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The Motion Analysis of Attacus Atlas Rigid Wing
PublikacjaThe remarkable aerodynamic efficiency of flapping insect wings has fascinated researchers for many years. Butterfly wings are distinguished by a much larger lifting surface, and thus, a different style of flapping flight. The considerations described in the article are an introduction to a fully flexible analysis of the wing in motion. The study of the rigid wing gives the basic knowledge necessary in the further process. The yaw,...
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The Design Development of the Sliding Table Saw Towards Improving Its Dynamic Properties
PublikacjaCutting wood with circular saws is a popular machining operation in the woodworking and furniture industries. In the latter sliding table saws (panel saws) are commonly used for cutting of medium density fiberboards (MDF), high density fiberboards (HDF), laminate veneer lumber (LVL), plywood and chipboards of different structures. The most demanded requirements for machine tools are accuracy and precision, which mainly depend on...
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NEW DESIGNS OF MAGNETIC FLUID SEALS FOR RECIPROCATING MOTION
PublikacjaT he operating conditions of magnetic fluid seals during reciprocating motion are so different from those observed in rotating motion that the use of their conventional structures for reciprocating motion seals yields no good results. The analysis of the sealing mechanism of magnetic fluid seals in reciprocating motion shows that the operation of these seals is affected by the carry-over phenomenon and magnetic fluid...
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Additive Manufacturing as a Solution to Challenges Associated with Heat Pipe Production
PublikacjaThe aim of this review is to present the recent developments in heat pipe production, which respond to the current technical problems related to the wide implementation of this technology. A novel approach in HP manufacturing is to utilise hi-tech additive manufacturing techniques where the most complicated geometries are fabricated layer-by-layer directly from a digital file. This technology might be a solution to various challenges...
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A general isogeometric finite element formulation for rotation‐free shells with in‐plane bending of embedded fibers
PublikacjaThis article presents a general, nonlinear isogeometric finite element formulation for rotation-free shells with embedded fibers that captures anisotropy in stretching, shearing, twisting, and bending - both in-plane and out-of-plane. These capabilities allow for the simulation of large sheets of heterogeneous and fibrous materials either with or without matrix, such as textiles, composites, and pantographic structures. The work...
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Hybrid Finite Element Method Development for Offshore Structures’ Calculation with the Implementation of Industry Standards
PublikacjaIn the design process of offshore steel structures, it is typical to employ commercial calculation codes in which simulationand evaluation of results are performed on the basis of the available standards (e.g. API, DNV, Lloyds). The modelingand solution rely on finite element methods and cover the simulation of the structure’s properties along with the influenceof the marine environment – sea currents, wave...
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The methodology of design of axial clearances compensation unit in hydraulic satellite displacement machine and their experimental verification
PublikacjaA new methodology of calculating the dimensions of the axial clearance compensation unit in the hydraulic satellite displacement machine is described in this paper. The methods of shaping the compensation unit were also proposed and described. These methods were used to calculate the geometrical dimensions of the compensation field in an innovative prototype of a satellite hydraulic motor. This motor is characterized by the fact...
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On local buckling of cold-formed channel members
PublikacjaThe paper deals with local buckling of the compressed flanges of cold-formed thin-walled channel beams subjected to pure bending or axially compressed columns. Arbitrarily shaped flanges of open cross-sections and the web-flange interactions are taken into account. Buckling deformation of a beam flange is described by displacement related to torsion of the flange about the line of its connection with the web. Total potential energy...
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NUMERICAL SIMULATIONS OF HONING PROCESS OF THIN WALL CYLINDER LINERS, WITH CONSTANT AND WITH VARIABLE THICKNESS OF WALL OF HONED PARTS
PublikacjaNumerical simulations of honing process of thin-wall cylinder liners, with constant and with variable thickness of the wall of honed workpieces can improve and can help to conduct the experimental research of honing process and can improve the honing process. A very valuable research assumption, before performing the numerical analysis of computer simulation of honing process, is the measurement of the real geometry of the honing...
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Effect of surface on the flexomagnetic response of ferroic composite nanostructures; nonlinear bending analysis
PublikacjaOur analysis incorporates the geometrically nonlinear bending of the Euler-Bernoulli ferromagnetic nanobeam accounting for a size-dependent model through assuming surface effects. In the framework of the flexomagnetic phenomenon, the large deflections are investigated referring to von-Kármán nonlinearity. Employing the nonlocal effects of stress coupled to the gradient of strain generates a scale-dependent Hookean stress-strain...
