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Search results for: LAYERWISE THEORY

A Generalized Framework Towards Structural Mechanics of Threelayered Composite Structures
PublicationThreelayered composite structures find a broad application. Increasingly, composites are being used whose layer thicknesses and material properties diverge strongly. In the perspective of structural mechanics, classical approaches to analysis fail at such extraordinary composites. Therefore, emphasis of the present approach is on arbitrary transverse shear rigidities and structural thicknesses of the individual layers. Therewith...

Elastoplastic law of Cosserat type in shell theory with drilling rotation
PublicationWithin the framework of sixparameter nonlinear shell theory, with strain measures of the Cosserat type, we develop smallstrain J2type elastoplastic constitutive relations. The relations are obtained from the Cosserat plane stress relations assumed in each shell layer, by throughthethickness integration employing the firstorder shear theory. The formulation allows for unlimited translations and rotations. The constitutive...

Structural Reliability Assessment Of Corroded Tanker Ship Based On Experimentally Estimated Ultimate Strength
PublicationThis work deals with the reliability assessment of a tanker ship hull structure subjected to a vertical bending moment and corrosion degradation. The progressive collapse and ultimate load carrying capacity are estimated based on experimentally tested scaled boxshapedspecimens. The translation of the strength estimate of the scaled specimen to the real tanker ship hull structure is performed based on the dimensional theory developing...

Equivalent singlelayer models in deformation analysis of laminated multilayered plates
PublicationThe performance of selected Equivalent SingleLayer (ESL) models is evaluated within several classical benchmark tests for linear static analysis of multilayered plates. The authors elaborated their own Finite Element software based on the firstorder shear deformation theory (FOSD) with some modifications incorporated including a correction of the transverse shear stiffness and an application of zigzag type functions. Seven...

Inplane shear nonlinearity in failure behavior of angleply laminated shells
PublicationThe paper concerns the progressive failure analysis of laminates with the inplane shear nonlinearity accounted for.The nonlinear shear response of the layer is described by the constitutive relation treating the stresses as a function of strains. Thus it can be easily incorporated into the displacementbased FEM codes. The brittle failure mechanisms of the fibers and the matrix of the layer are recognized with the use of the Hashin...

2D constitutive equations for orthotropic Cosserat type laminated shells in finite element analysis
PublicationWe propose 2D Cosserat type orthotropic constitutive equations for laminated shells for the purpose of initial failure estimation in a laminate layer. We use nonlinear 6parameter shell theory with asymmetric membrane strain measures and Cosserat kinematics as the framework. This theory is specially dedicated to the analysis of irregular shells, inter alia, with orthogonal intersections, since it takes into account the drilling...

The Dynamical Projectors Method Hydro and Electrodynamics
PublicationThe dynamical projectors method proves to reduce a multicomponent problem to the simplest onecomponent problem with its solution determined by specific initial or boundary conditions. Its universality and application in many different physical problems make it particularly useful in hydrodynamics, electrodynamics, plasma physics, and boundary layer problems. A great variety of underlying mechanisms are included making this book...

Size effect in concrete beams under bending – influence of the boundary layer and the numerical description of cracks
PublicationIn the paper the size effect phenomenon in concrete is analysed. The results of numerical simulations of using FEM on geometrically similar unnotched and notched concrete beams under bending are presented. Concrete beams of four different sizes and five different notch heights under threepoint bending test were simulated. In total 18 beams were analysed. Two approaches were used to describe cracks in concrete. First, eXtended...

Role of surface recombination in perovskite solar cells at the interface of HTL/CH3NH3PbI3
PublicationIn order to achieve the highest performance of organometal trihalide perovskite solar cells, it is required to recognize the dominant mechanisms which play a key role in a perovskite material. In the following studies, we have focused on the interfacial recombination between the hole transporting layer (HTL) and the perovskite CH3NH3PbI3 in solar cell devices with p–i–n architecture. It has been shown that Cu:NiOx : used as HTL...

