scholarly journals Active Control Method Based on Equivalent Stiffness and Damping Coefficient for an Electromagnetic Isolation System

2020 ◽  
Vol 10 (22) ◽  
pp. 7953
Author(s):  
Lei Zhang ◽  
Xiangtao Zhuan
Keyword(s):  
Control Method ◽  
Dynamic Performance ◽  
Damping Coefficient ◽  
Stiffness Coefficient ◽  
Equivalent Stiffness ◽  
Isolation System ◽  
Performance Indexes ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping ◽  
Active Control Method

For improving the performance of an electromagnetic isolation system with reasonable parameters and avoid the parameter tuning problem of a PID controller, an active control method is put forward based on equivalent stiffness and damping coefficient. In this paper, the range of equivalent stiffness coefficient and damping coefficient of the electromagnetic force are calculated based on the required range of dynamic performance indexes. According to the nonlinear expression between electromagnetic force and coil current and gap, the relationships between the coil current and equivalent stiffness coefficient and damping coefficient are established. Then, the equivalent stiffness coefficient and damping coefficient can be satisfied by the controlled current in different gaps for meeting the required dynamic performance indexes. For reducing the maximum overshoot and the number of oscillations of the system, the active control method with the piecewise equivalent stiffness and damping coefficient is proposed based on the piecewise control strategy to realize the variable control parameters of the isolation system. Simulation and experimental results verify that the control method based on the equivalent stiffness and damping coefficient can obtain the desired dynamic performance indexes and the proposed control method with the piecewise strategy can not only reduce the setting time of the system, but also ensure the stability of the system.

Experimental study on dynamic performance of typical nonballasted track systems using a full-scale test rig

2016 ◽  
Vol 231 (4) ◽  
pp. 470-481 ◽  
Author(s):  
Mingze Wang ◽  
Chengbiao Cai ◽  
Shengyang Zhu ◽  
Wanming Zhai
Keyword(s):  
Experimental Study ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Full Scale ◽  
Damping Coefficient ◽  
Full Scale Test ◽  
Test Rig ◽  
Scale Test ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping

This paper presents an experimental study on dynamic performance of China Railway Track System (CRTS) series track systems using a full-scale test rig. The test rig has been constructed based on 55.17 m long full-scale nonballasted tracks composed of four typical CRTS track elements in high-speed railways. First, the dynamic characteristics of different nonballasted tracks are investigated by conducting wheel-drop tests, where a wheel-drop testing vehicle with a dropping wheelset is devised to provide the wheel-drop load. The vibration levels of different track systems are assessed by the root-mean-square acceleration per one-third octave band, and the vibration transmission characteristics of the CRTS series tracks are evaluated by transfer functions. Further, a mathematical track model is used to extract the dynamic stiffness and damping coefficient of the four types of nonballasted track systems based on the wheel–rail impact response. The vibration characteristics, the dynamic stiffness, and damping coefficient of different nonballasted track systems under various wheel-drop heights are compared and discussed in detail.

A Theoretical Model for Calculating Vibration Characteristics of A Kind of Driver Seat with Air Spring and MR Damper

2011 ◽  
Vol 141 ◽  
pp. 8-14 ◽  
Author(s):  
Xing Xing Zhu ◽  
Si Hong Zhu
Keyword(s):  
Mr Damper ◽  
Damping Coefficient ◽  
Orifice Diameter ◽  
Equivalent Stiffness ◽  
Air Spring ◽  
Seat Suspension ◽  
Study Results ◽  
Stiffness And Damping Coefficient ◽  
Mr Damping ◽  
Stiffness And Damping

In order to further reduce the vibration transmitted from vehicle to driver, a new model of driver scissors linkage seat suspension was put forward, in which an air spring with auxiliary chamber and a MR damper are between the face and floor of the seat. The motion differential equation of this seat suspension system was established and the theoretical computing formulation of it’s equivalent vertical stiffness, equivalent damping coefficient, natural frequency and damping rate were deduced. Besides, taking HY-Z04 scissors linkage seat, SK37-6 air spring of ContiTech and RD-1005-3 MR damper of LORD as an example, the equivalent stiffness and damping coefficient in different conditions of the air spring pressure, the sprung mass, the orifice diameter and MR damping were computed and analyzed. The study results show that the air spring pressure, the sprung mass, the orifice diameter and MR damping all have obvious influence on the equivalent stiffness and damping coefficient, so the seat comfort can be improved by changing the air spring pressure, the orifice diameter and MR damping according to driver’s weight and road condition.

