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EN
An analytical solution has been developed developed in this research for electro-mechanical flexural response of smart laminated piezoelectric composite rectangular plates encompassing flexible-spring boundary conditions at two opposite edges. Flexible-spring boundary structure is introduced to the system by inclusion of rotational springs of adjustable stiffness which can vary depending on changes in the rotational fixity factor of the springs. To add to the case study complexity, the two other edges are kept free. Three advantages of employing the proposed analytical method include: (1) the electro-mechanical flexural coupling between the piezoelectric actuators and the plate’s rotational springs of adjustable stiffness is addressed; (2) there is no need for trial deformation and characteristic function—therefore, it has higher accuracy than conventional semi-inverse methods; (3) there is no restriction imposed to the position, type, and number of applied loads. The Linear Theory of Piezoelectricity and Classical Plate Theory are adopted to derive the exact elasticity equation. The higher-order Fourier integral and higher-order unit step function differential equations are combined to derive the analytical equations. The analytical results are validated against those obtained from Abaqus Finite Element (FE) package. The results comparison showed good agreement. The proposed smart plates can potentially be applied to real-life structural systems such as smart floors and bridges and the proposed analytical solution can be used to analyze the flexural deformation response.
EN
In this study, the elastic wave propagation method is used to observe the initiation and evolution of the fatigue failure form in the multilayered composite plate with an elliptical hole. The experimental tests with the use of active, pitch-catch elastic wave measurement techniques are used during the fatigue test of the composite specimens. The fatigue tests were preceded by the numerical, finite element analysis of the elastic wave propagation phenomenon in a composite plate with an elliptical hole. The sequential measurement related to the number of cycles during the fatigue tests was assumed. The time of flight (ToF) and amplitude change was monitored by piezoelectric sensors localized in the area of predictable failure form evolution. The analysis of the dynamic response of the structure under fatigue loading conditions by a relatively small number of piezoelectric transduces allows us to build cost-effective Structural Health Monitoring (SHM) system for damage detection and monitoring of the failure form evolution.
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.
4
Content available remote The influence of Helmholtz and Golay coil homogenity on rectangular plate bending
EN
The subject of the paper is a rectangular plate. The structure of the plate issymmetrical. The plate is made of a cellular structure of a core and two external faces. There isferrofluid in each cell of the porous core. The core is made of polyethylene foam and two facesare polyurethane sheets. It is assumed that cells in the core are regular and dense and the facesare thin, therefore, a plate filled in with ferrofluid can be treated as homogeneous. The plateis placed in the magnetic field. The magnetic field is generated by two systems of coils – theHelmholtz coil (HC ) and the Golay coil (GC). The former generates an almost fixed magneticfield in the considered volume (where the plate is placed), and the latter generates a gradientmagnetic field. The changing size of each subsystem of magnetic field coils, the distribution andstrength of the magnetic field change as well. The magnetic field induces loads in the plate,both perpendicular and in plane. The plate bending function is approximated by the bicubicspline function presented by normalized B-spline functions. The influence of changes in thehomogeneity volume and the magnetic field strength (by changing the coil size) on the platebending is analyzed in the paper. The results of the analysis are presented in tables and figures.
EN
The present research studied fault diagnosis of composite sheets using vibration signal processing and artificial intelligence (AI)-based methods. To this end, vibration signals were collected from sound and faulty composite plates. Using different time-frequency signal analysis and processing methods, a number of features were extracted from these signals and the most effective features containing further information on these composite plateswere provided as input to different classification systems. The output of these classification systems reveals the faults in composite plates. The different types of classification systems used in this research were the support vector machine (SVM), adaptive neuro-fuzzy inference system (ANFIS), k-nearest neighbor (k-NN), artificial neural networks (ANNs), Extended Classifier System (XCS) algorithm, and the proposed improved XCS algorithm. The research results were reflective of the superiority of ANFIS in terms of precision,while this method had the highest process duration with an equal number of iterations. The precision of the proposed improved XCS methodwas lower than that of ANFIS, but the duration of the processwas shorter than the ANFIS method with an equal number of iterations.
