scholarly journals Methodology for evaluating thermal track buckling in dual gauge tracks with continuous welded rail

2016 ◽  
Vol 231 (3) ◽  
pp. 269-279 ◽  
Author(s):  
Ignacio Villalba ◽  
Ricardo Insa ◽  
Pablo Salvador ◽  
Pablo Martinez
Keyword(s):  
Three Dimensional ◽  
Torsional Stiffness ◽  
Railway Network ◽  
Compressive Stresses ◽  
Freight Traffic ◽  
Lateral Resistance ◽  
Temperature Load ◽  
Continuous Welded Rail ◽  
Linear Behaviour ◽  
New Methodologies

In the National Spanish railway network, two types of track gauge with continuous welded rails are currently in use: the “Iberian” wide gauge (1668 mm) and the standard gauge (1435 mm). In order to improve links and freight traffic between different lines and with the rest of Europe, a dual gauge track with three rails was developed. This solution modifies the classical track configuration, so it is necessary to develop new methodologies and studies to understand its behavior. Among other loads applied on a continuous welded rail track, a considerable rise in temperature induces compressive stresses in the three rails that can lead to lateral track buckling. Moreover, on dual gauge tracks, the addition of the third rail increases the axial compression, which may lead to track instability. For this reason, a three-dimensional continuous welded rail model is developed in this study to be used for dual gauge track buckling analysis on straight tracks subjected to temperature load. The continuous welded rail dual gauge track model consists of beam, solid and spring elements, in which a non-linear behaviour of the ballast is considered. The results obtained may be used to predict the buckling capacity of the continuous welded rail on dual gauge tracks with respect to different parameters such as lateral resistance, lateral imperfections, sleeper spacing or torsional stiffness.

Three-Dimensional Nonlinear Stability Analysis of Tangent Continuous Welded Rail Track Under Temperature and Mechanical Loads

1997 ◽  
Vol 1584 (1) ◽  
pp. 31-40 ◽  
Author(s):  
Yulin Bao ◽  
Ernest J. Barenberg
Keyword(s):  
Stability Analysis ◽  
Lateral Displacement ◽  
Three Dimensional ◽  
Initial Slope ◽  
Lateral Loads ◽  
Rotational Stiffness ◽  
Geometric Imperfections ◽  
Mechanical Loads ◽  
Lateral Resistance ◽  
Continuous Welded Rail

Results from applications of the three-dimensional continuous welded rail (CWR) track model ILLIBUCKLE to a tangent CWR track with nonlinear resistance and lateral geometric imperfections are presented. Stability analysis is made of the tracks under temperature and mechanical loads by using temperature lateral-displacement curves. Tangent CWR track stability is highly sensitive not only to ballast lateral resistance and geometric imperfections of the the initial track but also to the vertical rotational stiffness in rail-pad fastener systems and vehicle lateral loads. It is concluded that not only the peak values but also the initial slope and the limit resistance in the ballast lateral-resistance curve obtained from a single-tie push test are important in evaluation of track stability. With regard to vertical rotational stiffness in a rail-pad fastener system, track stability is not significantly affected by the nonlinearities, but it is affected by the initial slope. Effects of the combination of mechanical and thermal loads on tangent track stability are presented. The reduction of ballast lateral resistance due to the uplift of rail tie under vehicle vertical loads as well as the magnitude of vehicle lateral loads significantly decrease track stability. A 1400-kg vehicle lateral load can buckle tangent CWR track under a rail-temperature increase as low as 56°C (100°F) under unfavorable conditions.

Suggestion for allowable additional compressive stress based on track conditions

2017 ◽  
Vol 232 (5) ◽  
pp. 1309-1325 ◽  
Author(s):  
Kyung-Min Yun ◽  
Beom-Ho Park ◽  
Hyun-Ung Bae ◽  
Nam-Hyoung Lim
Keyword(s):  
Compressive Stress ◽  
Structural Characteristics ◽  
Three Dimensional ◽  
Additional Stress ◽  
Analysis Model ◽  
Temperature Changes ◽  
Lateral Resistance ◽  
Ballasted Track ◽  
Continuous Welded Rail ◽  
Track Bridge

