Filtry
wszystkich: 711
wybranych: 534
Wyniki wyszukiwania dla: BEAMS, PLATES, AND SHELLS
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Partially prestressed concrete beams with bonded and unbonded strands
PublikacjaThis article relate the tests of partially prestressed concrete beams. There is presented the research programme - geometry of elements, method of loading, the materials and variables. There have been shown preliminary test results of prestressed concrete elements with bonded and unbonded strands, and compared to the test results of R.C. beam.
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Examination of selected failure criteria with asymmetric shear stresses in the collapse analysis of laminated shells
PublikacjaThe paper is concerned with failure analysis of composite shells performed with the usage of the nonlinear 6‐parameter shell theory with drilling rotation degree of freedom. This special theory embodies naturally unlim-ited translations and rotations and is suitable for analysis of irregular shells for instance with various, partic-ularly orthogonal, intersections. The presence of the drilling rotation is inherently accompanied...
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Modeling of Composite Shells in 6-Parameter Nonlinear Theory with Drilling Degree of Freedom
PublikacjaWithin the framework of a 6-parameter nonlinear shell theory, with strain measures of Cosserat type, constitutive relations are proposed for thin elastic composite shells. The material law is expressed in terms of five engineering constants of classical anisotropic continuum plus an additional parameter accounting for drilling stiffness. The theory allows for unlimited displacements and rotations. A number of examples are presented...
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Uncertainty assessment of ultimate strength of corroded stiffened plates subjected to different maintenance actions
PublikacjaThe study deals with the uncertainty assessment of different governing factors related to the ultimate strength of the corroded stiffened plates. The load-carrying capacity is predicted with the use of the nonlinear Finite Element Method. The most influencing governing factors in the non-linear FE analysis, such as material properties and initial imperfections are modeled and analysed as stochastic variables. The ultimate strength...
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Ultrasonic diagnostics of concrete T-beams used in bridge structures
PublikacjaThis paper describes a method of ultrasonic diagnostics used for prefabricated concrete elements. The studies are focused on the applicability of nondestructive techniques based on impulse and wave packet induced elastic waves for the condition assessment of T-shaped bridge beams. Experimental tests were performed for the prestressed beam used for the superstructure of the viaduct on A1 highway near Toruń. In addition numerical...
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Arc-length Algorithm Efficiency in the Analysis of Thermally Loaded Multilayered Shells
PublikacjaThis 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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Imaging of Increasing Damage in Steel Plates Using Lamb Waves and Ultrasound Computed Tomography
PublikacjaThis paper concerns inspection of steel plates, with particular emphasis on the assessment of in-creasing damage. Non-destructive tests were performed on four plates, one of which was un-damaged, while the remaining three had a defects in the form of circular holes with a diameter of 2, 5, and 10 cm. Guided Lamb waves were used in the research, and the image reconstruction was performed using ultrasound computed tomography. The...
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Experimental Study of Dapped-End Beams Subjected to Inclined Load
PublikacjaThis paper presents the results of an experimental investigation of the reinforced concrete (RC) dapped-end beams loaded with inclined forces, compared to identical ones loaded with vertical forces only. Such a load may occur in, for example, Gerber's joints or in dapped-end beams supported on corbels, where the vertical gravitation force is additionally completed with horizontal forces caused by temperature differences, shrinking,...
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On rotary inertia of microstuctured beams and variations thereof
PublikacjaWe discuss the classic rotary inertia notion and extend it for microstructured beams introducing new microinertia parameters as an additional dynamic response to microstructure changes. Slender structures made of beam- or platelet-lattice metamaterials may exhibit not only large translations and rotations but also general deformations of inner structure. Here we considered a few examples of beam-like structures and derive their...
