Annotation of the results obtained in 2019
An interdisciplinary project and the results obtained are a contribution of a team from research institutes of Russia, with a technical support of colleagues from University of Ulsan (Korea) to solve a key science and technology problem in developing “man-machine” systems. These are infra-low-frequency vibration and noise the most harmful and dangerous for human activity and operation of transport and energy systems, electronics, instruments. This progress in solving the problem is especially important because, along with improvement of vibration protection of humans and present machines, conceptually new methods are developed for vibration protection of the next-generation systems, what is impossible by using the known methods. These are manned (helicopters) and unmanned (nanosats, drones) aircrafts, rolling stock and infrastructure of high-speed rail systems for a long-distance under intensive development at present, complex and expensive (at the cost of $600M to $3B) high-energy systems such as future colliders for basic research and their use in high-techs. Improvement of the capacity (emittance) of radiation source and optical system of a collider depends no longer on improving the design and tightening the tolerances; however, the structural vibrations amplified by external technogenetics vibrations and seismic activity became a critical limiting factor in developing the colliders. Results of the project demonstrate a possibility to solve, and at a principally new level, the vibration problem of a next-generation of the “man-machine” systems. The most significant results of the project are: 1. A technology for obtaining a wide range of structural and functional micro- and nanopowders of metals and nonmetals, and intermediate products based on the chemical (in the liquid phase due to the chemical reactions), physical (evaporation of a solid by using the electron-beam accelerator system) and mechanochemical methods. The micro- and nanopowders can be used to design the multifunctional protective coatings, structures and mechanisms for vibration and noise control, in micro- and nanoelectronics, instrumentation, environmental engineering, chemical industry. 2. The theory and experimental methods for designing and study of the mechanisms with "negative" and "quasi-zero" stiffness which have the most promising for vibration protection of humans, machines and equipment in a wide range including close to zero frequencies. These include the algorithms and applied methods for modeling and analysis of elastic elements and systems under post-buckling "in the large", for designing the elastic, basic and body elements of the mechanisms made, for the first time, of light high-strength composites (e.g. carbon plastics) and ceramics. The methods are based on the hypotheses of the fundamental consistent theory of shells. The computation algorithms and procedures are based on the FEM using the integrated environment Delphi for Microsoft Windows. These basic methods are supplemented by the algorithms for computation of optimal geometric and functional parameters of the mechanisms using Nelder-Mead method. A method for computation elastic elements and systems with "quasi-zero" and "negative" stiffness for large linear and angular deformations and displacements is also proposed. The MSC.Marc software package is used to the elastic and elastic-plastic models in calculating the elements made of the composites. The elasticity problem is solved by the Newton-Raphson method, in the Total Lagrange setting. 