scholarly journals Экспериментальное и теоретическое исследование осциллятора с соударениями

2020 ◽  
Vol 90 (10) ◽  
pp. 1672
Author(s):  
В.В. Нарожнов
Keyword(s):  
Theoretical Model ◽  
Equations Of Motion ◽  
Spectral Characteristics ◽  
Contact Theory ◽  
Hertz Contact ◽  
Mechanical Oscillator ◽  
Impact Oscillator ◽  
Fourier Filtering ◽  
Nonlinear Mechanical ◽  
The Impact

The results of a study of a nonlinear mechanical oscillator with elastic impacts are presented. The experiment was carried out using an electromechanical impact oscillator. The theoretical model is based on the equations of motion, taking into account the elastic force, which is calculated under the Hertz contact theory. It is shown that bifurcations and attractors of the “stable focus” and “limit cycle” types can occur for the impact oscillator. Fourier filtering was used to analyze the spectral characteristics of the signals.

scholarly journals Robust Position Control of a Two-Sided 1-DoF Impacting Mechanical Oscillator Subject to an External Persistent Disturbance by Means of a State-Feedback Controller

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Firas Turki ◽  
Hassène Gritli ◽  
Safya Belghith
Keyword(s):  
State Feedback ◽  
Position Control ◽  
External Disturbance ◽  
Feedback Controller ◽  
Linear Matrix ◽  
Stability Conditions ◽  
Mechanical Oscillator ◽  
Impact Oscillator ◽  
State Feedback Controller ◽  
The Impact

This paper proposes a state-feedback controller using the linear matrix inequality (LMI) approach for the robust position control of a 1-DoF, periodically forced, impact mechanical oscillator subject to asymmetric two-sided rigid end-stops. The periodic forcing input is considered as a persistent external disturbance. The motion of the impacting oscillator is modeled by an impulsive hybrid dynamics. Thus, the control problem of the impact oscillator is recast as a problem of the robust control of such disturbed impulsive hybrid system. To synthesize stability conditions, we introduce the S-procedure and the Finsler lemmas by only considering the region within which the state evolves. We show that the stability conditions are first expressed in terms of bilinear matrix inequalities (BMIs). Using some technical lemmas, we convert these BMIs into LMIs. Finally, some numerical results and simulations are given. We show the effectiveness of the designed state-feedback controller in the robust stabilization of the position of the impact mechanical oscillator under the disturbance.

Model of Precision Loss for the Precision Ball Screw

2013 ◽  
Vol 753-755 ◽  
pp. 1680-1685 ◽  
Author(s):  
Guang Yuan Xu ◽  
Wei Jun Tao ◽  
Hu Tian Feng
Keyword(s):  
Dynamic Characteristics ◽  
Classical Mechanics ◽  
Load Condition ◽  
Ball Screw ◽  
Contact Theory ◽  
Hertz Contact ◽  
External Interference ◽  
Characteristics Analysis ◽  
The Impact ◽  
Dynamic Characteristics Analysis

Aiming at the precision retaining ability problems of the precision ball screw, the modeling on the motion precision loss process under load condition is studied. The mechanics and deformation of the interface of ball and groove under load condition is analyzed by using the classical mechanics and Hertz contact theory, also a precision loss model for precision ball screw is established based on the dynamic characteristics analysis of the ball screw. Regardless of the external interference, the impact of various factors on the precision loss is analyzed and calculated.

Effect of the Inhomogeneity in Races on the Dynamic Behavior of Rolling Bearing

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Wen-zhong Wang ◽  
Sheng-guang Zhang ◽  
Zi-qiang Zhao ◽  
Si-yuan Ai
Keyword(s):  
Surface Defect ◽  
Equations Of Motion ◽  
Rolling Bearing ◽  
Contact Theory ◽  
Hertz Contact ◽  
Local Surface ◽  
Material Inhomogeneity ◽  
Outer Race ◽  
First Time ◽  
Inner Race

This paper develops an analytical model to investigate the effect of inhomogeneity in races on the dynamic behaviors of rolling bearing. The governing differential equations are obtained based on the Hertz contact theory and bearing kinematic equations with the centrifugal force and frictions considered. The surface disturbed displacement caused by inhomogeneities is obtained by the semi-analytical method (SAM) and treated as local surface defect in equations of motion through load–deformation relation. For the first time, the effect of material inhomogeneity on dynamics of rolling bearing is explored. The result shows that the inhomogeneity can make the system motion more complicated. The inhomogeneity in the inner race has a greater influence than in the outer race.