EN
Paper presents the sensitivity of the three-layered plate structure on the acting of mechanical and thermal loads. The cases of the annular plates, whose individual layers: facings and core have homogeneous building and/or heterogeneous one expressed by the variable material properties in radial direction have been examined. Numerical investigations have been carried out modelling the select examples of plate structure with the use of the finite element method. Plate is loaded in the plane of facings or is subjected to the flat temperature field. The evaluation of the structure sensitivity has been carried out analysing the values of critical loads or critical temperatures and corresponding with them buckling modes. Numerous results presented in diagrams create the image of plate behaviours, show responses of plate structure and indicate on the means of structure designs, which can fulfil the expected conditions of plate work.
EN
This paper focuses on the free vibration analytical solution of a composite sandwich plate consisting of woven carbon laminated faces and a viscoelastic foam core. In addition to the dry condition, a case of floating on bounded water is considered for the sandwich plate not only in analytical work but also in verification experiments. The equations of motion for the first-order shear-deformation plate in contact with the fluid are derived by using Hamilton's principle, and analytically solved using Navier's procedure. Bounded water boundary conditions and velocity potential function are used to describe the fluid motion. The viscoelastic properties of a marine PVC foam core are extracted from dynamic mechanical analysis. Frequency response function (FRF) method is applied in modal testing for measuring the natural frequencies of the dry and wet sandwich plates. Experimental results demonstrate the validity of the analytical results. The effects of the foam core behavior, core thickness, plate dimension ratio, and the fluid density on the natural frequencies are examined and discussed. The decrease of the fundamental mode natural frequency with the presence of the viscoelastic foam core is more prominent for the dry sandwich plate with respect to the wet one already damped by water.
9
Content available Współczesne metalowe elewacje perforowane
PL
Stosowanie elewacji perforowanych umożliwia uzyskanie elewacji nadających bryle budynku indywidualny charakter. Spośród dużej liczby dostępnych na rynku wyrobów budowlanych materiałów elewacyjnych największe możliwości w zakresie formowania kształtu pojedynczego elementu okładzinowego, stopnia skomplikowania wzoru perforacji i jej intensywności zapewniają okładziny metalowe. Znajomość właściwości materiałów oraz technologii produkcji elementów perforowanych jest kluczowa dla uzyskania estetycznych i poprawnych technicznie, a jednocześnie akceptowalnych ze względu na koszty produkcji rozwiązań. W pracy omówiono wybrane zagadnienia związane z projektowaniem i wykonaniem metalowych elewacji perforowanych.
EN
Use of perforated elevations makes it possible to obtain elevations which provide the body of a building with an individual character. Out of a great number of elevation materials available on the construction market, the greatest possibilities in the scope of forming the shape of a single facing element, degree of complexity of the perforation pattern and its intensity, are provided by metal facings. Knowledge of properties of materials as well as of production technologies of perforated elements plays a key role in obtaining aesthetic and technically correct solutions, which at the same time are acceptable in terms of production costs. The paper discusses selected issues connected with designing and creation of perforated metal elevations.
PL
Metale kolorowe, nieoparte w swej budowie chemicznej na pierwiastku żelaza, jakimi są aluminium, cynk oraz miedź, stanowią dobrą, choć zdecydowanie droższą, alternatywę materiałową powszechnie stosowaną w pracach zarówno okładzinowych, jak i konstrukcyjnych wielu współczesnych budynków. Materiały te cenione są za ich odmienne właściwości w stosunku do wyrobów stalowych, w tym odporność na korozję, wygląd, charakter, jaki nadają obiektom. Inny aspekt to warunki ich stosowania, które wymagają czasami odmiennych metod obchodzenia się z wyrobami powstałymi z tych materiałów. W artykule opisano wybrane aspekty stosowania najpopularniejszych metali nieżelaznych w lekkich obudowach ścian i dachów.