A novel technique to compute static and dynamic performance characteristics of aerostatic thrust bearing

2018 ◽  
Vol 70 (1) ◽  
pp. 84-96 ◽  
Author(s):  
Saurabh Kumar Yadav ◽  
Arvind Kumar Rajput ◽  
Nathi Ram ◽  
Satish Chandra Sharma
Keyword(s):  
Finite Element ◽  
Thrust Bearing ◽  
Dynamic Performance ◽  
Finite Element Formulation ◽  
Damping Coefficient ◽  
Element Formulation ◽  
Content Type ◽  
Novel Technique ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping

Purpose This study aims to analyze the dynamic performance of aerostatic thrust bearing for different geometries of recess. Different geometries of recess of equal recess area, i.e. circular, elliptical, rectangular and annular, have been considered in analysis. The work also analyzes the influence of tilt angle on the performance of thrust bearing. To compute the unknown pressure field, the Reynolds equation governing the flow of compressible lubricant (air) has been solved using finite element formulation. Further, separate finite element formulations have been carried out to compute fluid film stiffness and damping coefficients directly. This method provides quick computation of stiffness and damping coefficients of aerostatic thrust bearing than the usual approach. Design/methodology/approach As the Reynolds equation governing the flow of compressible lubricant is nonlinear partial differential equation, the computation of the stiffness and damping coefficient follows an iterative procedure. It requires a lot of computational energy. Therefore, in the present work, a novel technique based on finite element formulation is suggested to compute air film stiffness and damping coefficient in aerostatic thrust bearing. Findings A novel technique based on finite element formulation is illustrated to simulate the performance of tilted pad aerostatic thrust bearing. On the basis of simulated results, following key conclusions may be drawn. The static and dynamic performance of a circular aerostatic tilted thrust pad bearing is significantly affected with a change in the value of tilt parameter and the shape of the recess. Research limitations/implications Implications are as follows: direct computation of air film damping coefficient is performed without perturbation method in finite element method (FEM); influence of tilt on aerostatic thrust bearing is studied; influence of recess shape on aerostatic thrust bearing is observed; and finite element formulation of aerostatic thrust bearing is performed. Originality/value The present work will be quite useful for bearing designer and academicians.

Numerical analysis of the dynamic performance of aerostatic thrust bearings with different restrictors

2018 ◽  
Vol 233 (3) ◽  
pp. 406-423 ◽  
Author(s):  
Hailong Cui ◽  
Yang Wang ◽  
Xiaobin Yue ◽  
Yifei Li ◽  
Zhengyi Jiang
Keyword(s):  
Load Capacity ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Dynamic Mesh ◽  
Eccentricity Ratio ◽  
Thrust Bearings ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping ◽  
The Impact ◽  
The Relationship

This study utilizes a dynamic mesh technology to investigate the dynamic performance of aerostatic thrust bearings with orifice restrictor, multiple restrictors, and porous restrictor. An experiment, which investigates the bearing static load capacity, was carried out to verify the calculation accuracy of dynamic mesh technology. Further, the impact of incentive amplitude, incentive frequency, axial eccentricity ratio, and non-flatness on the bearing dynamic performance was also studied. The results show incentive amplitude effect can be ignored at the condition of amplitude less than 5% film thickness, while the relationship between dynamic characteristics and incentive frequency presented a strong nonlinear relationship in the whole frequency range. The change law of dynamic stiffness and damping coefficient for porous restrictor was quite different from orifice restrictor and multiple restrictors. The bearing dynamic performance increased significantly with the growth of axial eccentricity ratio, and the surface non-flatness enhanced dynamic performance of aerostatic thrust bearings.

