Two-Frequency Oscillation With Combined Coulomb and Viscous Frictions

2002 ◽  
Vol 124 (4) ◽  
pp. 537-544 ◽  
Author(s):  
Gong Cheng ◽  
Jean W. Zu
Keyword(s):  
Steady State ◽  
Dry Friction ◽  
Single Frequency ◽  
Friction Oscillator ◽  
One Stop ◽  
Frequency Excitation ◽  
Stop Motion ◽  
The One ◽  
Coulomb Dry Friction ◽  
Mass Spring

In this paper, a mass-spring-friction oscillator subjected to two harmonic disturbing forces with different frequencies is studied for the first time. The friction in the system has combined Coulomb dry friction and viscous damping. Two kinds of steady-state vibrations of the system—non-stop and one-stop motions—are considered. The existence conditions for each steady-state motion are provided. Using analytical analysis, the steady-state responses are derived for the two-frequency oscillating system undergoing both the non-stop and one-stop motions. The focus of the paper is to study the influence of the Coulomb dry friction in combination with the two frequency excitations on the dynamic behavior of the system. From the numerical simulations, it is found that near the resonance, the dynamic response due to the two-frequency excitation demonstrates characteristics significantly different from those due to a single frequency excitation. Furthermore, the one-stop motion demonstrates peculiar characteristics, different from those in the non-stop motion.

Chaotic Motion of a Two-Frequency Forced Oscillator With Dry Friction

2003 ◽  
Author(s):  
Gong Cheng ◽  
Jean W. Zu
Keyword(s):  
Dry Friction ◽  
Periodic Motions ◽  
Bifurcation Diagrams ◽  
External Excitation ◽  
Forced Oscillator ◽  
Friction Oscillator ◽  
Frequency Excitation ◽  
Simulation Results ◽  
Excitation Frequencies ◽  
Insight Into

In this paper, the dynamic behavior of a dry friction oscillator subjected to simultaneous self- and external excitations is studied. The dry friction in the system follows the classical Coulomb’s law, and the external excitation consists of two harmonic forces with different frequencies. The focus of the paper is laid on bifurcation analysis to gain insight into the influence of the two-frequency excitation upon the qualitative features of system dynamics. Numerical simulations are performed and the simulation results are visualized by means of bifurcation diagrams, Poincare´ sections and Lyapunov exponents. New and interesting conclusions are reached from the study. It is shown that small excitation frequencies and amplitudes tend to cause chaos in the system, whereas large excitation amplitudes can induce only periodic motions. Furthermore, it is found that the probability of the occurrence of periodic motions increases, as the ratio between the two excitation frequencies increases.

scholarly journals Asymmetric and chaotic responses of dry friction oscillators with different static and kinetic coefficients of friction

Meccanica ◽  
2021 ◽  
Author(s):  
Gábor Csernák ◽  
Gábor Licskó
Keyword(s):  
Dry Friction ◽  
Continuation Method ◽  
Friction Model ◽  
Lugre Friction Model ◽  
Kinetic Coefficients ◽  
Friction Oscillator ◽  
Lugre Friction ◽  
Friction Parameters ◽  
Two Parameter ◽  
Parameter Bifurcation

AbstractThe responses of a simple harmonically excited dry friction oscillator are analysed in the case when the coefficients of static and kinetic coefficients of friction are different. One- and two-parameter bifurcation curves are determined at suitable parameters by continuation method and the largest Lyapunov exponents of the obtained solutions are estimated. It is shown that chaotic solutions can occur in broad parameter domains—even at realistic friction parameters—that are tightly enclosed by well-defined two-parameter bifurcation curves. The performed analysis also reveals that chaotic trajectories are bifurcating from special asymmetric solutions. To check the robustness of the qualitative results, characteristic bifurcation branches of two slightly modified oscillators are also determined: one with a higher harmonic in the excitation, and another one where Coulomb friction is exchanged by a corresponding LuGre friction model. The qualitative agreement of the diagrams supports the validity of the results.

scholarly journals The Impact of Heat Treatment on the Behavior of a Hot-Dip Zinc Coating Applied to Steel During Dry Friction

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 660
Author(s):  
Dariusz Jędrzejczyk ◽  
Elżbieta Szatkowska
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
Friction Coefficient ◽  
Dry Friction ◽  
Zinc Coating ◽  
Pin On Disc ◽  
The One ◽  
The Impact ◽  
Coating Hardness ◽  
Anticorrosion Properties

The analyzed topic refers to the wear resistance and friction coefficient changes resulting from heat treatment (HT) of a hot-dip zinc coating deposited on steel. The aim of research was to evaluate the coating behavior during dry friction after HT as a result of microstructure changes and increase the coating hardness. The HT parameters should be determined by taking into consideration, on the one hand, coating wear resistance and, on the other hand, its anticorrosion properties. A hot-dip zinc coating was deposited in industrial conditions (according EN ISO 10684) on disc-shaped samples and the chosen bolts. The achieved results were assessed on the basis of tribological tests (T11 pin-on-disc tester, Schatz®Analyse device, Sindelfingen, Germany), microscopic observations (with the use of optical and scanning microscopy), EDS (point and linear) analysis, and microhardness measurements. It is proved that properly applied HT of a hot-dip zinc coating results in changes in the coating’s microstructure, hardness, friction coefficient, and wear resistance.

