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Search results for: STRESSES
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Experiments and Analysis of the Limit Stresses of a Magnetorheological Fluid
PublicationPaper presents the results of a rheological test of a commercial magnetorheological (MR) fluid (MRF-132DG). The researchincludes the problem of measuring and interpreting limit stresses under conditions close to the magnetic saturation of the fluid. Fourdifferent limit stresses were determined, two related to the yield point and two related to the flow point. Methods for determining limitstresses, especially due to excitation...
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Bending of a Three-Layered Plate with Surface Stresses
PublicationWe discuss here the bending deformations of a three-layered plate taking into account surface and interfacial stresses. The first-order shear deformation plate theory and the Gurtin-Murdoch model of surface stresses will be considered and the formulae for stiffness parameters of the plate are derived. Their dependence on surface elastic moduli will be analyzed.
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Influence of geometrical imperfections on stresses in cylindrical shells
PublicationResults of the numerical analysis of the shells of storage tanks of 50 000 m3 capacity with geometrical imperfections are presented in the paper. Results were verified by tensometric tests performed on the real tank. It was recognized that real geometrical imperfections cause increase of stresses in the tank construction by 30%.
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Comparison of calculated and measured thermal stresses in asphalt concrete
PublicationThe paper presents the comparison of calculated and measured thermal stresses induced in restrained asphalt concrete specimens by cooling. Thermal stresses were measured in the Thermal Stress Restrained Specimen Test. The calculations of thermal stresses were performed with the use of a theoretical formula based on the temperature dependent stiffness modulus. The novel approach applied in this paper was that the stiffness modulus...
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Microstructure and residual stresses in surface coatings with PTFE reservoirs
PublicationThe paper presents the results of experimental study into the microstructure and changes in residual stresses resulting from sliding and rolling/sliding loaded interaction between metallic surface coatings with embedded PTFE reservoirs and various counter faces. It was found that before testing surface coatings had compressive residual stresses. Molybdenum coating with all types of PTFE reservoirs displayed, as a result of testing,...
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On stress singularity near the tip of a crack with surface stresses
PublicationIn the framework of the simplified linear Gurtin–Murdoch surface elasticity we discuss a singularity of stresses and displacements in the vicinity of a mode III crack. We show that inhomogeneity in surface elastic properties may significantly affect the solution and to change the order of singularity. We also demonstrate that implicitly or explicitly assumed symmetry of the problem may also lead to changes in solutions. Considering...
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On Nonlinear Dynamic Theory of Thin Plates with Surface Stresses
PublicationWe discuss the modelling of dynamics of thin plates considering surface stresses according to Gurtin–Murdoch surface elasticity. Taking into account the surface mass density we derive the two-dimensional (2D) equations of motion. For the reduction of the three-dimensional (3D) motion equations to the 2D ones we use the trough-the-thickness integration procedure. As a result, the 2D dynamic parameters of the plate depend not only...
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The effect of tensile stresses on aluminium passive layer durability
PublicationW niniejszej pracy przedstawiono wyniki badań DEIS dotyczących wpływu naprężeń rozciągających na trwałość warstwy pasywnej aluminium A91050, prowadzonych w środowisku chlorków w temperaturze pokojowej.Zastosowana technika pozwoliła na wyznaczenie krytycznej wartości wydłużenia, przy której doszło do pęknięcia warstwy pasywnej na badanym stopie.
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Estimation of Stresses in a Dry Sand Layer Tested on Shaking Table
PublicationTheoretical analysis of shaking table experiments, simulating earthquake response of a dry sand layer, is presented. The aim of such experiments is to study seismic-induced compaction of soil and resulting settlements. In order to determine the soil compaction, the cyclic stresses and strains should be calculated first. These stresses are caused by the cyclic horizontal acceleration at the base of soil layer, so it is important...
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Contribution of Exogenous Proline to Abiotic Stresses Tolerance in Plants: A Review
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Fe analysis of loadson the silo wall and stresses in the silo structure.
