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1

The Temperature Field Effect on Dynamic Stability Response of Three-layered Annular Plates for Different Ratios of Imperfection

Pawlus Dorota

Studia Geotechnica et Mechanica

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2023

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Vol. 45, nr 2

158--173

EN

The paper presents the temperature field effect on the dynamic stability problem of plates with imperfection. The main objective is to conduct numerical investigations which show the relations between the imperfection ratio and plate dynamic response in a thermal environment. The plate is composed of three layers: thin facings and a thicker core. The plate can be loaded mechanically and thermally or only thermally. The facings are mechanically compressed with the forces acting in a plane. The temperature field model is defined by the temperature difference, which occurs between the plate edges. Two plate models are examined as follows: built using the approximation methods – orthogonalization and finite differences – and composed of finite elements. The analytical and numerical solution procedure is the main one, which is the proposal to perform the problem analysis. The plate reaction is described by the obtained values of the critical temperature differences for plates loaded only thermally and by the critical mechanical load sand the corresponding temperature differences for plates loaded mechanically and subjected to the uncoupled temperature field. The effect of the plate imperfection ratio under time-dependent loads is shown by numerous observations and results, which are shown graphically. The importance of the imperfection ratio on the plate’s dynamic stability response in complex loading conditions is studied.

2

Dynamic stability analysis with real data of hybrid RES integration in southwest Algeria power system using Etap software

Zemitte Seddik, Hamouda Messaoud, Arama Fatima Zohra

Przegląd Elektrotechniczny

|

2023

|

R. 99, nr 6

237--242

EN

The power system is non-linear due to the constant change in loads, generators and operating conditions. In recent years, a substantial quantity of renewable energy sources (RES), has been integrated into the world power grid, which has provided alternatives to fossil fuels, especially since they are economical and environmentally friendly to the environment. But at the level of power system stability many concerns have been raised about its efficiency and its impact on its stability and reliability, so it is essential to investigate this impact. The simulation results demonstrated that the stability of the system is affected by this integration, particularly when conventional production plants predominate in the system.

PL

System elektroenergetyczny jest nieliniowy ze względu na ciągłe zmiany obciążeń, generatorów i warunków pracy. W ostatnich latach znaczna ilość odnawialnych źródeł energii (OZE) została włączona do światowej sieci elektroenergetycznej, co stanowi alternatywę dla paliw kopalnych, zwłaszcza że są one ekonomiczne i przyjazne dla środowiska. Jednak na poziomie stabilności systemu elektroenergetycznego zgłoszono wiele obaw dotyczących jego wydajności i wpływu na jego stabilność i niezawodność, dlatego konieczne jest zbadanie tego wpływu. Wyniki symulacji wykazały, że integracja ta ma wpływ na stabilność systemu, zwłaszcza gdy w systemie dominują konwencjonalne zakłady produkcyjne.

3

The dynamic stability problem of composite annular plates with auxetic properties

Pawlus Dorota

Engineering Transactions

|

2023

|

Vol. 71, iss. 3

329--349

EN

This paper presents the effect of the auxeticity on the behaviour of a plate subjected to the loss of stability. The plate structure is composed of three layers built of auxetic or conventional facings and a conventional core. The plate is loaded mechanically in the plane of facings with forces increasing in time. The main technique of the problem solution is based on the orthogonalisation and finite differences methods. Selected examples of plates were calculated with the use of the finite difference method. The obtained results allow observing the similarities and differences between plate models, whose structures are built of conventional layers or mixed layers: auxetic-foam-auxetic. Investigations complement the knowledge of the responses of the composite structures with auxetic properties. They show the possibility of using special plate structures whose materials are characterised by the negative value of Poisson’s ratio.

4

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

|

2023

|

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.

5

Dynamic stability of a cracked pipe conveying fluid and resting on a Pasternak elastic foundation

Lolov Dimitar, Lilkova-Markova Svetlana

Zeszyty Naukowe. Transport / Politechnika Śląska

|

2022

|

z. 117

103--113

EN

Pipeline transport is used worldwide in many sectors of the economy. Its main advantages are continuity of transport, large transportation volumes, small energy consumption, safety, reliability and high environmental benefits. However, the safety problems of pipes attract much interest in science and industry. This paper deals with a cracked pipe with a static scheme of a simply supported beam. It rests along its entire length on a Pasternak elastic foundation. The flowing fluid is considered non-compressible and heavy. The Galerkin method is employed to approach the problem numerically. Conclusions are drawn based on the influence of the crack and the parameters of the Pasternak elastic foundation on the critical flow velocity of the fluid.