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Analiza temperatury ekwiwalentnej do projektowania nawierzchni asfaltowych w Polsce z wykorzystaniem metody AASHTO 2004
PublikacjaW artykule przedstawiono analizę temperatury ekwiwalentnej obliczanej w oparciu o kryterium spękań zmęczeniowych warstw asfaltowych z metody AASHTO 2004 oraz kryterium deformacji strukturalnych Instytutu Asfaltowego. Do obliczeń przyjęto konstrukcję nawierzchni KR5 oraz wykorzystano dane temperaturowe z 50 stacji meteorologicznych z okresu 30 lat od roku 1989 do roku 2019 włącznie udostępnione przez Instytut Meteorologii i Gospodarki...
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The significance of the underground experience: Selection of reference design cases from the underground public transport stations and interchanges of the European Union
PublikacjaAbstract Background Recent research into the way public transport users appreciate stations and interchanges has highlighted several key aspects. Importantly, the optimization of these facilities should not simply aim to resolve dissatisfiers, but should also focus on addressing satisfiers, through the incorporation of factors such as comfort and experience. ‘Soft requirements,’ which have emerged in architecture and urban design,...
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Mechanical analysis of eccentric defected bilayer graphene sheets considering the van der Waals force
PublikacjaIn this article, we have tried to simulate nonlinear bending analysis of a double-layered graphene sheet which contains a geometrical imperfection based on an eccentric hole. The first-order shear deformation theory is considered to obtain the governing equations. Also, the nonlinear von Kármán strain field has been assumed in order to obtain large deformations. Whereas the double-layered graphene sheet has been considered, the...
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Mechanical Behavior of Bi-Layer and Dispersion Coatings Composed of Several Nanostructures on Ti13Nb13Zr Alloy
PublikacjaTitanium implants are commonly used because of several advantages, but their surface modification is necessary to enhance bioactivity. Recently, their surface coatings were developed to induce local antibacterial properties. The aim of this research was to investigate and compare me-chanical properties of three coatings: multi-wall carbon nanotubes (MWCNTs), bi-layer composed of an inner MWCNTs layer and an outer TiO2 layer, and...
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Investigation of the 0.4C-35Cr-45Ni-Nb Alloy after Service in High-Temperature Steam and Hydrocarbons Environment
PublikacjaThe paper presents the results of investigation of the 0.4C-35Cr-45Ni-Nb alloy, which operated in the cracked hydrocarbon feeds and dilution steam at 1125 C. The material originated from the pyrolytic furnace coil tubes, of which internal walls were in contact with the aforementioned medium, whereas the external walls were in contact with the flue gases. The examination included metallographic and mechanical tests on the material...
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Assessment of FSW Welds Made of Aluminum Alloy AW7075-T651.
PublikacjaThis paper summarizes the results of experimental studies in which the aluminum alloy AW7075-T651 was friction stir welded (FSW) using various combinations of process parameters (rotational - R and travel speed - T). Mechanical properties of the test welds were assessed by using static tensile test and Vickers hardness measurement. The temperature of the welded plates was monitored during welding by means of thermocouples placed...
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Experimental study on polymer mass used to repair damaged structures
PublikacjaA new method of repairing damaged structures by injecting the cracks with specially designed polymer mass (flexible two-component grout based on polyurethane resin) has been recently proposed. The technique is mainly dedicated to damaged masonries, especially historical structures where minimum intervention is permitted. The cracks are filled with the special injection, forming the flexible joints bonding the disrupted structural...
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Stability analysis of single-walled carbon nanotubes embedded in winkler foundation placed in a thermal environment considering the surface effect using a new refined beam theory
PublikacjaThis article is devoted to investigate the stability of different types of Single Walled Carbon Nanotubes (SWCNTs) such as zigzag, chiral, and armchair types which are rested in Winkler elastic foundations exposing to both the low and high temperature environments. Also, the Surface effects which include surface energy and surface residual stresses, are taken into consideration in this study. It may be noted that the surface energy...
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Influence of the air phase on water flow in dikes
PublikacjaNumerical models are often used to describe flow and deformation processes occurring in dikes during flood events. Modeling of such phenomena is a challenging task, due to the complexity of the system, consisting of three material phases: soil skeleton, pore water and pore air. Additional difficulties are transient loading caused by variable in time water levels, heterogeneity of the soil or air...
