Národní úložiště šedé literatury Nalezeno 3 záznamů.  Hledání trvalo 0.01 vteřin. 
Forced movement of a ball in spherical cavity under kinematic excitation
Náprstek, Jiří ; Fischer, Cyril
In the paper the response of a heavy ball rolling inside a semi-spherical cavity under horizontal kinematic excitation is investigated. The system with six degrees of freedom with three non-holonomic constraints is considered. The contact between the ball and the cavity surface is supposed to be perfect without any sliding. The mathematical model using the Appel-Gibbs function of acceleration energy is developed and discussed. The most important post-critical regimes are outlined and qualitatively evaluated on the frequency axis. Numerical experiments have been performed when excitation frequency is slowly swept up and down. Results obtained by means of semi-analytical investigation and numerical simulation are evaluated and physically interpreted. Some applications in civil engineering as a tuned mass damper used on slender structures is outlined. Strengths and weaknesses of solution method are evaluated.
Dynamic response of a heavy ball rolling inside a spherical dish under external excitation
Náprstek, Jiří ; Fischer, Cyril
The set of a heavy metallic ball which is rolling freely inside a semispherical dish with larger diameter, being fixed to structure, is frequently used as tuned mass damper of vibration. Ratio of both diameters, mass of the rolling ball, quality of contact surfaces and other parameters should correspond with characteristics of the structure. The ball damper is modelled as a non-holonomic system. Hamiltonian functional including an adequate form of the Rayleigh function is formulated in moving coordinates using Euler angles and completed by ancillary constraints via Lagrangian multipliers. Subsequently Lagrangian differential system is carried out. Together with rolling conditions the governing system of seven equations is formulated. Later Lagrangian multipliers character is analysed and redundant motion components are eliminated. First integrals are derived and main energy balances evaluated together with their physical interpretation. Discussion of basic dynamic properties of the system is provided.
Analytic model of a ball rolling on a spherical surface under harmonic kinematic excitation
Náprstek, Jiří ; Fischer, Cyril
The set of a heavy metallic ball which is rolling freely inside a semi-spherical dish with larger diameter, being fixed to structure, is frequently used as tuned mass damper of vibration. Ratio of both diameters, mass of the rolling ball, quality of contact surfaces and other parameters should correspond with characteristics of the structure. The ball damper is modeled as a non-holonomic system. Hamiltonian functional including an adequate form of the Rayleigh function is formulated in moving coordinates using Euler angles and completed by ancillary constraints via Lagrangian multipliers. Subsequently Lagrangian differential system is carried out. Together with rolling conditions the governing system of seven equations is formulated. Later Lagrangian multipliers character is analyzed and redundant motion components are eliminated. First integrals are derived and main energy balances evaluated together with their physical interpretation.

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