6

Stability of a Bomb with a Wind-Stabilised-Seeker

Kowaleczko Grzegorz, Klemba Tomasz, Pietraszek Mariusz

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

|

2022

|

Vol. 13, Nr 3 (49)

43--66

EN

The primary purpose of this article is to consider the main factors affecting the stability of a bomb with a Wind-Stabilised-Seeker (WSS). The article contains a full mathematical description of the bomb-WSS system motion. It allows you to calculate the spatial motion of the bomb and the motion of WSS in relation to the bomb. The method of calculating the aerodynamic forces is also described. The sample simulation results were presented and discussed. The equations of motion of the system were determined. They constituted the basis for the development of a computer program to simulate the motion of the system. Aerodynamic forces and moments were calculated using the Prodas software and based on the results of the bomb tests in the wind tunnel. The mass and geometrical data of the system relate to the tested prototype of an aerial bomb. The result of the research is a comprehensive assessment of the influence of the geometric parameters of the mobile tracking system on the dynamic stability of the bomb-WSS system. This knowledge is necessary for proper design of control laws based on the signals registered by the WSS. The main parameter influencing the WSS-bomb stability is the aerodynamic focus position of the tracking system. It should be behind the WSS attachment point. The position of the WSS centre of mass in relation to the attachment point also has an adverse effect on its stability. The length of the stick connecting the WSS with the bomb is irrelevant.

PL

Podstawowym celem tego artykułu jest rozważenie głównych czynników wpływających na stabilność bomby z układem śledzącym stabilizowanym przepływem (WSS). Artykuł zawiera pełny opis matematyczny ruchu systemu bomba-WSS. Model ten został uzyskany z wykorzystaniem zasad mechaniki. Pozwala obliczyć ruch przestrzenny bomby i ruch WSS względem bomby. Sposób obliczania sił aerodynamicznych jest również opisany odpowiednimi wyrażeniami. Przedstawiono i omówiono przykładowe wyniki symulacji dotyczące wpływu geometrii układu na dynamikę jego ruchu. Równania ruchu układu zostały określone z wykorzystaniem praw mechaniki dotyczących układu wieloczłonowego. Stanowiły one podstawę do opracowania programu komputerowego do symulacji ruchu układu. Siły i momenty aerodynamiczne obliczono z wykorzystaniem oprogramowania Prodas oraz w oparciu o wyniki badań bomby w tunelu aerodynamicznym. Dane masowe i geometryczne układu dotyczą badanego prototypu bomby lotniczej. Wynikiem badań jest wszechstronna ocena wpływu parametrów geometrycznych ruchomego układu śledzącego na stateczność dynamiczną układu bomba-WSS. Wiedza ta jest niezbędna do właściwego zaprojektowania praw sterowania bazujących na sygnałach rejestrowanych przez WSS. Podstawowym parametrem wpływającym na stateczność dynamiczną układu jest położenie ogniska aerodynamicznego układu śledzącego. Powinien on znajdować się za punktem mocowania WSS do bomby. Położenie środka masy WSS względem punktu mocowania ma również niekorzystny wpływ na jego stateczność. Natomiast długość żerdzi łączącej WSS z bombą jest nieistotna.

7

Experimental study on dynamic stability of rubber-cement composites by SHPB and high-speed slicing

Yang Rongzhou, Xu Ying, Chen Pei Yuan

Archives of Civil Engineering

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2022

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Vol. 68, nr 1

319--334

EN

Improper disposal of waste tires will not only bring environmental impact and safety risks but also cause a serious waste of resources. In the field of civil engineering materials, waste tire particles are used as a substitute for non-renewable aggregates to produce flexible rubber-cement composites (RCC). To explore the high-speed slicing stability of RCC, this test took normal cement mortar (NCM) and rubber cement mortar (RCM) as research objects. The SHPB tests with the same impact energy level and the high-speed slicing tests with a slice thickness range of about 1.4 mm ~ 4.4 mm were carried out. The results showed that NCM and RCM showed different stability differences in the process of high-speed slicing. In the case of ensuring the integrity of the slice, the minimum thickness of the slice can be better decreased with the increase of the rubber content. Finally, from the perspectives of split Hopkinson pressure bar (SHPB) test results and mesoscopic structure states, the essential reason for ensuring the stability of high-speed slicing lied in the improvement of rubber particles (dominant role) and pores on material deformation and flexible energy dissipation.