A continuous welded rail has immovable zones due to its structural characteristics. In an immovable zone, thermal expansion and contraction of rails are restricted when the temperature changes, thereby causing excessive axial force on the rail. When the immovable zone of the continuous welded rail is located on a bridge, additional stress and displacement occur through track–bridge interactions. Additional stress and displacement of the rail compared to the embankment area are restricted when constructing the bridge under the continuous welded rail track to prevent problems with the track–bridge interaction according to UIC 774-3R and Euro codes. According to the various codes, the maximum allowable additional compressive stress is 72 MPa, with the conditions of a curve with a radius (R) ≥ 1500 m, UIC 60 continuous welded rail (tensile strength of at least 900 MPa), ballasted track with concrete sleepers and 30 cm of deep for a well-consolidated ballast. However, the lateral resistance that has the greatest effect on track stability can depend on the conditions mentioned above. Therefore, an additional review of various track conditions is required. In this paper, an evaluation of the current criteria was performed using the minimum buckling strength calculation formula, and the allowable additional stress on the rail suggested by codes could only be used on tracks with a large lateral resistance above 18 kN/m/track. Thus, a three-dimensional nonlinear analysis model was developed and analyzed to calculate the allowable additional compressive stress considering various track conditions. According to the results of the analysis, the allowable additional compressive stress was reduced with a comparatively small lateral resistance. The freedom of design can be enhanced with respect to the parameters of various track and bridge conditions using this model.

A NEW METHODOLOGY FOR EVALUATING THE SAFE TEMPERATURE IN CONTINUOUS WELDED RAIL TRACKS

2013 ◽  
Vol 13 (02) ◽  
pp. 1350016 ◽  
Author(s):  
J. CARVALHO ◽  
J. DELGADO ◽  
R. CALÇADA ◽  
R. DELGADO
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Three Dimensional ◽  
Nonlinear Behavior ◽  
Track Structure ◽  
Compressive Stresses ◽  
Continuous Welded Rail ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Conventional Algorithm

The use of continuous welded rails (CWR) is increasingly common and is particularly important when it comes to high-speed ballasted tracks. As the longitudinal displacements are restricted in CWR tracks, a considerable rise in temperature induces compressive stresses in the rails that can lead to track buckling. Given the nonlinear behavior of the ballast, usually represented by a linear plastic model, the problem of snap-through buckling may occur, for which only a few nonlinear analysis methods can trace the full response of the track structure. However, these methods fail to yield convergent solutions for problems with thermal loads when implemented in their conventional algorithm. For this reason, a new methodology is presented allowing the calculation of the safe temperature. In addition, some analytical results are also derived for comparison with the numerical results, obtained using three-dimensional finite element beam models provided by ANSYS.

Torsional Analysis of a Steel Cord-Rubber Tire Belt Structure

1996 ◽  
Vol 24 (4) ◽  
pp. 339-348 ◽  
Author(s):  
R. M. V. Pidaparti
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Composite Structures ◽  
Three Dimensional ◽  
Element Model ◽  
Torsional Stiffness ◽  
Element Analysis ◽  
Rubber Belt ◽  
Steel Cord ◽  
Torsional Analysis

Abstract A three-dimensional (3D) beam finite element model was developed to investigate the torsional stiffness of a twisted steel-reinforced cord-rubber belt structure. The present 3D beam element takes into account the coupled extension, bending, and twisting deformations characteristic of the complex behavior of cord-rubber composite structures. The extension-twisting coupling due to the twisted nature of the cords was also considered in the finite element model. The results of torsional stiffness obtained from the finite element analysis for twisted cords and the two-ply steel cord-rubber belt structure are compared to the experimental data and other alternate solutions available in the literature. The effects of cord orientation, anisotropy, and rubber core surrounding the twisted cords on the torsional stiffness properties are presented and discussed.

scholarly journals Ballast bed resistance characteristics based on discrete-element modeling

2018 ◽  
Vol 10 (6) ◽  
pp. 168781401878146 ◽  
Author(s):  
Zhiping Zeng ◽  
Shanyi Song ◽  
Weidong Wang ◽  
Haijian Yan ◽  
Guoshu Wang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Discrete Element ◽  
Discrete Element Modeling ◽  
Slope Gradient ◽  
Three Dimensional Model ◽  
Lateral Resistance ◽  
In Situ Experiments ◽  
Distribution Limits ◽  
Longitudinal Resistance

