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Search results for: GEOMETRICALLY NON-LINEAR STRUCTURES
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On geometrically non-linear FEA of laminated FRP composite panels
PublicationThe paper presents a state-of-art review on Finite Element Analysis (FEA) of geometrically non-linear problems for laminated composite plates and shells made as fibre reinforced polymer (FRP) laminates. Besides a subjective overview of the historical development of geometrically non-linear FEA of laminated FRP composite panels, some remarks on possible future issues in this research area are given
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Drilling couples and refined constitutive equations in the resultant geometrically non-linear theory of elastic shells
PublicationIt is well known that distribution of displacements through the shell thickness is non-linear, in general. We introduce a modified polar decomposition of shell deformation gradient and a vector of deviation from the linear displacement distribution. When strains are assumed to be small, this allows one to propose an explicit definition of the drilling couples which is proportional to tangential components of the deviation vector....
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Reliability of imperfect structures (simple non-linear models)
PublicationPrzyjęto proste modele prętów umożliwiających analizę układów o niestatecznych i statecznych punktach bifurkacji. Wykorzystano symulacyjną metodę wyznaczania niezawodności. Zastosowano metodę Monte Carlo i równania 3 poziomu dokładności. Uzyskano rozkłady prawdopodobieństwa obciążenia granicznego nieliniowych modeli konstrukcji z losowymi imperfekcjami. Wykazano, że histogramy siły granicznej modelu statecznego i niestatecznego...
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On the non-linear dynamics of torus-shaped and cylindrical shell structures
PublicationIn this study, the non-linear dynamic analysis of torus-shaped and cylindrical shell-like structures has been studied. The applied material is assumed as the functionally graded material (FGM). The structures are considered to be used for important machines such as wind turbines. The effects of some environmental factors on the analysis like temperature and humidity have been considered. The strain field has been calculated in...
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Fem and time stepping procedures in non-linear dynamics of flexible branched shell structures.
PublicationW pracy dyskutowano problemy całkowania równań ruchu, sformułowanych w ramach nieliniowej sześcioparametrowej teorii powłok. Główne myśli dotyczą zbieżności rozwiązań uzyskanych w procesie aproksymacji przestrzennej i czasowej oraz analizy stabilności rozwiązań MES.
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Non-Linear Analysis of Structures Utilizing Load-Discretization of Stiffness Matrix Method with Coordinate Update
PublicationThis paper proposes a stiffness method based structural analysis algorithm for geometrically non-linear structures. In this study, the applied load on the joints has been discretized to a sequence of a few loadings applied. Each loading step produces incremental external nodal displacements, which are added to the corresponding coordinates to get a new geometrical shape of the structure. This process is iteratively repeated until...
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Ireneusz Kreja dr hab. inż.
PeopleGraduated from the mathematical class at the Nicolaus Copernicus High School in Gdańsk (1974). Master of Sciences in Civil Engineering after studies at Gdansk University of Technology (GUT), Poland (1974-1979). Since 1979 became an employee of the GUT. In 1989 earned a Ph.D. degree in Civil Engineering (with grade "Summa cum Laude") from the GUT. In 2008 obtained a D. Sc. (Habilitation) degree in Civil Engineering (with grade...
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Optimal shape and stress control of geometrically nonlinear structures with exact gradient with respect to the actuation inputs
PublicationThis paper presents an efficient and robust optimization methodology for stress and shape control of actuated geometrically nonlinear elastic structures, applied to 3D trusses. The actuation inputs, modeled as prescribed strains, serve as the optimization variables. The objective is to minimize total actuation while satisfying several constraints: (i) actuation bounds in each actuated element and (ii) target ranges for nodal displacements...
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Thermo-elastic non-linear analysis of multilayered plates and shells
PublicationGeometrically nonlinear FEM analysis of multilayered composite plates and shells is performed in order to resolve the stability problem of the structures being under the influence of temperature field. The Riks-Wempner-Ramm algorithm with a specially modified multi-choice unloading condition has been implemented in authors’ numerical code. As the representation of multilayered medium the Equivalent Single Layer approach with the...