8

Online monitoring of the power system stability based on the critical clearing time

Eleschová Žaneta, Beláň Anton, Cenký Matej, Bendík Jozef, Cintula Boris, Janiga Peter

Przegląd Elektrotechniczny

|

2021

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R. 97, nr 6

122--127

EN

This work refers to the concept of online monitoring of generators' dynamic stability based on the critical clearing time (hereinafter referred to as "CCT"). The CCT may be considered a basic criterion of the dynamic stability of a synchronous generator. The work presents an analysis of factors (operating condition of a generator, short-circuit power of the system, increase of the proportion of distributed production in the distribution system (hereinafter referred to as "DS ") influencing the CCT and analysis of possibilities to increase the value of the CCT. In this work, we present a relatively simple concept built on the calculation of the CCT using a swing equation, which may be implemented into the dispatch control of power systems (hereinafter referred to as "PS").

PL

Praca odnosi się do koncepcji monitorowania online dynamicznej stabilności generatorów w oparciu o krytyczny czas rozliczeniowy (zwany dalej „CCT”). CCT można uznać za podstawowe kryterium stabilności dynamicznej generatora synchronicznego. W pracy dokonano analizy czynników (stan pracy generatora, moc zwarciowa systemu, zwiększenie udziału produkcji rozproszonej w systemie dystrybucyjnym (dalej „DS”) wpływających na CCT oraz analizę możliwości zwiększyć wartość CCT W pracy przedstawiamy stosunkowo prostą koncepcję opartą na obliczeniu CCT za pomocą równania wahadłowego, która może zostać zaimplementowana w sterowaniu dyspozycją systemów elektroenergetycznych (dalej „PS”).

9

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

|

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.

10

Dynamic stability of mechanically and thermally loaded three-layered annular plate with viscoelastic core

Pawlus Dorota

Vibrations in Physical Systems

|

2020

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Vol. 31, nr 2

art. no. 2020223

EN

The problem of dynamic stability of composite three-layered annular plate with viscoelastic core is the subject of the consideration. Plate composed of thin outer layers and soft core is loaded quickly in time with forces compressing facings and with temperature gradient in radial direction. Two kinds of plate support system are analysed: plate slideably clamped in thermo-mechanical problem and plate clamped on both edges in thermal analysis. The analytical and numerical solution, which is based on the orthogonalization and finite difference methods includes axisymmetric and asymmetric forms of buckling and rheological properties of plate core.

11

Influence of the damping effect on the dynamic response of a plate

Borkowski Łukasz

Journal of Theoretical and Applied Mechanics

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2019

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Vol. 57 nr 1

263--272

EN

The subject of the research is analysis of the influence of the damping effect on the dynamic response of a plate. During the tests, the areas of dynamic stability and instability for the plate with and without damping are compared. Besides, exact analysis of the nature of the solution by applying criteria such as phase portraits, Poincar´e maps, FFT analysis, the largest Lyapunov exponents are carried out and found.

12

Dynamic stability of a model of a tractor-lorry-trailer combination

Sakno O., Moysya D. L., Kolesnikova T.

Zeszyty Naukowe. Transport / Politechnika Śląska

|

2018

|

z. 99

163--175

EN

In this paper, we consider the mobility and stability of a model of a tractor-lorry-trailer combination, consisting of a two-axle tractor and a single-axle semi-trailer, and its possible stationary states with fixed steering. A feature of this research is the study of a non-linear mathematical model of a two-link tractor-lorry-trailer combination. The set of steady-state conditions for the movement of the tractor-lorry-trailer combination model is determined on the basis of the developed mathematical model; it provides the necessary mobility for the passage of the circular overall traffic lane. The range of stable steady-state conditions of the road train is limited and the character of the loss of stability in the direct motion of the road train (divergent, flutter) is checked. The phase portraits of the system are constructed at different speeds, which allow us to estimate the range of attraction for direct motion. Stability issues are also considered, namely, the influence of the control parameters (θ, v) on stability or instability.

13

Dynamic Response of Three-Layer Annular Plate with Damaged Composite Facings

Pawlus D.

Archive of Mechanical Engineering

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2018

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Vol. LXV, nr 1

83--105

EN

The paper presents the dynamic behaviour of three-layer annular plates with damaged facings. The plate is composed of thin laminated, fibre-reinforced composite facings and thicker, foam core. Failure of the plate facings is modelled as fibre or matrix cracks. The plate loaded in the plane of facings with quickly increasing radially compressed forces loses its dynamic stability. Evaluation of the critical state of the plate with failures was carried out using both analytical and numerical solutions. The comparison of results between plates with material properties treated as isotropic, quasi-isotropic and composite has been conducted. Presented tables and figures create the image of dynamic responses of examined composite plates with structure failures.