Chaos Control of an Impact Mechanical Oscillator Based on the OGY Method

2015 ◽  
pp. 259-278 ◽  
Author(s):  
Hassène Gritli ◽  
Safya Belghith ◽  
Nahla Khraief
Keyword(s):  
Fixed Point ◽  
Poincaré Map ◽  
Control Method ◽  
Poincare Map ◽  
Mechanical Oscillator ◽  
Control Of Chaos ◽  
Impact Oscillator ◽  
Control Approach ◽  
Rigid Constraint ◽  
The Impact

This chapter deals with the control of chaos exhibited in the behavior of a one-degree-of-freedom impact mechanical oscillator with a single rigid constraint. The mathematical model of such impact oscillator is represented by an impulsive hybrid linear non-autonomous dynamics. The proposed control approach is based chiefly on the OGY method. First, an analytical expression of a constrained controlled Poincaré map is derived. Secondly, the linearized controlled Poincaré map around the fixed point of the constrained map is determined. Relying on the linearized map, a state feedback controller is designed. It is shown that the proposed control strategy is efficient for the control of chaos for the desired fixed point and for the fixed parameter. It is shown also that, by changing the system parameter, the behavior of the impact mechanical oscillator changes radically. Thus, the drawback of the developed OGY control method is revealed and some remedies are given.

Mathematical Model to Study the Impact Response of a Viscoelastic Auxetic Plate

2019 ◽  
Vol 799 ◽  
pp. 205-210 ◽  
Author(s):  
Marina Shitikova ◽  
Yury Rossikhin ◽  
Oleg Ajeneza
Keyword(s):  
Mathematical Model ◽  
Green Function ◽  
Contact Zone ◽  
Time Dependent ◽  
Impact Response ◽  
Contact Theory ◽  
Hertz Contact ◽  
The Green Function ◽  
The Impact ◽  
Contact Domain

In the present paper, a mathematical model has been constructed in order to describe the impact response of a linear Kirchhoff-Love plate made of viscoelastic auxetic material possessing fractional viscosity. Auxetic’s Poisson’s ratio is a time-dependent value changing from negative to positive magnitudes with time. In the case of a linear plate, the solution out of the contact domain is found through the Green function, and within the contact zone via the modified Hertz contact theory. Integral equations for the contact force and local indentation have been obtained.

Investment climate and government turnover in russian regions

2014 ◽  
pp. 88-117 ◽  
Author(s):  
G. Syunyaev ◽  
L. Polishchuk
Keyword(s):  
Economic Development ◽  
Theoretical Model ◽  
Private Sector ◽  
Authoritarian Regimes ◽  
Russian Regions ◽  
Investment Climate ◽  
Regional Data ◽  
Endogenous Property Rights ◽  
The Impact

We study the impact of Russian regional governors’ rotation and their affiliation with private sector firms for the quality of investment climate in Russian regions. A theoretical model presented in the paper predicts that these factors taken together improve “endogenous” property rights under authoritarian regimes. This conclusion is confirmed empirically by using Russian regional data for 2002—2010; early in that period gubernatorial elections had been canceled and replaced by federal government’s appointments. This is an indication that under certain conditions government rotation is beneficial for economic development even when democracy is suppressed.

Farm wages and public works

2015 ◽  
Vol 8 (1) ◽  
pp. 19-72 ◽  
Author(s):  
Kanika Mahajan
Keyword(s):  
Theoretical Model ◽  
Wage Rate ◽  
Fixed Effects ◽  
Positive Impact ◽  
Wage Growth ◽  
State Level ◽  
Random Allocation ◽  
Farm Sector ◽  
Content Type ◽  
The Impact

Purpose – The purpose of this paper is to examine the impact of National Rural Employment Guarantee Scheme (NREGS) on farm sector wage rate. This identification strategy rests on the assumption that all districts across India would have had similar wage trends in the absence of the program. The author argues that this assumption may not be true due to non-random allocation of districts to the program’s three phases across states and different economic growth paths of the states post the implementation of NREGS. Design/methodology/approach – To control for overall macroeconomic trends, the author allows for state-level time fixed effects to capture the differences in growth trajectories across districts due to changing economic landscape in the parent-state over time. The author also estimates the expected farm sector wage growth due to the increased public work employment provision using a theoretical model. Findings – The results, contrary to the existing studies, do not find support for a significantly positive impact of NREGS treatment on private cultivation wage rate. The theoretical model also shows that an increase in public employment work days explains very little of the total growth in cultivation wage post 2004. Originality/value – This paper looks specifically at farm sector wage growth and the possible impact of NREGS on it, accounting for state specific factors in shaping farm wages. Theoretical estimates are presented to overcome econometric limitations.

