Filtry
wszystkich: 11668
wybranych: 461
Wyniki wyszukiwania dla: FEM.
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Experimental and Numerical Investigation of Tensile and Flexural Behavior of Nanoclay Wood-Plastic Composite
PublikacjaIn this study, the effect of wood powder and nanoclay particle content on composites’ mechanical behavior made with polyethylene matrix has been investigated. The wood flour as a reinforcer made of wood powder was at levels of 30, 40, and 50 wt.%, and additional reinforcement with nanoclay at 0, 1, 3, and 5 wt.%. Furthermore, to make a composite matrix, high-density polyethylene was used at levels of 70, 60, and 50% by weight....
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Novel analysis methods of dynamic properties for vehicle pantographs
PublikacjaTransmission of electrical energy from a catenary system to traction units must be safe and reliable especially for high speed trains. Modern pantographs have to meet these requirements. Pantographs are subjected to several forces acting on their structural elements. These forces come from pantograph drive, inertia forces, aerodynamic effects, vibration of traction units etc. Modern approach to static and dynamic analysis should...
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Reinforced concrete thin wall dome after eighty years of operation in maritime climate environment
PublikacjaThe paper presents a description of the construction elements of the Gdynia Seaport main hall dome. Firstly, it provides information about the technical condition of the dome’s structure. Secondly, it examines the strength analysis of the thin-walled reinforced concrete dome covering. Throughout the last 80 years the building has been exposed to an unfavourable marine climate. The analysis of the state of stress and deformations...
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Wybrane elementy nieliniowej dynamiki struktur kratowych
PublikacjaW pracy jest dyskutowany problem nieliniowej dynamiki struktur kratowych. Zastosowano stacjonarny opis Lagrange'a (ang. Total Lagrange), pokazano silne i słabe sformułowanie dla pręta kratowego, jego aplikację do MES. W zakresie całkowania równań ruchu przedstawiono metodę Newmarka i metodę-a dla problemów liniowych i nieliniowych. Załączony przykład numeryczny ilustruje cechy przedstawionych metod.
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Application of the Bodner-Partom constitutive equations for modelling of the technical fabric Valmex used for the hanging roof of the Forest Opera in Sopot
PublikacjaThe study of an inelastic properties of the technical fabric Valmex used for 20 years as the roof structure of the Forest Opera in Sopot (Poland) is presented. The uniaxial tensile laboratory tests with constant strain rate have been conducted and analysed. Parameters of the Bodner-Partom constitutive model have been identified and verified by numerical simulations. Two approaches of the parameters identification have been proposed:...
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A Stand for Measurement and Prediction of Scattering Properties of Diffusers
PublikacjaIn this paper we present a set of solutions which may be used for prototyping and simulation of acoustic scattering devices. A system proposed is capable of measuring sound field. Also a way to use an open source solution for simulation of scattering phenomena occurring in proximity of acoustic diffusers is shown. The result of our work are measurement procedure and a prototype of the simulation script based on FEniCS - an open source...
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Vibration of the bridge under moving singular loads - theoretical formulation and numerical solution
PublikacjaThe paper presents the results of the numerical analysis of a simple vehicle passing over a simply supported bridge span. The bridge is modelled by a Euler-Bernoulli beam. The vehicle is modelled as a linear, visco-elastic oscillator, moving at a constant speed. The system is described by a set of differential equations of motion and solved numerically using the Runge-Kutta algorithm. The results are compared with the solution...
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O obliczaniu kablobetonowych ciągłych dźwigarów mostowych
PublikacjaPrzedstawiono analityczną metodę obliczania kablobetonowych ciągłych dźwigarów z wykorzystaniem metody sił. Podano przykład analizy zrealizowanego kablobetonowego wiaduktu o schemacie dwuprzęsłowej belki ciągłej. Porównano wyniki obliczeń analitycznych i numerycznych (model belkowy, program Sofistik).
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The Influence of Shear Deformation in analysis of plane frames
PublikacjaThe focus of the paper is to investigate the influence of shear deformation effect on the distribution of internal forces and frame deformation. To estimate shear deformation effect, the Timoshenko beam theory and the concept of shear deformation coefficients are used. Analysis of example frames gives the possibility to evaluate what have the most impact on size of shear deformation and in which type of frames the shear deformation...
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Scientific research in the Department of Machine Design and Automotive Engineering
PublikacjaShort descriptions of various research subjects taken up at the Department of Machine Design and Automotive Engineering are included in the paper. The subjects cover a wide range of bearing systems and tribology research and the research on tires and road surfaces. A third field of activity is biomedical engineering – with the attempts to improve methods of modelling biological materials in FEM calculations. The Department has...