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Guided waves for monitoring of plate structures with linear cracks of variable length
PublicationDamage occurring at the work of plate structures may grow to a considerable size. The joint action – the detection of a defect at the earliest possible stage, the monitoring of its growth and the determination of its critical size in the context of structural reliability allows optimizing the cost of the maintenance and repair of structural elements. Thus the development of monitoring systems for permanent observation of fault...
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Zdzisław Kowalczuk prof. dr hab. inż.
PeopleZdzislaw Kowalczuk received his M.Sc. degree in 1978 and Ph.D. degree in 1986, both in Automatic Control from Technical University of Gdańsk (TUG), Gdańsk, Poland. In 1993 he received his D.Sc. degree (Dr Habilitus) in Automatic Control from Silesian Technical University, Gliwice, Poland, and the title of Professor from the President of Poland in 2003. Since 1978 he has been with Faculty of Electronics, Telecommunications and Informatics...
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An Approximate Linear Analysis of Structures Utilizing Incremental Loading of Force Method
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Correlation between natural frequencies and buckling load in a stiffened shell
PublicationThe paper deals with correlation between natural frequencies and buckling load of a stiffened shell composed of corrugated sheets and vertical stiffeners (columns). The simplified shell segment represents the buckling behaviour of a whole silo with sparsely distributed columns. The paper covers variants of linear buckling anal-yses, dynamic eigenvalue analyses and geometrically non-linear analyses of a segment modelled with shell...
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Investigation of natural frequencies of axially loaded thin-walled columns
PublicationThe paper deals with correlation between natural frequencies of two steel thin-walled columns and the corresponding applied load. The structures are made of cold-formed lipped channel sections. The columns lengths were assumed to follow two buckling patterns – global flexural and flexural-torsional buckling. In the thicker structure two material models were considered – linearly-elastic and elastic-perfectly plastic. Numerical...
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Comparison of non-linear statical analysis of truss with linear and rotational side supports and 3d roof model
PublicationIn the paper geometrically non-linear analysis of example truss with linear and rotational elastic side supports is compared with geometrically non-linear analysis of part of the roof construction with purlins and truss-bracing. For different stiffness of side-supports a non linear relation between normal force in compressed chord due to out of truss plane displacement has been calculated.
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Impact of Geometrical Imperfections on Estimation of Buckling and Limit Loads in a Silo Segment Using the Vibration Correlation Technique
PublicationThe paper examines effectiveness of the vibration correlation technique which allows determining the buckling or limit loads by means of measured natural frequencies of structures. A steel silo segment with a corrugated wall, stiffened with cold-formed channel section columns was analysed. The investigations included numerical analyses of: linear buckling, dynamic eigenvalue and geometrically static non-linear problems. Both perfect...
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Technical fabrics in costruction of large scale roofs - numerical and experimental aspects
PublicationDesigning and construction of textile hanging roofs is the challenging subject for engineers. This type of structure needs geometrically and very often also physically non-linear calculations. Due to different behaviour of two families of threads (warp and weft), which during deformation can change the angle between their directions, they require special constitutive modelling. Also the loading of hanging roofs is very special....
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Jacek Chróścielewski prof. dr hab. inż.
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Natalia Stawicka-Morawska dr inż.
PeopleMgr inż. Natalia Stawicka-Morawska pracuje na Politechnice Gdańskiej od października 2017 r. na stanowisku Asystenta, na Wydziale Inżynierii Mechanicznej i Okrętownictwa (poprzednio: Wydziale Mechanicznym), w Instytucie Mechaniki i Konstrukcji Maszyn (poprzednio: Katedrze Mechaniki i Mechatroniki).Prowadzona przez nią działalność naukowa dotyczy dziedziny nauk technicznych w dyscyplinie naukowej budowa i eksploatacja maszyn. Główną...
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Direct Constraint Control for EM-Based Miniaturization of Microwave Passives
PublicationHandling constraints imposed on physical dimensions of microwave circuits has become an important design consideration over the recent years. It is primarily fostered by the needs of emerging application areas such as 5G mobile communications, internet of things, or wearable/implantable devices. The size of conventional passive components is determined by the guided wavelength, and its reduction requires topological modifications,...