14

Influence of parameters of core Bingham material on critical behaviour of three-layered annular plate

Pawlus D.

Studia Geotechnica et Mechanica

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2017

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Vol. 39, nr 4

99--110

EN

The paper presents the dynamic response of annular three-layered plate subjected to loads variable in time. The plate is loaded in the plane of outer layers. The plate core has the electrorheological properties expressed by the Bingham body model. The dynamic stability loss of plate with elastic core is determined by the critical state parameters, particularly by the critical stresses. Numerous numerical observations show the influence of the values of viscosity constant and critical shear stresses, being the Bingham body parameters, on the supercritical viscous fluid plate behaviour. The problem has been solved analytically and numerically using the orthogonalization method and finite difference method. The solution includes both axisymmetric and asymmetric plate dynamic modes.

15

Badanie możliwości estymacji naprężeń szczątkowych na podstawie gradientu pola namagnesowania

Antoniuk W., Sandomirskij S., Jaroszewicz J.

Przegląd Mechaniczny

|

2017

|

nr 2

34--38

PL

W układach napędowych wielkowymiarowych wywrotek, eksploatowanych przy budowie dróg i w kopalniach odkrywkowych, szeroko stosowane są wielotarczowe sprzęgła mokre i hamulce cierne. Podstawowymi elementami roboczymi są tarcze cierne, które narażone są na duże naciski powierzchniowe i przegrzanie w wyniku wydzielania ogromnej ilości ciepła. W celu zapewnienia niezawodnej pracy tarcz ciernych konieczne jest wyeliminowanie naprężeń szczątkowych, które powstają podczas ich produkcji i które w wielu przypadkach są przyczyną wypaczenia i utraty płaskości powierzchni oraz prowadzą do przedwczesnej utraty możliwości skutecznego hamowania. Ponieważ tarcze wykonywane są z określonych gatunków stali sprężynowej - jako efektywną metodę kontroli w procesie produkcji proponuje się wykorzystanie zjawiska efektu magnetosprężystego. Przeprowadzone badania zależności gradientu pola namagnesowania szczątkowego od naprężeń rozciągających w próbkach pokazały złożony charakter ich zależności i ujawniły istotne zmiany tego wskaźnika w różnych punktach rozmieszczonych na powierzchni czołowej tarcz. Otrzymane wyniki potwierdzają, że zastosowanie opisanej w niniejszej pracy metody i przyrządu do badań naprężeń szczątkowych w tarczach hamulców i sprzęgieł jest celowe, gdyż znacząco poprawi jakość ich produkcji.

EN

Multi-disc wet clutches and friction brakes are widely applied in drive units of large-size tippers, used in road construction and open-pit mining. The basic working elements are friction discs, exposed to high surface pressures and overheating due to release of significant amounts of heat. In order to ensure reliable operation of friction discs it is necessary to eliminate the residual stresses created in the manufacturing process, and which, in many cases cause distortion and loss of surface flatness, and lead to premature loss of the effective braking. Since discs are made of certain types of spring steel, magneto-spring effect is suggested as an effective method of control in the production process. The study based on dependency of gradient of residual magnetism field on tensile stress in the samples showed the complexity of their relationships and demonstrated significant changes of this ratio at different points, located on frontal areas of discs. The results confirm that the application of the method, described in this paper, and the device for testing the residual stresses in the discs of brakes and clutches is appropriate as this will significantly improve quality of production.

16

Nonconservative stability of viscoelastic plates subject to triangularly distributed follower loads

Robinson M.T.A., Adali S.

Journal of Theoretical and Applied Mechanics

|

2017

|

Vol. 55 nr 3

1015--1027

EN

Divergence and flutter instabilities of viscoelastic rectangular plates under triangularly distributed tangential follower loads are studied. Two sets of boundary conditions are considered, namely, simply supported plates and plates with a combination of clamped and simply supported edges. The constitutive relations for the viscoelastic plates are of Kelvin-Voigt type with the effect of viscoelasticity on stability studied numerically. The method of solution is differential quadrature which is employed to discretize the equation of motion and the boundary conditions leading to a generalized eigenvalue problem. After verifying the method of solution, numerical results are given for the real and imaginary parts of the eigenfrequencies to investigate flutter and divergence characteristics and dynamic stability of the plates with respect to various problem parameters.

17

Application of the Teager-Kaiser energy operator to detect instability of a plain bearing

Blaut J., Korbiel T., Batko W.