PublicationArtykuł przedstawia numeryczne wyniki naporu materiałów sypkich na ścinanie podczas przepływu w silosach z lejem w kształcie osiowo-symetrycznego stożka.
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Combining of global and local stresses in ship hulls on ocean waves.
PublicationOpisano zagadnienia superpozycji naprężeń dynamicznych od zginania ogólnego i strefowego, we wzdłużnych wiązarach kadłuba statku. Krytycznie skomentowano wymagania przepisów klasyfikacji i budowy statków, dotyczące oceny wytrzymałości tych elementów konstrukcji. Przedstawiono sposób wykonywania prognozy długoterminowej naprężeń w tych elementach i zaproponowano sposób sumowania charakterystycznych wartości naprężeń od zginania...
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Evaluation of Thermal Stresses in Asphalt Layers in Comparison with TSRST Test Results
PublicationThe paper presents the results of calculations and laboratory determination of thermal stresses at low temperatures. The modified Hills and Brien's method was used to calculate the thermal stresses in asphalt layers of pavements and the results were compared against the values obtained at a laboratory with the Thermal Stress Restrained Specimen Test (TSRST) method. The laboratory investigations were conducted using plain grade...
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The Influence of Modelling Material Zones on Strains and Stresses at Weld Toe Notch
PublicationThe latest development in the field of welding technology enabled prefabrication of thin-walled sandwich structures in an industrial scale. Sandwich structures fabricated of steel, or aluminium alloy plates and stiffeners are welded with the use of hi-power CO2 lasers. Strength analysis of such structures with the use of finite element method needs proper material modelling.In this paper the material model of steel sandwich panel...
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Evaluation of Thermal Stresses in Asphalt Layers Incomparison with TSRST Test Results
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Stresses in the zone of process openings in the shell of a vertical cylindrical steel tank
PublicationW dolnej części płaszcza zbiornika walcowego na ciecze konieczne jest wykonanie różnego rodzaju otworów technologicznych. Artykuł poświęcony jest analizie stanu naprężeń w strefie wzmocnień wykonywanych w sąsiedztwie otworów na rurociągi oraz na włazy wyczystkowe w płaszczu zbiornika. Ponieważ charakter zmian naprężeń, a więc i wzmocnień w strefie obu rodzajów otworów jest różny dlatego artykuł podzielony jest na dwie części, z...
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On long-term prediction of stresses in principal members of ship hull structures.
PublicationOpisano krytycznie wymagania towarzystw klasyfikacyjnych dotyczące oceny wytrzymałości wzdłużnych wiązarów i wzdłużnych usztywnień poszycia kadłuba statku. Przedstawiono sposób prognozowania długoterminowego dynamicznych składowych tych naprężeń oraz zaproponowano sposób składania charakterystycznych wartości poszczególnych składowych naprężeń do zastosowania w przepisach Polskiego Rejestru Statków. Sposób ten bazuje na koncepcji...
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Numerical calculation wall pressure and stresses in cylindrical silos withconical hopper
PublicationOmówiono wyniki numerycznego obliczania naporu materiału sypkiego na ściany silosu. Obliczenia wykonano stosując metodę elementów skończonych i sprężysto idealnie plastyczne prawo konstytutywne według Druckera-Pragera. W analizie uwzględniono wpływ osiowy i mimośrodowy.
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Imaging of grains and internal stresses in GO Fe-Si alloy with Barkhauseneffects
PublicationBadano próbki stali transformatorowej Fe-Si ze strukturą zorientowaną (GO). Polowy efekt Barkhausena wykorzystano do zobrazowania ziaren pod warstwą ochronną a poziom naprężeń wewnętrznych wyznaczono wykorzystując mechaniczny efekt Barkhausena.