Estimation of the Linearized Damping Coefficients of a Squeeze-Film Vibration Isolator

1987 ◽  
Vol 201 (3) ◽  
pp. 181-191 ◽  
Author(s):  
R Stanway ◽  
R Firoozian ◽  
J E Mottershead
Keyword(s):  
Single Frequency ◽  
Squeeze Film ◽  
Experimental Facility ◽  
Vibration Isolator ◽  
New Approach ◽  
Filtering Algorithm ◽  
Damping Coefficients ◽  
Performance Predictions ◽  
Frequency Excitation ◽  
Extract Information

In this paper the authors present experimental confirmation of the feasibility of a new approach to the estimation of the four damping coefficients associated with a squeeze-film vibration isolator. The design and construction of the experimental facility is described in detail. A time-domain filtering algorithm is applied to process the displacement responses to single-frequency excitation and thus extract information on the linearized dynamics of the squeeze-film. The estimated coefficients are validated by comparing performance predictions with those obtained from spectrum analysis and from short-bearing theory. The significance of the results is discussed and suggestions are made for further work in this area.

The One-Stop Gyrification Station - Challenges and New Technologies

2021 ◽  
pp. 102111
Author(s):  
Ryan Alexander Hickmott ◽  
Abdulhameed Bosakhar ◽  
Sebastian Quezada Rojas ◽  
Mikaela Barresi ◽  
David Walker ◽  
...  
Keyword(s):  
New Technologies ◽  
One Stop ◽  
The One

scholarly journals Study on a Novel High-Efficiency Bridgeless PFC Converter

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Cao Taiqiang ◽  
Chen Zhangyong ◽  
Wang Jun ◽  
Sun Zhang ◽  
Luo Qian ◽  
...  
Keyword(s):  
Steady State ◽  
High Efficiency ◽  
Control Policy ◽  
Switching Frequency ◽  
Fast Recovery ◽  
Zero Current Switching ◽  
Zero Current ◽  
The One ◽  
Gain Characteristic ◽  
Conduction Mode

In order to implement a high-efficiency bridgeless power factor correction converter, a new topology and operation principles of continuous conduction mode (CCM) and DC steady-state character of the converter are analyzed, which show that the converter not only has bipolar-gain characteristic but also has the same characteristic as the traditional Boost converter, while the voltage transfer ratio is not related with the resonant branch parameters and switching frequency. Based on the above topology, a novel bridgeless Bipolar-Gain Pseudo-Boost PFC converter is proposed. With this converter, the diode rectifier bridge of traditional AC-DC converter is eliminated, and zero-current switching of fast recovery diode is achieved. Thus, the efficiency is improved. Next, we also propose the one-cycle control policy of this converter. Finally, experiments are provided to verify the accuracy and feasibility of the proposed converter.

Bibliopolis, developing the one-stop shop for the history of the book in the Netherlands

Quaerendo ◽  
2000 ◽  
Vol 30 (3) ◽  
pp. 240-249
Author(s):  
Marieke Van Delft ◽  
Marco De Niet
Keyword(s):  
The Netherlands ◽  
History Of The Book ◽  
History Of ◽  
One Stop ◽  
The One

Fluid turbulence simulations of divertor heat load for ITER hybrid scenario using BOUT++

2021 ◽  
Author(s):  
Xueyun Wang ◽  
Xueqiao Xu ◽  
Philip B Snyder ◽  
Zeyu Li
Keyword(s):  
Heat Flux ◽  
Steady State ◽  
Energy Loss ◽  
Heat Load ◽  
Type I ◽  
Fluid Turbulence ◽  
Drift Model ◽  
Steady State Operation ◽  
Different Types ◽  
The One

Abstract The BOUT++ six-field turbulence code is used to simulate the ITER 11.5MA hybrid scenario and a brief comparison is made among ITER baseline, hybrid and steady-state operation (SSO) scenarios. Peeling-ballooning instabilities with different toroidal mode numbers dominate in different scenarios and consequently yield different types of ELMs. The energy loss fractions (ΔWped/Wped) caused by unmitigated ELMs in the baseline and hybrid scenarios are large (~2%) while the one in the SSO scenario is dramatically smaller (~1%), which are consistent with the features of type-I ELMs and grassy ELMs respectively. The intra ELM divertor heat flux width in the three scenarios given by the simulations is larger than the estimations for inter ELM phase based on Goldston’s heuristic drift model. The toroidal gap edge melting limit of tungsten monoblocks of divertor targets imposes constraints on ELM energy loss, giving that the ELM energy loss fraction should be smaller than 0.4%, 1.0%, and 1.2% for ITER baseline, hybrid and SSO scenarios, correspondingly. The simulation shows that only the SSO scenario with grassy ELMs may satisfy the constraint.

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