Diagnostyka

|

2016

|

Vol. 17, No. 4

99--105

EN

The paper presents application of a non-linear method (energy operator) to monitor the operation of a plain bearing. The possibility of using the energy operator to evaluate the energy of a simulated mechanical system was analysed. Then, an experiment was conducted in the laboratory environment which involved observation of oil vortexes. This allowed to show the possibility of using the energy operator as a descriptor of operating state of a hydrodynamic bearing.

PL

W artykule zaprezentowano użycie metody analizy nieliniowej jaką jest operator energetyczny w celu monitorowania pracy łożyska ślizgowego. Przeanalizowano możliwość użycia operatora energetycznego w celu oceny energii symulowanego układu mechanicznego. Potwierdziło to zależność pomiędzy energią w ujęciu newtonowski a wartością operatora energetycznego. Następnie przeprowadzono eksperyment na stanowisku laboratoryjnym polegający na obserwowaniu powstawania drgań olejowych. Pozwoliło to wskazać na możliwość stosowania operatora energetycznego jako deskryptora stanu pracy łożyska hydrodynamicznego.

18

Dynamic analysis of CWR track work on one- and two-parameter elastic foundation

Bednarek W. A.

Archiwum Instytutu Inżynierii Lądowej

|

2016

|

Nr 22

7--22

EN

In the paper a dynamical analysis of the deflection of CWR track resting on one- and two-parameter is shown. This problem is considered in the subject matter of railroads literature [1, 7, 11, 17, 19-27]. A model of railway track on foundation without damping and calculation model with damping is analyzed. For one- and two-parameter foundation an appropriate calculation examples, reflecting an influence of velocity, damping, foun-dation parameters and track strength parameters changes are enclosed. The paper has got also a review character, shows the formulas form on calculation of essential parameters for calculation of dynamic railway track deflections.

PL

W pracy przedstawiono analizę dynamicznych ugięć bezstykowego toru kolejowego spoczywającego na podłożu jedno- i dwuparametrowym, rozpatrywaną w literaturze z zakresu dróg kolejowych [1, 7, 11, 17, 19-27]. Przeanalizowano model toru na podłożu bez tłumienia oraz model obliczeniowy z uwzględnieniem tłumienia. Dla podłoża jedno- i dwuparametrowego zamieszczono stosowne przykłady obliczeniowe, obrazujące wpływ zmian prędkości, tłumienia i parametrów podłoża oraz parametrów wytrzymałościowych toru. Praca posiada także charakter przeglądowy, prezentuje postać wzorów na obliczanie niezbędnych parametrów do obliczeń dynamicznych ugięć toru kolejowego.

19

Dynamic behaviour of three-layered annular plates with viscoelastic core under lateral loads

Pawlus D.

Journal of Theoretical and Applied Mechanics

|

2015

|

Vol. 53 nr 4

775--788

EN

This paper presents the dynamic behaviour of three-layered, annular plates with a linear viscoelastic core. The annular plate is loaded in plane of facings with variable in time forces acting on the inner or outer plate edges. The analysed plate structure is symmetric and composed of three-layers: thin facings and a thicker, soft core. The core material is considered as linear with viscoelastic properties. Analytical and numerical solution will be presented including the wavy forms of dynamic loss of plate stability. In the analytical and numerical solution, two approximation methods: orthogonalization and finite difference have been applied to obtain the system of differential equations for the analysed problem of dynamic deflections of the examined plate with the viscoelastic core. Additionally, the suitable plate model using the finite element method has been built. The numerical calculations carried out in ABAQUS system show the results which are compatible with those obtained for the analytical and numerical solution. Presented in figures time histories of plate deflections and velocity of deflections as well as buckling forms of the plate model show the dynamic response of the examined plate on time-dependent loads and core material properties.

20

Analiza numeryczna stateczności dynamicznej belki swobodnie podpartej z ciągłym rozkładem masy

Majcher K.

Inżynieria i Budownictwo

|

2015

|

R. 71, nr 12

664--666

PL

Przedstawiono kombinowany algorytm bazujący na komercyjnych pakietach obliczeniowych COSMOS/M i MATHEMATICA, umożliwiający analizę skomplikowanych zagadnień teoretycznych mechaniki budowli, w których występuje problem zmiennych w czasie parametrów układu, np. właściwości geometryczno-materiałowych. Zamieszczono przykład takiej analizy.

EN

In this paper the combined algorithm based on two commercial systems (COSMOS/M and MATHEMATICA) is presented. The algorithm enables analyzing complex theoretical problems of structural mechanics, especially if the system parameters are time-dependent, e.g. geometric and material properties. The efficiency of the algorithm is verified by numerical analysis of dynamic stability problem of simply supported beam with continuous mass distribution.