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Linear Micropolar Elasticity Analysis of Stresses in Bones Under Static Loads
PublicationWe discuss the finite element modeling of porous materials such as bones using the linear micropolar elasticity. In order to solve static boundary-value problems, we developed new finite elements, which capture the micropolar behavior of the material. Developed elements were implemented in the commercial software ABAQUS. The modeling of a femur bone with and without implant under various stages of healing is discussed in details
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Effect of Laser Treatment on Intrinsic Mechanical Stresses in Titanium and Some of Its Alloys
PublicationLaser surface treatment conducted at different power levels is an option to modify titanium bone implants to produce nano- and microtopography. However, such processing can lead to excess mechanical stress within the surface layer. This research aims to calculate the level of such residual stresses after the surface processing of Ti grade IV, Ti15Mo, and Ti6Al7Nb alloys with an Nd:YAG laser. Light and scanning electron microscopies...
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Sawing Processes as a Way of Determining Fracture Toughness and Shear Yield Stresses of Wood
PublicationA new computational model, based on fracture mechanics, was used to determine cutting forces. Unlike traditional computing methods, which depend on many coefficients reflecting the machining of solid wood, the new model uses two main parameters: fracture toughness and shear yield stresses. The aim of this study was to apply this new method to determine these parameters for the tooth cutting edge principal positions and longitudinal...
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The Influence of Selected Parameters of Numerical Modelling on Strains and Stresses at Weld Toe Notch
PublicationLatest development in the field of welding technology and prefabrication enabled massive production of thin-walled sandwich structures. Multi-layered sandwich structures are fabricated with the use of high-power CO2 lasers, friction welding, arc welding, hybrid welding, or other technique designed for the special purpose. Steel or aluminium alloy plates with thickness between 1 and 5 mm are connected by internal stiffeners. Strength...
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Application of Barkhausen method to determine internal stresses in cold-rolled and hot-rolled sheets
PublicationThe paper presents investigations on internal stress distribution in plane hot—or cold-rolled sheets dedicated for the cold-formed profiles. The motivation of the research is a new profile design whose bending technology, incorporating a longitudinal welded joint and hot-dip galvanization after bending and welding introduces additional internal stresses. In order to identify the entirety of stresses in the process of sheet production...
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Effects of CO2 and Nd:YAG Laser Remelting of the Ti6Al4V Alloy on the Surface Quality and Residual Stresses
PublicationThe titanium alloys are materials susceptible to tribological wear and the laser treatment can be applied in surface treatment processes to obtain for example higher hardness level. From the other side, it is important to take into consideration, that hardness increase that can be connected with cracks . The aim of this research was to investigate the effects of different lasers and the process parameters on the form and level...
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The Influence of Impact Velocity on Stresses and Failure of S355j2 Steel Under Slurry Erosion Conditions
PublicationThe purpose of this work was to determine the essence of the influence of the impact velocity (5, 7, and 9 m/s) on Hertzian stresses and the erosion mechanism of ferritic-pearlitic S355J2 steel. The investigations were carried out using a slurry pot tester. S355J2 steel showed a strong sensitivity to changes in impact velocity. A significant increase in erosion rate was observed at a velocity of 9 m/s. This increase was 5-fold...
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Influence of Surface Laser Treatment on Mechanical Properties and Residual Stresses of Titanium and its Alloys
PublicationSurface modification of the titanium and its alloys used in implantology with a long-pulse laser can change the surface topography, but it also leads to changes in the stress sign and magnitude in the resulting subsurface layer. The presented research was aimed at evaluating the state of stress after laser remelting with the Nd:YAG laser of pre-etched titanium alloys Ti6Al4V and Ti13Nb13Zr and pure titanium. The obtained surface...
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A new viscoelastic method of calculation of low-temperature thermal stresses in asphalt layers of pavements
PublicationThe paper presents a new method of calculation of thermal stresses in asphalt layers of pavements induced by cooling or heating. The method, developed by the author, is based on the analytical solution for the linear viscoelastic Burgers model extended numerically for the case of asphalt layers whose rheological parameters are strongly dependent on temperature. The coefficient of thermal expansion and Poisson’s ratio may optionally...