3. The experimental models have been developed for studying the propagation of sound waves through micro- and nanoporous media, and used for designing single-layer structures and systems of passive (active) sound absorption in the narrow bands of the low-frequency spectrum 125-1600 Hz, as well as multilayer structures for wideband sound absorption. This allows designing a structure with properties of porous, resonant and membrane sound-absorbers simultaneously and, thus, maximize the efficiency of noise control using relatively thin structures. This approach allows designing e.g. two-layer sound-absorbing structures with a total thickness of 25-40 mm, which can be effective in the whole spectrum 125-1600 Hz. For comparison, the known sound-absorbing materials and multilayer structures used in transport and construction with a total thickness of 170 mm are effective starting 500 Hz over. 4. A technology for producing the sound-absorbing materials using the micro- and nanopowder fillers and non-toxic intermediates has been developed. The technology consists in producing inorganic compounds (salts), preparing solutions using the compounds for impregnation the porous (with open porosity) and fiber materials. A series of dozens salt combinations was produced giving a positive result, e.g. CuSO4+NaHCO3, CaCl2+KH2PO4, BaCl2+KH2PO4, SrCl2+KH2PO4, AlCl3+Na2CO3, Na2SiO3+NaHCO3. Advantages: (a) simple manufacturing of a sound-absorber, (b) use of cheap, non-toxic ingredients and intermediates, (c) a possibility of using the technology in producing a new or modification of an off-the-self acoustic material, (d) providing 2-3-time increase of efficiency in the range, 125-1000 Hz, in comparison with known materials. 5. A method for synthesis of sulfamates and orthophosphates has been developed for impregnating the sound-absorbing materials to increase their fire resistance (the materials and structures become non-combustible). This result is extremely important for ensuring the safety of human environment and operation of a man-machine system, since off-the-self decorative and sound-absorbing materials and structures used in a vehicle, sleeping-car and cabin of a plane burn out completely within 9-10, 6-12 and 3-6 minutes, respectively. 6. Scaled models and prototypes of vibration-isolating mechanisms with “quasi-zero” and “negative” stiffness with passive and active parametric control were developed. In particular, a mini-platform with a payload of 500–600 N for a vibration sensitive instrument. A feature of the platform is the use of elastic elements with “quasi-zero” and “negative” stiffness of lightweight high-strength composites (e.g. carbon plastics). This made it possible to increase 4–5 times the effective stroke but without increasing the workspace, in comparison with analogues using the spring steels. Using the similarity theory, one may design a mechanism with a payload of 150 to 5000 N, without a significant change in the platform dimensions. Under development, the mechanisms with "negative" stiffness for vibration protection systems of a heavy object (payload up to 250,000 N). These are e.g. the transport and power machinery, structural elements of buildings, bridges for areas with a high seismic activity. 7. The algorithmic methods, software and instrument have been developed for noise and vibration diagnostics and control. In particular, this is a combined algorithmic method of noise control in a reverberant environment. The algorithms for measuring and analyzing the RIR (transient response) of speech signals in real time with reverberation and background noise in closed spaces with variable boundary conditions are developed. An algorithm for monitoring and diagnostics of basic elements (bearings and transmissions) based on the FFT- and wavelet methods of vibration spectral analysis is proposed. A method is proposed to estimate the size of a defect in a basic element of a mechanism (e.g. an outer ring of a rolling bearing at a variable rotation speed). An adaptive diagnostic approach based on an empirical wavelet transform is proposed for a quick search of a transmission failure source. 8. The project results are published in the Journals Shock and Vibration, Applied Sciences, in Proceedings of the 26th International Congress on Sound and Vibration (ICSV26). Cambridge University Press is preparing a monograph for publication. Some results of the development are registered at the Federal Agency for Intellectual Property of Russia.

