Influences of Subgrade Structure Form on Dynamic Responses of Railway Subgrade under Cyclic Loading

2016 ◽  
Vol 851 ◽  
pp. 757-762
Author(s):  
Jun Hua Xiao
Keyword(s):  
Plastic Deformation ◽  
Cyclic Loading ◽  
Maximum Stress ◽  
Dynamic Stress ◽  
Dynamic Stiffness ◽  
Field Tests ◽  
Dynamic Responses ◽  
Structure Form ◽  
The One ◽  
Moving Train

This paper presents conducted field tests of cyclic loading for railway subgrade. These tests studied the influences of subgrade structure forms of embankment and cutting on the dynamic responses of railway subgrade. The considered dynamic responses included the distribution of dynamic stress in railway subgrade, and the elastic deformation, dynamic stiffness, and cumulative plastic deformation on subgrade surface. The number of cyclic loading in testing was separately about two millions for an embankment and a cutting. The dynamic deviator stress applied on subgrade surface was 92kPa to simulate the maximum stress induced by moving train for the designed railway. Gathered data showed that the dynamic stiffness on subgrade surface for a cutting was approximately a half of the one for an embankment. However, the cumulative plastic deformation was essentially the same for the two forms of subgrade (i.e. the embankment and the cutting). These results provide references for the design of railway subgrade.

scholarly journals Influence of Non-Homogeneous Foundations On the Dynamic Responses of Railway Sleepers

2020 ◽  
pp. 2150002
Author(s):  
Le-Hung Tran ◽  
Tien Hoang ◽  
Denis Duhamel ◽  
Gilles Foret ◽  
Samir Messad ◽  
...  
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Dynamic Stiffness ◽  
Substantial Reduction ◽  
Element Model ◽  
Dynamic Responses ◽  
Railway Track ◽  
Computational Time ◽  
Beam Model ◽  
The One

In a railway track, the sleeper’s responses on a non-homogeneous foundation have been investigated by researchers focusing on the foundation behavior along the rails. However, the foundation can also vary along the sleeper length, particularly when the track is newly tamped. The foundation at the sleeper center is often weaker than those under the rails and this non-homogeneity directly affects the sleeper responses. This paper presents a new model to calculate the influence of such foundations on the dynamic responses of the railway sleepers. This model is developed by combining a finite element model for the sleepers and foundation and a model of periodically supported beams subjected to moving loads for the rails. In this paper, the foundation contains three parts with different mechanical behaviors. The sleeper’s responses can be calculated by transforming the finite-element dynamic stiffness matrix to the one considering the boundary conditions and the relation between the rail seat forces and rail displacements governed by the beam model. This method reduces all the degrees of freedom of the railway track to its one period which gives a substantial reduction in computational time. The numerical applications show that the more homogeneous (so-called consolidated) the foundation is, the larger the sleeper strain is at its center. This result shows the potential application of the sleeper responses to estimating the consolidation level of the foundation.

An Experimental Study of Inhomogeneous Cyclic Plastic Deformation

2001 ◽  
Vol 123 (3) ◽  
pp. 274-280 ◽  
Author(s):  
Yanyao Jiang
Keyword(s):  
Plastic Deformation ◽  
Cyclic Loading ◽  
Small Strain ◽  
Local Deformation ◽  
Gage Section ◽  
Strain Gages ◽  
Cyclic Plastic ◽  
Symmetrical Loading ◽  
Increasing Cyclic Loading ◽  
Cyclic Plastic Deformation

A localized inhomogeneous cyclic plastic deformation phenomenon was experimentally investigated in a mild steel. Small strain gages were utilized to characterize the local deformation within the gage section and the gross deformation was measured with an extensometer. Both fully reversed symmetrical loading and asymmetrical loading with a mean stress were used in the cyclic experiments. Plastic deformation was initiated in local areas of the specimen and it propagated into the whole gage section in the specimen with increasing cyclic loading. The local inhomogeneous cyclic deformation was dependent on the loading magnitude and evolved with continued cyclic loading.

scholarly journals Results from field tests of the one-dimensional Time-Encoded Imaging System.

2014 ◽  
Author(s):  
Peter Marleau ◽  
James S. Brennan ◽  
Erik Brubaker
Keyword(s):  
Imaging System ◽  
Field Tests ◽  
One Dimensional ◽  
The One

Tackling the Methane Quandary: Curbing Emissions from Control Valves

2021 ◽  
Author(s):  
Andrea Pacini ◽  
Stefano Rossini
Keyword(s):  
Oil And Gas ◽  
Petroleum Industry ◽  
Field Tests ◽  
Control Valve ◽  
Methane Emissions ◽  
Fugitive Emissions ◽  
Fugitive Emission ◽  
Control Valves ◽  
One Year ◽  
The One

