scholarly journals Methodic for evaluating the performance of a continuous welded track according to the criterion of compliance of the actual rail fastening temperature with the standardized value

2021 ◽  
Vol 80 (6) ◽  
pp. 327-333
Author(s):  
G. M. Volokhov ◽  
S. V. Chunin ◽  
A. V. Ushanov
Keyword(s):  
Experimental Data ◽  
Natural Frequency ◽  
Safety Evaluation ◽  
Field Tests ◽  
Element Model ◽  
Longitudinal Force ◽  
Computational Method ◽  
Actual Temperature ◽  
Current Assessment ◽  
The Given

Problem of safety evaluation of continuous welded track operation is considered. A comparative analysis of the current assessment methods is carried out and a method is proposed for identifying dangerous track sections according to the criterion of compliance of the actual rail fastening temperature with the standardized one. Under the actual fxing temperature in the article, the temperature of the rail is taken at which, as a result of its thermal expansion or contraction, a zero value of the longitudinal force is formed in it. A method is presented for calculating the actual temperature of rail fastening using the dependence of the natural frequency of rail vibrations on the applied longitudinal force, which was obtained by the computational method using the fnite element model of the track section created by the authors by means of modal calculations for various values of the longitudinal force applied to the rail. Its verifcation was carried out using experimental data obtained as a result of testing at a specialized stand. The method of tests carried out on the stand and section of the continuous track of the Ozerskaya branch of the Moscow Railway is described, which consists in determining the natural frequency of the first mode of rail vibration at different values of the longitudinal force, and in the case of field tests at different values of the rail temperature. The calculation of the actual temperature of rail fastening is given on the example of a section of a continuous-welded track of the Ozerskaya branch of the Moscow railway. It was found that the temperature of rail fastening on the investigated section corresponds to the normative for the given region.

Experimental Study and Numerical Analysis of Sihui Metro Depot and the Superstructure

2012 ◽  
Vol 226-228 ◽  
pp. 176-180
Author(s):  
Jing Zhang ◽  
Bin Zhang ◽  
Ying Hua Liu ◽  
Long Qi Wang ◽  
Yu Bin Wu
Keyword(s):  
Time History ◽  
Field Tests ◽  
Element Model ◽  
Test Analysis ◽  
3 Dimensional ◽  
Dimensional Finite Element ◽  
Calculation Results ◽  
History Of ◽  
The Given ◽  
The Waves

Field tests were carried out on Sihui metro depot of Beijing metro line 1 and its superstructure. The acceleration time history of sleepers and floors of the building was obtained, and the waves-propagation laws of building were studied through the tests. Test analysis shows that the structure vibrations show zigzag tendencies ascends with the height of the building. Based on current situation of Sihui metro depot, a metro-soil-building 3-dimensional finite element model is established on ANSYS. By using actual acceleration of sleepers as inputs, the dynamic responds rule of the superstructure is obtained. Compared calculation results with the experimental results, the given numerical model can predict the vibrations of the building induced by moving trains quite well. This method can provide guidance and technical support for future development of superstructure.

scholarly journals Layout Optimization of Rail Expansion Joint on Long-Span Cable-Stayed Bridge for High-Speed Railway

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Xiaopei Cai ◽  
Wanli Liu ◽  
Kaize Xie ◽  
Wenjun Zhu ◽  
Xiyuan Tan ◽  
...  
Keyword(s):  
High Speed ◽  
Field Tests ◽  
Element Model ◽  
Longitudinal Force ◽  
Main Beam ◽  
Expansion Joint ◽  
Cable Stayed Bridge ◽  
Long Span ◽  
Small Resistance ◽  
Set Up

Continuous welded rail (CWR) has been widely applied to the Chinese high-speed railways. It is interesting to reduce the effect of rail longitudinal force on the long-span cable-stayed bridges. Taking the pile-soil interaction into account, the finite element model of CWR on the long-span cable-stayed bridge is established based on the bridge-track interaction theory. The rail longitudinal force can be reduced and the track stability can be improved significantly by installing Rail Expansion Joint (REJ). The layout scheme of REJ plays a controlling role on designing CWR on bridges. Results show that the unidirectional REJ should be laid on both ends of the long-span cable-stayed bridge. Switch rails of REJ are set up on the main beam, stock rails are laid on the simply supported beams and crossing over beam joints, and several-meter long small resistance fasteners need to be laid on the sides of stock rails to reduce the fixed pier longitudinal force near the main beam. The range of REJ laid on cable-stayed bridge is mainly determined by temperature, rail breaking, and seismic condition; the bending and braking loads have little influence on it. Multiple field tests are carried out to prove the validity of the numerical model and the design methodology.