 

Publications

---

Annotation of the results obtained in 2017
A strategy is proposed that includes theoretical and experimental methods for designing the elements of structures, mechanisms and systems with extreme elastic-dissipative characteristics for broadband vibration and noise isolation of humans and engineering using composite materials whose structural and/or elements are formed from polydisperse media. Including: 1) By using novel technologies based on the physical and chemical methods for the synthesis of micro- and nanopowders, the semi-products (in particular, nanoporous granules filled with polydisperse powders) were produced and used in designing the models of structural composites, as well as the porous (foamed) acoustic materials for manufacturing a car interior parts. 2) The propagation of waves in one-dimensional mono and polydisperse phonon crystals, through the boundary of a phonon crystal and a homogeneous continuous medium, and through the boundary of two phonon crystals under various assumptions about the spatial structure and physical properties of inhomogeneous media is studied. The problems were solved using the theory of the group representations in the space of solutions. As a result of the work, dispersion curves representing dependence of the oscillation frequency on the oscillations phase shift in the neighboring fundamental cells of the translation group were obtained, the mechanics of oscillations at waveguide frequencies was studied, and the structure of the frequency spectrum was described. In studying the problem of the acoustic waves propagation through the boundary of phonon crystals with a homogeneous medium and the problem of the acoustic waves propagation through the boundary of two phonon crystals with different spatial and physical structure, the dependence of the transmission and reflection coefficients on the geometrical and physical parameters of the crystals was derived. The behavior of the transmission and reflection coefficients of acoustic energy near the boundaries of the pass and stop bands of the phonon crystals spectra was described. Study of propagation of nonlinear hydroelastic waves in cracks and pores of an elastic material was carried out. Assuming that the transverse dimensions of the cracks and pores are small in comparison with the propagating wavelengths, the problem was modeled with a one-dimensional elastic channel filled with liquid media (fluid or gas). By using the methods of study quasi-linear hyperbolic partial derivative equation systems the dependence of the hydroelastic waves propagation velocity on the elastic characteristics of the channel and the properties fluid was obtained. It was shown that the velocity of hydroelastic waves is less than the sound velocity the fluid and the velocity of the elastic waves in the channel. Using the theory of the weak discontinuities propagation for the channels with different geometrical properties the conditions for gradient catastrophe of the solution to occur was obtained. Conditions on the strong discontinuity curve of hyperbolic hydroelastic waves were determined. On the basis of theoretical study a nonlinear mechanism for the wave energy conversion on a strong discontinuity curve is described. 3) Using the method of shock-wave pressing of the initial powders, a sample of a structural material constituting a metal-ceramic cylindrical composite Steel-Al2O3-Steel was produced. The method is based on high-speed plastic deformation of an external cylindrical metal shell and pressing of a powder located between coaxial cylindrical metal tubes under the influence of the energy of expanding detonation products. The sample of a vibration isolator made of new composite material were tested by the methods of modal analysis. 4) A method of volumetric filling of foamed materials with nanoporous granules ("microchips") and polydisperse powders showed its efficiency in modifying the noise isolation systems of a car interior. The test results of the system scaled models shows that the method makes it possible to increase the efficiency by 60−100% (absorption ratio), while transmission loss can be reduced by 20 to 22 dB. At the same time, the frequency range of the efficiency is significantly expanded and shifted to lower frequencies (from usual, 5−6.3 kHz, to 0.5−6.3 kHz). Besides, the acoustic characteristics are improved when using a composite in the form of a multilayer sandwich made of the porous materials filled with polydisperse powders, where each i-layer has a small thickness (~2 to 2.5 mm). 5) An algorithm for measuring and FFT-auto spectra analysis of acoustic characteristics of the models of the composites and structures is developed. The algorithm is based on the method of transfer matrix and makes it possible to obtain a high correlation of the characteristics of the composite structural elements. The algorithm allows predicting the characteristics change in the models of a noise isolation system of any complexity. The efficiency of the algorithm is shown through the modeling of the parts for a car interior. 6) A method of the type and number synthesis of the mechanisms for vibration isolation systems with extreme stiffness and damping (from "negative" to nearly zero values) is under development. Such systems have promising to protect humans and precision equipment from the most harmful and dangerous vibrations in the infra- and low frequency range (0.5−40 Hz). The method includes a theory and an algorithm to design a "perfect" spatial structure of the system of any complexity, as well as an atlas of 24 groups of new type diagrams. The diagrams in the atlas are only some of many possible ones that can be obtained by the method and applied to design of the system for any type of a vehicle of equipment and their operation conditions. Minimization of undesirable structural redundancy by the method allows reducing the system damping 3.5−4 times and, thus, to obtain extremely small stiffness. 7) A method of an optimal dimensioning of the mechanisms, which parametric elements are the compositions made as the multi-layer thin-walled elastic structures under post buckling "in the large" is underdevelopment as well. In particular, the use of interlayer gap-elements in the models of deflected mode of the structures lets more accurate analysis of structural damping, and provides formulation of additional design parameters so that to significantly expand a range of the control of extreme (“negative”) stiffness. The method is sensitive to change of the main and additional design parameters. This makes it possible to increase by an order and more the range of "negative" stiffness, and with a small (12 to 15%) increase in the size of the mechanisms. The method is applicable to design of both a man-operator's vibration isolation systems, e.g. for a helicopter pilot, and a technical system, e.g. for the railroad rolling stock. It is remarkable, the maximum dimensions of the mechanisms for the "railway" system with a load of 250−300 kN increase only 2.2-2.5 times, in comparison with the size of the mechanisms for the “aviation” system with a load of less than 1.4 kN.

 