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Influence of service ageing on polyester-reinforced polyvinyl chloride-coated fabrics reported through mathematical material models
PublikacjaIn this paper the coupled service (constructional tension) and environmental (sunlight, rainfalls, temperature variations) ageing influence on the polyester-reinforced polyvinyl chloride (PVC)-coated fabric VALMEX is studied. Two cases of the same fabric have been analyzed: one USED for 20 years on the real construction of the Forest Opera in Sopot (Poland), and one kept as a spare material (NOT USED). The following tests have...
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FEM analysis of composite materials failure in nonlinear six field shell theory
PublikacjaThe monography deals with the problem of failure initiation in thin laminated composites. Known techniques of laminate structures modelling are briefly characterised. Eventually, shell based approach is chosen for the purpose of the description of the composite structures behaviour, as it predicts their deformation and states of stress effectively in a global sense. The nonlinear six parameter shell theory (6p theory) with asymmetric...
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Mechanical and fracture properties of concrete reinforced with recycled and industrial steel fibers using Digital Image Correlation technique and X-ray micro computed tomography
PublikacjaPaper presents investigation of fracture phenomenon in plain concrete and in concrete reinforced with both recycled steel fibers (RSF) and industrial steel fibers (ISF). The wedge splitting test (WST), which enables stable crack propagation for quasi-brittle materials, was carried out on 75 75 75 mm cube samples. Initially, fracture process zone development was investigated only on the surface of samples using Digital Image Correlation...
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Estimation of Failure Initiation in Laminated Composites by means of Nonlinear Six-Field Shell Theory and FEM
PublikacjaThe monography deals with the problem of failure initiation in thin laminated composites. Known techniques of laminate structures modelling are briefly characterised. Eventually, shell based approach is chosen for the purpose of the description of the composite structures behaviour, as it predicts their deformation and states of stress effectively in a global sense. The nonlinear six parameter shell theory (6p theory) with asymmetric...
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Thermal buckling of functionally graded piezomagnetic micro- and nanobeams presenting the flexomagnetic effect
PublikacjaGalerkin weighted residual method (GWRM) is applied and implemented to address the axial stability and bifurcation point of a functionally graded piezomagnetic structure containing flexomagneticity in a thermal environment. The continuum specimen involves an exponential mass distributed in a heterogeneous media with a constant square cross section. The physical neutral plane is investigated to postulate functionally graded material...
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Self-organising maps in the analysis of strains of human abdominal wall to identify areas of similar mechanical behaviour.
PublikacjaThe study refers to the application of a type of artificial neural network called the Self-Organising Map (SOM) for the identification of areas of the human abdominal wall that behave in a similar mechanical way. The research is based on data acquired during in vivo tests using the digital image correlation technique (DIC). The mechanical behaviour of the human abdominal wall is analysed during changing intra-abdominal pressure....
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Effect of rPET Content and Preform Heating/Cooling Conditions in the Stretch Blow Molding Process on Microcavitation and Solid-State Post-Condensation of vPET-rPET Blend: Part I—Research Methodology and Results
PublikacjaPolyethylene terephthalate (PET) is widely used in bottle production due to its costeffectiveness and low environmental impact. The first part of this article describes the research and statistical analysis methodology of the influence of the virgin PET (vPET) and recycled PET (rPET) content in the vPET-rPET blend, as well as the preform heating/cooling conditions in the stretch blow molding (SBM) process on the microscopic bottle...
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Experimental observations on the creep behaviour of frozen soil
PublikacjaConstitutive models in the literature for creep of frozen soil are based on the direct use of time counted from the onset of creep. An explicit time dependence in a constitutive equation violates the principles of rational mechanics. No change in stress or temperature is allowed for during creep, using the time-based formulations. Moreover, the existing descriptions need much verification and improvement on the experimental side...
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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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Experimental Evaluation of ND: YAG Laser Parameters and Sample Preparation Methods for Texturing Thin AISI 316L Steel Samples
PublikacjaIn mechanical and material engineering, the effect of laser texturing depends on many factors besides device specification, primarily the properties of the materials being processed, and, secondly, the preparation of the sample. Laser texturing of thin (<5 mm) samples is mostly performed utilizing short-pulse lasers, but depending on the power of the laser beam, the process can also be performed by using continuous operation lasers....
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Deformable model of a butterfly in motion on the example of Attacus atlas
PublikacjaInsect wings can undergo significant chordwise (camber) as well as spanwise (twist) deformation during flapping flight but the effect of these deformations is not well understood. The shape and size of butterfly wings leads to particularly large wing deformations, making them an ideal test case for investigation of these effects. High-speed videogrammetry was used to capture the wing kinematics and deformations. The movements of...