Solubility and Thermodynamic Transfer Functions of Cesium Dianilinetetraisothiocyanatochromate(III)

1998 ◽  
Vol 63 (3) ◽  
pp. 293-298
Author(s):  
Vladislav Holba
Keyword(s):  
Experimental Data ◽  
Isopropyl Alcohol ◽  
Transfer Functions ◽  
Butyl Alcohol ◽  
Aqueous Methanol ◽  
Gibbs Energies ◽  
Gibbs Energy Of Transfer ◽  
Energy Of Transfer ◽  
The Given ◽  
Reference Electrolyte

The solubilities of cesium dianilinetetraisothiocyanatochromate(III) in water as well as in aqueous methanol, isopropyl alcohol, tert-butyl alcohol and acetonitrile were measured as a function of temperature and solvent composition. The Gibbs energies, enthalpies and entropies of transfer of the salt from water to the given solvents have been evaluated from experimental data. The contribution of [Cr(C6H5NH2)2(NCS)4]- ion to the Gibbs energy of transfer of the investigated salt has been calculated using the tetraphenylarsonium tetraphenylborate (TATB) reference electrolyte assumption.

scholarly journals Fatigue Modeling and Numerical Analysis of Re-Filling Probe Hole of Friction Stir Spot Welded Joints in Aluminum Alloys

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2171
Author(s):  
Armin Yousefi ◽  
Ahmad Serjouei ◽  
Reza Hedayati ◽  
Mahdi Bodaghi
Keyword(s):  
Experimental Data ◽  
Tensile Strength ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Behavior ◽  
Element Model ◽  
Plastic Strain Amplitude ◽  
Friction Stir ◽  
Probe Hole ◽  
Good Agreement

In the present study, the fatigue behavior and tensile strength of A6061-T4 aluminum alloy, joined by friction stir spot welding (FSSW), are numerically investigated. The 3D finite element model (FEM) is used to analyze the FSSW joint by means of Abaqus software. The tensile strength is determined for FSSW joints with both a probe hole and a refilled probe hole. In order to calculate the fatigue life of FSSW joints, the hysteresis loop is first determined, and then the plastic strain amplitude is calculated. Finally, by using the Coffin-Manson equation, fatigue life is predicted. The results were verified against available experimental data from other literature, and a good agreement was observed between the FEM results and experimental data. The results showed that the joint’s tensile strength without a probe hole (refilled hole) is higher than the joint with a probe hole. Therefore, re-filling the probe hole is an effective method for structures jointed by FSSW subjected to a static load. The fatigue strength of the joint with a re-filled probe hole was nearly the same as the structure with a probe hole at low applied loads. Additionally, at a high applied load, the fatigue strength of joints with a refilled probe hole was slightly lower than the joint with a probe hole.

scholarly journals Investigation of the Thickness Differential on the Formability of Aluminum Tailor Welded Blanks

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 875
Author(s):  
Jie Wu ◽  
Yuri Hovanski ◽  
Michael Miles
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Numerical Model ◽  
Plastic Strain ◽  
Finite Element Model ◽  
Equivalent Plastic Strain ◽  
Element Model ◽  
Dome Height ◽  
Tailor Welded Blanks ◽  
Simulation Results

A finite element model is proposed to investigate the effect of thickness differential on Limiting Dome Height (LDH) testing of aluminum tailor-welded blanks. The numerical model is validated via comparison of the equivalent plastic strain and displacement distribution between the simulation results and the experimental data. The normalized equivalent plastic strain and normalized LDH values are proposed as a means of quantifying the influence of thickness differential for a variety of different ratios. Increasing thickness differential was found to decrease the normalized equivalent plastic strain and normalized LDH values, this providing an evaluation of blank formability.

scholarly journals Numerical Evaluation of Structural Safety of Linear Actuator for Flap Control of Aircraft Based on Airworthiness Standard

Aerospace ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 104
Author(s):  
Dong-Hyeop Kim ◽  
Young-Cheol Kim ◽  
Sang-Woo Kim
Keyword(s):  
Numerical Analysis ◽  
Analytical Method ◽  
Safety Evaluation ◽  
Experimental Tests ◽  
Structural Safety ◽  
Linear Actuator ◽  
The Finite Element Method ◽  
Margin Of Safety ◽  
Verification Methodology ◽  
The Given

Airworthiness standards of Korea recommend verifying structural safety by experimental tests and analytical methods, owing to the development of analysis technology. In this study, we propose a methodology to verify the structural safety of aircraft components based on airworthiness requirements using an analytical method. The structural safety and fatigue integrity of a linear actuator for flap control of aircraft was evaluated through numerical analysis. The static and fatigue analyses for the given loads obtained from the multibody dynamics analysis were performed using the finite element method. Subsequently, the margin of safety and vulnerable area were acquired and the feasibility of the structural safety evaluation using the analytical method was confirmed. The proposed numerical analysis method in this study can be adopted as an analytical verification methodology for the airworthiness standards of civilian aircraft in Korea.

scholarly journals CoBold: a method for identifying different functional classes of transient RNA structure features that can impact RNA structure formation in vivo

2020 ◽  
Author(s):  
Adrián López Martín ◽  
Mohamed Mounir ◽  
Irmtraud M Meyer
Keyword(s):  
Structure Formation ◽  
Rna Structure ◽  
Rna Secondary Structure ◽  
Computational Method ◽  
Data Visualisation ◽  
Multiple Sequence ◽  
Functional Roles ◽  
Functional Classes ◽  
The Given

Abstract RNA structure formation in vivo happens co-transcriptionally while the transcript is being made. The corresponding co-transcriptional folding pathway typically involves transient RNA structure features that are not part of the final, functional RNA structure. These transient features can play important functional roles of their own and also influence the formation of the final RNA structure in vivo. We here present CoBold, a computational method for identifying different functional classes of transient RNA structure features that can either aid or hinder the formation of a known reference RNA structure. Our method takes as input either a single RNA or a corresponding multiple-sequence alignment as well as a known reference RNA secondary structure and identifies different classes of transient RNA structure features that could aid or prevent the formation of the given RNA structure. We make CoBold available via a web-server which includes dedicated data visualisation.