Investigation on penetration model of shaped charge jet in water

2016 ◽  
Vol 30 (02) ◽  
pp. 1550268 ◽  
Author(s):  
Jinwei Shi ◽  
Xingbai Luo ◽  
Jinming Li ◽  
Jianwei Jiang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Model Simulation ◽  
Theoretical Models ◽  
Theoretical Research ◽  
Water Medium ◽  
Simulation Results ◽  
Jet Penetration ◽  
The Impact ◽  
Penetration Velocity

To analyze the process of jet penetration in water medium quantitatively, the properties of jet penetration spaced target with water interlayer were studied through test and numerical simulation. Two theoretical models of jet penetration in water were proposed. The theoretical model 1 was established considering the impact of the shock wave, combined with the shock equation Rankine–Hugoniot and the virtual origin calculation method. The theoretical model 2 was obtained by fitting theoretical analysis and numerical simulation results. The effectiveness and universality of the two theoretical models were compared through the numerical simulation results. Both the models can reflect the relationship between the penetration velocity and the penetration distance in water well, and both the deviation and stability of theoretical model 1 are better than 2, the lower penetration velocity, and the larger deviation of the theoretical model 2. Therefore, the theoretical model 1 can reflect the properties of jet penetration in water effectively, and provide the reference of model simulation and theoretical research.

Free vibration analysis and post-critical free vibrations of nanocomposite rotating beams reinforced with graphene platelet

2021 ◽  
pp. 107754632110511
Author(s):  
Arameh Eyvazian ◽  
Chunwei Zhang ◽  
Farayi Musharavati ◽  
Afrasyab Khan ◽  
Mohammad Alkhedher
Keyword(s):  
Natural Frequency ◽  
Thermal Environment ◽  
Rotational Velocity ◽  
Equations Of Motion ◽  
Free Vibration Analysis ◽  
Beam Theory ◽  
Weight Fraction ◽  
Free Vibrations ◽  
Graphene Platelet ◽  
The Impact

Treatment of the first natural frequency of a rotating nanocomposite beam reinforced with graphene platelet is discussed here. In regard of the Timoshenko beam theory hypothesis, the motion equations are acquired. The effective elasticity modulus of the rotating nanocomposite beam is specified resorting to the Halpin–Tsai micro mechanical model. The Ritz technique is utilized for the sake of discretization of the nonlinear equations of motion. The first natural frequency of the rotating nanocomposite beam prior to the buckling instability and the associated post-critical natural frequency is computed by means of a powerful iteration scheme in reliance on the Newton–Raphson method alongside the iteration strategy. The impact of adding the graphene platelet to a rotating isotropic beam in thermal ambient is discussed in detail. The impression of support conditions, and the weight fraction and the dispersion type of the graphene platelet on the acquired outcomes are studied. It is elucidated that when a beam has not undergone a temperature increment, by reinforcing the beam with graphene platelet, the natural frequency is enhanced. However, when the beam is in a thermal environment, at low-to-medium range of rotational velocity, adding the graphene platelet diminishes the first natural frequency of a rotating O-GPL nanocomposite beam. Depending on the temperature, the post-critical natural frequency of a rotating X-GPL nanocomposite beam may be enhanced or reduced by the growth of the graphene platelet weight fraction.

Global Analysis of the Double Impact Oscillator Dynamics

1999 ◽  
Author(s):  
František Peterka
Keyword(s):  
Global Analysis ◽  
Impact Oscillator ◽  
System Parameters ◽  
Impact Oscillators ◽  
Real Value ◽  
Simulation Results ◽  
The Impact ◽  
Impact Motion ◽  
Double Impact ◽  
Phase Motion

Abstract The double impact oscillator represents two symmetrically arranged single impact oscillators. It is the model of a forming machine, which does not spread the impact impulses into its neighbourhood. The anti-phase impact motion of this system has the identical dynamics as the single system. The in-phase motion and the influence of asymmetries of the system parameters are studied using numerical simulations. Theoretical and simulation results are verified experimentally and the real value of the restitution coefficient is determined by this method.

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