Study on the Influence of the Damping to Nonlinear Vibration Caused by Pair Clearance

2010 ◽  
Vol 139-141 ◽  
pp. 2376-2380 ◽  
Author(s):  
Ying Cai Yuan ◽  
Yan Li ◽  
Yi Ming Wang
Keyword(s):  
Nonlinear Vibration ◽  
Relative Motion ◽  
Nonlinear Dynamic Model ◽  
Continuous Contact ◽  
Object A ◽  
Large Pair ◽  
Joint Clearances ◽  
Continuous Contact Model ◽  
Weak Damping ◽  
Lubrication Conditions

Because the two components have relative motion, pair clearance is inevitable. With the machine’s speed increasing, nonlinear vibration phenomenon caused by clearance is much obviously. The state of damping in pair clearance will often make mechanism’s nonlinear vibration appear different status. For the study of damping in joint clearances impact to nonlinear vibration, four-bar mechanism with clearance is taken as research object. A nonlinear dynamic model has been established based on continuous contact model. Through analysis the nonlinear vibration in different damping and clearance, it can be found that in weak damping condition, nonlinear vibration in small pair clearance is more sensitive to the small changes of damping than that in large pair clearance. So, it’s very important to keep the pair clearance in proper lubrication conditions.

Application of Dry-Friction Whip and Whirl Solution Methods to Systems With Support Asymmetry

2018 ◽  
Author(s):  
Jason C. Wilkes
Keyword(s):  
Relative Motion ◽  
General Model ◽  
Dry Friction ◽  
Current Work ◽  
General Sense ◽  
Continuous Contact ◽  
Solution Methods ◽  
Asymmetric Rotor ◽  
Two Bodies

Dry-friction whip and whirl occurs when a rotor contacts a stator across a clearance annulus. In a general sense, the relative motion between the two bodies is described by a circular precessing motion. While this problem is generally well understood, the author is unaware of any papers that discuss the problem for systems having asymmetric rotor or stator supports. The current work will investigate a general model to describe dry-friction whip and whirl for the case of continuous contact between a rotor and stator in the presence of asymmetry. This paper will show that for light asymmetry, the rotor and stator motions are elliptical; however, the relative motion between the two bodies remains circular.

scholarly journals Self-synchronization characteristics of a class of nonlinear vibration system with asymmetrical hysteresis

2019 ◽  
Vol 39 (1) ◽  
pp. 114-128
Author(s):  
Nan Zhang
Keyword(s):  
Nonlinear Vibration ◽  
Power Supply ◽  
The Self ◽  
Vibration System ◽  
Nonlinear Dynamic Model ◽  
Synchronous System ◽  
Vibrating System ◽  
Synchronous Operation ◽  
Hysteretic Characteristics ◽  
Nonlinear Vibration System

The self-synchronization characteristics of the two excited motors for the nonlinear vibration system with the asymmetrical hysteresis have been proposed in the exceptional circumstances of cutting off the power supply of one of the two excited motors. From the point of view of the hysteretic characteristics with the asymmetry, a class of nonlinear dynamic model of the self-synchronous vibrating system is presented for the analysis of the hysteretic characteristics of the soil, which is induced by the relation between the stress and the strain in the soil. The periodic solutions for the self-synchronous system with the asymmetrical hysteresis are investigated using nonlinear asymptotic method. The synchronization condition for the self-synchronous vibrating pile system with the asymmetrical hysteresis is theoretical analyzed using the rotor–rotation equations of the two excited motors. The synchronization stability condition also is theoretical analyzed using Jacobi matrix of the phase difference equation of the two excited motors. Using Matlab/Simlink, the synchronous operation of the two excited motors and the synchronous stability operation of the self-synchronous system with the asymmetrical hysteresis are analyzed through the selected parameters. Various synchronous phenomena are obtained through the difference rates of the two excited motors, including the different initial phase and the different initial angular velocity, and so on. Especially, when there is a certain difference in the two excited motors, the synchronous operation of the two excited motors and the synchronous stability operation of the self-synchronous vibrating system with the asymmetrical hysteresis can still be achieved after the power supply of one of the two excited motors has been disconnected. It has been shown that the research results can provide a theoretical basis for the research of the vibration synchronization theory.