EN
This paper presents the capabilities of ABAQUS finite-element program [1] in modelling sandwich beams and plates resting on deformable foundations. Specific systems of sandwich beams and plates separated by an elastic core layer were subjected to the action of point and distributed moving loads. A few theoretical examples are provided to present different techniques of modelling the foundations and the moving loads. The effects of the boundary conditions and of the foundation parameters on the deflections of the analysed structures are also presented.
PL
Ograniczeniem zastosowania metod analitycznych do rozwiązania zagadnień dynamicznych belek i płyt pod obciążeniami ruchomymi są przede wszystkim trudności w spełnieniu warunków brzegowych w belkach i płytach. Z tego też powodu w większości przypadków stosuje się metody przybliżone typu MES, MECZ, MEB, DQM oraz metodę różnic skończonych, w których łatwo jest zamodelować dowolne warunki brzegowe. Metody te pozwalają również na uwzględnienie różnorodności materiałów i elementów konstrukcyjnych. W niniejszej pracy przedstawiono możliwości wykorzystania programu metody elementów skończonych (MES) ABAQUS [1] do modelowania belek i płyt warstwowych spoczywających na odkształcalnych podłożach. Układy takie poddano działaniu ruchomych obciążeń, zarówno skupionych jak i rozłożonych. W kilku przykładach pokazano różne techniki modelowania podłoża i ruchomego obciążenia.
EN
The subject of this paper are thin composite rectangular plate. The plates are made of two families of ribs and homogeneous material of a matrix. The main feature of the considered plates is, that a distance between the ribs is comparable to the thickness of the plate. The widths of the ribs can vary slowly in the midplane of the plate. This allows you to get a desirable frequency of natural vibrations of the plate. The formulation of averaged model equations is based on the tolerance averaging approach (Wozniak et al. 2008, 2010). The general results of the contribution are illustrated using the analysis of natural vibrations of the plates under consideration. It will be carried out validation of the obtained mathematical model by comparison of results from obtained model equations with results from finite elements method (Abaqus program).
PL
Elewacyjne wyroby z aluminium znajdują powszechne zastosowanie w budownictwie, szczególnie do wykonywania okładzin wentylowanych. Jako wykończenie dużych powierzchni stosuje się odpowiednio wyprofilowane płyty kompozytowe, których zewnętrzne warstwy stanowią zabezpieczone blachy aluminiowe. Do oceny trwałości porównano płyty kompozytowe z blachami ze stali ocynkowanej i powlekanej metodą „coil coating”.
EN
Facade aluminum products are widely used in construction, especially for making ventilated claddings. Composite panels appropriately contoured are used as a finishing of large surfaces. The outer layers on these panels are the protected aluminum sheets. For the purpose of evaluation of the durability, two kinds of composite panels: with the sheets of galvanized steel and coated using the „coil coating” methods, were compared.
EN
In practical applications, sandwich plates are often connected to other members, supported by damaged clamped/simply supported boundary conditions or supported by elastic restraints. Therefore, the mentioned structures may not always be simulated by the classical boundary conditions, i.e., ideal simply supported, clamped and free edges. Also, these structures may be subjected to various loads. In this study, for the first time, a novel economical analytical solution procedure is presented for axisymmetric static analysis of sandwich annular plates, by using the layerwise and 3D elasticity theories. Based on the proposed approach, functionally graded sandwich annular plates with various elastically restrained edges under arbitrary distributed loads may be analyzed and all of the displacements and stresses components may be exactly achieved. Also, imposed loads at the boundaries may be evaluated. Transverse shear and normal stresses boundary conditions on the top and bottom of the sandwich plate and the interlaminar continuity conditions of the in-plane displacement, transverse shear and normal stresses are exactly satisfied. Accuracy and efficiency of the presented solution procedure are demonstrated by comparing the obtained results for sandwich plates with the classical edge conditions as some special cases of the elastic supports with results of the three-dimensional theory of elasticity.