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Examination of selected failure criteria with asymmetric shear stresses in the collapse analysis of laminated shells
PublicationThe 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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The Influence of Impact Velocity on Stresses and Failure of S355j2 Steel Under Slurry Erosion Conditions
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Numerical calculations of wall pressures and stresses in steel cylindrical silos with concentric and eccentric hoppers
PublicationArtykuł przedstawia numeryczną analize naprężeń w płaszczu silosa. Porównane zostały wyniki dla silosów o przepływie centrycznym i mimośrodowym.
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Comparison of anti-plane surface waves in strain-gradient materials and materials with surface stresses
PublicationHere we discuss the similarities and differences in anti-plane surface wave propagation in an elastic half-space within the framework of the theories of Gurtin–Murdoch surface elasticity and Toupin–Mindlin strain-gradient elasticity. The qualitative behaviour of the dispersion curves and the decay of the obtained solutions are quite similar. On the other hand, we show that the solutions relating to the surface elasticity model...
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The effect of external load on ultrasonic wave attenuation in steel bars under bending stresses
PublicationThe stress state in deformed solids has a significant impact on the attenuation of an ultrasonic wave propagating through the medium. Measuring a signal with certain attenuation characteristics can therefore provide useful diagnostic information about the stress state in the structure. In this work, basic principles behind a novel attenuation-based diagnostic framework are introduced. An experimental study on steel bars under three-point...
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JOURNAL OF THERMAL STRESSES
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Analysis of Residual Stresses and Dislocation Density of AA6082 Butt Welds Produced by Friction Sir Welding
PublicationThe Friction Stir Welding (FSW) method was employed to join AA6082 sheets. The welds were produced with different tool traverse speed (200 and 250 mm/min), rotational speed (1000 and 1250 RPM) and tool tilt angle (0 and 2 deg). Based on the analysis of XRD patterns, the total precipitation volume fractions in the nugget zones and the base material were calculated. The FSW process resulted in a reduction in the fraction of precipitates...
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Modeling of the Two-Dimensional Flow Caused by Sea Conditions and Wind Stresses on the Example of Dead Vistula
PublicationThe article presents the results of two-dimensional modeling of flows caused by the sea conditions and wind stresses on the example of Dead Vistula. Based on the available bathymetric data, a numerical model of the river section was created, which was supplemented with data on the position of the water table depending on hydrometeorological conditions. To describe the flow field in steady conditions, a simplified model of two-dimensional...
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Application of the Finite Element Method for Modelling of the Spatial Distribution of Residual Stresses in Hybrid Surface Layers
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Dynamic electrochemical impedance spectroscopy measurements of passive layer cracking under static tensile stresses
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Residual stresses distribution in long seam-welded offshore catenary riser of high-manganese steel
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Dynamic elektrochemical impedance spectroscopy measurements of passive layer cracking under static tensile stresses.
PublicationDynamiczna elektrochemiczna spektroskopia impedancyjna umożliwia badanie podatności i odporności korozyjnej różnych materiałów konstrukcyjnych, a w szczególności określenie właściwości elektrochemicznych warstw pasywnych występujących na ich powierzchni. W wielu przypadkach pęknięcie warstwy pasywnej pod wpływem działania naprężeń rozciągających prowadzi do korozji naprężeniowej. Z tego względu badania pękania warstw pasywnych...
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Dynamic electrochemical impedance spectroscopy measurements of passive layer cracking under static tensile stresses.
PublicationDynamiczna Elektrochemiczna Spektroskopia Impedancyjna umożliwia badanie podatności i odporności korozyjnej różnych materiałów konstrukcyjnych, a w szczególności określenie właściwości elektrochemicznych warstw pasywnych występujących na ich powierzchni. W wielu przypadkach pęknięcie warstwy pasywnej pod wpływem działania naprężeń rozciągających prowadzi do korozji naprężeniowej. Z tego względu badania pękania warstw pasywnych...
