Nonlinear Investigation of the Effect of Primary Suspension on the Hunting Stability of a Rail Wheelset

Joint Rail ◽  
2004 ◽  
Author(s):  
Anant Mohan ◽  
Medhi Ahmadian
Keyword(s):  
Nonlinear Dynamics ◽  
Single Point ◽  
Stability Study ◽  
Lateral Stiffness ◽  
Lateral Stability ◽  
Longitudinal Stiffness ◽  
Creep Characteristics ◽  
Hunting Stability ◽  
Stiffness And Damping ◽  
The Mathematical Model

The mathematical model of a single railway wheelset moving with constant speed on a smooth, level, and tangential track is used to numerically investigate the nonlinear dynamics of the wheelset. Nonlinearities in the wheelset model include the nonlinear wheel-rail profile and the friction-creep characteristics of the wheel-rail contact geometry. Wheelset numerical simulations consider single-point and two-point wheel-rail contact scenarios. Sensitivity of the critical hunting velocity to primary stiffness and damping parameters is examined. Results of the lateral stability study indicate that the critical hunting velocity of the wheelset is most sensitive to the primary longitudinal and lateral stiffness. Methods involving semi-active and active control of the primary longitudinal stiffness are developed to raise the critical velocity of hunting. These approaches are seen to considerably increase the wheelset critical hunting velocity.

Over Voltage Protection Device Based on Multi-Strategy

2011 ◽  
Vol 464 ◽  
pp. 53-56
Author(s):  
Hai Tao Zhang ◽  
Gang Li
Keyword(s):  
Electromagnetic Interference ◽  
Measurement Errors ◽  
Fuzzy Neural Network ◽  
Single Point ◽  
Protection Device ◽  
Fuzzy Neural ◽  
Single Strategy ◽  
Sensor Monitoring ◽  
The Mathematical Model ◽  
Control Accuracy

Strong electromagnetic interference occurs when the locomotive was running. Therefore, measurement errors resulted from interference exist when monitoring the rail potential only at single point. This will lead to misoperation of the protection device. An over voltage protection device based on multipoint and multi-strategy was designed. The mathematical model of rail potential distribution was built. Fuzzy neural network and multi-sensor monitoring technology were applied in this design. The emulation analysis demonstrated that the proposed device has better reliability and higher control accuracy than the single strategy approach.

scholarly journals Research on the Influencing Factors of "Scale Veins" of Single Point Incremental Forming Workpieces Surface

2015 ◽  
Vol 9 (1) ◽  
pp. 1025-1032
Author(s):  
Shi Pengtao ◽  
Li Yan ◽  
Yang Mingshun ◽  
Yao Zimeng
Keyword(s):  
Surface Quality ◽  
Incremental Forming ◽  
Single Point ◽  
Spindle Speed ◽  
Experimental Results ◽  
Feed Speed ◽  
Single Point Incremental Forming ◽  
Machining Parameters ◽  
The Mathematical Model

To furthermore optimize the machining parameters and improve the surface quality of the workpieces manufactured by single point incremental forming method, the formation mechanism of the sacle veins on the metal incremental froming workpieces was studied through experiment method. The influence principle of the spindle speed, the feed speed and the material of tip of tools on the length of scale veins was obtained through analyzing the experimental results and building the mathematical model among the length of scale veins were feed speed and spindle speed through measuring the roughness of surfaces and observing the appearance of the forming workpieces. The experimental results showed that, the spindle speed, the feed speed and the material of tool tips have a significant effect on the scale veins formation on the surface of forming workpieces. Therefore, an appropriate group of spindle speed and feed speed can reduce the effect of scale veins on the roughness of single point incremental forming workpieces and furthermore improve the surface quality of forming workpieces.

scholarly journals The Vibration of Simply Supported Non-Uniform Cross Sectional Pipe Conveying Fluid Resting on Viscoelastic Foundation

2020 ◽  
Vol 15 ◽  
Keyword(s):  
Natural Frequencies ◽  
Flexural Vibration ◽  
Bernoulli Model ◽  
Viscoelastic Foundation ◽  
Cross Sectional ◽  
Flowing Fluid ◽  
Simply Supported ◽  
Critical Velocities ◽  
Stiffness And Damping ◽  
The Mathematical Model

The induced flexural vibration of slender pipe systems with continuous non uniform cross sectional area containing laminar flowing fluid lying on extended Winkler viscoelastic foundation is considered. The Euler Bernoulli model of the pipe has hinged ends. The inlet flow is considered constant steady that interacts with the wall of the pipe. The mathematical model is developed and its corresponding solution is obtained. The influence of the combination of variation of cross section, foundation stiffness and damping on the critical velocities, complex natural frequencies and stabilization of the system is presented.

