In many modern engineering designs are applied membranes of various shapes. This can be electroacoustic devices, medical equipment, and the skin of the aircraft body with triangular cells. Solutions for free vibrations of rectangular and circular membranes are known by the Fourier method. There are also quite a few solutions to the problems of vibrations of membranes of various shapes by the finite element method. Analytical solutions for membranes of more complex shapes are of great interest due to the complex geometry of the contour and the difficulty of obtaining the solution itself. In this paper, we obtained partial solutions for the problem of free vibrations of a regular triangular membrane with different initial surface bending and found eigenfrequencies of vibrations.
Keywords: Free vibrations of the membrane, the membrane of the correct triangular shape, natural frequencies of vibrations
On the basis of the proposed Timoshenko S. P. solution of the problem of pure bending of an elastic rectangular plate under the action of moments of constant intensity acting on its boundary, the theory of bending of viscoelastic plates fixed in the vertices is proposed for the first time. The proposed solution uses the hereditary theory taking into account the hypothesis of N. H. Harutyunyan about the constancy of the coefficient of transverse deformation. For the first time, a method of recalculation of the distributed transverse load applied on the surface of the plate at equivalent moments of constant intensity, time-dependent and applied at the edges, is proposed. For the first time with the help of this theory, the problem of bending a plate pinched at a single angular point distributed by a transverse load is solved. As examples, calculations of rectangular plates under the action of their own weight are given.
Keywords: roller blade, horizontal mixer, optimization, design, process, material procurement, machining, reduction of production costs
The problem of identification of defects in the construction in the form of a wall element is considered. Numerical simulation of the structure is carried out in the Ansys finite element complex. The investigated model of a wall structure has a defect in the form of a through crack, of a certain length. The edges of the cracks do not interact with each other. The excitation of the structure under pulsed loading is considered. Wave field displacements at control points are analyzed. Identified signs of identification of crack-like defect.
Keywords: numerical modeling, wall element, defect, crack, identification, finite element modeling, dynamic analysis, oscillations, displacement wave field
The problem of identification of defects in the construction in the form of a wall element is considered. Numerical simulation of the structure is carried out in the Ansys finite element complex. The investigated model of a wall structure has a defect in the form of a through crack, of a certain length. The edges of the cracks do not interact with each other. The excitation of the structure under pulsed loading is considered. Wave field displacements at control points are analyzed. Identified signs of identification of crack-like defect.
Keywords: numerical modeling, wall element, defect, crack, identification, finite element modeling, dynamic analysis, oscillations, displacement wave field
The main maintenance of a diversification of production as activity of subjects of managing is considered. being shown in purchase of the operating enterprises, the organizations of the new enterprises, redistribution of investments in interests of the organization and development of new production on available floor spaces. The most important organizational economic targets of a diversification of management are presented by innovative activity of the industrial enterprise.
Keywords: velocity of crack propagation. Gorilla Glass, fast fracture, Sapphire, displacement of deformed bodies,
The article presents the quality assessment of repair work for electricity pilons of transmission line performed by the method of vibration diagnostics. The suggested criterion for assessing the quality of the repair is relative adhesion of repair layers to the base of the stand. Modeling of structural oscillations strut mount, transmission lines and calculations in the finite-element complex Ansys. The dependence of the parameters own frequency of fluctuations of the value of damage at different values of the space adhesion. The resulting equations based on changes in natural frequencies on the magnitude of adhesion. The calculation of the relative adhesion of the repair composition to the concrete model of the design. The material presented can be used for assessing the quality of repair work of different structures of the core type reinforced concrete structures.
Keywords: vibration diagnostics, quality, repair of structures, defect, adhesion, natural frequencies
The article presents the algorithm of repair work for electricity pilons of transmission line.The technical diagnostics based on complex method includes a visual inspection, instrumental and vibration diagnostics for electricity pilons of transmission lines. Pilons has defects: inclined cracked faces with a length of 25-30 cm , with a crack width of 0,4-0,7 mm . Were selected effective repair compositions for restoring reinforced concrete structures rack transmission towers:modified fine-grained concrete, polymer concrete. The article presents an example of analytical modeling of natural vibrations of a reinforced concrete pilons of transmission lines with defects in the base. This article contains a list of repair works. The material presented can be used in the development of methods of diagnostics and monitoring of technical condition of different structures of the core type.
Keywords: Algorithm, repair, category of defects, non-destructive testing methods, pilons of transmission lines, vibrodiagnostics
This paper proposes a method for detecting damage truss rod cantilever structure on the basis of new information sign "Express - distinguishing between" damage. It is based on the analysis of the phase diagrams for modeling its transient oscillations. Produced comparison of various parameters damped oscillations truss rod design for the structure without damage and corruption. Processed and analyzed the frequency response based on them phase diagrams. To analyze the response considered in the frequency range from 0 to 100 Hz. An analysis of the phase diagrams in different frequency regions design is presented as an information sign "Express - distinction" of having damage to the truss.
Keywords: Truss rod design, damage, finite element modeling, information sign, transient fluctuations of the amplitude-frequency analysis, phase diagrams
The article presents the vibration diagnostics method for pilons of transmission lines. Pilons has defects: inclined cracked faces with a length of 25-30 cm , with a crack width of 0,4-0,7 mm . The article presents an example of analytical modeling of natural vibrations of a reinforced concrete pilons of transmission lines with defects in the base. Analytical modeling was based on the hypotheses of Euler-Bernoulli. Built an equivalent model of the pilons with defect in the form of an elastic element, simulating the damage in the area of trapping. The calculation of natural frequencies of first five modes of transverse oscillations for different values of stiffness of the defect. The result of this work is to obtain the dependencies of the relative frequencies from the stiffness of the defect and establishment of sufficiently informative criterion for predicting the alarm state of structures. The material presented can be used in the development of methods of diagnostics and monitoring of technical condition of different structures of the core type.
Keywords: vibration analysis, pilons of transmission lines, the defect, analytic modeling, transverse vibrations, natural vibrations, natural frequencies
Тhe analysis of methods and means of evaluation of technical condition of building structures under construction. The developed algorithm of a complex estimation of state of reinforced concrete structures with expired period of preservation. The algorithm of complex diagnostics of a condition of constructions involving complementation of known techniques of estimation of parameters of safety of structures with joint processing of the results, is an effective tool for assessing the actual condition of structures and end-of-life.
Keywords: safe operation, defect, nondestructive control methods, dynamic loading, vibration diagnostics, vibration sensors
the paper considers the comparison of natural modes for the first and second transverse oscillation modes obtained by numerical simulation and finite element package of analytical calculation of the core model with an elastic element based on the application of the Euler-Bernoulli hypothesis. The analysis compared waveforms for different values of the defect shows their satisfactory agreement.
Keywords: rod design, vibrations, defect, finite element modeling, analytical modeling, waveform
The dynamic problem of an anisotropic poroelastic plane under an influence of point source in the steady-state oscillation mode is studied. An analytical solution of the problem as a single integrals over a finite interval is given. Numerical experiments on the construction of solutions are made and the results are compared with the known classical solutions.
Keywords: poroelasticity, vibrations, anisotropy
The features of the construction of effective solutions to the problems of excitation of multi-media internal sources of oscillations. Examples of numerical calculations of the displacements and strains in the environment depending on the position of the source and observation point.
Keywords: many layers of base, internal source, harmonic oscillations