PL
W pracy przedstawiono technologię wytwarzania wielowarstwowych, wielkogabarytowych płyt kompozytowy kształtowanych metodą prasowania próżniowego. Wskazano zalety i możliwości zastosowania płyt kompozytowych, jako nowoczesnego materiału do budowy systemów transportu specjalnego przeznaczenia zastępującego tradycyjne zabudowy stalowe i aluminiowe. Przedstawiono przykłady rozwiązań konstrukcyjnych mobilnych systemów transportu specjalistycznego. W budowie ścian, dachów, podłóg, drzwi użyto płyt kompozytowych o szczególnych wymaganiach wytrzymałościowych, estetycznych i higienicznych. Dzięki zastosowaniu lekkich i wytrzymałych płyt kompozytowych i zastosowanej technologii ich łączenia uzyskano wytrzymałe na skrajne warunki atmosferyczne, sztywne, lekkie i funkcjonalne pozbawione wszelkich mostków termicznych, o bardzo dobrych parametrach izolacyjnych mobilne systemy kontenerowe.
EN
At work shows the manufacturing technology of multi-layered, large size composite plate, shape with vacuum pressing method. Indicated advantages and opportunities to use of composite panels as modern material to build special transport systems to replace traditional steel and aluminum buildings. Shows examples of design solutions to mobile systems of specialist transport. In the constructions of walls, roofs, floors and doors used composite plate with special endurance esthetic and hygienic requirements. Thanks to the use of light and durable composite plate and technology to combine them to gained resistant to bad weather conditions, rigid, light and functional devoid of any thermal bridge with very good insulation parameters of mobile container systems.
16
Content available remote Kształtowanie płyt pomostów mostów drogowych z kompozytów FRP
PL
Konieczność zwiększenia trwałości pomostów drogowych obiektów mostowych nadała w ostatnich latach bardzo duży impuls pracom badawczym, których celem jest stworzenie nowych rodzajów płyt pomostów mostów drogowych: trwałych, lekkich i łatwych w montażu, wykonanych z zaawansowanych technologicznie materiałów. Wśród tych materiałów najszersze zastosowanie w mostach w ostatnich latach mają kompozyty FRP (fibre reinforced polymers). W artykule przedstawiono przegląd systemów płyt pomostów wykonywanych z kompozytów FRP. Nacisk położono głównie na kształtowanie geometryczne płyt w zależności od przyjętej technologii wytworzenia kompozytu. Dokonano podziału na trzy główne grupy kompozytowych płyt pomostowych: wykonywanych metodą infuzji, pultruzji oraz płyt hybrydowych, tj. kompozytowo-betonowych. Porównano wady i zalety poszczególnych rodzajów płyt pomostów oraz dokonano wyboru optymalnej kosztowo konstrukcji i technologii do własnych prac badawczych. W ramach badań własnych zaprojektowano i wykonano trzy prototypowe panele pomostów z kompozytów warstwowych (typu sandwich) o różnym układzie konstrukcyjnym. Na podstawie wyników badań wytrzymałościowych ustalono nośność i sztywność poszczególnych paneli. Porównanie tych parametrów pozwoliło na wybór rozwiązania panelu do dalszych prac badawczych i wdrożeniowych.
EN
The growing need of durability enhancement for road bridge decks has recently caused the big impulse for research on new, durable, lightweight and easy to handle bridge decks, made of advanced materials, f.e. FRP (fibre reinforced polymers). The paper reviews the most common bridge deck systems made of FRP composites. The emphasis was mainly on the shaping the geometric depending on the technology manufacturing. The systems were divided into three groups: bridge decks made by pultrusion, infusion and hybrid concrete-FRP composite. In the next step own cross-section of decks were developed, designed and three different prototypes of panels were made in full scale (dimensions in plan 1,1 × 2,7 m). The last stages were tests of the three bridges sandwich panels with different structural arrangement. Based on tests, the strength of panels its load capacity and stiffness were established. Comparison of these characteristics and experience gained during making prototypes, allowed to choose the best panel for further research and implementation.
