scholarly journals Mathematical Modelling and Computational Simulation of the Hydraulic Damper during the Orifice-Working Stage for Railway Vehicles

2020 ◽  
Vol 2020 ◽  
pp. 1-23
Author(s):  
Hongxing Gao ◽  
Maoru Chi ◽  
Liangcheng Dai ◽  
Jungang Yang ◽  
Xiaozhi Zhou
Keyword(s):  
Mathematical Model ◽  
Dynamic Characteristics ◽  
Computational Simulation ◽  
Gas Content ◽  
Secondary Development ◽  
Railway Vehicle ◽  
Development Environment ◽  
Hydraulic Damper ◽  
Force Element ◽  
Different Diameters

The objective of this paper is to establish an accurate nonlinear mathematical model of the hydraulic damper during the orifice-working stage. A new mathematical model including the submodels of the orifices, hydraulic fluids, pressure chambers, and reservoir chambers is established based on theories of the fluid mechanics, hydropneumatics, and mechanics. Subsequently, a force element based on the established model of the hydraulic damper which contains 56 inputs, 6 force states, and 47 outputs is developed with the FORTRAN language in the secondary development environment of the multibody dynamics software SIMPACK. Using the force element, the damping characteristics of the modified yaw damper with different diameters of the base orifice are calculated under different amplitudes and frequencies of the sine excitation, and then the simulation results are compared with the experimental results which are obtained under the same conditions. Results show that during the orifice-working stage, the new established mathematical model can accurately reproduce the nonlinear static and dynamic characteristics of hydraulic dampers such as the force-displacement characteristic, force-velocity characteristic, fluid shortage, hysteresis effect, and pressure limited effect. Furthermore, it also shows that the nonlinear characteristics of the orifice, air release, cavitation, leakage for high frequencies, and dynamic characteristics of fluid (i.e., the density, bulk modulus, and air/gas content) should be taken seriously during the modelling of the hydraulic damper at the orifice-working stage. The mathematical model proposed in this paper is more applicable to the railway vehicle system dynamics and individual system description of the hydraulic damper.

scholarly journals Determination of the Vertical Load on the Carrying Structure of a Flat Wagon with the 18–100 and Y25 Bogies

2021 ◽  
Vol 11 (9) ◽  
pp. 4130
Author(s):  
Oleksij Fomin ◽  
Alyona Lovska ◽  
Václav Píštěk ◽  
Pavel Kučera
Keyword(s):  
Mathematical Model ◽  
Fatigue Strength ◽  
Service Life ◽  
Dynamic Characteristics ◽  
Dynamic Load ◽  
Field Tests ◽  
Vertical Load ◽  
Mathcad Software ◽  
The Mathematical Model

The study deals with determination of the vertical load on the carrying structure of a flat wagon on the 18–100 and Y25 bogies using mathematic modelling. The study was made for an empty wagon passing over a joint irregularity. The authors calculated the carrying structure of a flat wagon with the designed parameters and the actual features recorded during field tests. The mathematical model was solved in MathCad software. The study found that application of the Y25 bogie for a flat wagon with the designed parameters can decrease the dynamic load by 41.1% in comparison to that with the 18–100 bogie. Therefore, application of the Y25 bogie under a flat wagon with the actual parameters allows decreasing the dynamic loading by 41.4% in comparison to that with the 18–100 bogie. The study also looks at the service life of the supporting structure of a flat wagon with the Y25 bogie, which can be more than twice as long as the 18–100 bogie. The research can be of interest for specialists concerned with improvements in the dynamic characteristics and the fatigue strength of freight cars, safe rail operation, freight security, and the results of the research can be used for development of innovative wagon structures.

scholarly journals Effect of Rail Vehicle–Track Coupled Dynamics on Fatigue Failure of Coil Spring in a Suspension System

2021 ◽  
Vol 11 (6) ◽  
pp. 2650
Author(s):  
Sunil Kumar Sharma ◽  
Rakesh Chandmal Sharma ◽  
Jaesun Lee
Keyword(s):  
Mathematical Model ◽  
Fatigue Fracture ◽  
Suspension System ◽  
Railway Vehicle ◽  
Coil Spring ◽  
Internal Resonances ◽  
Rail Vehicle ◽  
Rail Vehicles ◽  
Stress Result ◽  
Wheel Track

In a rail vehicle, fatigue fracture causes a significant number of failures in the coil spring of the suspension system. In this work, the origin of these failures is examined by studying the rail wheel–track interaction, the modal analysis of the coil springs and the stresses induced during operation. The spring is tested experimentally, and a mathematical model is developed to show its force vs. displacement characteristics. A vertical 10-degree-of-freedom (DOF) mathematical model of a full-scale railway vehicle is developed, showing the motions of the car body, bogies and wheelsets, which are then combined with a track. The springs show internal resonances at nearly 50–60 Hz, where significant stresses are induced in them. From the stress result, the weakest position in the innerspring is identified and a few guidelines are proposed for the reduction of vibration and stress in rail vehicles.