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Experimental and numerical investigations of ultimate strength of imperfect stiffened plates of different slenderness
PublikacjaThe 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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Discussion - Experimental study of dapped–end beams subjected to inclined load
PublikacjaDiscussion - Experimental study of dapped–end beams subjected to inclined load
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Investigations on strength and fracture in RC beams scaled along height or length
PublikacjaThe objective of the present paper is to identify experimentally and theoretically differing failure mechanisms in reinforced concrete beams subjected to four-point bending for a separate variation of the depth and length at the constant thickness. Experiments were performed on reinforced concrete beams under four-point bending. Different failure mechanisms included steel yielding, diagonal tension or shear- compression depending...
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Ultimate compressive strength assessment of uncleaned and cleaned corroded plates with locked crack
PublikacjaThe work presented here investigates the structural response of cleaned corroded plates, subjected to compressive load in the presence of a locked crack, where the change of mechanical properties as a result of corrosion development and the cleaning process is also accounted for. A Finite Element model for assessing the compressive strength, considering geometric and material nonlinearities, is developed, and the analysed plates...
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Extended non-linear relations of elastic shells undergoing phase transitions
PublikacjaThe non-linear theory of elastic shells undergoing phase transitions was proposed by two first authors in J. Elast. 79, 67-86 (2004). In the present paper the theory is extended by taking into account also the elastic strain energy density of the curvilinear phase interface as well as the resultant forces and couples acting along the interface surface curve itself. All shell relations are found from the variational principle of...
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Torque Transmitted by Multi-plate Wet Clutches in Relation to Number of Friction Plates and Their Dimensions
PublikacjaIn the paper results of experimental tests on multi-plate wet clutch torque capacity for various diameters and numbers of friction plates are presented. Construction of an apparatus for laboratory tests of wet clutch engagement, drag torque and maximum torque is shown. Methodology of maximum torque capacity experiment and hydraulic circuit diagram, which supplies a motor and an actuator for the experiment are described. Analytically...
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A Novel Approach to Fully Nonlinear Mathematical Modeling of Tectonic Plates
PublikacjaThe motion of the Earth's layers due to internal pressures is simulated in this research with an efficient mathematical model. The Earth, which revolves around its axis of rotation and is under internal pressure, will change the shape and displacement of the internal layers and tectonic plates. Applied mathematical models are based on a new approach to shell theory involving both two and three-dimensional approaches. It is the...
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Equivalent single-layer models in deformation analysis of laminated multilayered plates
PublikacjaThe performance of selected Equivalent Single-Layer (ESL) models is evaluated within several classical benchmark tests for linear static analysis of multi-layered plates. The authors elaborated their own Finite Element software based on the first-order shear deformation theory (FOSD) with some modifications incorporated including a correction of the transverse shear stiffness and an application of zig-zag type functions. Seven...
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2-D constitutive equations for orthotropic Cosserat type laminated shells in finite element analysis
PublikacjaWe propose 2-D Cosserat type orthotropic constitutive equations for laminated shells for the purpose of initial failure estimation in a laminate layer. We use nonlinear 6-parameter 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...
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Problems of reinforcement designing for plates
PublikacjaPrzedstawiono problem projektowania zbrojenia nietrajektorialnego płyt w aspekcie ich odkształcalności. Na podstawie niektórych wyników badań doświadczalnych, przeprowadzonych na żelbetowych płytach skręcanych, zweryfikowano procedury wymiarowania. Analiza wykazuje, że pomimo formalnego zapewnienia nośności przekroju płyt nietrajektorialnie zbrojonych, ich odkształcalność znacznie wzrasta. Aby zapewnić im sztywność na poziomie...
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Nonlinear material identification of heterogeneous isogeometric Kirchhoff–Love shells
PublikacjaThis work presents a Finite Element Model Updating inverse methodology for reconstructing heterogeneous materialdistributions based on an efficient isogeometric shell formulation. It uses nonlinear hyperelastic material models suitable fordescribing incompressible material behavior as well as initially curved shells. The material distribution is discretized by bilinearelements such that the nodal values...
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Geometrically nonlinear analysis of shells
PublikacjaArtykuł porusza zagadnienia nieliniowej analizy powłok wykonanych z materiałów izotropowych. Obliczenia wykonano przy wykorzystaniu dwóch komercyjnych programów wykorzystujących Metodę Elementów Skończonych (Robot Millennium v. 19.0 i MSC.Marc v.2005r2 ). Główną uwagę skupiono na zjawisku zakleszczenia.