Testing of modified primary stiffness for heavy-haul locomotives operating on sharper-radius curves

2019 ◽  
Vol 233 (3) ◽  
pp. 531-548
Author(s):  
Pengfei Liu ◽  
Kai Wei ◽  
Kaiyun Wang ◽  
Quanbao Feng
Keyword(s):  
Load Transfer ◽  
Ride Comfort ◽  
Lateral Force ◽  
Mean Value ◽  
Lateral Stiffness ◽  
Coupled Vibration ◽  
Radial Stiffness ◽  
Longitudinal Stiffness ◽  
Negotiation Performance ◽  
Heavy Haul

For the typical wheelset drive subsystem with axle-suspended motor, the coupled vibration differential equations of wheelset and axle hung motor are derived. The mechanical model of traction rod is established. The subsystems are integrated into a whole locomotive-track coupled dynamic model which is verified from the aspects of load transfer and curving negotiation performance. To reduce the wheel–rail dynamic interaction of six-axle heavy-haul locomotive passing through curves in old existing lines, the parametric optimization flow of primary rubber joint is presented. The stiffness of 12 new rubber joints equipped in drawbars is tested and the stiffness dispersions are investigated. The research results show that, for a single rubber joint, the maximum and minimum values of radial stiffness can, respectively, increase and reduce by 16.2% and 33% with respect to the test mean value. For the assembled axle-box with upper and lower drawbars, the test longitudinal and lateral stiffness increase by 18% and 46%, respectively, relative to the designed values. A distinct dispersion phenomenon in the stiffness distributions of rubber samples is found. By combining with the numerical simulation results, the primary longitudinal stiffness is optimized from 199 MN/m to 52 MN/m, as the lateral stiffness changes from 6.89 MN/m to 2.6 MN/m. The final running test indicates that the optimized parameters can reduce the wheel–rail lateral force by 12% in the 300 m radius curve. The ride comfort could still keep in the same level, and the running stability has not been deteriorated.

scholarly journals Modern Surfboards and Their Structural Characterization: Towards an Engineering Approach

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 65
Author(s):  
Luca Oggiano ◽  
Marc in het Panhuis
Keyword(s):  
Computer Aided Design ◽  
Polyester Resin ◽  
Expanded Polystyrene ◽  
Torsional Stiffness ◽  
Hydrodynamic Properties ◽  
Longitudinal Stiffness ◽  
Custom Made ◽  
Computer Aided ◽  
Stiffness And Damping ◽  
Aided Design

Recently, manufactures who produce surfboards using computer aided design and robotic (CNC) shaping tools have gained a larger share of the surfing market, allowing board producers and shapers to produce lighter and more durable boards. The improvement in design and production process of surfboards has been directly linked with the adaption of technologies tested and validated in other industries. However, the surfing industry still lacks methodologies, standards and testing facilities to scientifically investigate and quantify the structural and hydrodynamic properties of surfboards. It is widely accepted that distributed rigidity, damping and stiffness in the three directions play a huge role in defining surfboard performance. These properties are rarely stated by producers and never measured. The present paper compares two boards with equal outline and geometric shape but built with two different technologies: one board built with a traditional high density polyurethane (PU) blank, polyester resin and a stringer to improve longitudinal stiffness and one board built with bio epoxy resin, expanded polystyrene (EPS) and two side inserts made of cork to improve longitudinal stiffness and damping. Different tests were carried out to compare the two boards and a testing methodology with the aim to evaluate board structural properties and identify key parameters that will influence the board performances. Accelerometers were used to characterize stiffness and damping while a custom-made flex machine was used to evaluate the torsional stiffness. Differences between the two boards are highlighted, leading to the fact that the two boards, even being identical in size, will behave differently in different wave conditions and for different surfers.