The static and dynamic characteristics of a pressure relief valve with a proportional solenoid-controlled pilot stage

2002 ◽  
Vol 216 (2) ◽  
pp. 143-156 ◽  
Author(s):  
R Maiti ◽  
R Saha ◽  
J Watton
Keyword(s):  
Mathematical Model ◽  
Dynamic Characteristics ◽  
Dynamic Behaviour ◽  
Practical Experience ◽  
Pressure Relief Valve ◽  
Relief Valve ◽  
Pressure Relief ◽  
Static And Dynamic Characteristics ◽  
Good Comparison ◽  
The Mathematical Model

The steady state and dynamic characteristics of a two-stage pressure relief valve with proportional solenoid control of the pilot stage is studied theoretically as well as experimentally. The mathematical model is studied within the MATLAB-SIMULINK environment and the non-linearities have been considered via the use of appropriate SIMULINK blocks. The detailed modelling has resulted in a good comparison between simulation and measurement, albeit assumptions had to be made regarding the solenoid dynamic characteristic based upon practical experience. The use of this characteristic combined with additional dynamic terms not previously considered allows new estimations of internal characteristics to be made such as the damping flowrate. The overall dynamic behaviour has been shown to be dominated by the solenoid characteristic relating force to applied voltage.

An Applied Mathematical Model for Business Transformation and Enterprise Architecture

2020 ◽  
pp. 103-130
Keyword(s):  
Mathematical Model ◽  
Enterprise Architecture ◽  
Real Life ◽  
Development Project ◽  
Advanced Mathematics ◽  
Development Environment ◽  
Business Transformation ◽  
Natural Language Programming ◽  
High Level ◽  
Transformation Processes

The HMM research and development project concept (RDPC) uses factor-driven research and reasoning concept that is supported by a behaviour-driven development environment or a natural language programming that can be easily adopted by any RDPC, where the HMM framework offers such a high level factors editing their logic implementation environment that it can be used by any RDPC researchers without any prior knowledge in computer sciences, technical, or even advanced mathematics. The RDPC is a meta-model that can be used for research topics on enterprise architecture, business transformation or decision-making systems, mathematical models-algorithms. It is supported by many real-life cases. The uniqueness of this RDPC also promotes the future transformation project's unbundling and the alignment of various enterprise resources including services, architecture standards, and strategies to support business transformation processes as the first.

The Research and the Development of the 3D System Platform of Shafting Parts Based on CAA

2016 ◽  
Vol 693 ◽  
pp. 1886-1892 ◽  
Author(s):  
Hui Min Fang ◽  
Gang Zhao ◽  
Guo Zheng Zhang ◽  
Ping Xiao
Keyword(s):  
Secondary Development ◽  
Test Results ◽  
System Operation ◽  
Development Environment ◽  
Design Efficiency ◽  
Development Platform ◽  
Rapid Design ◽  
Component Development ◽  
Set Up

The enterprises when the designer worked with CATIA. In order to improve the efficiency, the research took the shaft parts as the research object to realize the secondary development of CATIA V5R18. The development platform of Shafting parts was set up through the embedded component development environment of CATIA CAA RADE and CAA API and was based on the development platform of VC++. At the end, this paper took the typical parts as examples to introduce the method of system operation. The test results show that this system could realize the rapid design and enhance the design efficiency, and it could provide the experience for the deeper development of CATIA.

Switched Model and Dynamic Analysis of a Hydroturbine Governing System in the Process of Load Rejection Transient

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Huanhuan Li ◽  
Diyi Chen ◽  
Feifei Wang ◽  
Hao Zhang
Keyword(s):  
Mathematical Model ◽  
Dynamic Analysis ◽  
Numerical Simulations ◽  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Hydropower Station ◽  
Transfer Coefficients ◽  
Operational Conditions ◽  
Governing System ◽  
Hammer Impact

In this paper, we pay attention to studying the switched model of the hydroturbine governing system (HTGS) by introducing the concept of the switching of operational conditions. More specifically, utilizing the data of an existent hydropower station in China, we propose six nonlinear dynamic transfer coefficients of the hydroturbine, which can better describe the dynamic characteristics of the HTGS in the process of load rejection transient. Moreover, the elastic water hammer-impact of the penstock system and the nonlinearity of the generator for the process of load rejection transient are considered. Based on the combination of the different regulation modes of the governor and the corresponding running conditions of the hydroelectric generating unit, a novel nonlinear dynamic switched mathematical model of the HTGS is finally established. Meanwhile, the nonlinear dynamic behaviors of the governing system are exhaustively investigated using numerical simulations. These methods and analytical results will provide some theory bases for running a hydropower station.