Research on the Tension Effects on Automobile Damping Synchronous Belt Transmission System Damping and Dynamic Stiffness

2014 ◽  
Vol 687-691 ◽  
pp. 407-410
Author(s):  
Yao Chen Shi ◽  
Zhan Guo Li ◽  
Dan Liu
Keyword(s):  
Solution Method ◽  
Dynamic Stiffness ◽  
Damping Coefficient ◽  
Stiffness Coefficient ◽  
Driving System ◽  
Automotive Engine ◽  
Vibration Absorption ◽  
Belt Transmission ◽  
Stiffness And Damping ◽  
Main Factor

because of the synchronism belts driving has the advantages of vibration absorption, noise reduction, constant transmission ratio, so it is widely used in automotive engine timing driving system, The stiffness and damping coefficients of the synchronous belt is the main factor affecting the synchronous belt transmission in the process of vibration and noise. In this paper, the model W automotive synchronous belt is simplified as a spring damper system, to solve the stiffness coefficient and damping coefficient of synchronous belt, design of a device for measuring the synchronous belt stiffness coefficient and damping coefficient, measured the belt stiffness coefficient and damping coefficient in the conditions of different tension, and the accuracy of the solution method for synchronous belt stiffness coefficient and damping coefficient was verified as well.

Study on Dynamics Characteristics of SINS Damping System in Shock Environment

2013 ◽  
Vol 397-400 ◽  
pp. 355-358
Author(s):  
Xia Qing Tang ◽  
Jun Qiang Gao ◽  
Li Bin Guo ◽  
Huan Zhang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Optimal Design ◽  
Vibration Isolation ◽  
Damping Coefficient ◽  
Shock Environment ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping ◽  
Element Method

Dynamics characteristics of SINS damping system in shock environment were analyzed by finite element method, as the deformation of dampers may leads to the accuracy loss of SINS. In addition, the influence of absorber stiffness and damping coefficient on dynamics characteristics were studied. The results indicate that the decoupling of vibrations is significant for the accuracy of SINS. However, considering the almost impossible of completely decoupled vibrations, its necessary to carry out an optimal design of the absorber stiffness and damping coefficient to maintain the accuracy of SINS while meeting the requirement of vibration isolation.

scholarly journals Influence of Floating Ring Seal Working Condition Parameters on the Dynamic Characteristics of Transient Gas Film

2021 ◽  
Vol 2108 (1) ◽  
pp. 012087
Author(s):  
Lishan Xu ◽  
Weizheng Zhang ◽  
Junjie Lu ◽  
Zhu Liu
Keyword(s):  
Film Thickness ◽  
High Speed ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Spiral Groove ◽  
Low Leakage ◽  
Ring Seal ◽  
Stiffness And Damping Coefficient ◽  
Small Perturbation Method ◽  
Stiffness And Damping

Abstract The high requirements for sealing performance in high-speed rotating machinery has led to the design of floating seal with annular spiral groove that offer the advantages of low leakage and extended stability. However, efforts to model the dynamic performance of these floating seal have suffered from the great complexity of the flow field. The present work addresses this issue by establishing a transient Reynolds formulation of a floating seal with annular spiral groove in a rotating coordinate system based on the small perturbation method. In addition, the influence of radial eccentricity and film thickness on the solution divergence and calculation accuracy is calculated. The dynamic stiffness and dynamic damping matrixes are built. Then the variation rules of the dynamic stiffness and damping coefficient of the gas film with structure and working conditions are investigated in detail. The results show that the floating ring seal is more suitable for the service conditions of small film thickness, low pressure, high speed and large eccentricity. Accordingly, the results obtained lay a theoretical foundation for evaluating real-world applications of floating ring seal.

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