COMPARISON OF INFINITE ELEMENT MODELS
PublicationThe main objective of this paper is to show the comparison of two models of inﬁnite ab sorbing layer with increasing damping in numerical investigations of elastic wave prop agation in unbounded structures. This has been achieved by the Authors by a careful in vestigation of two different engineering structures characterised by gradually increasing geometrical and mathematical description complexities. The analysis included...

FEM simulation of laminate failure in the three point bending
PublicationThe paper presents a FEM simulation of failure of laminate subjected to the three point bending. The numerical model is based on the equivalent single layer approach with 6paramater nonlinear shell theory kinematics. It is implemented in the noncommercial FEM code. The failure initiation is detected with the use of TsaiWu criterion. After the failure onset the progressive failure process is modelled through the appropriate...

Numerical analysis of elastic wave propagation in unbounded structures
PublicationThe main objective of this paper is to show the effectiveness and usefulness of the concept of an absorbing layer with increasing damping (ALID) in numerical investigations of elastic wave propagation in unbounded engineering structures. This has been achieved by the authors by a careful investigation of three different types of structures characterised by gradually increasing geometrical and mathematical description complexities....

Effect of adhesive compliance in the assessment of soft adhesives with the wedge test
PublicationWedge tests are usually analysed assuming that the free, unbonded members may be treated as encastré cantilever beams. However, if the adhesive layer is sufficiently flexible (e.g., due to low elastic modulus), then significant strain in the bonded region may occur and lead to modification of the behaviour outside this region. Using in conjunction a sensitive strain gauge method on asymmetric wedge tests and a mathematical analysis...

Large thermoelastic displacement and stability FEM analysis of multilayered plates and shells
PublicationThe paper concerns the load capacity analysis of thermally loaded multilayered plates and shells. The multilayered body is treated as an equivalent single layer whose kinematics is consistent with first order shear deformation theory. The authors focus on the thermoelastic stability problem of the thinwalled structures. The equilibrium paths are traced with the use of RiksWempnerRamm algorithm. By making use of the TsaiWu...

Mechanical analysis of eccentric defected bilayer graphene sheets considering the van der Waals force
PublicationIn this article, we have tried to simulate nonlinear bending analysis of a doublelayered graphene sheet which contains a geometrical imperfection based on an eccentric hole. The firstorder shear deformation theory is considered to obtain the governing equations. Also, the nonlinear von Kármán strain field has been assumed in order to obtain large deformations. Whereas the doublelayered graphene sheet has been considered, the...

Adhesive Monitoring with Instrumented Wedge Test
PublicationThe wedge test (sometimes called the Boeing wedge test) is amongst the most readily exploitable techniques for assessment of the ratedependent fracture energy of adhesive materials when used to bond relatively rigid substrates. With its siblings: the double cantilever beam (DCB), and the tapered double cantilever beam (TDCB), a force is applied, essentially in cleavage, to provoke substrate separation perpendicularly to the bondline...

Evolution of Ag nanostructures created from thin films: UV–vis absorption and its theoretical predictions
PublicationAgbased plasmonic nanostructures were manufactured by thermal annealing of thin metallic films. Structure and morphology were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), highresolution transmission electron microscopy (HRTEM) and Xray photoelectron spectroscopy (XPS). SEM images show that the formation of nanostructures is influenced by the initial layer thickness as well as the...

Structural Design and Sensitivity Analysis of SemiRigid Pavement of a Motorway
PublicationThis paper presents application of mechanisticempirical methods in design of semirigid pavement for a section of a motorway in Poland. The stage construction was assumed. Three fatigue criteria were applied in the design. For asphalt fatigue cracking and subgrade soil the criteria from the Asphalt Institute (1981) were applied. For fatigue cracking of cement stabilized bases the Dempsey (1984) and De Beer (1992) criteria were...

Assessment of dynamic characteristics of thin cylindrical sandwich panels with magnetorheological core
PublicationBased on the equivalent singlelayer linear theory for laminated shells, free and forced vibrations of thin cylindrical sandwich panels with magnetorheological core are studied. Five variants of available magnetorheological elastomers differing in their composition and physical properties are considered for smart viscoelastic core. Coupled differential equations in terms of displacements based on the generalized kinematic hypotheses...