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Optimal Rotating Receiver Angles Estimation for Multicoil Dynamic Wireless Power Transfer
PublikacjaThis study proposed an approach to dynamic wireless charging that uses a rotating receiver coil. Our simulation study focused on the verification of a novel way of increasing the coupling coefficient and power transfer stability by following the flux of the transmitting coils. To obtain the highest possible coupling by means of the FEM analysis, we studied the optimization of the trajectory of the angular velocity of the rotating...
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Jacobi and gauss-seidel preconditioned complex conjugate gradient method with GPU acceleration for finite element method
PublikacjaIn this paper two implementations of iterative solvers for solving complex symmetric and sparse systems resulting from finite element method applied to wave equation are discussed. The problem under investigation is a dielectric resonator antenna (DRA) discretized by FEM with vector elements of the second order (LT/QN). The solvers use the preconditioned conjugate gradient (pcg) method implemented on Graphics Processing Unit (GPU)...
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Influence of an applied bearing system on behaviour of multi-span footbridge
PublikacjaThe cycle overpass in Gdynia is a box structure over 300 metres long, 10-span. It was opened for bicycle traffic in the second half of 2013. At the end of its construction, there was failure due to excessive horizontal displacement of the system. A number of bearings exceeded the range of permissible transverse shifts thus it was necessary to temporarily protect the spans from slipping. The FEM analysis of the original solution...
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Failure of cold-formed beam: How does residual stress affect stability?
PublikacjaIn machine industry, stresses are often calculated using simple linear FEM analysis. Occasional failures of elements designed in such a way require recomputation by means of more sophisticated methods, eg. including plasticity and non-linear effects. It usually leads to investigation of failure causes and improvement of an element in order to prevent its unwanted behavior in the future. The study presents the case where both linear...
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Numerical crash analysis of the cable barrier
PublikacjaSafety barriers are used to increase road safety. Their basic task is to prevent the errant vehicle from getting off the road in places which are potentially dangerous for vehicle passengers. Barriers, which are used on European roads, must fulfill the requirements of EN 1317 standards by passing appropriate crash tests. Because of their high cost, numerical simulations are increasingly used to evaluate the properties of safety...
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Thermo-elastic non-linear analysis of multilayered plates and shells
PublikacjaGeometrically 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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Fracture simulations in concrete beam under bending using a mesoscopic model with cohesive elements
PublikacjaThe main aim of this paper was to investigate a complex fracture process in a concrete beam subjected to 3-point bending test by means of the 2D meso-scale FEM with 4-node cohesive elements embedded in the initial mesh of 3-node solid elements. The material heterogeneity was taken into account by considering 3 different phases (aggregate, cement matrix, ITZs) on the basis of randomly generated internal structure of concrete and...
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Modal analysis of cylindrical steel tanks
PublikacjaCylindrical steel tanks are very popular structures used for storage of products of chemical and petroleum industries. Their safety and reliability is crucial because any failure could have serious consequences. The aim of present paper is to show the results of the first phase of investigation of seismic behaviour such structures. Modal analysis using Finite Element Method (FEM) for three models of real tanks used in Poland has...
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Ocena pracy dźwigara zadaszenia Hali Blanika w Gdańsku
PublikacjaWartykule przedstawiono kompleksowe sprawdzenie nośności stalowej konstrukcji zadaszenia Hali Leszka Blanika w Gdańsku. Dokonano oceny wpływu otworów dużej średnicy w środnikach dźwigara na jego nośność. Oszacowano nośność nietypowego, zginanego styku doczołowego łączącego elementy dwuteowe klasy 4. Obliczenia wykonano na podstawie norm i analiz modeli MES.
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Distortional buckling of composite thin-walled columns of a box-type cross section with diaphragms
PublikacjaDistortional buckling of axially compressed columns of box-like composite cross sections with andwithout internal diaphragms is investigated in the framework of one-dimensional theory. The channel membersare composed of unidirectional fibre-reinforced laminate. Two approaches to the member orthotropic materialare applied: homogenization based on the theory of mixture and periodicity cells, and homogenization basedon the Voigt–Reuss...
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Study on 19th-century cast iron columns from the former financial office building in Kwidzyn
PublikacjaThe article presents the results for cast iron columns used as floor supports in the former financial office building in Kwidzyn (Poland).The stocktaking drawings provided the general and detailed data about the 19th century designer’s decisions. During the research, architectural and structural analysis was carried out. The graphics were used as a starting material for preparing 3D calculation models. The FEM-based numerical simulations...