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A Diagnostic Method Based on Deflection Analysis for Monitoring Post-elastic Response of Beams
PublikacjaA non-destructive diagnostic method based on deflection analysis for monitoring the post-elastic response of beams was developed, and a diagnostic indicator was proposed. The indicator was defined as the second moment of the normalised curvature function about the mid-span, where the curvature was computed from the normalised deflection function. Elastic reference values of the indicator were computed for simply supported beams...
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Design of experiments approach for ultimate strength assessment of corroded stiffened plates
PublikacjaThe impact of corrosion degradation on the ultimate strength of stiffened plates subjected to compressive loading is investigated. The DoE technique is used considering different plate and column slenderness ratios and corrosion severity. The FE method, considering geometrical and material nonlinearities, is employed. A two-stage corrosion degradation model is adopted. Firstly, a uniform thickness loss is adopted to reflect the...
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Infrared techniques for natural convection investigations in channels between two vertical, parallel, isothermal and symmetrically heated plates
PublikacjaThe effect of the gap width between two symmetrically heated vertical, parallel, isothermal plates on intensity of natural convective heat transfer in a gas (Pr = 0.71) was experimentally studied using the balance and gradient methods. In the former method heat fluxes were determined based on measurements of the voltage and electric current supplying the heaters placed inside the walls. In the latter, heat fluxes were calculated...
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Investigations on fracture in reinforced concrete beams in 3-point bending using continuous micro-CT scanning
PublikacjaThis study explores a fracture process in rectangular reinforced concrete (RC) beams subjected to quasi-static three-point bending. RC beams were short and long with included longitudinal reinforcement in the form of a steel or basalt bar. The ratio of the shear span to the effective depth was 1.5 and 0.75. The focus was on the load–deflection diagram and crack formation. Three-dimensional (3D) analyses of the size and distribution...
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Influence of Material Thickness on the Ductile Fracture of Steel Plates for Shipbuilding
PublikacjaIn the shipbuilding industry, the risk of brittle fractures is relatively high because some units operate in arctic or subarcticzones and use high thickness (up to 100 mm) steel plates in their structures. This risk is limited by employing certifiedmaterials with a specific impact strength, determined using the Charpy method (for a given design temperature) and byexercising control over the welding processes (technology qualification,...
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Thermal self-action effects for acoustic beams containing fronts in a Maxwell relaxing fluid
PublikacjaThis paper examines the thermal self-action of acoustic beams in a Maxwell relaxing fluid. This type of thermal self-action differs from that in a Newtonian fluid and behaves differently depending on a ratio of sound period and time of thermodynamic relaxation. The self-action which relates to sound beams containing shock fronts is also discussed. In addition, stationary and non-stationary types of self-action are considered.
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Assessment of Wooden Beams from Historical Buildings Using Ultrasonic Transmission Tomography
PublikacjaThe main goal of this study was non-destructive evaluation of wooden elements using ultrasonic waves. The inspection was carried out on wooden beams from a historical object. Elastic wave signals were processed by ultrasonic transmission tomography to obtain imaging of the internal structure of tested elements without disturbing their state and integrity. The focus was on the influence of wood anisotropy on the propagation of ultrasonic...
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Debonding Detection in Reinforced Concrete Beams with the Use of Guided Wave Propagation
PublikacjaOne of the most frequent damage of the reinforced concrete structures is debonding between steel bar and concrete cover. In the case of debonding occurrence not only the strength of the structure decreases, but also it is more vulnerable to corrosion damages. For this reason fast and effective methods of debonding detection in an early stage of its development need a significant boost. The paper presents analytical and experimental...