BOUNDARYLAYER METEOROLOGY
Journals 
Piecewise constant approximation method of identification of RTS noise
PublicationPrzedstawiono nową metodę wydzielania szumów RTS z całkowitych szumów przyrządów półprzewodnikowych. Metoda ta oparta jest na aproksymacji liniowo odcinkowej przebiegu szumowego.Przedstawiono wyniki zastosowania tej metody do wydzielenia dwupoziomowego szumu RTS z szumu przyrządu półprzewodnikowego.

Rekonstrukcja ewolucji układu przestrzennego średniowiecznego miasta i portu Szczecin Reconstruction of the Spatial Evolution of the Medieval City and Port of Szczecin
PublicationPraca rekonstruuje ewolucję układu osadniczego Szczecina w okresie od połowy VIII w. do początku XIV w., w oparciu o interpretację dostępnej literatury naukowej dotyczącej historii i archeologii Szczecina oraz metodę analizy planistycznej. Bardzo istotnym elementem opisu struktury urbanistycznej wczesnośredniowiecznego Szczecina było określenie roli i położenia portu. W wyniku analizy zmian układu przestrzennego miasta w omawianym...

Unusual structural properties of water within the hydration shell of hyperactive antifreeze protein
PublicationMany hypotheses can be encountered explaining the mechanism of action of antifreeze proteins. One widespread theory postulates that the similarity of structural properties of solvation water of antifreeze proteins to ice is crucial to the antifreeze activity of these agents. In order to investigate this problem, the structural properties of solvation water of the hyperactive antifreeze protein from Choristoneura fumiferana were...

Workshop on Graph Theory
EventsThe Gdańsk Workshop on Graph Theory (GWGT) is an annual, informal workshop whose goal is to provide a forum for scientists to meet, present their work, interact, and establish collaborations in the field of Graph Theory

The importance of the bottom layer in doublelayer porous asphalt for noise reduction
PublicationDoublelayer porous asphalt concrete (DPAC) surfaces are generally considered to be the acoustically most effective low noise road surfaces ready for implementation. While DPAC used on highways in warm climates may have an average life of around 8 years, in Scandinavia with severe winter climate DPAC usually survive only about 3 years; partly due to wear of studded tyres. An ongoing project in Sweden, applying DPAC and singlelayer...

Wojciech Litwin dr hab. inż.
People1992÷1996  study on Mechanical Department at Gdansk University of Technology1996 – employed in the Faculty of Ocean Engineering and Ship Technology at the Gdansk University of Technology2004 – PhD2014 – habilitation2016  vice dean for science at Faculty of Ocean EngineeringHe participated in a number of designing and research programs connected with water lubricated bearings, solar technology and modern ship propulsion. Since...

Recent Developments in the Theory of Shells
PublicationThis book commemorates the 80th birthday of Prof. W. Pietraszkiewicz, a prominent specialist in the field of general shell theory. Reflecting Prof. Pietraszkiewicz’s focus, the respective papers address a range of current problems in the theory of shells. In addition, they present other structural mechanics problems involving dimensionreduced models. Lastly, several applications are discussed, including material models for such...

Nanocrystalline cathode functional layer for SOFC
PublicationRecently, it was shown that thin functional layers introduced between an electrolyte and cathode might improve cathode performance. However, the mechanism of this improvement still needs analysis. In this paper, a thin (∼140 nm), spincoated perovskite layer (La0.6Sr0.4Co0.2Fe0.8O3δ) was placed between a cathode (La0.6Sr0.4Co0.2Fe0.8O3δ) and an electrolyte (Ce0.8Gd0.2O2δ) and the effects of this investigated. The microstructure...

Electrocatalytic gas sensor with reference layer
PublicationIn recent years electrochemical gas sensors based on solid state electrolytes have been intensively developed. They are easy to obtain, use and relative durable. Nasicon is one of the most promising materials, which have been used in construction of gas sensors. Most of these devices work in potentiometric or amperometric mode. However, some works are dedicated to sensors working in electrocatalytic mode. Principle of operation...