scholarly journals A Mathematical Model to Study the Coupling Effect of Deformation-Seepage-Heat Transfer on Coalbed Methane Transport and Its Simulative Application

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Jianlin Xie ◽  
Yangsheng Zhao
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
High Temperature ◽  
Pore Pressure ◽  
Coalbed Methane ◽  
Coupling Effect ◽  
Gas Content ◽  
High Temperature Water ◽  
Heat Injection ◽  
Temperature Water

Injection of high-temperature water or steam into low-permeability coalbed for efficient and rapid extraction of coalbed methane has been studied by our university for many years and will soon be implemented in the field. With comprehensive consideration of coupling of heat transfer, water seepage, desorption of coalbed methane, and coal-rock mass deformation, the paper establishes a more comprehensive mathematical model of the coupling effect of deformation-seepage-heat transfer on coalbed methane transport. Compared with the previous studies, this theoretical model considers the change of adsorbed and free coalbed methane at high temperature and the coalbed methane transport caused by a high-temperature gradient. Using the Tunlan Coal Mine of Shanxi Coking Coal Group to conduct the numerical simulations on the coalbed methane extraction project using heat injection technology, results show that (1) high-temperature water flowed towards the extraction hole along fractured fissures, with seepage towards the coal mass on both sides of the fissure at the same time, gradually heating the coalbed and forming an arcuate distribution of temperature from high to low for an area from the fractured fissure to the coalbed upper and lower boundaries. On the thirtieth day of heat injection, the temperature of the coalbed in the heat injection area ranged from 140°C to 260°C. (2) Under high temperatures, desorption of the coalbed gas was quick, and the adsorption gas content formed an oval funnel from the heat injection hole towards the extraction hole, centered by the fractured fissure, and migrating towards the coalbed upper and lower boundaries. Along with heat injection and extraction, the absorbed gas content rapidly decreased, and on the thirtieth day of injection, the absorbed gas content of the entire heat injection area decreased to 1.5 m3/t, only 7% of the original. (3) During heat injection, the coalbed gas pore pressure rapidly increased and reached 5.5 MPa on the tenth day, about 4.5 times the original, and the pore pressure steadied at 3.5 MPa on the thirtieth day of extraction. Such a high gas pressure gradient promoted the rapid flow and drainage of the gas.

Adapted Bouc-Wen Analytical Model for Romanian SERB-C Seismic Dampers Used in Buildings Protection System

2016 ◽  
Vol 823 ◽  
pp. 91-94 ◽  
Author(s):  
Adriana Ionescu ◽  
Cristian Burada ◽  
Mihai Negru
Keyword(s):  
Mathematical Model ◽  
Computational Simulation ◽  
Experimental Tests ◽  
Protection System ◽  
Hysteretic Model ◽  
Specific Adaptation ◽  
Analytical Simulation ◽  
The Mathematical Model ◽  
Force Displacement ◽  
Unusual Shape

In this paper is presented a new mathematical model which is intended to simulate the hysteretic phenomenon of SERB-C Romanian friction device for damping and dissipation of earthquake energy used for buildings. These devices have unusual shape of force-displacement loop which can be simulated with our new model which represents a specific adaptation of the well known Bouc-Wen hysteretic model. The purpose of this analytical simulation is to determine a relation for the hysteretic loop which was obtained by experimental tests performed by the authors. The mathematical model presented in this paper can be used in computational simulation of a building protected with these types of devices, in order to determine the anti-seismic performances of a Romanian friction building protection system.

Exact Solutions of the Vibration Problem of Beam Structures

2013 ◽  
Vol 390 ◽  
pp. 242-245 ◽  
Author(s):  
Alexander V. Chekanin
Keyword(s):  
Mathematical Model ◽  
Exact Solutions ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Numerical Solutions ◽  
High Accuracy ◽  
Displacement Method ◽  
Actual Problem ◽  
Beam Structures ◽  
The Mathematical Model

The article deals with the actual problem of improving the accuracy of determining the dynamic characteristics of beam structures. To solve such problems the displacement method is used. Defining matrices are calculated with the Godunovs scheme. Numerical solutions in this case can be obtained practically with any accuracy within accepted hypotheses of the mathematical model of the calculated object. This suggests that the resulting solutions are standard. The examples of determining the natural frequencies of vibrations of beam structures that demonstrate an extremely high accuracy of the proposed algorithm are given.

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