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1
Content available Influence of spatial distribution and the type of material on the occurrence of bandgaps in phononic crystals
Garus Sebastian, Sochacki Wojciech, Kwiatoń Paweł, Nabiałek Marcin, Petrů Jana, Kubanek Mariusz
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2023
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Vol. 71, nr 3
art. no. e144609
EN
The study investigated the effect of the fill factor, lattice constant, and the shape and type of meta-atom material on the reduction of mechanical wave transmission in quasi-two-dimensional phononic structures. A finite difference algorithm in the time domain was used for the analysis, and the obtained time series were converted into the frequency domain using the discrete Fourier transform. The use of materials with large differences in acoustic impedance allowed to determine the influence of the meta-atom material on the propagation of the mechanical wave.
2
Content available Influence of material distribution and damping on the dynamic stability of Bernoulli-Euler beams
Garus Sebastian, Garus Justyna, Sochacki Wojciech, Nabiałek Marcin, Petru Jana, Borek Wojciech, Šofer Michal, Kwiatoń Paweł
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2023
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Vol. 71, nr 4
art. no. e145567
EN
The study analyzed the influence of materials and different types of damping on the dynamic stability of the Bernoulli-Euler beam. Using the mode summation method and applying an orthogonal condition of eigenfunctions and describing the analyzed system with the Mathieu equation, the problem of dynamic stability was solved. By examining the influence of internal and external damping and damping in the beam supports, their influence on the regions of stability and instability of the solution to the Mathieu equation was determined.
3
Content available Minimizing the number of layers of the quasi one-dimensional phononic structures
Garus Sebastian, Sochacki Wojciech, Kubanek Mariusz, Nabiałek Marcin
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2022
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Vol. 70, nr 1
art. no. e139394
EN
In the work, multi-criteria optimization of phononic structures was performed to minimize the transmission in the frequency range of acoustic waves, eliminate high transmission peaks with a small half-width inside of the band gap, and what was the most important part of the work – to minimize the number of layers in the structure. Two types of the genetic algorithm were compared in the study. The first one was characterized by a constant number of layers (GACL) of the phononic structure of each individual in each population. Then, the algorithm was run for a different number of layers, as a result of which the structures with the best value of the objective function were determined. In the second version of the algorithm, individuals in populations had a variable number of layers (GAVL) which required a different type of target function and crossover procedure. The transmission for quasi-one-dimensional phononic structures was determined with the use of the transfer matrix method algorithm. Based on the research, it can be concluded that the developed GAVL algorithm with an appropriately selected objective function achieved optimal solutions in a much smaller number of iterations than the GACL algorithm, and the value of the k parameter below 1 leads to faster achievement of the optimal structure.
4
Content available Mechanical vibrations: recent trends and engineering applications
Garus Sebastian, Błachowski Bartłomiej, Sochacki Wojciech, Jaskot Anna, Kwiatoń Paweł, Ostrowski Mariusz, Šofer Michal, Kapitaniak Tomasz
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2022
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Vol. 70, nr 1
art. no. e140351
EN
Although the study of oscillatory motion has a long history, going back four centuries, it is still an active subject of scientificr esearch. In this review paper prospective research directions in the field of mechanical vibrations were pointed out. Four groups of important issues in which advanced research is conducted were discussed. The first are energy harvester devices, thanks to which we can obtain or save significant amounts of energy, and thus reduce the amount of greenhouse gases. The next discussed issue helps in the design of structures using vibrations and describes the algorithms that allow to identify and search for optimal parameters for the devices being developed. The next section describes vibration in multi-body systems and modal analysis, which are key to understanding the phenomena in vibrating machines. The last part describes the properties of granulated materials from which modern, intelligent vacuum-packed particles are made. They are used, for example, as intelligent vibration damping devices.
5
Content available The Effect of Layer Thickness on the Reflectance of a Quasi One-Dimensional Composite Built with Zr55Cu30Ni5Al10 Amorphous Alloy and Epoxy Resin
Garus Sebastian, Sochacki Wojciech
Archives of Metallurgy and Materials
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2021
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Vol. 66, iss. 2
503--510
EN
The study examined the impact of the angle of incidence of mechanical waves on various types of quasi one-dimensional superlattice. Binary periodic structure, quasi-periodic distribution of Thue-Morse layers and Severin’s aperiodic multilayer were used. Using the concatenation and recursive rules, the distribution of layers was determined for individual structure types for generation numbers equal to 3, 4 and 5. The structures were selected so that the thickness of the composite was the same for each type of distribution for a given generation number value. Transfer Matrix Method algorithm was used to determine reflectance. The band structure of reflectance has been demonstrated for incidence angles up to 90 degrees at mechanical wave frequencies up to 50 kHz. The existence of wide bands of high reflectance above the acoustic frequencies was demonstrated for the analyzed structures. Increasing the layer thickness caused an inhomogeneous shifts of transmission peaks towards lower frequencies.