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Structural Assessment of Reinforced Concrete Beams Incorporating Waste Plastic Straws
PublikacjaThe behavior of reinforced concrete beams containing fibers made of waste plastic straws (WPSs) under the three point bending test is examined. The effect of WPS fiber addition on the compressive and split tensile strength is reported. Four concrete mixes were prepared. The control mix PS-0 had a proportion of 1 cement: 1 sand: 2 coarse aggregate and a water cement ratio of 0.4. In the other three mixes PS-0.5, PS-1.5 and PS-3,...
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Drilling couples and refined constitutive equations in the resultant geometrically non-linear theory of elastic shells
PublikacjaIt 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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Failure characterisation of sandwich beams using integrated acoustic emission and digital image correlation techniques
PublikacjaThe paper presents the experimental study of the failure behaviour of sandwich beams subjected to bending. The samples examined are sandwich beams made of polyethylene terephthalate foam core and glass fibre-reinforced polymer laminate face sheets. In a series of experiments, it has been proposed to integrate diagnostic techniques with acoustic emission and digital image correlation to accurately track the cracking process on the...
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Stress–strain model of lower corroded steel plates of normal strength for fitness-for-purpose analyses
PublikacjaThis study investigates the mechanical properties of specimens made of normal strength steel subjected to lower marine immersed corrosion degradation levels (below 25 %). The specimens were corroded in laboratory conditions, and only natural factors were controlled to raise the corrosion rate (reaching the level of 1 mm/year). Three different thicknesses of plates made of normal strength of shipbuilding steel are investigated (between...
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Exact resultant equilibrium conditions in the non-linear theory of branching and self-intersecting shells
PublikacjaWe formulate the exact, resultant equilibrium conditions for the non-linear theory of branching and self-intersecting shells. The conditions are derived by performing direct through-the-thickness integration in the global equilibrium conditions of continuum mechanics. At each regular internal and boundary point of the base surface our exact, local equilibrium equations and dynamic boundary conditions are equivalent, as expected,...
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Numerical and experimental study on effect of boundary conditions during testing of stiffened plates subjected to compressive loads
PublikacjaThis study analyses the effect of boundary conditions during testing on the structural behaviour stiffened plates with different thicknesses subjected to compressive loads. The goal of the compressive tests is to analyse the ultimate strength of a stiffened plate. During the test, relevant physical quantities are measured and investigated. The supporting structure's behaviour is investigated by analysing the force-displacements...
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Equivalent Single Layer Models in Free Vibration Analysis of Laminated Multi-Layered Plates
PublikacjaThe performance of selected equivalent single-layer (ESL) models is evaluated within several classical benchmark tests for small amplitude free vibration analysis of multi-layered plates. The authors elaborated their own Finite Element software based on the first-order shear deformation (FOSD) theory with some modifications incorporated including a correction of the transverse shear stiffness and an application of zigzag type functions....
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Technology of welding hard wearing plates
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Mode vibrations of plates – experimental analysis
PublikacjaIn this paper results of the square MDF plate and circular saw blades examination with the use of the harmonic method to static identification of resonant frequencies and shapes of mode vibrations are presented. Obtained results reveled that for circular saws with large holes in a saw blade appeared two resonant frequencies for the same nodal number.
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On some constitutive equations for micropolar plates
PublikacjaW pracy porównano równania konstytutywne dla płyt podane przez Altenbacha i Eremeyeva. Na podstawie ich wyprowadzeń określono zakres zmienności współczynnika momentów owinięcia i jego możliwy wpływ na wyniki otrzymane w rozwiązaniach MES w zakresie liniowym
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Forming of explosively welded metal plates.
PublikacjaW pracy przedstawiono możliwości kształtowania plastycznego poprzez walcowanie, tłoczenie, gięcie, skręcanie blach wielowarstwowych zgrzewanych wybuchowo.
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The influence of applying supplementary web plates on structural joint moment resistance and rotational stiffness
PublikacjaContinual trend to simplify structural elements and find less time-consuming solutions on construction site as well as inevitable increase in labour costs determine for instance elimination of those technological steps that are difficult to automation. Welding additional reinforcements and web stiffeners is a great example of such a step. The method presented in EN 1993-1-8 [8] is a result of long-term studies focused on calculating...