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On the non-linear dynamics of torus-shaped and cylindrical shell structures
PublikacjaIn 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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Mechanical simulation of artificial gravity in torus-shaped and cylindrical spacecraft
PublikacjaLarge deformations and stress analyses in two types of space structures that are intended for people to live in space have been studied in this research. The structure under analysis is assumed to rotate around the central axis to create artificial gravitational acceleration equal to the gravity on the Earth's surface. The analysis is fully dynamic, which is formulated based on the energy method by using the first-order shear deformation...
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Non-Destructive Testing of the Longest Span Soil-Steel Bridge in Europe—Field Measurements and FEM Calculations
PublikacjaThe article describes interdisciplinary and comprehensive non-destructive diagnostic tests of final bridge inspection and acceptance proposed for a soil-steel bridge made of corrugated sheets, being the European span length record holder (25.74 m). As an effect of an original concept a detailed and precise information about the structure short-term response was collected. Periodic diagnostics of bridge deformations was done one...
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DETERMINATION OF THE AERODYNAMIC DRAG OF PNEUMATIC LIFE RAFTS AS A FACTOR FOR INCREASING THE RELIABILITY OF RESCUE OPERATIONS
PublikacjaEnsuring the safety of ship crews at sea is of the utmost importance. Life rafts are one of the basic components of any seagoing vessel and ensuring their stability is an important component of maritime research. This study concerns the determination of the aerodynamic drag coefficients of pneumatic life rafts in a full range of wind speed and directions. The drag coefficients are based on full-scale experimental studies and numerical...
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A chemo-mechano-thermodynamical contact theory for adhesion, friction, and (de)bonding reactions
PublikacjaThis work presents a self-contained continuum formulation for coupled chemical, mechanical, and thermal contact interactions. The formulation is very general and, hence, admits arbitrary geometry, deformation, and material behavior. All model equations are derived rigorously from the balance laws of mass, momentum, energy, and entropy in the framework of irreversible thermodynamics, thus exposing all the coupling present in the...
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Accuracy improvement of the prestressed concrete structures precise geometry assessment by use of bubble micro-sampling algorithm
PublikacjaPrestressed concrete structures are well-known technology for a vast period, but nevertheless, this very technology is a leading solution, currently used in construction industry. Prestressed concrete structures have a huge advantage over conventional methods because it uses the properties of concrete in a very efficient way. The main idea behind this technology is to introduce into the cross-section of the structure, the internal...
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Performance Characteristics of a Micro-Turbine
PublikacjaIn the paper a design of a multi-stage micro-turbine with partial admission of all the stages is described in detail and the results of particular experimental investigations and numerical calculations are shown, followed by conclusions. The co-generative micro-power plant with the HFE7100 as a working medium was designed and built for experimental investigations. The values of the main cycle parameters were as follows:heat output:...
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Performance Characteristics of a Micro-turbine, International
Publikacja. In the paper a design of a multi-stage micro-turbine with partial admission of all the stages is described in detail and the results of particular experimental investigations and numerical calculations are shown, followed by conclusions. The co-generative micro-power plant with the HFE7100 as a working medium was designed and built for experimental investigations. The values of the main cycle parameters were as follows:- heat...
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Mechanical Performance and Environmental Assessment of Sustainable Concrete Reinforced with Recycled End-of-Life Tyre Fibres
PublikacjaThe presented research’s main objective was to develop the solution to the global problem of using steel waste obtained during rubber recovery during the tire recycling. A detailed comparative analysis of mechanical and physical features of the concrete composite with the addition of recycled steel fibres (RSF) in relation to the steel fibre concrete commonly used for industrial floors was conducted. A study was carried out using...
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Characteristics of silver-dopped carbon nanotube coating destined for medical applications
PublikacjaCarbon nanotubes are materials demonstrating outstanding mechanical, chemical, and physical properties and are considered coatings of titanium implants. The present research is aimed to characterize the microstructure and properties of the multi-wall carbon nanotubes (MWCNTs) layer decorated with silver nanoparticles (Ag NPs) on the Ti13Nb13Zr alloy destined for long-term implants. The electrophoretic deposition of coatings...