Characterization of the Damping Coefficient in the Continuous Contact Model

2019 ◽  
Author(s):  
Mohammad Poursina ◽  
Parviz E. Nikravesh
Keyword(s):  
Contact Force ◽  
Analytical Formula ◽  
Deformation Characteristic ◽  
Contact Model ◽  
Damping Coefficient ◽  
Force Model ◽  
Separation Condition ◽  
Continuous Contact ◽  
Continuous Contact Model ◽  
The Impact

Abstract This article presents an analytical formula to characterize the damping coefficient in a continuous force model of the direct central impact. The contact force element consists of a linear damper which is in a parallel connection to a spring with Hertz force-deformation characteristic. Unlike the existing models in which the separation condition is assumed to be at the time at which both zero penetration (deformation) and zero force occur, in this study, zero contact force is considered as the separation condition. To ensure that the continuous contact model obtains the desired restitution, an optimization process is performed to find the damping coefficient. The numerical investigations show that the damping coefficient can be analytically expressed as a function of system’s parameters such as the effective mass, penetration speed just before the impact, Hertz spring constant, and the coefficient of restitution.

Analysis on Motion Precision Reliability of Hydraulic Support

2011 ◽  
Vol 48-49 ◽  
pp. 224-227
Author(s):  
Dong Chen Qin ◽  
Qiang Zhu ◽  
Hong Xia Wu ◽  
Zhe Feng Guo
Keyword(s):  
Mathematical Model ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Theoretical Calculation ◽  
Calculation Method ◽  
Effective Length ◽  
Future Research ◽  
Hydraulic Support ◽  
Continuous Contact ◽  
Continuous Contact Model

In order to research the motion precision reliability of hydraulic support when the influence of the bar length error and gap error is considered, the motion trace mathematical model for the top beam of hydraulic support is established, with the calculation method of motion precision reliability and the effective length of bar based on continuous contact model. Taking some type of hydraulic support as an example, its motion precision reliability is calculated and analyzed. The Monte Carlo simulation is also used to verify the model, and the T-R curve of the gap error and the reliability is plotted. The results from simulation accord with those from the theoretical calculation, which verifies the model established and can provide some valuable reference for the related future research.

A Simulator for Biped Robot with a Continuous Contact Model

1998 ◽  
Vol 31 (27) ◽  
pp. 183-188
Author(s):  
G. Beurier ◽  
L. Roussel ◽  
B. Perrin
Keyword(s):  
Biped Robot ◽  
Contact Model ◽  
Continuous Contact ◽  
Continuous Contact Model

scholarly journals Nonlinear Vibration Signal Tracking of Large Offshore Bridge Stayed Cable Based on Particle Filter

2015 ◽  
Vol 22 (4) ◽  
pp. 70-75
Author(s):  
Qingwei Ye ◽  
Zhimin Feng ◽  
Debin Yuan
Keyword(s):  
Particle Filter ◽  
Nonlinear Vibration ◽  
Vibration Signal ◽  
State Equation ◽  
Least Square ◽  
Nonlinear Dynamic Model ◽  
State Equations ◽  
Temporal Dimension ◽  
Filter Model ◽  
Particle Filter Algorithm

Abstract The stayed cables are key stress components of large offshore bridge. The fault detection of stayed cable is very important for safe of large offshore bridge. A particle filter model and algorithm of nonlinear vibration signal are used in this paper. Firstly, the particle filter model of stayed cable of large offshore bridge is created. Nonlinear dynamic model of the stayed-cable and beam coupling system is dispersed in temporal dimension by using the finite difference method. The discrete nonlinear vibration equations of any cable element are worked out. Secondly, a state equation of particle filter is fitted by least square algorithm from the discrete nonlinear vibration equations. So the particle filter algorithm can use the accurate state equations. Finally, the particle filter algorithm is used to filter the vibration signal of bridge stayed cable. According to the particle filter, the de-noised vibration signal can be tracked and be predicted for a short time accurately. Many experiments are done at some actual bridges. The simulation experiments and the actual experiments on the bridge stayed cables are all indicating that the particle filter algorithm in this paper has good performance and works stably.

scholarly journals A Quasispecies Continuous Contact Model in a Critical Regime

2016 ◽  
Vol 163 (2) ◽  
pp. 357-373 ◽  
Author(s):  
Yuri Kondratiev ◽  
Sergey Pirogov ◽  
Elena Zhizhina
Keyword(s):  
Contact Model ◽  
Critical Regime ◽  
Continuous Contact ◽  
Continuous Contact Model
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