Module structure in Conley theory with some applications
PublicationA multiplicative structure in the cohomological versjon of Conley index is described . In the case of equivariant flows we apply the normalization procedure known from equivariant degree theory and we propose a new continuation invariant. The theory is then applied to obtain a mountain pass type theorem. Another application is a result on multiple bifurcations for some elliptic PDE.

Structure of the Resource Theory of Quantum Coherence
PublicationQuantum coherence is an essential feature of quantum mechanics which is responsible for the departure between the classical and quantum world. The recently established resource theory of quantum coherence studies possible quantum technological applications of quantum coherence, and limitations that arise if one is lacking the ability to establish superpositions. An important open problem in this context is a simple characterization...

Analysis of elementary cellular automata using the theory of conflict
PublicationThe paper contains decomposition of elementary cellular automata (ECA in short) to subsystems that are defined according to a new theory called theory of conflict (ToC in short). The decomposition is a completely new approach to analysis of ECA and complex systems in general.

Towards Resource Theory of Coherence in Distributed Scenarios
PublicationThe search for a simple description of fundamental physical processes is an important part of quantum theory. One example for such an abstraction can be found in the distance lab paradigm: if two separated parties are connected via a classical channel, it is notoriously difficult to characterize all possible operations these parties can perform. This class of operations is widely known as local operations and classical communication....

Photovoltaic phenomena in devices with perfluorozincphthalocyanine layer
PublicationThe course of photovoltaic phenomenon in organic photovoltaic cells utilizing thin layers of perfluorozincphthalocyanine was studied in few single and planar bilayer configurations. Mechanisms of photogeneration and recombination of free charge carriers were determined and active interfaces were localized. In case of single layer cells these interfaces were located at the front electrode/F16ZnPc junctions, whereas photogeneration...

Electromagneticbased derivation of fractionalorder circuit theory
PublicationIn this paper, foundations of the fractionalorder circuit theory are revisited. Although many papers have been devoted to fractionalorder modelling of electrical circuits, there are relatively few foundations for such an approach. Therefore, we derive fractionalorder lumpedelement equations for capacitors, inductors and resistors, as well as Kirchhoff’s voltage and current laws using quasistatic approximations of fractionalorder...

On the effective properties of foams in the framework of the couple stress theory
PublicationIn the framework of the couple stress theory, we discuss the effective elastic properties of a metal opencell foam. In this theory, we have the couple stress tensor, but the microrotations are fully described by displacements. To this end, we performed calculations for a representative volume element which give the matrices of elastic moduli relating stress and stress tensors with strain and microcurvature tensors.

Characteristics of La0.8Sr0.2Ga0.8Mg0.2O3delta supported microtubular solid oxide fuel cells with bilayer and trilayer electrolytes
PublicationIn this study, La0.8Sr0.2Ga0.8Mg0.2O3−δ (LSGM)supported micro tubular solid oxide fuel cells (TSOFCs) with two different configurations, one containing an LSGM–Ce0.6La0.4O2−δ (LDC) bilayer electrolyte (Cell A) and one containing an LDC–LSGM–LDC trilayer electrolyte (Cell B), were fabricated using extrusion and dipcoating. After optimizing the paste formulation for extrusion, the flexural strength of the dense and uniform LSGM...

KOALA Graph Theory Internet Service
PublicationKOALA has been created with the idea of C++ library templates, implementing a broad set of procedures in the fields of algorithmic graph theory and network problems in discreate optimization. During the C2NIWA project, a library has been greatly ectended, the code refactored and enclosed with the internet service available in the public repository of thr project. Today it contains interconnected educational materials in the form...

Electrocatalytic Gas Sensor with Reference Layer
PublicationThis paper presents studies of gas sensors prepared in ceramic technology with Nasicon as a solid electrolyte. Sensors work in the voltammetric mode thus based on the excitation of a sensor with a periodic potential signal while current response is recorded. The main aim is to investigate a Bi8Nb2O17 reference layer influence on sensor properties. Sensors IV characteristics in different concentration of nitrogen dioxide have been...

