This article provides a detailed analysis of the problem of the optimal choice of parameters of dynamic dampers with two degrees of freedom. The choice method is based on calculating the difference between the resonant frequency of the system without absorbers and the nearest resonant frequency of the system with absorbers. The optimal parameters are determined and the effectiveness of many mass-dynamic vibration dampers with various types of viscosity under vibrational impacts is estimated. It has been shown that frequency-independent friction equally affects how viscous friction affects the behavior of the protected structure and damper and its effectiveness. A sufficient condition for damping vibrations in both coordinates is the presence of two dampers for movement, installed at different points. Frequency limits are set to suppress damping simultaneously in the upper and lower surroundings with respect to the resonant frequency of the main system, and also only in the upper neighborhood. It was found that the use of more than two absorbers while maintaining their total mass affects the frequency band in which it is possible to dampen the oscillations of the system.
The fundamentals of theoretical methods for engineering calculations of bending vibrations of thin plates, the material of which has hereditary properties, are presented. The manifestation of the hereditary properties of the material of the plate under consideration at a given stress-strain state can be judged by the relaxation core of the material. The dependence of the creep and relaxation kernels on the time difference corresponds to the fact that the “memory” of the material about the force effect produced at a given moment is determined by the elapsed time interval. In particular, this means that if the force action on the elastic-viscous body is cyclic, then the deformation of the body will also be cyclic with some phase shift. A technique for solving forced vibrations of plates under the influence of harmonic loads is proposed. An exact solution to the problem of forced vibrations of a supported rectangular plate, whose dissipative properties are described by memory functions, is constructed.
Increased machine efficiency, increased speeds of working bodies, reduced material consumption, increased load, the need to ensure reliable operation of equipment and safe working conditions are the main factors, that determine attention to vibration protection problems. This constitutes the current trend in the modern dynamics of machines. In this work, we propose a method for the dynamic synthesis of dynamic vibration dampers of a viscoelastic mechanical system having the structure of several (two) bodies elastically attached to the object. The aim of the work is to develop methods of mathematical and computer modeling of the processes of dynamics of active and passive vibration protection systems, as well as to increase the efficiency of using passive and active vibration protection of objects. When developing a system for protecting radio-electronic devices (RED) at resonant frequencies, elements of the theory of automatic control and mathematical modeling were used. An algorithm for generating feedback signals for the information-measuring system for active control of vibration-protective radio-electronic devices is proposed. A method is developed for numerically - analytical study of oscillatory processes of nonlinear mechanical systems consisting of spatial rigid bodies interconnected by massless viscoelastic elements.
This article is dedicated to the operation and management of systems of machine-building and aviation enterprises, systems of production, transport, storage of oil and gas, issues of control of technological processes are of great importance. Control of technological processes is carried out by monitoring the pressure and other parameters. These measuring instruments must have high reliability and the necessary accuracy. In this connection, there is a sharp increase in interest in determining the dynamic parameters of the elements of measuring devices. The main elements of such devices are monomeric tubular springs (Bourdon tubes). The paper considers the natural and forced steady-state oscillations of a thin curved rod interacting with a liquid. Based on the principle of possible displacements, a resolving system of partial differential equations and the corresponding boundary conditions are obtained. The problem is solved numerically by the Godunov orthogonal run method, and the Muller method and the Eigen frequencies found are compared with the experimental results. As a result, for a given axial perturbation, it was possible to select such an effect, in the orthogonal direction, that the amplitude of the longitudinal vibrations of the rod at the first resonance decreased by 20 times. The described vibration damping effect is due to the interrelation of transverse and longitudinal vibrations and is fundamentally impossible in the case of a straight rod.
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