Kai Wei ◽  
Zhe Luo
Keyword(s):  
Cyclic Loading ◽  
Railway Ballast

scholarly journals CUMULATIVE DEFORMATION CAPACITY OF BRACES UNDER VARIOUS CYCLIC LOADING HISTORIES

2012 ◽  
Vol 77 (677) ◽  
pp. 1131-1140 ◽  
Author(s):  
Toru TAKEUCHI ◽  
Makoto NISHIMAKI ◽  
Ryota MATSUI ◽  
Akira IMAMURA
Keyword(s):  
Cyclic Loading ◽  
Deformation Capacity ◽  
Cumulative Deformation

Shakedown Limit Load Determination for a Kinematically Hardening 90 deg Pipe Bend Subjected to Steady Internal Pressures and Cyclic Bending Moments

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Hany F. Abdalla ◽  
Maher Y. A. Younan ◽  
Mohammad M. Megahed
Keyword(s):  
Cyclic Loading ◽  
Internal Pressure ◽  
Limit Load ◽  
Material Model ◽  
Small Displacement ◽  
Bending Moments ◽  
Pipe Bend ◽  
Cyclic Bending ◽  
Fe Simulations ◽  
Shakedown Limit

A simplified technique for determining the lower bound shakedown limit load of a structure, employing an elastic–perfectly plastic (EPP) material model, was previously developed and successfully applied to a long radius 90 deg pipe bend (Abdalla et al., 2006, “Determination of Shakedown Limit Load for a 90 Degree Pipe Bend Using a Simplified Technique,” ASME J. Pressure Vessel Technol., 128, pp. 618–624). The pipe bend is subjected to steady internal pressure magnitudes and cyclic bending moments. The cyclic bending includes three different loading patterns, namely, in-plane closing, in-plane opening, and out-of-plane bending moment loadings. The simplified technique utilizes the finite element (FE) method and employs a small displacement formulation to determine the shakedown limit load without performing lengthy time consuming full elastic-plastic (ELPL) cyclic loading FE simulations or conventional iterative elastic techniques. In the present research, the simplified technique is further modified to handle structures employing an elastic-linear strain hardening material model following Ziegler’s linear kinematic hardening (KH) rule. The shakedown limit load is determined through the calculation of residual stresses developed within the pipe bend structure accounting for the back stresses, determined from the KH shift tensor, responsible for the rigid translation of the yield surface. The outcomes of the simplified technique showed an excellent correlation with the results of full ELPL cyclic loading FE simulations. The shakedown limit moments output by the simplified technique are utilized to generate shakedown diagrams (Bree diagrams) of the pipe bend for a spectrum of steady internal pressure magnitudes. The generated Bree diagrams are compared with the ones previously generated employing the EPP material model. These indicated relatively conservative shakedown limit moments compared with the ones employing the KH rule.

Study Behavior of Railway Ballast under Cyclic Loading

2014 ◽  
Vol 919-921 ◽  
pp. 1155-1159
Author(s):  
Tao Yong Zhou ◽  
Bin Hu ◽  
Bin Hua
Keyword(s):  
Numerical Simulation ◽  
Cyclic Loading ◽  
Discrete Element Method ◽  
Discrete Element ◽  
Railway Track ◽  
Experimental Facility ◽  
Railway Ballast ◽  
Study Behavior ◽  
Rate Of Increase ◽  
Simulation Results

Densification and settlement are two important behavior parameters of railway ballast under cyclic loading. This paper presents numerical simulation using discrete element method which studies the evolution of densification of railway ballast in specified region under cyclic loading. The simulation results show that with the increase of cyclic loading time, the densification of railway ballast under sleeper is also increasing, and the rate of increase becomes smaller and smaller. This paper presents a new full-scale complete railway track loading experimental facility which studies the evolution of settlement of ballasted railway track under cyclic loading. The experimental results show that with the increase of number of load cycles, the settlement of ballasted railway track is also increasing, and the rate of increase becomes smaller and smaller.

Determination of Shakedown Limit Load for a 90-Degree Pipe Bend Using a Simplified Technique

2006 ◽  
Vol 128 (4) ◽  
pp. 618-624 ◽  
Author(s):  
Hany F. Abdalla ◽  
Mohammad M. Megahed ◽  
Maher Y. A. Younan
Keyword(s):  
Finite Element ◽  
Cyclic Loading ◽  
Internal Pressure ◽  
Bending Moment ◽  
Limit Load ◽  
Heat Fluxes ◽  
Bench Mark ◽  
Pipe Bend ◽  
Elastic Plastic ◽  
Shakedown Limit

In this paper a simplified technique is presented to determine the shakedown limit load of a 90-degree pipe bend subjected to constant internal pressure and cyclic in-plane closing bending moment using the finite element method. The simplified technique determines the shakedown limit load without performing time consuming full elastic-plastic cyclic loading simulations or conventional iterative elastic techniques. Instead, the shakedown limit load is determined by performing two finite element analyses namely; an elastic analysis and an elastic-plastic analysis. By extracting the results of the two analyses, the shakedown limit load is determined through the calculation of the residual stresses developed in the pipe bend. In order to gain confidence in the simplified technique, the output shakedown limit moments are used to perform full elastic-plastic cyclic loading simulations to check for shakedown behavior of the pipe bend. The shakedown limit moments output by the simplified technique are used to generate the shakedown diagram of the pipe bend for a range of constant internal pressure magnitudes. The maximum moment carrying capacity (limit moment) the pipe bend can withstand and the elastic limit are also determined and imposed on the shakedown diagram of the pipe bend. In order to get acquainted with the simplified technique, it is applied beforehand to a bench mark shakedown problem namely, the Bree cylinder (Bree, J., 1967, J. Strain Anal., 3, pp. 226–238) problem. The Bree cylinder is subjected to constant internal pressure and cyclic high heat fluxes across its wall. The results of the simplified technique showed very good correlation with the analytically determined Bree diagram of the cylinder.

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