In this study, in situ experiments were conducted to study the changing characteristics of the lateral and longitudinal resistance of a ballast bed, and a three-dimensional model for the ballast bed and sleeper was constructed based on the discrete-element method. The effects of the lateral and longitudinal resistance of the ballast bed, such as gravel ballast grading, sleeper depth, the angle of the shoulder slope, and ballast bed shoulder width, among others, were studied. The results suggest that (1) the lateral and longitudinal resistance of the ballast bed increases with the widening of ballast grading, and within the size distribution limits, the resistance of the ballast bed satisfies the specification; (2) the lateral and longitudinal resistance of ballast bed increases with an increase in the sleeper depth and the resistance of ballast bed satisfies the specifications for sleeper depth greater than 150 mm; (3) the lateral resistance of the ballast bed increases with a decrease in the angle of the shoulder slope, whereas the longitudinal resistance remains unchanged and the resistance of the ballast bed satisfies the specifications for slope gradient of 1:1.75 or less; and finally, (4) the lateral resistance of the ballast bed increases with the widening of the ballast bed shoulder, whereas the longitudinal resistance remains unchanged, and the resistance of ballast bed satisfies the specifications when the shoulder width is greater than 400 mm.

Stress State of Turbine Blade Root and Rim Considering Manufacturing Variations

2014 ◽  
Vol 492 ◽  
pp. 56-59
Author(s):  
Qin Zhou ◽  
Wei Zhao
Keyword(s):  
Centrifugal Force ◽  
Load Distribution ◽  
High Stress ◽  
Three Dimensional ◽  
Load Condition ◽  
Blade Root ◽  
Temperature Load ◽  
Influence Of Temperature On ◽  
Manufacturing Variation ◽  
Room Temperature Increase

Three-dimensional thermoelastic analysis on the fir-tree root and rim of the I-P cylinder’s first stage blade was performed in two cases of load condition: only centrifugal force and both centrifugal force and temperature load, and five different manufacturing variations were taken into account. The results show that: with high temperature, the stress level of root which is well-designed under room temperature increase obviously, and the load of the four root teeth is unevenly distributed. Moreover, manufacturing variation between contact surfaces lead to serious stress concentration and extremely high stress, and load distribution of the four root teeth is completely uneven. In addition, the influence of temperature on the stress distribution of blade root and rim is much different with different manufacturing variations.

scholarly journals Geosynthetic reinforced column supported embankments and the role of ground improvement installation effects

2018 ◽  
Vol 55 (6) ◽  
pp. 792-809 ◽  
Author(s):  
Daniel J. King ◽  
Abdelmalek Bouazza ◽  
Joel R. Gniel ◽  
R. Kerry Rowe ◽  
Ha H. Bui
Keyword(s):  
Soil Structure ◽  
Ground Improvement ◽  
Three Dimensional ◽  
Installation Effects ◽  
Lateral Forces ◽  
Lateral Resistance ◽  
Embankment Stability ◽  
Numerical Approaches

For geosynthetic reinforced column supported embankments (GRCSE) supporting a high embankment, lateral forces associated with lateral sliding and embankment stability often govern the acceptability of a given design under serviceability conditions. Frequently, the complex soil–structure–geosynthetic interaction, the size, and the three-dimensional nature of a GRCSE necessitate the use of numerical analysis to assess embankment performance relative to serviceability criteria. However, traditional finite element method techniques used to model serviceability behaviour are limited in their ability to model the geotechnical mechanisms associated with column installation, equilibration, and group installation effects. These installation effects are examined herein based on a GRCSE field case study located in Melbourne, Australia, that has been extensively instrumented. The role that these installation effects have on the performance of the GRCSE is highlighted and the behaviour of the columns supporting the embankment is emphasized. It is shown that cracking of the unreinforced columns supporting the embankment is likely inevitable and that the reduction of lateral resistance provided by the columns should be accounted for in design. The suitability of various numerical approaches currently used in design to model the columns supporting the GRCSE, and the embankment itself, are discussed and recommendations are made.