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Impact of an unsecured excavation on an underground pipeline
PublikacjaThe paper presents a numerical analysis of the impact of an unsecured excavation on an underground pipeline in selected soil conditions. The research was inspired by a real-life failure of a water pipeline which was caused by a nearby unsecured excavation (Sikora et al. 2015). The failure was triggered by displacement of soil mass in the vicinity of the pipeline. The study conducted in the framework of Finite Element...
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Local mesh morphing technique for parametrized macromodels in the finite element method
PublikacjaThis paper presents a novel approach for enhancing the efficiency of the design process of microwave devices by means of the finite element method. It combines mesh morphing with local model order reduction (MOR) and yields parametrized macromodels that can be used to significantly reduce the number of variables in the FEM system of equations and acceleration of computer simulation. A projection basis for local reduction is generated...
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Experimental tests and numerical simulations of full scale composite sandwich segment of a foot- and cycle- bridge
PublikacjaIn the paper experimental tests and numerical simulations of a full cross-section segment of ultimately designed foot-and cycle-bridge are presented. The experimental tests were conducted on element with length reduced to 3 m and unchanged (target) cross-section dimensions. The external skin of structure is GFRP laminate while internal core is PET foam. Several quasi-static tests were performed using hydraulic cylinder to generate...
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Evaluation of apparent Young׳s modulus of the composite polymer layers used as sliding surfaces in hydrodynamic thrust bearings
PublikacjaHydrodynamic bearings with a polymer sliding layer are able to operate in severe conditions, mainly due to favorable properties of the polymers. The goal of this research was to evaluate apparent Young׳s modulus of two types of the polymer composite layers used for sliding surfaces in hydrodynamic bearings, as a function of temperature. The Young׳s modulus was evaluated on the basis of compression tests carried out on samples obtained...
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Probabilistic estimation of diverse soil condition impact on vertical axis tank deformation
PublikacjaThe calculations of fuel tanks should take into account the geometric imperfections of the structure as well as the variability of the material parameters of the foundation. The deformation of the tank shell can have a significant impact on the limit state of the structure and its operating conditions. The paper presents a probabilistic analysis of a vertical-axis, floating-roof cylindrical shell of a tank with a capacity of 50000...
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Influence of Added Water Mass on Ship Structure Vibration Parameters in Virtual and Real Conditions
PublikacjaModelling of ship structures in a virtual environment is now standard practice. Unfortunately, many engineers forget to consideri the influence of added water on the frequency values and the amplitude of natural vibrations. The article presents the effect of water damping on the frequency values of the individual natural vibration modes. The tests were carried out in two stages. First, the mentioned values were determined using...
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NUMERICAL SIMULATION OF CRATER CREATING PROCESS IN DYNAMIC REPLACEMENT METHOD BY SMOOTH PARTICLE HYDRODYNAMICS
PublikacjaA theoretical base of SPH method, including the governing equations, discussion of importance of the smoothing function length, contact formulation, boundary treatment and finally utilization in hydrocode simulations are presented. An application of SPH to a real case of large penetrations (crater creating) into the soil caused by falling mass in Dynamic Replacement Method is discussed. An influence of particles spacing on method...
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An influence of the ship's block coefficient implementation on the evaluation of it's hull girder bending
PublikacjaAn influence of the three different ways of implementation ship's block coefficient δ (three geometrical models) on the stresses due to wave bending moment have been investigated. Two models have been applied and compared: beam one (description of the shape usingparameters) and FEM shell model (direct representation of the shape). The outcomes have been compared to Polish Register of Shipping (PRS) rules. The results show that...
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Identification of plate dynamic parameters for structural health monitoring
PublikacjaPraca przedstawia technikę wyznaczania parametrów modalnych wykorzystywanych w diagnostyce konstrukcji. Modalna masa, sztywność, tłumienie i postacie drgań wyznaczone są dla prostokątnej stalowej płyty na podstawie badań eksperymentalnych. Teoretyczne parametry modalne otrzymaneo z modelu MES. Omówiony został wpływ dodatkowej masy na parametry modalne konstrukcji.This paper presents a technique for modal parameters estimation for...
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A material model of asphalt mixtures based on Monte Carlo simulations
PublikacjaThe paper aims to numerically reflect mineral-asphalt mixture structure by a standard FEM software. Laboratory test results are presented due to bending tests of circular notched elements. The result scatter is relatively high. An attempt was made to form a random aggregate distribution in order to obtain various results corresponding to laboratory tests. The material structure calibration, its homogenization and finite element...