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Geometrically nonlinear analysis of shells - Benchmark problems for Autocad Robot Analysis Professional
PublicationThe aim of this work is to verify the suitability of commercial engineering software for geometrically nonlinear analysis of shells. This paper deals with the static, geometrically nonlinear analysis of shells made of an isotropic material. The Finite Element Method (FEM) is chosen to solve the problem. The results of the commercial software Autocad Robot Structural Analysis Professional (ARSAP) are compared with the litera-ture...
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Stability of roof trusses stiffened by corrugated sheets
PublicationThe present parametric study is devoted to the stability analysis of a set of trusses stiffened by decking of corrugated steel sheets. For different parameters of corrugated sheets the critical loading of the roof is calculated. In the parametrical analysis the threshold bracing condition of the roof is obtained. Then the geometrically non-linear analysis of trusses braced by corrugated sheets was conducted. As a results of non-linear...
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Marek Czachor prof. dr hab.
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Buckling of simplified models of silo with corrugated walls and vertical stiffeners
PublicationThe paper deals with buckling of cylindrical silos composed of corrugated sheets and vertical stiffeners (columns). Comprehensive finite element analyses were carried out for a perfect silo by means of a linear buckling approach. Corrugated walls were simulated as an equivalent orthotropic shell and vertical thin-walled columns as beam elements. Calculations for perfect silos with different numbers of columns made it possible to...
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Modelling and Measurement of Folk Guitar: Truss Rod and Strings in Numerical Analysis of Tone
PublicationThe study makes an attempt to model a complete vibrating guitar including its non-linear features, specifically the tension-compression of truss rod and tension of strings. The purpose of such a model is to examine the influence of design parameters on tone. Most experimental studies are flawed by uncertainties introduced by materials and assembly of an instrument. Since numerical modelling of instruments allows for deterministic...
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Arc-length Algorithm Efficiency in the Analysis of Thermally Loaded Multilayered Shells
PublicationThis paper concerns the efficiency study of the arc-length algorithm in the geometrically non-linear analysis of thermally loaded multilayered shells. The thermal loading is considered as the one-way thermo-mechanical coupling effect. Two implementations of the arc-length method are examined: the path-following technique available in NX-Nastran and the RiksWempner-Ramm algorithm adopted in the authors’ computer code SHLTH. It is...
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Nonlinear finite element modeling of vibration control of plane rod-type structural members with integrated piezoelectric patches
PublicationThis paper addresses modeling and finite element analysis of the transient large-amplitude vibration response of thin rod-type structures (e.g., plane curved beams, arches, ring shells) and its control by integrated piezoelectric layers. A geometrically nonlinear finite beam element for the analysis of piezolaminated structures is developed that is based on the Bernoulli hypothesis and the assumptions of small strains and finite...
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Stability of truss with side - supports. The case of linear and rotational elastic supports
PublicationThe research is devoted to study lateral buckling of truss with linear and rotational elastic side-supports. Geometrically nonlinear analysis of example truss with linear and rotational elastic sidesupports is carried out. The limit normal force in compressed chord of the truss due to stiffness of side supports is calculated. The elastic support reaction in relation to force in compressed chordand coefficient of buckling length...
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Automatic Correction of Non-Anechoic Antenna Measurements using Low-Pass Filters
PublicationPrototype measurements belong to key steps in the development of antenna structures. They are normally performed in expensive facilities, such as anechoic chambers (ACs). Alternatively, antenna performance can be extracted (at a low cost) in non-anechoic conditions upon appropriate post-processing. Unfortunately, existing correction algorithms are difficult to set up and prone to failure, which limits their practical usefulness....
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Generation of random fields to reflect material and geometric imperfections of plates and shells
PublicationThe paper covers two patterns of random field generation: conditional acceptance – rejection method and Karhunen – Loève expansion. The generation of two-dimensional random fields is essential in plates and shells analysis, allowing for a relevant limit and critical state assessment of geometrically and ma-terially imperfect structures. The features of both generation methods dedicate them to selected problems.
