The complicated bifurcation of an archetypal self-excited SD oscillator with dry friction

2017 ◽  
Vol 89 (1) ◽  
pp. 91-106 ◽  
Author(s):  
Zhixin Li ◽  
Qingjie Cao ◽  
Alain Léger
Keyword(s):  
Dry Friction ◽  
Sd Oscillator

Analytical Approximations for Dry Friction-induced Stick-Slip and Pure-Slip Vibration Amplitudes of a Self-Excited SD Oscillator

2021 ◽  
Author(s):  
Junfeng Yan ◽  
Zehao Huang
Keyword(s):  
Perturbation Method ◽  
Friction Force ◽  
Dry Friction ◽  
Homotopy Perturbation Method ◽  
Perturbation Methods ◽  
Stick Slip ◽  
Homotopy Perturbation ◽  
Analytical Approximations ◽  
Sd Oscillator ◽  
Analytical Expressions

Abstract An analytical and numerical investigation into pure-slip and stick-slip oscillations induced by dry friction between a rigid mass linked by an inclined spring, modeled by the archetypal self-excited smooth and discontinuous (SD) oscillator, and the classical moving rigid belt, is presented. The friction force between surface contacts is modeled in the sense of Stribeck effect to formulate the friction model that the friction force firstly decreases and then increases with increasing relative sliding speed. Some perturbation methods are considered into this system for establishing the approximate analytical expressions of the occurring conditions, vibration amplitudes, and base frequencies of dry friction-induced stick-slip and pure-slip oscillations. For pure-slip oscillations, two different approaches are applied to analyze this self-excited SD oscillator. One of them is the homotopy perturbation method by constructing the nonlinear amplitude and frequency. Based on the multiple-scales homotopy perturbation method, a nonlinear equation for amplitude of the analytical approximate solution is constructed, which containing all parameters of problem. For stick-slip oscillations, the analytical approximations for amplitude and frequency are obtained by perturbation methods for finite time intervals of the stick phase, which is linked to the subsequent slip phase under the conditions of continuity and periodicity. The accuracy of analytical approximations is verified by the comparison between analytical approximations and numerical simulations. These analytical expressions are needed for gaining a deeper understanding of dry friction-induced pure-slip and stick-slip oscillations for the friction system with geometric nonlinearity.

Output trajectory tracking for mechanical systems with dry friction: A DPC approach

1997 ◽  
Author(s):  
D. von Wissel ◽  
R. Nikoukhah ◽  
F. Delebecque ◽  
P.-A. Bliman ◽  
M. Soline
Keyword(s):  
Trajectory Tracking ◽  
Dry Friction ◽  
Mechanical Systems ◽  
Output Trajectory

Improving the wear resistance of hoe blades by modifying of restoration coatings

2019 ◽  
Vol 24 (94/4) ◽  
pp. 27-32
Author(s):  
T.S. Skoblo ◽  
I.N. Rybalko ◽  
A.V. Tihonov ◽  
T.V. Maltsev
Keyword(s):  
Wear Resistance ◽  
Transition Layer ◽  
Surface Coating ◽  
Dry Friction ◽  
Raw Materials ◽  
Bentonite Clay ◽  
Magnetic Fraction ◽  
Cutting Surface ◽  
Agricultural Machines ◽  
Modifying Additive

The possibility of using a non-magnetic fraction of a detonation charge with a diamond fraction from the disposal of ammunition to modify the restoration coatings of a natural product – clay and secondary raw materials — was studied. Four different coating variants were investigated. For this, a T-620 electrode was used with its additional modification by coating with bentonite clay, as well as with a non-magnetic fraction of the detonation charge and applying it in the form of a slip coating on the cutting surface of the cultivator. It is shown that the use of such additives allows to increase the resistance of the working tool of agricultural machines, reduces its tendency to damage due to the minimum penetration of the thin-walled product of the hoe blade and a decrease in the cross section of the transition layer and the level of stress. Each modifier makes changes to increase the microhardness to varying degrees. An increase in microhardness is observed on the surface of the coating and its gradual decrease to the transition layer. The surface coating with the additional introduction of bentonite clay in a liquid bath has the highest microhardness. Its microhardness varies from HV-50-1009.7 to HV-50-615.2. Similarly, the effect of the modifying additive of the detonation charge, the microhardness varies from HV-50-969.6 to HV-50-633.26. When clay or a mixture is introduced into the restoration coating, the wear resistance increases by 1.3 - 2 times with respect to the deposited surfacing only by the electrode and by 2 - 3 times to the initial material of the cultivator. It was found that the lowest coefficient is characteristic for dry friction, as well as for hydroabrasive, for samples with additional modification with clay or a detonation charge

Study of Characteristics of Dry Friction Damping.

1985 ◽  
Author(s):  
A. V. Srinivasan ◽  
B. N. Cassenti ◽  
D. G. Cutts
Keyword(s):  
Dry Friction ◽  
Friction Damping ◽  
Dry Friction Damping

Investigation into steering wheel nibble

2002 ◽  
Vol 216 (4) ◽  
pp. 267-277 ◽  
Author(s):  
U Neureder
Keyword(s):  
Design Of Experiments ◽  
Natural Frequency ◽  
Dry Friction ◽  
Parameter Sensitivity ◽  
Steering Wheel ◽  
New Model ◽  
The Past ◽  
Force Variation

Many studies of mechanisms contributing to steering wheel nibble have been carried out in the past. This paper deals with some aspects that have not yet been studied, or those that have been presented by several authors but are deemed to be controversial. Firstly, an overview of stimulation sources (disturbance factors), and the significance these have with respect to steering nibble, is given. As an example of the controversial aspects of the problem, this paper deals with the assumption of dry friction in steering gear models and its conflict with the observed transfer of vibration caused by small (realistic) amounts of imbalance or tyre force variation. After modelling the steering gear resistance correctly, it is possible to identify, in the steering gear, a natural frequency that contributes reasonably to the nibble phenomenon. Based on this new model, a CAE study on parameter sensitivity, using the ‘design of experiments’ approach, is presented.

scholarly journals A study on the vibration dissipation mechanism of the rotating blade with dovetail joint

2021 ◽  
pp. 146134842098533
Author(s):  
Chaofeng Li ◽  
Zengchuang Shen ◽  
Zilin Chen ◽  
Houxin She
Keyword(s):  
Dry Friction ◽  
Vibration Reduction ◽  
Friction Model ◽  
Rotating Speed ◽  
System Parameters ◽  
Tangential Stiffness ◽  
Damping Characteristics ◽  
Rotating Blade ◽  
Spatial Beam ◽  
Dissipation Mechanism

The vibration dissipation mechanism of the rotating blade with a dovetail joint is studied in this paper. Dry friction damping plays an indispensable role in the direction of vibration reduction. The vibration level is reduced by consuming the total energy of the turbine blade with the dry friction device on the blade-root in the paper. The mechanism of the vibration reduction is revealed by the variation of the friction force and the energy dissipation ratio of dry friction. In this paper, the flexible blade with a dovetail interface feature is discretized by using the spatial beam element based on the finite element theory. Then the classical Coulomb-spring friction model is introduced to obtain the dry friction model on the contact interfaces of the tenon-mortise structure. What is more, the effects of the system parameters (such as the rotating speed, the friction coefficient, the installation angle of the tenon) and the excitation level on blade damping characteristics are discussed, respectively. The results show that the variation of the system parameters leads to a significant change of damping characteristics of the blade. The variation of the tangential stiffness and the position of the external excitation will affect the nonlinear characteristics and vibration damping characteristics.

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