The Finite Element Analysis and Optimization for the Grinder Based on the Joint Surface

2013 ◽  
Vol 281 ◽  
pp. 165-169 ◽  
Author(s):  
Xiang Lei Zhang ◽  
Bin Yao ◽  
Wen Chang Zhao ◽  
Ou Yang Kun ◽  
Bo Shi Yao
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Element Model ◽  
Joint Surface ◽  
Weak Links ◽  
Response Analysis ◽  
Element Analysis ◽  
Static And Dynamic Analysis ◽  
Harmonic Response Analysis ◽  
Grinding Machine

Establish the finite element model for high precision grinding machine which takes joint surface into consideration and then carrys out the static and dynamic analysis of the grinder. After the static analysis, modal analysis and harmonic response analysis, the displacement deformation, stress, natural frequency and vibration mode could be found, which also helps find the weak links out. The improvement scheme which aims to increase the stiffness and precision of the whole machine has proposed to efficiently optimize the grinder. And the first natural frequency of the optimized grinder has increased by 68.19%.

A Dynamic Test of Fully Prestressed Concrete Beams

2011 ◽  
Vol 368-373 ◽  
pp. 2483-2490
Author(s):  
Yao Ting Zhang ◽  
Yi Zheng ◽  
Hong Jian Li
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Theoretical Analysis ◽  
Natural Frequency ◽  
Axial Force ◽  
Prestressed Concrete ◽  
Concrete Beams ◽  
Dynamic Test ◽  
Modified Formula

A dynamic test of two unbonded fully prestressed concrete beams has been conducted. The results indicate that the natural frequency of beams increases with the prestress force, which is opposite to the analytical arguments for homogeneous and isotropic beams subject to axial force. This paper explains the change in frequencies by discussing the change in the elastic modulus. A modified formula is also proposed, and the experimental data agree well with the theoretical analysis.

Risk-Controlled Wellbore Stability Criterion Based on Machine Learning Assisted Finite Element Model

2021 ◽  
Author(s):  
Hussain AlBahrani ◽  
Nobuo Morita
Keyword(s):  
Machine Learning ◽  
Experimental Data ◽  
Finite Element ◽  
Finite Element Model ◽  
Stability Criterion ◽  
Element Model ◽  
Rock Failure ◽  
Wellbore Stability ◽  
Wellbore Instability ◽  
Conventional Methods

Abstract In many drilling scenarios that include deep wells and highly stressed environments, the mud weight required to completely prevent wellbore instability can be impractically high. In such cases, what is known as risk-controlled wellbore stability criterion is introduced. This criterion allows for a certain level of wellbore instability to take place. This means that the mud weight calculated using this criterion will only constrain wellbore instability to a certain manageable level, hence the name risk-controlled. Conventionally, the allowable level of wellbore instability in this type of models has always been based on the magnitude of the breakout angle. However, wellbore enlargements, as seen in calipers and image logs, can be highly irregular in terms of its distribution around the wellbore. This irregularity means that risk-controlling the wellbore instability through the breakout angle might not be always sufficient. Instead, the total volume of cavings is introduced as the risk control parameter for wellbore instability. Unlike the breakout angle, the total volume of cavings can be coupled with a suitable hydraulics model to determine the threshold of manageable instability. The expected total volume of cavings is determined using a machine learning (ML) assisted 3D elasto-plastic finite element model (FEM). The FEM works to model the interval of interest, which eventually provides a description of the stress distribution around the wellbore. The ML algorithm works to learn the patterns and limits of rock failure in a supervised training manner based on the wellbore enlargement seen in calipers and image logs from nearby offset wells. Combing the FEM output with the ML algorithm leads to an accurate prediction of shear failure zones. The model is able to predict both the radial and circumferential distribution of enlargements at any mud weight and stress regime, which leads to a determination of the expected total volume of cavings. The model implementation is first validated through experimental data. The experimental data is based on true-triaxial tests of bored core samples. Next, a full dataset from offset wells is used to populate and train the model. The trained model is then used to produce estimations of risk-controlled stability mud weights for different drilling scenarios. The model results are compared against those produced by conventional methods. Finally, both the FEM-ML model and the conventional methods results are compared against the drilling experience of the offset wells. This methodology provides a more comprehensive and new solution to risk controlling wellbore instability. It relies on a novel process which learns rock failure from calipers and image logs.

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