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Advanced numerical modelling for predicting residual compressive strength of corroded stiffened plates
PublikacjaAn advanced methodology for predicting the residual compressive strength of corroded stiffened plates is developed here using the non-linear finite element method. The non-uniform loss of a plate thickness is accounted for on a macro-scale. In contrast, mechanical properties are changed using the constitutive model to reflect the corrosion degradation impact on a micro-scale. Three different stiffened plate thicknesses are considered,...
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Singular curves in the resultant thermomechanics of shells
PublikacjaSome geometric and kinematic relations associated with the curve moving on the shell base surface are discussed. The extended surface transport relation and the extended surface divergence theorems are proposed for the piecewise smooth tensor fields acting on the regular and piecewise regular surfaces. The recently formulated resultant, two-dimensionally exact, thermodynamic shell relations - the balances of mass, linear and angular...
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Imperfection sensitivity of multilayered composite shells
PublikacjaW pracy analizowana jest stateczność cylindrycznej powłoki warstwowej poddanej osiowemu ściskaniu. Badany jest wpływ początkowych imperfekcji geometrycznych na zachowanie konstrukcji. Obliczenia realizowane są w programie Nastran (ver. 6.0).
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On dynamically and kinematically exact theory of shells
PublikacjaW rozważanej dynamicznie i kinematycznie ścisłej teorii powłok, powłokę reprezentuje materialna powierzchnia podstawowa wyposażona w tzw. tensor struktury. Nieograniczoną deformację włókien materialnych przekroju poprzecznego powłoki opisuje wektor przesunięć powierzchni podstawowej i tensor obrotów, wyrażający energetycznie uśrednioną po grubości rotację przekroju. Dyskutowane są relacje między trójwymiarowymi polami w ciele typu...
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The vibration-based assessment of the influence of elevated temperature on the condition of concrete beams with pultruded GFRP reinforcement
PublikacjaConcrete beams reinforced with glass fiber reinforced polymer (GFRP) bars subjected to elevated temperature have been experimentally studied. The influence of high temperatures on GFRP-reinforced concrete beams condition has been check both, destructively and nondestructively. The nondestructive tests foresaw vibration-based tests to obtain the natural frequency values after exposure to varying temperatures. The vibration-based...
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A simple and efficient hybrid discretization approach to alleviate membrane locking in isogeometric thin shells
PublikacjaThis work presents a new hybrid discretization approach to alleviate membrane locking in isogeometric finite element formulations for Kirchhoff–Love shells. The approach is simple, and requires no additional dofs and no static condensation. It does not increase the bandwidth of the tangent matrix and is effective for both linear and nonlinear problems. It combines isogeometric surface discretizations with classical Lagrange-based...
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Application of twin-plane ECT sensor for identification of the internal imperfections inside concrete beams
PublikacjaThe main purpose of this paper is to investigate application of special construction of Electrical Capacitance Tomography (ECT) sensor to concrete beams internal homogeneity tests. Identification of internal imperfection inside the concrete beams is one of the main problems related to analysis of the construction structure bearing capacity. Therefore, this paper shows attempts to study the measurement prospects for this non-invasive,...
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Ultimate strength of stiffened plates subjected to compressive load and spatially distributed mechanical properties
PublikacjaThe present study deals with the ultimate strength of stiffened plates subjected to spatially distributed mechanical properties and compressive load. Normally, mean values of mechanical properties based on tensile tests are used to validate the numerical assessment with experimental results. However, mechanical properties may vary within a single specimen. To investigate the impact of that, random fields of yield stress and Young...
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Using the ultrasonic tomography method to study the condition of wooden beams from historical buildngs
PublikacjaThe need to evaluate the integrity of wooden structural elements is constantly increasing. Non-destructive methods are becoming more popular in this field of research. One type of non-destructive testing is the ultrasonic imaging method, which allows the analysis of internal wood structures without disturbing their state and integrity. In this study, we are interested in assessing the effect of wood condition on the ultrasound...