Abstract In the wake of Eni's strategy to curb fugitive emissions - in particular methane – an innovative control valve (Clarke Shutter Valve) has been deployed and tested in an Italian Eni facility. This shutter type valve is capable of reducing the fugitive emissions by more than 90%, as well as greatly curbing purchase costs, thanks to an innovative design in bonnet and regulating mechanism. In order to assess the real potentiality of the innovation, four Fisher globe valves and one Fisher V-ball were substituted with the Shutter Valves on different hydrocarbon streams of the Trecate facility (Piedmont), in particular on streams containing oil, gas and corrosive fluids. The valves were monitored for more than a year and fugitive emissions tests have been performed to detect and estimate methane leak rates. Since this represented a first deployment of this technology in Europe, a thorough analysis and technology validation of the valves has been performed. A successful installation and start-up were performed in 3 days by Eni's staff at in February of 2020. The valves were fully operational after the installation and to date no issues have been reported. In order to monitor the valves performances of flow control, continuous data collection on each valve has been implemented, and the analysis performed showed that all valves behave correctly as to Eni's standards. A fugitive emission test that has been performed at the end of 2020 with a certified portable FID/PID analyzer displayed that no methane emissions were detected from the valves. Lastly the one year and half long technology validation concluded that the Shutter Valves are a valid technology for curbing methane emissions from the Oil and Gas plants, and that suggested to qualify the company as Eni partner for control valves. This deployment and field tests, as well as the technological assessment performed by Eni's professionals showed the potentiality of this new type of valves in reducing the methane emissions from the petroleum industry. Understanding the potentiality of intrinsically carbon neutral technology is a crucial step for the mitigation of greenhouse gases emissions and towards the creation of a more environmentally friendly industry.

A model for the vibrator–ground coupling vibration and the dynamic responses under excitation of sweep signal

2019 ◽  
Vol 22 (8) ◽  
pp. 1855-1866 ◽  
Author(s):  
Gang Li ◽  
Zhi-Qiang Huang ◽  
Zhang-Hua Lian ◽  
Lei Hao
Keyword(s):  
Dynamic Stiffness ◽  
Low Frequency ◽  
Dynamic Responses ◽  
Coupling Vibration ◽  
Lower Velocity ◽  
Dynamic Damping ◽  
Velocity Response ◽  
Cell Test ◽  
Three Stages ◽  
Good Agreement

To analyze the behavior of the vibrator–ground coupling vibration, a model containing equivalent dynamic stiffness and equivalent dynamic damping to describe the interaction between the vibrator and the ground is established based on half-space theory. According to load cell test, this model shows a good agreement with the experimental data. Dynamic responses of the structure are analyzed on displacement, velocity, acceleration, and ground force. Results show that the stroke and pump displacement are main constraints that limit the bandwidth of vibrator toward low frequency, and the stroke of conventional vibrator is not long enough to achieve lower frequency. Analysis of velocity response indicates that with the increase of frequency, a larger mass results in a lower velocity under external force. The influence of the ground acting on the baseplate is limited, and the acceleration of the baseplate is determined by its own mass beyond 80 Hz. Analysis of ground force shows that the response of the structure can be divided into three stages. The reaction mass, the baseplate, and the ground play different roles in dominating the ground force at different frequency bands.

scholarly journals Dynamic Characteristics of Deeply Buried Spherical Biogas Digesters in Viscoelastic Soils

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Hongwei Hou ◽  
Shihu Gao ◽  
Qianqian Guo ◽  
Long Chen ◽  
Bing Wu ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Fractional Derivative ◽  
Elastic Medium ◽  
Shell Structure ◽  
Fractional Derivatives ◽  
Analytic Solution ◽  
Analytic Solutions ◽  
Dynamic Responses ◽  
Significant Difference ◽  
The Continuum

The harmonic vibration characteristics of a deeply buried spherical methane tank in viscoelastic soil subjected to cyclic loading in the frequency domain are investigated. The dynamic behavior of the soil is described based on the theory of fractional derivatives. By introducing potential functions, the closed-form expressions for the displacement and the stress of the viscoelastic soil surrounding the deeply buried spherical methane tank are obtained. Two die structures are considered: a homogeneous elastic medium and a shell structure. Based on the theory of elastic motion and the Flügge theory, analytic solutions for the dynamic responses of the spherical methane tank in a fractional-derivative viscoelastic soil are derived explicitly. Analytic solution expressions of the undetermined coefficients are determined by using the continuum boundary conditions. The system dynamic responses to the homogeneous elastic medium and the shell structure and the influences of the parameters of the fractional derivative, soil, and die on the dynamic characteristic of the system are compared and analyzed. The results indicate a significant difference between the dynamic responses of the die structures for the two models.

Effect of Interface Damage on Loosening Behavior of Acetabular Cup Subjected to Cyclic Loading

2018 ◽  
Vol 941 ◽  
pp. 1841-1845 ◽  
Author(s):  
Yuichi Otsuka ◽  
Kengo Kagaya ◽  
Yuki Hakozaki ◽  
Yukio Miyashita ◽  
Yoshiharu Mutoh
Keyword(s):  
Cyclic Loading ◽  
Mechanical Loading ◽  
Failure Modes ◽  
Fatigue Testing ◽  
Biological Effects ◽  
Stress Singularity ◽  
Testing System ◽  
Acetabular Cup ◽  
Edge Part ◽  
The One

This study aims at experimentally revealing the effects of damages/fractures in HAp coating layer of acetabular cups on loosening behavior of the acetabular cups. Aseptic loosening is occurred due to degradation of fixing force of acetabular cups by biological effects or mechanical loading. However, effects of mechanical loading on loosening behaviour have not been observed yet. In order to simulate cyclic loading conditions of gaits, a testing system which can load entire components of joint including acetabular cups and stem parts was designed. Moreover, by applying two positions of AE sensors during fatigue testing, it was possible to observe the damage behavior of HAp coating. AE measurement detected different failure modes of HAp coating, which were locally occurred at an edge part of the acetabular cup due to stress singularity at that region. In the cases of changing fixation angles, even though damages in simulated cancellous bone surrounding acetabular cups were less occurred, extents of rotational displacements were compatible with the one in an original fixation angle.

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