FINITE ELEMENT MODELING OF HUMAN THORACIC SPINE

2004 ◽  
Vol 08 (04) ◽  
pp. 133-144 ◽  
Author(s):  
Tian-Xia Qiu ◽  
Ee-Chon Teo
Keyword(s):  
Finite Element ◽  
Thoracic Spine ◽  
Three Dimensional ◽  
Axial Rotation ◽  
Torsional Stiffness ◽  
Fe Model ◽  
Thoracic Vertebrae ◽  
Fundamental Information ◽  
Flexion Extension ◽  
Scoliosis Correction

Mathematical models, which can accurately represent the geometric, material and physical characteristics of the human spine structure, are useful in predicting biomechanical behaviors of the spine. In this study, a three-dimensional finite element (FE) model of thoracic spine (T1–T12) was developed, based on geometrical data of embalmed thoracic vertebrae (T1–T12) obtained from a precise flexible digitizer, and validated against published thoracolumbar experimental results in terms of the torsional stiffness of the whole thoracic spine (T1–T12) under axial torque alone and combined with distraction and compression loads. The torsional stiffness was increased by over 60% with application of a 425 N distraction force. A trend in increasing torsional stiffness with increasing distraction forces was detected. The validated model was then loaded under moment rotation in three anatomical planes to determine the ranges of motion (ROMs). The ROMs were approximately 37°, 31°, 32°, 51° for flexion, extension, lateral bending and axial rotation, respectively. These results may offer an insight to better understanding the kinematics of the human thoracic spine and provide clinically relevant fundamental information for the evaluation of spinal stability and instrumented devices functionality for optimal scoliosis correction.

scholarly journals The effect of prosthetic torsional stiffness on the golf swing kinematics of a left and a right-sided trans-tibial amputee

2004 ◽  
Vol 28 (2) ◽  
pp. 121-131 ◽  
Author(s):  
J. P. Rogers ◽  
S. C. Strike ◽  
E. S. Wallace
Keyword(s):  
Ankle Joint ◽  
Perceived Stress ◽  
Sagittal Plane ◽  
Three Dimensional ◽  
Transverse Plane ◽  
Golf Swing ◽  
Torsional Stiffness ◽  
The Difference ◽  
The Right ◽  
Socket Interface

The golf swing is a biomechanically complex movement requiring three-dimensional movements at the ankle joint complex (AJC), the hips and shoulders. Trans-tibial amputees lose the natural AJC movements as many prostheses do not allow three dimensional foot movements. Torsion devices have been developed and incorporated into prostheses to facilitate internal and external transverse plane rotations. These devices can help amputees to compensate for the loss of movement and to reduce shearing stresses at the stump-socket interface. The primary aim of the present study was to investigate the effects of three torsion devices on body rotations during the golf swing. Two trans-tibial amputees (one right-sided and one left-sided) were analysed using three-dimensional video analysis at address (ADR), the top of the backswing (TBS) and at the end of the follow-through (EFT). The participants played shots with a 3-wood under three different prosthetic conditions (two with a torsion device set to different stiffness values, and one with no torsion device). The results showed that the torsion device served to improve the hip and shoulder rotations of the left-side amputee without increasing perceived stress at the stump. The torsion device had minimal effect on the hip and shoulder rotations of the right-side amputee, although perceived stress was reduced. The difference in results between the right-sided and left-sided amputees was due to the different requirements of each foot during the golf swing. The main problem faced by the right-side amputee was a loss of the sagittal plane movement of ankle joint plantarflexion at EFT, rather than the transverse plane movement.

scholarly journals Field Investigations on the Effects of Track Lateral Supports on the Ballasted Railway Lateral Resistance

2020 ◽  
Author(s):  
Jabbar Ali Zakeri ◽  
Milad Alizadeh Galdiani ◽  
Seyed Ali Mosayebi
Keyword(s):  
Numerical Modeling ◽  
Bilinear Form ◽  
Field Tests ◽  
New Method ◽  
Railway Track ◽  
Lateral Forces ◽  
Lateral Resistance ◽  
Field Investigations ◽  
Continuous Welded Rail ◽  
Lateral Displacements

Lateral movements of the ballasted railway track especially in the continuous welded rail (CWR) occur in sharp curves because of high lateral forces. Several strategies have been proposed to increase the track lateral resistance which most of them related to track curves with small radii. In this paper, track lateral supports as a new method have been utilized and a series of field tests have been conducted by using the Single Tie Push Tests (STPT) and Multi Tie Push Tests (MTPT) and their results are compared with the numerical modeling. The results of numerical modeling and field tests show that the track lateral resistance significantly increases in the railway with lateral supports, so that the lateral displacements of track are as a bilinear form.

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