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Multi-Taper-Based Automatic Correction of Non-Anechoic Antenna Measurements
PublicationPrototype measurements belong to the key steps in the development of antenna structures. Although accurate validation of their far-field performance can be realized in dedicated facilities, such as anechoic chambers, the high cost of their construction and maintenance might not be justified if the main goal of measurements is to support teaching or low-budget research. Instead, they can be performed in non-anechoic conditions and...
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On FEM analysis of Cosserat-type stiffened shells. Static and stability linear analysis
PublicationThe present research investigates the theory and numerical analysis of shells stiffened with beams in the framework based on the geometrically exact theories of shells and beams. Shell’s and beam’s kinematics are described by the Cosserat surface and the Cosserat rod respectively, which are consistent including deformation and strain measures. A FEM approximation of the virtual work principle leads to the conforming shell and beam...
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Numerical and experimental investigation of rotational stiffness of zed-purlins connection with sandwich panels
PublicationA rotational resistant stiffness of the zed-purlins connection with sandwich panels is investigated. A simple finite element method model of the connection is proposed. The numerical analysis of the model performed by ABAQUS software, in physically linear and geometrically nonlinear ranges, leads to the rotational resistant stiffness sought. The numerical solution obtained is verified experimentally. Two variants of distribution...
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Stateczność i niezawodność pełnomorskich platform wiertniczych
PublicationW pracy przedstawiono wieloletnie doświadczenia Autora w zakresie wybranych aspektów numerycznej analizy pełnomorskich platform wiertniczych, w szczególności stacjonarnych platform stalowych poddanych działaniu fal wiatrowych i wiatru. W opisie zachowania się platform uwzględniono współoddziaływanie trzech ośrodków: materiału konstrukcji, morskich fal wiatrowych i podłoża gruntowego. Przyjęcie do opisu stochastycznych właściwości...
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Uproszczone metody obliczania wyboczenia silosów z blachy falistej wzmocnionych słupami na podstawie analizy MES i wyników doświadczalnych
PublicationRozprawa doktorska dotyczy zagadnienia stateczności i nośności granicznej stalowych silosów z płaszczem z blachy falistej wzmocnionych pionowymi słupami. Przeprowadzono zaawansowane analizy numeryczne MES oraz badania doświadczalne dotyczące wyboczenia/stateczności analizowanych silosów. Analizy numeryczne zostały przeprowadzone w zakresie liniowej oraz nieliniowej analizy stateczności, z uwzględnieniem wstępnych imperfekcji geometrycznych...
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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 un-notched and notched concrete beams under bending are presented. Concrete beams of four different sizes and five different notch heights under three-point bending test were simulated. In total 18 beams were analysed. Two approaches were used to describe cracks in concrete. First, eXtended...
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An isogeometric finite element formulation for geometrically exact Timoshenko beams with extensible directors
PublicationAn isogeometric finite element formulation for geometrically and materially nonlinear Timoshenko beams is presented, which incorporates in-plane deformation of the cross-section described by two extensible director vectors. Since those directors belong to the space R3, a configuration can be additively updated. The developed formulation allows direct application of nonlinear three-dimensional constitutive equations without zero...
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Radiation pattern measurements of geometrically small antennas performed in non-anechoic environments
Open Research DataThe dataset contains unprocessed measurements of radiation pattern characteristics performed in non-anechoic regime for three geometrically small antenna structures: a spline-parameterized Vivaldi structure, a compact spline-based monopole, and a quasi-Yagi geometry with enhanced bandwidth. The responses have been obtained over broad frequency ranges...
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The description of non-linear interactions of wave and non-wave modes in a non-adiabatic plasma flow
PublicationThe method of derivation of non-linear equations for interacting modes is explained and applied to a plasma's flow affected by a magnetic field. It is based on the linear projecting of the total perturbation field into specific variations of variables in individual modes of a flow. The method may be applied in many examples of fluid flows with different mechanisms of non-adiabaticity. It is of special importance in complex flows...
