NONLINEAR ANALYSIS OF SELF-EXCITED VIBRATION IN WHEELED TRACTOR VEHICLE’S DRIVELINE

X.-H. LI,J.-W. ZHANG,C.-C. ZENG 한국자동차공학회 2006 International journal of automotive technology Vol.7 No.5

A nonlinear analysis of torsional self-excited vibration in the driveline system for wheeled towing tractors was presented, with a 2-DOF mathematical model. The vibration system was described as a second-order ordinary differential equation. An analytical approach was proposed to the solution of the second-order ODE. The mathematical neighborhood concept was used to construct the interior boundary and the exterior boundary. The ODE was proved to have a limit cycle by using Poincare-Bendixson Annulus Theorem when two inequalities were satisfied. Because the two inequalities are easily satisfied, the self-excited vibration is inevitable and even the initial slip rate is little. However, the amplitude will be almost zero when the third inequality is satisfied. Only in a few working modes of the towing tractor the third inequality is not satisfied. It is shown by experiments that the torsional self-excited vibration in the driveline of the vehicle is obvious.

Vibration control of high-speed trains self-excitation under-chassis equipment by HSLDS vibration isolators

Yu Sun,Jinsong Zhou,Dao Gong,Wenjing Sun,Zhanghui Xia 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1

To minimize the self-excitation effects of the equipment on the carbody, a high static and low dynamic stiffness (HSLDS) vibration isolator is proposed by connecting a negative stiffness unit and a positive linear stiffness spring in parallel. The nonlinear stiffness of the HSLDS isolator can be designed according to the needs of any target stiffness curve. A vibration test is applied to obtain the vibration acceleration of the under-chassis equipment. A rigid-flexible coupling multi-body dynamic model of a high-speed train is established which considers the elastic vibration of the carbody and the self-excitation of the under-chassis equipment based on the tested result. Different connection methods of the under-chassis equipment including rigid hanging, vibration isolation theory (VIT) hanging, dynamic vibration absorber (DVA) hanging and HSLDS hanging are applied and their effects on the carbody vibration and ride quality are investigated. The simulation results reveal that the proposed HSLDS vibration isolator can effectively isolate the self-excitation of the under-chassis equipment from the carbody and enhance the ride quality of the high-speed train.

NONLINEAR ANALYSIS OF SELF-EXCITED VIBRATION IN WHEELED TRACTOR VEHICLE'S DRIVELINE

Li, X.H.,Zhang, J.W.,Zeng, C.C. The Korean Society of Automotive Engineers 2006 International journal of automotive technology Vol.7 No.5

A nonlinear analysis of torsional self-excited vibration in the driveline system for wheeled towing tractors was presented, with a 2-DOF mathematical model. The vibration system was described as a second-order ordinary differential equation. An analytical approach was proposed to the solution of the second-order ODE. The mathematical neighborhood concept was used to construct the interior boundary and the exterior boundary. The ODE was proved to have a limit cycle by using $Poincar\'{e}-Bendixson$ Annulus Theorem when two inequalities were satisfied. Because the two inequalities are easily satisfied, the self-excited vibration is inevitable and even the initial slip rate is little. However, the amplitude will be almost zero when the third inequality is satisfied. Only in a few working modes of the towing tractor the third inequality is not satisfied. It is shown by experiments that the torsional self-excited vibration in the driveline of the vehicle is obvious.

The self-excited vibrations of an axially retracting cantilever beam using the Galerkin method with fitted polynomial basis functions

Hongliang Hua,Zhenqiang Liao,Xiangyan Zhang 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.1

In the present study, the self-excited vibrations of an axially retracting beam under gravity is investigated. A GFB method is presented to discretize the system energy functions, in which the orthogonality relationships between the basis functions are needless. In this way, the motion equations can be derived in a much simpler way of matrix. The presented method and the derived motion equations are validated by comparing the computed results with which from previous literature. Based on the computed dynamic responses, the effect of gravity on beam dynamic behavior is investigated. An interesting phenomenon of self-excited vibration is observed as the beam retracts with a certain axial speed. Finally, the effects of retracting speed, structural damping and static tip deflection on self-excited vibration are investigated.

Coupled bending and torsional vibration of a rotor system with nonlinear friction

Chunli Hua,Guohua Cao,Zhushi Rao,Na Ta,Zhencai Zhu 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.6

Unacceptable vibrations induced by the nonlinear friction in a rotor system seriously affect the health and reliability of the rotating machinery. To find out the basic excitation mechanism and characteristics of the vibrations, a coupled bending and torsional nonlinear dynamic model of rotor system with nonlinear friction is presented. The dynamic friction characteristic is described with a Stribeck curve, which generates nonlinear friction related to relative velocity. The motion equations of unbalance rotor system are established by the Lagrangian approach. Through numerical calculation, the coupled vibration characteristics of a rotor system under nonlinear friction are well investigated. The influence of main system parameters on the behaviors of the system is discussed. The bifurcation diagrams, waterfall plots, the times series, orbit trails, phase plane portraits and Poincaré maps are obtained to analyze dynamic characteristics of the rotor system and the results reveal multiform complex nonlinear dynamic responses of rotor system under rubbing. These analysis results of the present paper can effectively provide a theoretical reference for structural design of rotor systems and be used to diagnose selfexcited vibration faults in this kind of rotor systems. The present research could contribute to further understanding on the self-excited vibration and the bending and torsional coupling vibration of the rotor systems with Stribeck friction model.

