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Subharmonic motions of the oscillator with soft impacts
Peterka, František ; Tondl, Aleš
The excited one degree of freedom mechanical system with soft impacts, characterised by triangle hysteresis loop, is investigated using numerical simulation. Small viscous damping is assumed. Phenomena of subharmonic motions are explained by regions of their existence and stability in plane of dimensionless excitation frequency and static clearance. Bifurcation diagrams are evaluated during quasistationary changes of frequency by constant clearance.
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Response curves of vibroimpact system
Půst, Ladislav ; Peterka, František
Dynamical properties of 1DOF mechanical system impacting on soft stop are studied at excitation by harmonic force. Soft stop is of Hertzs type with viscous damping. Properties of system are analyzed by means of response curves obtained by simulation of motion at slow variation of excitation frequency. Response curves are completed by phase plane trajectories at selected frequencies and time history record. The influences of clearance in system on the response curves, type and level of oscillations are presented. This paper is in narrow connection with contribution [1], where the regions of various type of oscillations of the same system are analyzed.
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Behaviour of mechanical model of piercing machine
Peterka, František
Abstrakt:The dynamics of oscillators with soft impacts is a new direction in the investigation of strongly non-linear systems in the Institute of Thermomechanics. Notion 'soft' is used for an impact, the duration of which is impossible to neglect, unlthe 'rigid' impact described by the Newton elementary theory with coefficient of restitution. It signifies that there exist a large variety of mathematical models of soft impacts corresponding to every real practical situation, which should be invested. The numerical simulation of non-linear system dynamics is the most effective method for it.
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Global view on dynamics of impact oscillator
Peterka, František
Impact oscillator is the simplest mechanical system with one degree of freedom, the periodically excited mass of which can impact on the stop. The aim of this paper is to explain the dynamics of the system, when the stiffness of the stop changes from** to infinity. It corresponds to the transition from the linear system into strongly nonlinear system with rigid impact.
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Dynamics of oscillator with piecewise linear model of soft impacts
Peterka, František ; Tondl, Aleš
The aim of this contribution is to present a more detail explanation of different types of motion of the oscillator with soft impacts using regions of existence and stability, phase trajectories and time series of impact motions. The explanation is exteded into lower and negative values of static clearance. Negative clearance corresponds to a static prestress of vibrating mass to the stop.
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Impact system with the hertz contact
Půst, Ladislav ; Peterka, František
Analytical model of dynamic impact based on Hertz theory and connected with nonlinear damping is presented for different values of contact stiffness. Hysteresis loops are shown. The Hertz constact model is applied for investigation of properties of 1 impact system excited by harmonic force. After introducing dimensionless parameters, the domains of different periodic and chaotic impact oscillators are ascertained for the Hertz coefficient kH=3;10;30;100.
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