EN
In the continuum mechanics there is a class of problems that cannot be solved directly or the solutions of these problems are affected by large errors when the classical equations of thermoviscoelasticity are considered. The paper discusses a special case of such problems - the cyclic bending of a composite plate with a circular hole subjected to the stationary self-heating, which was solved within the framework of a moment theory of thermoviscoelasticity.
EN
The present paper deals with the experimental studies carried out on free vibration of isotropic and laminated composite skew plates. The natural frequencies were also determined using QUAD8 finite element of MSC/NASTRAN and a comparison was made between the experimental values and the finite element solution. The effects of the skew angle and aspect ratio on the natural frequencies of isotropic skew plates were studied. The effects of the skew angle, aspect ratio, fiber orientation angle and laminate sequence (keeping the number of layers constant) on the natural frequencies of antisymmetric composite laminates were also studied. The experimental values of natural frequencies are in good agreement with the FE solutions. The natural frequencies are found to increase with an increase in the skew angle. The variation of natural frequencies with the aspect ratio is small and negligible both for isotropic and laminated composite skew plates.
EN
The presented paper discusses the minimum weight design of multilayered fiber composite plates with tolerances in individual ply thicknesses. These tolerances are given by the maximum acceptable deviation of every individual ply thickness from its nominal value. The robustness of the design is achieved by diminishing the design state variable (buckling load factor) by the product of arbitrary assumed tolerances and appropriate sensitivities. The proposed approach is illustrated with examples of a simply supported rectangular laminated plate design under uni- and bi-axial compression. The minimum weight identified by the total number of layers is found to assure plate stability. For the discussed analysis, buckling load sensitivity formulas with respect to ply thicknesses are given. Based on these relations, the impact of the discussed variations on the optimal laminate stacking sequence and buckling mode shape is studied in detail. The achieved results emphasize the importance of robust design opposed to merely nominal approaches.
PL
Przedstawiono zagadnienie optymalizacji wielowarstwowych płyt kompozytowych z włóknami ukierunkowanymi dyskretnie z uwzględnieniem występowania tolerancji grubości poszczególnych lamin. Rozważane tolerancje zostały zdefiniowane jako maksymalne dopuszczalne odchylenia rzeczywistej grubości każdej z warstw od jej wartości nominalnej. W zaproponowanym podejściu do zagadnienia rozwiązanie optymalne uzyskano poprzez zmniejszenie zmiennej stanu zadania o wartość iloczynu przyjętych arbitralnie tolerancji i odpowiednich wrażliwości tej zmiennej stanu. Metodę rozwiązania zilustrowano przykładami ściskania jedno- i dwuosiowego płyty prostokątnej, swobodnie podpartej czterostronnie. Jako kryterium optymalizacji przyjęto minimum ciężaru (grubości) płyty. Zapisano rekurencyjne zależności na wrażliwość siły krytycznej względem grubości poszczególnych warstw laminatu. Następnie, na podstawie tych zależności, wyznaczono zmodyfikowaną wartość siły krytycznej obciążenia. Szczegółowo omówiono wpływ badanych tolerancji na układ i kolejność warstw w laminacie wielowarstwowym. Uzyskane wyniki w pełni potwierdzają zasadność stosowania optymalizacji odpornościowej jako metody projektowania gwarantującej lepsze (bezpieczniejsze) rozwiązania niż standardowe ujęcie nominalne zagadnienia.
EN
The wavelet transform is one of the most effective tools for many tasks concerning signal and image processing, however it is difficult to obtain all of the necessary properties in one scalar wavelet. This leads to the development of new types of transforms such as a multiwavelet transform, which possesses more than one scaling and wavelet function and makes a possibility to combine these functions in order to obtain necessary properties. In the present study the CL2, LV and DGHM multiwavelets were used for an identification of spatial damage in a composite plate based on the analysis of its modal shapes. The obtained results show that some properties of the multiwavelet transform may improve the damage identification algorithm and replace the classical wavelet-based methods
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