Publications

---

Annotation of the results obtained in 2018
A methodology has been developed to design and study the materials, structures and mechanisms for special systems of the vibration isolation and noise control in the infra- and low frequency ranges, which are the most harmful and dangerous for human activity and engineering operation. The methodology includes: 1) A method of "chemical" synthesis of micro- and nanopowders of metals and oxides for designing multifunctional composites, e.g., foamed polymers with fillers, for manufacture of the room or vehicle interior structures capable to provide effective sound-absorption and fire protection. The method can also be successfully applied to produce the nanopowders with an impurity no more than 1 ppm, which is important in designing structural composites for some promising applications, e.g., in micro- and nanoelectronics. 2) A method of reducing vibration noise, which consists in the control of the absorption ratio by introducing combined fillers into the material, and each filler is “responsible” for a certain bandwidth of the low-frequency acoustic spectrum, while the material plays the role of a “matrix”, on which inner surface different salts and oxides, including those formed in situ, could be deposited, e.g. from aqueous solutions. 3) A method of noise control in a production area or lecture-room, which consists in pre-processing of audio signals (voice channel) using an integrated algorithm of modified PDMSE-method and improved FIF-method. The method reduces a background noise and significantly improve the speech intelligibility in such indoor reverberant environments. 4) A method of designing an optimal structure of mechanisms with "quasi-zero" and "negative" stiffness for the systems of the infra-frequency vibration protection of humans and engineering. Theoretical validity of the method is demonstrated in terms of the development of active pneumatic systems that are most effective for the infra-frequency vibration protection of humans, as well as the systems for secondary suspensions of high-speed passenger train cars. 5) A method, based on the hypotheses and statements of consistent theory of thin shells, for studying and analysis of the stress-strain state of elastic thin-walled structures made of spring steels under post-buckling in large (with “negative” stiffness), as well as for an optimal on-line dimensioning the mechanisms with such elastic structures. The method makes it possible to design a multi-stage system of the infra-frequency vibration protection containing geometrically and dynamically similar mechanisms with “negative” stiffness. For the first time, in terms of the method, a possibility of substitution of the spring steels with lightweight and high-strength composites, such as carbon plastics, is demonstrated, what could fundamentally change the philosophy of design of the mechanisms with “negative” and “quasi-zero” stiffness for vibration protecting and measuring systems for various purposes. 6) New functional composites for sound-absorption in the low frequency range, and for fire barrier. New structural composites made of spring steels and, for the first time, of lightweight elastic carbon plastics, for the vibration isolating and measuring systems with “negative” and “quasi-zero” stiffness. 7) Methods of the experimental study, including the goals and objectives, a set of standard and original test equipment, theory, algorithms and software to process the loading, measuring and FFT- and wavelet spectral vibration and noise analysis, as well as performing the comparative assessments of the quality of initial and projectable composites, structures and mechanisms for systems of the low-frequency noise control and infra-frequency vibration isolation. 8) Publications in 2018. Articles S.P. Bardakhanov, C.-M. Lee, V.N. Goverdovskiy, A.P. Zavjalov, K.V. Zobov, M. Chen, Z.H. Xu, I.K. Chakin, D.Yu. Trufanov. Hybrid sound-absorbing foam materials with nanostructured Applied Acoustics. 2018, 139, p.69-74. DOI: 10.1016/j.apacoust.2018.04.024 Q1 V. Syzrantsev, E. Paukshtis, T. Larina Tatyana, Yu. Chesalov, S. Bardakhanov, A. Nomoev. Features of Surface Structures of Alumina and Titanium Dioxide Nanoparticles Produced Using Different Synthesis Methods // Journal of Nanomaterials . 2018, Article number, 2065687, 10 pages. DOI: 10.1155/2018/2065687 C.-M. Lee and V. N. Goverdovskiy Intelligent structural design of transport pneumatic suspensions with extreme characteristics // International Journal of Automotive Technology. 2018, 2018:3, 13 pages. DOI: Q1 H.-Yu Dong and C.-M. Lee. Speech intelligibility improvement in noisy reverberant environments based on speech enhancement and inverse filtering // Eurasip Journal on Audio, Speech, and Music Processing. 2018, 2018:3, 13 pages. DOI: 10.1186/s13636-018-0126-8 V.V. Syzrantsev, L.S. Vikulina, S.P. Bardakhanov, A.V. Nomoev, N.O. Kopanitsa, Y.A. Abzaev, O.V. Demyanenko, G.D. Kopanitsa. The Different Fractal Structure of Oxide Nanopowders Depending // Solid State Phenomena. 2018, Vol. 271 SSP, p. 124-132. DOI: 10.4028/www.scientific.net/SSP.271.124 Proceedings S. Bardakhanov, M. Katasonov. Bluff bodies and wake flow-induced acoustic resonance // Proceedings of the 25th International Congress on Sound and Vibration,Sound of Peace Bell, 2018_Silesian University of Technology Press, Gliwice, Poland K. Zobov, C.-M. Lee, V. Goverdovskiy, D. Trufanov, S. Bardakhanov. Nanostructured sound-absorbing foam materials // Proceedings of the 25th International Congress on Sound and Vibration,Sound of Peace Bell, 2018_Silesian University of Technology Press, Gliwice, Poland C.-M. Lee, V. Goverdovskiy, A. Shutov, A. Larichkin. Vibration protection systems with extremely small stiffnes and damping intelligent structural design and dimensioning // Proceedings of the 25th International Congress on Sound and Vibration,Sound of Peace Bell, 2018_Silesian University of Technology Press, Gliwice, Poland

 

Publications

---