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Dynamic modeling of non-cylindrical curved viscoelastic single-walled carbon nanotubes based on the second gradient theory
PublikacjaThis paper is devoted to the theoretical study of the dynamic response of non-cylindrical curved viscoelastic single-walled carbon nanotubes (SWCNTs). The curved nanotubes are largely used in many engineering applications, but it is challenging in understanding mechanically the dynamic response of these curved SWCNTs when considering the influences of the material viscosity. The viscoelastic damping effect on the dynamic response...
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Bending Moment Control and Weight Optimization in Space Structures by Adding Extra Members in the Optimal Locations
PublikacjaThis paper investigates the reduction of bending moment in critical members by adding some extra members in the optimum location. Instead of enlarging the size of members to resist the moment, eight additional members are added in the optimum location to reduce the bending moment in the critical members. The total weight of the proposed structure with extra members is less than that of the original structure that resists the induced...
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The effect of shear deformations' rotary inertia on the vibrating response of multi-physic composite beam-like actuators
PublikacjaIn consecutive studies on flexomagneticity (FM), this work investigates the flexomagnetic reaction of a vibrating squared multi-physic beam in finite dimensions. It is assumed that the bending and shear deformations cause rotary inertia. In the standard type of the Timoshenko beam the rotary inertia originated from shear deformations has been typically omitted. It means the rotary inertia resulting from shear deformation is a new...
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Experimental investigation of joint with positive eccentricity in CFS truss
PublikacjaDue to technological restrictions, in the case of trusses made of CFS open cross-sections, positive eccentricities in the truss joints have become very frequent. Therefore studies concerning the load-bearing capacity of truss joints with positive eccentricity were undertaken. It was assumed that the resistance of cold-formed steel (CFS) open cross-section truss joints located on compression chords and with positive eccentricity...
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Cavity-expansion approximation for projectile impact and penetration into sand
PublikacjaA one-dimensional problem of a spherical cavity expanding at a constant velocity from zero initial radius in an infinite granular medium, which has the first-kind self-similar solution, is considered. We are solving this dynamic spherical cavity-expansion problem to model rigid spheres penetrating into a granular media. Elastic–plastic deformation of the granular media is described in a barotropic approximation, using the high-pressure...
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The FEM analysis of pressure installation elements after simulated accidental overheating
PublikacjaThe paper presents innovative analysis focused on the safety aspects of existing pressure installation operation after overheating accidents. Results presented here can be applied in decision-making process concerning further operation of existing pressure installation after cooling system failure. In this paper the results of FEM analysis performed for a straight pipe and 90 degrees elbow, made of super duplex stainless steel,...
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On nonlinear dilatational strain gradient elasticity
PublikacjaWe call nonlinear dilatational strain gradient elasticity the theory in which the specific class of dilatational second gradient continua is considered: those whose deformation energy depends, in an objective way, on the gradient of placement and on the gradient of the determinant of the gradient of placement. It is an interesting particular case of complete Toupin–Mindlin nonlinear strain gradient elasticity: indeed, in it, the...
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Non-linear static stability of bi-layer carbon nanosheets resting on an elastic matrix under various types of in-plane shearing loads in thermo-elasticity using nonlocal continuum
PublikacjaIn this research, the shear and thermal buckling of bi-layer rectangular orthotropic carbon nanosheets embedded on an elastic matrix using the nonlocal elasticity theory and non-linear strains of Von-Karman was studied. The bi-layer carbon sheets were modeled as a double-layered plate, and van der Waals forces between layers were considered. The governing equations and boundary conditions were obtained using the first order shear...
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Machine learning-based prediction of residual drift and seismic risk assessment of steel moment-resisting frames considering soil-structure interaction
PublikacjaNowadays, due to improvements in seismic codes and computational devices, retrofitting buildings is an important topic, in which, permanent deformation of buildings, known as Residual Interstory Drift Ratio (RIDR), plays a crucial role. To provide an accurate yet reliable prediction model, 32 improved Machine Learning (ML) algorithms were considered using the Python software to investigate the best method for estimating Maximum...
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Właściwości niskotemperaturowe betonów asfaltowych o wysokim module sztywności (AC-WMS) w badaniach trzypunktowego zginania
PublikacjaArtykuł przedstawia właściwości niskotemperaturowe betonów asfaltowych o wysokim module sztywności. Przedstawione wyniki zostały uzyskane w dwóch badaniach zginania trzypunktowego próbek belkowych: ze stałą prędkością przemieszczenia oraz pod stałym obciążeniem. Obie te metody są od dawna stosowane na Politechnice Gdańskiej do oceny właściwości niskotemperaturowych betonów asfaltowych. Badaniu poddano pięć betonów asfaltowych –...