An analysis of the self-excited torsional vibration of high-speed train drive system

Kun Xu,Jing Zeng,Lai Wei 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.3

In this paper, a simplified torsional vibration model of drive system with three degrees of freedom is established, and the elasticity of wheelset is considered. In addition to the same wheel-rail adhesion condition for the two wheels, the different wheel-rail adhesion conditions for the two wheels have been considered for the first time, and the mechanism of the vibration forms is explained from the viewpoint of energy. The nonlinear system is linearized at the origin (equilibrium position), and the critical stability curve of the linearized system is drawn according to the eigenvalues of the linearized system in the state space. The results show that the vibration forms of the system are mainly determined by the relationships between the average creep rate and the critical creep rate of the wheel driven directly by motors. When the resistance moments do positive work on the system, they input energy to the system, and the responses do not tend to the origin and produce self-excited vibration. When the resistance moments do negative work on the system, they dissipate energy to system, and the responses tend to the origin. For the linearized system at the origin, the system is more stable at the origin when following factors occur, a gentler negative slope of the adhesion curve, a faster speed, a lighter wheel load, and a larger the moment of inertia of wheels.

Aerodynamic and aero-elastic performances of super-large cooling towers

Lin Zhao,Xu Chen,Shitang Ke,Yaojun Ge 한국풍공학회 2014 Wind and Structures, An International Journal (WAS Vol.19 No.4

Hyperbolic thin-shell cooling towers have complicated vibration modes, and are very sensitive to the effects of group towers and wind-induced vibrations. Traditional aero-elastic models of cooling towers are usually designed based on the method of stiffness simulation by continuous medium thin shell materials. However, the method has some shortages in actual engineering applications, so the so-called “equivalent beam-net design method” of aero-elastic models of cooling towers is proposed in the paper and an aero-elastic model with a proportion of 1: 200 based on the method above with integrated pressure measurements and vibration measurements has been designed and carried out in TJ-3 wind tunnel of Tongji university. According to the wind tunnel test, this paper discusses the impacts of self-excited force effect on the surface wind pressure of a large-scale cooling tower and the results show that the impact of self-excited force on the distribution characteristics of average surface wind pressure is very small, but the impact on the form of distribution and numerical value of fluctuating wind pressure is relatively large. Combing with the Complete Quadratic Combination method (hereafter referred to as CQC method), the paper further studies the numerical sizes and distribution characteristics of background components, resonant components, cross-term components and total fluctuating wind-induced vibration responses of some typical nodes which indicate that the resonance response is dominant in the fluctuating wind-induced vibration response and cross-term components are not negligible for wind-induced vibration responses of super-large cooling towers.

Aerodynamic and aero-elastic performances of super-large cooling towers

Zhao, Lin,Chen, Xu,Ke, Shitang,Ge, Yaojun Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.19 No.4

Hyperbolic thin-shell cooling towers have complicated vibration modes, and are very sensitive to the effects of group towers and wind-induced vibrations. Traditional aero-elastic models of cooling towers are usually designed based on the method of stiffness simulation by continuous medium thin shell materials. However, the method has some shortages in actual engineering applications, so the so-called "equivalent beam-net design method" of aero-elastic models of cooling towers is proposed in the paper and an aero-elastic model with a proportion of 1: 200 based on the method above with integrated pressure measurements and vibration measurements has been designed and carried out in TJ-3 wind tunnel of Tongji university. According to the wind tunnel test, this paper discusses the impacts of self-excited force effect on the surface wind pressure of a large-scale cooling tower and the results show that the impact of self-excited force on the distribution characteristics of average surface wind pressure is very small, but the impact on the form of distribution and numerical value of fluctuating wind pressure is relatively large. Combing with the Complete Quadratic Combination method (hereafter referred to as CQC method), the paper further studies the numerical sizes and distribution characteristics of background components, resonant components, cross-term components and total fluctuating wind-induced vibration responses of some typical nodes which indicate that the resonance response is dominant in the fluctuating wind-induced vibration response and cross-term components are not negligible for wind-induced vibration responses of super-large cooling towers.

Synchronization of pneumatic vibroexciters under air cushion operating mode in a self-exciting autovibration regime

Edmundas Kibirkštis,Darius Pauliukaitis,Valdas Miliūnas,Kazimieras Ragulskis 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.9

A synchronization and phase control method for pneumatic vibroexciters that operate under a self-exciting vibration mode was proposed using a channel with an aerodynamic link. A mathematical model for nonlinear equations that numerically described the dynamics of two vibroexciters was built. Results showed that the qualitative model described the dynamics of a mechanical system. Vibrations of equal phases were obtained in both vibroexciters. A consistent pattern of transformation into a self-exciting vibration regime was determined. The synchronization conditions of the vibroexciters were presented. The effects of the geometric parameters of the synchronization channel on the vibrations of the working body of a vibroexciter were determined. Lastly, the range of the vibration transformation of the vibroexciters toward a synchronous equal frequency was investigated.

摩擦面에서 發生되는 스퀼 騷音에 關한 硏究

한경,이민호,이준서,이해철,차경옥 明知大學校 産業技術硏究所 1999 産業技術硏究所論文集 Vol.18 No.-

There are various noises generated by friction. Among the rest, eliminating squeal noise generated during braking is an important task for the improvement of vehicle passenger's comport. The parameters affecting brake squeal noise are the material properties of the braking pad, the dynamic properties of the brake parts and the dimensions of the brake assembly etc. Also, the squeal noise changes its inherent form(i.e. its sound pressure level and its frequency) with the normal load and sliding speed. In this study, the characteristics of brake squeal noise generated by friction is analyzed experimentally. The experiment focused on the analysis of friction self-excited vibration and squeal noise level. Friction self-excited vibration is caused by the dry friction between pads and rotor, and occurs as a function of their relative sliding speeds. and Friction self-excited vibration is raised the brake squeal noise.