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Buckling and initial post-local buckling behaviour of cold-formed channel member flange
PublikacjaThe initial post-buckling behaviour of a cold-formed channel member flange after its local buckling is investigated. An axially compressed column or beam subjected to pure bending is considered. The member material is assumed to follow a linear stress-strain relationship. The governing non-linear differential equation of the problem is derived using the minimum total potential energy principle. An approximate solution for the equation...
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Stress analysis of a strip under tension with a circular hole
PublikacjaThe paper addresses stress analysis of a strip with a circular hole under uniform uniaxial tension based oncircumferential stress expressionρπ. Stresses are analyzed in the infinite-length strips under tension with holes, the ratioof the hole radiusa to the strip half-widthb is either equal to:κ =a/b = 0.1 orκ = 0.5. Circumferential stresses aredetermined in selected cross-sections of the strip. The stress diagrams display local...
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Flexural buckling and post-buckling of columns made of aluminium alloy
PublikacjaThe paper concerns flexural buckling and initial post-buckling of axially compressed columns made of aluminium alloy described by the Ramberg-Osgood relationship. The non-linear differential equation of the problem is derived using the stationary total energy principle and the assumptions of classical beam theory within a finite range. The approximate analytical solution of the equation leading to the buckling loads and initial...
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Local buckling of compressed flange of cold-formed channel members made of aluminum alloy
PublikacjaThe paper deals with local buckling of a compressed single flange of thin-walled channel cold- formed columns and beams made of aluminum alloy. Material is described by means of the Ramberg-Osgood constitutive equation. Axial compression of the columns and beams undergoing bending is taken into consid- eration. A simple model of the member flange in the form a long beam elastically connected to the web is used to find the critical...
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Shell model of multiple-row moment I-section end-plate joint
PublikacjaThe paper deals with a problem of application of shell elements in the models of multiple-row moment end-plate connections. The extended connection of I-section with a cross-section W760x265x220 made of steel S355 was analyzed. Comparison analysis of FEM, complex volume and shell models has been done. Three cases with different end-plate thickness: 14, 18 and 36 mm were analyzed and compared with the reference results. Comparison...
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Rozkład naprężeń mechanicznych w łyżce o szerokości 500 mm, przeznaczonej do koparki podsiębiernej
PublikacjaW artykule zaprezentowano optymalizację kształtu łyżki koparki przedsiębiernej z wykorzystaniem analizy wytrzymałościowej. Analizę oparto na trójwymiarowym modelu konstrukcji łyżki z zastosowaniem metody elementów skończonych (MES). Opracowanie wspomnianej metody pozwoliło na modyfikację konstrukcji łyżki, która dała w efekcie obniżenie naprężeń złożonych w newralgicznych obszarach konstrukcji łyżki. Przedstawiona analiza okazała...
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Influence of the notch rounding radius on estimating the elastic notch stress concentration factor in a laser welded tee joint
PublikacjaIn recent years an increased interest of industry in sandwich-type metal structures can be observed. These structures consist of thin plates of 2.5 mm in thickness separated by stiffeners of different shapes and forms. Welds joining the plates and stiffeners are made on the outer side of the plates using laser welding technique. A locally focused source of heat causes the plate to melt creating a very narrow and elongated joint....
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Zmodernizowany most Łazienkowski w Warszawie – analizy z wykorzystaniem modelu numerycznego MES
PublikacjaW artykule przedstawiono proces modelowania statycznego przęseł mostu Łazienkowskiego w Warszawie, który został poddany odbudowie po pożarze 14 lutego 2015 r. Sprawdzające obliczenia numeryczne wykonano w związku z badaniami konstrukcji podczas próbnego obciążenia. Przeprowadzono weryfikację obliczeń projektowych i zaprojektowano próbne obciążenie. Podsumowano wyniki analizy i badań. Dodatkowo opisano nową, stalową konstrukcję...
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Hybrid model of geared rotor system
PublikacjaIn the paper a hybrid model of a geared multirotor system has been developed. The model is obtained by application of both the modal decomposition methodology and the spatial discretization method. Reduced modal model was constructed for the system without gyroscopic and damping effects. The gyroscopic interaction, damping and other phenomena which are difficult to include in the modal approach were modeled by application of simply...