An Efficient Approach to Define the Input Stimuli to Suppress Epileptic Seizures Described by the Epileptor Model

2020 ◽  
Vol 30 (11) ◽  
pp. 2050062
Author(s):  
João Angelo Ferres Brogin ◽  
Jean Faber ◽  
Douglas Domingues Bueno
Keyword(s):  
Nonlinear Dynamics ◽  
Mathematical Model ◽  
Exact Solution ◽  
Feedback Control ◽  
Epileptic Seizures ◽  
Neural Dynamics ◽  
Practical Application ◽  
Control Gain ◽  
The World ◽  
The Mathematical Model

Epilepsy affects about 70 million people in the world. Every year, approximately 2.4 million people are diagnosed with epilepsy, two-thirds of them will not know the etiology of their disease, and 1% of these individuals will decease as a consequence of it. Due to the inherent complexity of predicting and explaining it, the mathematical model Epileptor was recently developed to reproduce seizure-like events, also providing insights to improve the understanding of the neural dynamics in the interictal and ictal periods, although the physics behind each parameter and variable of the model is not fully established in the literature. This paper introduces an approach to design a feedback-based controller for suppressing epileptic seizures described by Epileptor. Our work establishes how the nonlinear dynamics of this disorder can be written in terms of a combination of linear sub-models employing an exact solution. Additionally, we show how a feedback control gain can be computed to suppress seizures, as well as how specific shapes applied as input stimuli for this purpose can be obtained. The practical application of the approach is discussed and the results show that the proposed technique is promising for developing controllers in this field.

Research on Vibration Model of Special Vehicle Based on Dual-Mass System

2013 ◽  
Vol 385-386 ◽  
pp. 89-92 ◽  
Author(s):  
Ya Jun Shao ◽  
Qin He Gao ◽  
Hong Jie Cheng
Keyword(s):  
Characteristic Curve ◽  
Suspension System ◽  
Mass System ◽  
Nonlinear Characteristics ◽  
Actual Structure ◽  
Vibration Model ◽  
Special Vehicle ◽  
Set Up ◽  
Stiffness And Damping ◽  
The Mathematical Model

Taking a special vehicle vibration system as the research object, according to the actual structure of the chassis, the spring damping and stiffness of the nonlinear characteristics and the tire vertical elastic accounted, a nonlinear vibration model of special vehicle based on dual-mass-system is set up. The tire radial stiffness value is analyzed in Ansys, a simulation is performed by leading the mathematical model of suspension system into Adams, a characteristic curve of stiffness and damping of suspension system is obtained.

Dynamic Modelling and Analysis of Rectangle-Shaped Plastic-Coated Slideways in Machine Tools

2011 ◽  
Vol 50-51 ◽  
pp. 37-41
Author(s):  
Jian Fu Zhang ◽  
Zhi Jun Wu ◽  
Ping Fa Feng ◽  
Ding Wen Yu
Keyword(s):  
Mathematical Model ◽  
Machine Tools ◽  
Vibration Mode ◽  
Dynamic Modelling ◽  
Rigid Bodies ◽  
Theoretical Research ◽  
Damping Characteristics ◽  
Vibration Properties ◽  
Stiffness And Damping ◽  
The Mathematical Model

The plastic-coated slideways have been widely used for form-generating movement in machine tools. Its dynamic behavior plays an important role in the vibration properties of the whole machine. In this work, according to the situation that researches on this subject were rather insufficient, a theoretical research was analyzed concerning the stiffness and damping characteristics of rectangle-shaped plastic-coated slideways. The mathematical model was firstly suggested especially based on the assembly of the saddle and worktable. Both stiffness and damping characteristics on vertical and horizontal directions were theoretically determined. To derive the governing motion equation of the slideway system, the carriage and rail were considered as rigid bodies and connected with a series of spring and damping elements at the joint face. Moreover, through the Lagrange’s approach, the frequencies of the carriage at vertical, pitching, yawing and rolling vibration mode were identified.

Investigation of Rub-Impact Setup Supported on Flexible Multi-Bearing Rotor

2012 ◽  
Author(s):  
Abdulazim H. Falah ◽  
Emad A. Khorshid ◽  
Khalid A. Alhazza
Keyword(s):  
Nonlinear Dynamics ◽  
Mathematical Model ◽  
Ball Bearings ◽  
Vibration System ◽  
Test Rig ◽  
Chaotic Response ◽  
Impact Device ◽  
Modeling And Experiments ◽  
In The Beginning ◽  
The Mathematical Model

Vibration system investigation of the chaotic response of full annular rub impact rotor system supported on two ball bearings is investigated. Modeling and experiments of nonlinear dynamics on flexible multi-bearing rotor test rig is presented in this work. The test rig has two balancers that are assembled on rotor shaft, a rub impact device at the center, and ball bearings at both ends of the shaft. A 12-degree-of-freedom (DOF) linear model was developed for this test rig. The mathematical model was developed in the beginning without considering the rub impact part in order to validate the model with the experiment results. Then, then experimentally chaotic response and bifurcation diagram of the rub impact system were investigated.

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