Discussiones Mathematicae Graph Theory
Journals 
Composite shells in 6field nonlinear shell theory
PublicationW pracy przedstawiono równanie konstytutywne uwzględniające wielowarstwowość materiału powłoki. Równania wyprowadzono bazując na podejściu Equivalent Single Layer

On constitutive relations in the resultatnt nonlinear theory of shells
PublicationThe authors summarize their current research in the field of constitutive modelling in the framework of nonlinear 6parameter shell theory. In particular the description of isotropic, multilayered composite and functionally graded shells is presented.

Ceramic composites for singlelayer fuel cells
PublicationComposite materials consisting of acceptor doped lanthanum orthoniobate electrolyte phase (La0.98Ca0.02NbO4) and Li2O:NiO:ZnO semiconducting phase were synthesized. The precursor powder of La0.98Ca0.02NbO4 was prepared in nanocrystalline (mechanosynthesis) and microcrystalline (solidstate synthesis) form. The composite can be applied in a singlelayer fuel cell, because of the presence of two phases acting as an anode and a cathode...

Theory of systems & cybernetics as a bridge between theory and practice. .
PublicationW pracy przedstawiono sposoby posługiwania się Teorią Systemów i Cybernetyką celem identyfikacji efektu synergii między nauką i działalnością praktyczną.

Elastoplastic material law in 6parameter nonlinear shell theory
PublicationWe develop the elastoplastic constitutive relations for nonlinear exact 6parameter shell theory. A J2type theory with strain hardening is formulated that takes into account asymmetric membrane strain measures. The incremental equations are solved using implicit Euler scheme with closest point projection algorithm. The presented test example shows the correctness of the proposed approach. Influence of micropolar material parameters...

Noise in electrical doublelayer capacitors (EDLCs)
PublicationWe present methods and problems of noise measurements in electrical doublelayer capacitors (EDLC). Detailed noise equivalent electronic circuit is considered, and two possible ways of observations of random processes generated in the EDLCs structures are studied. We conclude that noise is a useful tool for characterization of the EDLC structures and their stateofhealth, as in other materials and electronic devices. Eventual,...

Acoustic heating produced in the boundary layer
Publication: Instantaneous acoustic heating of a viscous fluid flow in a boundary layer is the subject of investigation. The governing equation of acoustic heating is derived by means of a special linear combination of conservation equations in the differential form, which reduces all acoustic terms in the linear part of the final equation but preserves terms belonging to the thermal mode. The procedure of decomposition is valid in a weakly...

Facing the brainstorming theory. A case of requirements elicitation
PublicationKnowledge is still considered to be power and its externalization makes it possible for others to use that power. In this paper, we examine the theory of brainstorming, and the claim by father Alex Osborn that in a group session an individual can think of twice as many ideas than working alone. In the context of requirements elicitation, we performed an experiment on a “nominal” and a “real” group of participants, following a procedure...

On the Buckling Response of Axially Pressurized Nanotubes Based on a Novel Nonlocal Beam Theory
PublicationIn the present study, the buckling analysis of singlewalled carbon nanotubes (SWCNT) on the basis of a new refined beam theory is analyzed. The SWCNT is modeled as an elastic beam subjected to unidirectional compressive loads. To achieve this aim, the new proposed beam theory has only one unknown variable which leads to one equation similar to Euler beam theory and is also free from any shear correction...

Fracture Energy of Bonded Joints with 2D Elastic Adhesive Layer
PublicationWhen bonded joint is subjected to mode I fracture loading, the adhesive joints analytical solutions treats the adhesive layer, usually, as not existing or 1D Hooke elastic layer. In the case of 1D elastic layer, represented as Hookes spring element, is acting, only, in direction contrary to the applied load. Basing on the information yielded from sensitive laser profilometry technique, where deflections of bonded part of the joint...