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Synteza układu sterowania statkiem morskim dynamicznie pozycjonowanym w warunkach niepewności
PublicationNiniejsza monografia obejmuje zagadnienia związane z syntezą układu dynamicznego pozycjonowania statku w środowisku morskim z zastosowaniem wybranych nieliniowych metod sterowania. W ramach pracy autorka rozważała struktury sterowania z zastosowaniem wektorowej adaptacyjnej metody backstep oraz metod jej pokrewnych, takich jak regulatory MSS (ang. multiple surface sliding), DSC (ang. dynamic surface control), NB (ang. neural backstepping)....
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On rotational instability within the nonlinear six-parameter shell theory
PublicationWithin the six-parameter nonlinear shell theory we analyzed the in-plane rotational instability which oc- curs under in-plane tensile loading. For plane deformations the considered shell model coincides up to notations with the geometrically nonlinear Cosserat continuum under plane stress conditions. So we con- sidered here both large translations and rotations. The constitutive relations contain some additional mi- cropolar parameters...
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INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
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Experimental study and numerical optimization of tensegrity domes – A case study
PublicationThe paper deals with the design, experimental analysis and numerical optimization of tensegrity dome models. Two structures are analyzed – a Geiger system dome (preliminary dome), with PVC-U bars and PA6/PP/PET tendons and a Fuller system dome (target dome), with wooden bars and steel cables as tendons. All used materials are experimentally tested in terms of Young's modulus and yield stress values, the compressed bars are also...
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Experimental and numerical investigations of ultimate strength of imperfect stiffened plates of different slenderness
PublicationThe objective of this study is to analyse the behaviour of compressed stiffened plates of different slenderness using experimental and numerical methods. The presented results are part of a long-term project to investigate the ultimate strength of geometrically imperfect structures subjected to different degradation phenomena, including corrosion degradation and locked cracks. Several specimens were subjected to a uniaxial compressive...
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On constitutive relations in the resultatnt non-linear theory of shells
PublicationThe authors summarize their current research in the field of constitutive modelling in the framework of non-linear 6-parameter shell theory. In particular the description of isotropic, multilayered composite and functionally graded shells is presented.
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Examination of advanced isotropic constitutive laws under complex stress states in plain and reinforced concrete specimens
PublicationThe performance of advanced isotropic constitutive laws under complex stress states in plain and reinforced concrete specimens is investigated. Three different formulations are chosen: original Mazars model, Mazars mi model and model proposed by Pereira and coworkers. The degradation of the material in all formulations is described via a single variable, but a strain/stress state is taken into account via quite sophisticated relationships....
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Non-linear FEM analysis of pounding-involved response of buildings under non-uniform earthquake excitation
PublicationThe aim of the paper is to show the results of the study investigating the influence of non-uniform earthquake excitation, due to spatial seismic effects connected with the propagation of seismic wave, on the pounding-involved response of two buildings. The three-dimensional non-linear FEM analysis has been conducted using the detailed models of colliding structures. Acceleration records for different structural supports have been...
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A non-linear direct peridynamics plate theory
PublicationIn this paper a direct non-local peridynamics theory for thin plates is developed. Peridynamic points are assumed to behave like rigid bodies with independent translation and finite rotation degrees of freedom. The non-local mechanical interaction between points is characterized by force and moment vectors. The balance equations including the linear momentum, the angular momentum and the energy are presented. Peridynamic deformation...
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Special Issue: “Non-Destructive Testing of Structures”
PublicationThe Special Issue “Non-Destructive Testing of Structures” has been proposed to present recent developments in the field of diagnostics of structural materials and components in civil and mechanical engineering. The papers highlighted in this editorial concern various aspects of non-invasive diagnostics, including such topics as condition assessments of civil and mechanical structures and connections of structural elements, the...
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Flood Routing by the Non-Linear Muskingum Model: Conservation of Mass and Momentum
PublicationIn this paper, the conservative properties of the Muskingum equation, commonly applied to solve river flood routing, are analysed. The aim of this analysis is to explain the causes ofthe mass balance error, which is observed in the numerical solutions of its non-linear form. The linear Muskingum model has been considered as a semi-discrete form of the kinematic wave equation and therefore it was possible to derive its two non-linear...