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Potential and strain rate impact on the electrochemical properties of 304L stainless steel under tensile stresses.
PublicationPraca skupia się na badaniach aspektu elektrochemicznego i mechanicznego pękania warstwy pasywnej obecnej na stali 304L. Przedstawione zostały wyniki chwilowych zmian impedancji oraz zmiany parametrów elektrochemicznych warstwy pasywnej podczas testów rozciągania przy różnych poziomach polaryzacji anodowej oraz szybkości rozciągania. Na ich podstawie można stwierdzić, że zarówno czynnik elektrochemiczny, jak i mechaniczny wpływają...
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The determination of deformations and stresses of laser welds used for fatigue assessment of steel sandwich panel joints
PublicationPanele typu sandwich znajdują szerokie zastosowanie w wielu gałęziach przemysłu. W przypadku niektórych zastosowań wymagających ocenę ryzyka dużą rolę odgrywa ocena trwałości zmęczeniowej spoin laserowych paneli. W pracy prezentowane są metody wyznaczania lokalnych odkształceń i naprężeń w połączeniach spawanych w celu oceny trwałości zmęczeniowej według hipotez lokalnych naprężeń i odkształceń.
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The Impact of Thermal Stresses on Volume Resistivity: Performance Comparison between TR-XLPE and XLPE Cables
PublicationMost failures in electric power cables are attributed to the development of water trees inside the insulating materials. Thus, the development and utilization of Tree Retardant Cross-Linked Polyethylene (TR-XLPE) based cables have recently been given great attention to overcome the treeing issues. TR-XLPE cables use low-density polyethylene compounds suppressing the formation of water trees while retaining excellent electrical,...
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Experiments and Numerical Simulations of the Annealing Temperature Influence on the Residual Stresses Level in S700MC Steel Welded Elements
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Transcriptome Dynamics Underlying Planticine®-Induced Defense Responses of Tomato (Solanum lycopersicum L.) to Biotic Stresses
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SHEAR YIELD STRESSES AND FRACTURE TOUGHNESS OF SCOTS PINE (PINUS SYLVESTRIS L.) ACCORDING TO THE RAW MATERIAL PROVENANCE
PublicationIn this paper values of the fracture toughness and of shear yield stress in the shear zone of Scots pine are presented. Tests of cutting were carried on samples of Scotch pine (Pinus sylvestris L.) wood of five provenances from Poland. These experimentally cutting tests were carried on the sash gang saw PRW-15M and the values of cutting power were obtained. The values of fracture toughness and shear yield stress based on Atkins’s...
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Assessment of Thermal Stresses in Asphalt Mixtures at Low Temperatures Using the Tensile Creep Test and the Bending Beam Creep Test
PublicationThermal stresses are leading factors that influence low-temperature cracking behavior of asphalt pavements. During winter, when the temperature drops to significantly low values, tensile thermal stresses develop as a result of pavement contraction. Creep test methods can be suitable for the assessment of low-temperature properties of asphalt mixtures. To evaluate the influence of creep test methods on the obtained low-temperature...
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Wire Arc Additive Manufactured Mild Steel and Austenitic Stainless Steel Components: Microstructure, Mechanical Properties and Residual Stresses
PublicationWire arc additive manufacturing (WAAM) is an additive manufacturing process based on the arc welding process in which wire is melted by an electric arc and deposited layer by layer. Due to the cost and rate benefits over powder-based additive manufacturing technologies and other alternative heat sources such as laser and electron beams, the process is currently receiving much attention in the industrial production sector. The gas...
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INFLUENCE OF SINGLE-STAGE AND DUPLEX SHOT PEENING ON SURFACE ROUGHNESS AND RESIDUAL STRESSES IN Al Mg5 Mn1 Sc0,8 Zr0,4 ALLOY
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