6
Content available Optimization of a Bandgap in the Ultrasonic Phononic Coating
Garus Sebastian, Sochacki Wojciech, Garus Justyna, Sandu Andrei Victor
Archives of Metallurgy and Materials
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2021
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Vol. 66, iss. 2
537--542
EN
This work concerns the study of the coatings for the ultrasound frequency range as a quasi one-dimensional phononic crystal structure protecting a sea object against high resolution active sonar in the frequency range most commonly found for this type of equipment. The topology of the examined structure was optimized to obtain a band gap in the 2.2-2.3 MHz frequency band. For this purpose, a genetic algorithm was used, which allows for optimal distribution of individual elements of the ultrasound multilayer composite. By optimal distribution is meant to achieve a structure that will allow minimal reflectance in a given frequency range without height reflectance peaks with a small half width. Analysis of the wave propagation was made using the Transfer Matrix Method (TMM). As part of the research, 15 and 20-layer structures with reflectance at the level of 0.23% and 0.18%, respectively, were obtained. increasing the number of layers in the analyzed structures resulted in finding such a distribution in which a narrow band of low reflectance was obtained, such distributions could also be used as bandpass filters. The use of a genetic algorithm for designing allows to obtain modern coatings, the characteristics of which result from the structure.
7
Content available Influence of Material Defects on the Dynamic Stability of the Bernoulli-Euler Beam
Sochacki Wojciech, Garus Sebastian, Garus Justyna
Archives of Metallurgy and Materials
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2021
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Vol. 66, iss. 2
519--522
EN
The paper presents the results of tests on dynamic stability of Bernoulli-Euler beam with damages. Damages (cracks) were modeled using three rotational springs. An analysis of the influence of crack depth and their position relative to the beam ends on dynamic stability of the beam was carried out. The problem of dynamic stability was solved by applying the mode summation method. Applying an orthogonal condition of eigenfunctions, the dynamic of the system was described with the use of the Mathieu equation. The obtained equation allowed the dynamic stability of the tested system to be analyzed. Stable and unstable solutions were analyzed using the Strutt card.
8
Content available Designing of quasi one-dimensional acoustic filters using genetic algorithm
Garus Sebastian, Sochacki Wojciech
Vibrations in Physical Systems
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2019
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Vol. 30, nr 2
art. no. 2019210
EN
In phononic quasi one-dimensional structures, there is a phenomenon of a phononic bandgap (PhBG), which means that waves of a given frequency do not propagate in the structure. The location and size of PhBG depend on the thickness of the layers, the type of materials used and their distribution in space. The theoretical study examined the transmission properties of quasi one-dimensional structures designed using a genetic algorithm (GA). The objective function minimized the transmission integral and integral of the absolute value of the transmission functions derivative (to eliminate high transmission peaks with a small half width) in a given frequency range. The paper shows the minimization of transmission in various frequency bands for a 40-layer structure. The distribution of multilayer structure transmission was obtained through the Transfer Matrix Method (TMM) algorithm. Structures surrounded by water were analyzed and built of layers of glass and epoxy resin.
9
Content available remote Free and parametric vibration of the system: telescopic boom - hydraulic cylinder (changing the crane radius).
Sochacki Wojciech, Tomski Lech
Archive of Mechanical Engineering
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1999
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Vol. XLVI, nr 3
257-271
EN
In this work, authors present the development of a model of the system: telescopic boom - hydraulic cylinder (that one which controls the crane radius of the track crane). The problem is formulated by means of the Hamilton's pronciple and is solved as a geometrically non-linear problem by the small parameter methd. Within the range of free vibration, the vibration frequencies of the system have been determined. The effect of cetrain parameters of the system on its vibration frequency has also been studied. Solution of the Mathieu equation (describing parametric vibration of the system) enables one to determine the dynamic stability regions of the system. Possibility of existence of the parametric resonance in the system has been investigated. It has been fund that, for each of the studied examples, there exists such a wire length for witch the critical value of the coefficient "a" (in the Mathieu equation) is obtained. This means that for specified geometrical and load conditions, the system may loose its dynamic stability (unless vibration damping is considered).
PL
W niniejszej pracy zbudowano model układu wysięgnik teleskopowy-siłownik zmiany wysięgu żurawia samochodowego. Zagadnienie formułuje się z wykorzystaniem zasady Hamiltona i rozwiązuje jako geometrycznie nieliniowe metodą małego parametru. W zakresie drgań swobodnych wyznaczono częstości drgań układu i zbadano wpływ niektórych parametrów układu na jego częstości drgań. Rozwiązanie równania Mathieu opisującego drgania parametryczne układu prowadzi do wyznaczenia obszarów stateczności dynamicznej rozpatrywanego układu. Zbadano możliwość istnienia rezonansów parametrycznych w badanym układzie i stwierdzono, ze w każdym z badanych przypadków istnieje taka długość liny, dla której otrzymuje się krytyczną wartość współczynnika "a" w równaniu Mathieu. Oznacza to, że układ dla pewnych warunków geometrycznych i obciążenia (bez uwzględniania tłumienia) może stracicć stateczność dynamiczną nawet dla małych wartości współczynnika "b" w równaniu Mathieu.
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