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Non-Salient Brushless Synchronous Generator Main Exciter Design for More Electric Aircraft
PublikacjaThis paper presents a prototype of high speed brushless synchronous generators (BSG) design for the application in autonomous electric power generation systems (e.g., airplane power grid). Commonly used salient pole field of the main generator part of BSG was replaced with a prototype non-salient pole field. The main objective of the research is an investigation into the advantages and disadvantages of a cylindrical field of the...
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Experimental and numerical evaluation of mechanical behaviour of composite structural insulated wall panels under edgewise compression
PublikacjaA composite structural insulated sandwich panel (CSIP) is a quite novel approach to the idea of sandwich structures. A series of natural-scale experimental test is required each time a change in panel’s geometry is planned and a reliable computational tool is required to precede actual laboratory testing with virtual simulations. An attempt of creating such a tool has been made with use of a commercial FEM code ABAQUS, in order...
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Numerical modeling and experimental validation of full-scale segment to support design of novel GFRP footbridge
PublikacjaThe paper contains analysis of full-scaled three meters long segment of a novel composite footbridge. Both numerical modeling and experimental validation were performed. Analyzed object is a shell type sandwich channel-like structure made of composite sandwich with GFRP laminates as a skin and PET foam as a core. Several static load schemes were performed including vertical and horizontal forces. In FEM analysis multilayered laminate...
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High-quality Experiment Dedicated to microGravity Exploration, Heat Flow and Oscillation Measurement from Gdańsk
PublikacjaIn this paper we propose HEDGEHOG (High-quality Experiment Dedicated to microGravity Exploration, Heat flow and Oscillation measurement from Gdańsk) REXUS experiment to investigate vibrational and heat flow phenomena during the whole (ascent, microgravity phase, descent and recovery) flight of a sounding rocket. First, a proposed system of cantilever beams is discussed to study dynamic behaviour of dummy payload. Dimensioning has...
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NUMERICAL MODEL QUALITY ASSESSMENT OF OFFSHORE WIND TURBINE SUPPORTING STRUCTURE BASED ON EXPERIMENTAL DATA
PublikacjaAs a structure degrades some changes in its dynamical behavior can be observed, and inversely, observation and evaluation of these dynamical changes of the structure can provide information of structural state of the object. Testing of the real structure, besides of being costly, can cover only limited working states. It is particularly considerable in case of hardly accessible, and randomly/severely dynamically loaded offshore...
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THREE-DIMENSIONAL numerical investigation of MHD nanofluid convective heat transfer inside a CUBIC porous container with corrugated bottom wall
PublikacjaSimultaneous use of porous media and nanofluid as a heat transfer improvement method has recently captivated a great deal of attention. The heat transfer and entropy production of the Cu-water nanofluid inside a cubic container with a heated bottom wavy wall and an elliptic inner cylinder were numerically analyzed in this study. The container is partitioned into two sections: the left side is filled with permeable media and...
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Analiza następstw potencjalnej awarii wanty mostu podwieszonego w Bydgoszczy
PublikacjaMost Uniwersytecki został zamknięty po siedmiu latach od oddania do użytkowania. Powodem były widoczne gołym okiem objawy znacznego przeciążenia w obrębie zakotwień. Krytyczne elementy konstrukcji mostu zostały wzmocnione i przywrócono go do ruchu. W artykule przedstawiono nieliniowe analizy statyczne i dynamiczne wykonane na modelu MES, prezentujące cztery scenariusze przebiegu zachowania konstrukcji po utracie nośności mocowania...
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On the necessity of experimental verification of numerical results in biomedical applications
PublikacjaPorous structures made of metal or biopolymers with a structure similar in shape and mechanical properties to human bone can be easily produced by stereolitography techniques, e.g. selective laser melting (SLM). Numerical techniques, like finite element method (FEM) have great potential in testing new, even the most sophisticated designs, according to their mechanical properties, i.e. strength or stiffness. However, due to different...
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Behaviour of steel columns under impact
PublikacjaOne of import issues related to the idea of sustainable society is the safety of civil engineering structures. The safety and reliability of steel structures under impact loading is among a number of different aims during the design state. The aim of this paper is to present the results of investigation focused on dynamic behaviour of steel columns under impact loading. Modal and transient dynamic analyses using Finite Element...
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Monitoring of CRT by means of impedance multiple measurements - simulation studies
PublikacjaCardiac resynchronization therapy (CRT) is a very promising treatment for patients with congestive heart failure. An Impedance Cardiography (ICG) is used for evaluation of heart mechanical activity. A simulation study with the use of a FEM model was performed. The developed realistic model of the thorax, based on CT data obtained from examination of a 68-year-old man, consisted of 212 000 tetrahedral elements. Different configurations...