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Wyniki wyszukiwania dla: mechanics of materials
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Models of Structures in Didactics
PublikacjaThe final aim of teaching students subjects, such as structural mechanics, reinforced concrete, and steel structures is to teach them how structures work in a given building as well as to provide them with skills enabling them to calculate and design structures. The behavioral model of the structure, contrary to the architectural model, which focuses mainly on the external form of the building, shows workings from both the static...
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Quantum Steering Inequality with Tolerance for Measurement-Setting Errors: Experimentally Feasible Signature of Unbounded Violation
Publikacjauantum steering is a relatively simple test for proving that the values of quantum-mechanical measurement outcomes come into being only in the act of measurement. By exploiting quantum correlations, Alice can influence — steer — Bob ’ s physical system in a way that is impossible in classical mechanics, as shown by the violation of steering inequalities. Demonstrating this and similar quantum effects for systems of increasing size,...
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Local hidden–variable models for entangled quantum states
PublikacjaWhile entanglement and violation of Bell inequalities were initially thought to be equivalent quantum phenomena, we now have different examples of entangled states whose correlations can be described by local hidden-variable models and, therefore, do not violate any of the Bell inequalities. We provide an up-to-date overview of the existing literature regarding local hidden-variable models for entangled quantum states, in both...
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Wavepacket of the Universe and its Spreading
PublikacjaWavepackets in quantum mechanics spread and the Universe in cosmology expands. We discuss a formalism where the two effects can be unified. The basic assumption is that the Universe is determined by a unitarily evolving wavepacket defined on space-time. Space-time is static but the Universe is dynamic. Spreading analogous to expansion known from observational cosmology is obtained if one regards time evolution as a dynamical process...
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Identification of the mechanical properties of the skin by electromechanical impedance analysis of resonant piezoelectric actuator
PublikacjaThis paper is devoted to the analysis and verification of developed piezoelectric sensor/actuator for measuring the mechanical properties of soft tissues, especially human skin. The key element of the measurement structure is an electromechanical system that uses both the reverse piezoelectric effect (vibration generation – stimulation of the tissues in the appropriate frequency range) and direct piezoelectric effect (system response...
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Steering is an essential feature of non-locality in quantum theory
PublikacjaA physical theory is called non-local when observers can produce instantaneous effects over distant systems. Non-local theories rely on two fundamental effects: local uncertainty relations and steering of physical states at a distance. In quantum mechanics, the former one dominates the other in a well-known class of non-local games known as XOR games. In particular, optimal quantum strategies for XOR games are completely determined...
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Constitutive Modelling of Knitted Abdominal Implants in Numerical Simulations of Repaired Hernia Mechanics
PublikacjaThe paper presents a numerical approach to describe mechanical behavior of anisotropic textile material, which is a selected abdominal prosthesis. Two constitutive nonlinear concepts are compared. In the first one the material is considered composed from two families of threads (dense net model) and in the second one the material is homogeneous but anisotropic (as proposed by Gassel, Ogden, Holzapfel). Parameters of both models...
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A concept for reducing PM 10 emissions for car brakes by 50%
PublikacjaWith regard to airborne particles with an aerodynamic diameter of less than 10 μm (PM10), in countries in the European Union, the mass of brake emissions equals approximately 8–27% of the total traffic-related emissions. Using a research methodology combining tests at different scale levels with contact mechanics simulations and PM10 chemical characterization, the REBRAKE EU-financed project had the following aims: i) to demonstrate...
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Structure of the Resource Theory of Quantum Coherence
PublikacjaQuantum coherence is an essential feature of quantum mechanics which is responsible for the departure between the classical and quantum world. The recently established resource theory of quantum coherence studies possible quantum technological applications of quantum coherence, and limitations that arise if one is lacking the ability to establish superpositions. An important open problem in this context is a simple characterization...
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On Accuracy Modeling of Gas Turbine Cycles by the In-house COM-GAS Code
PublikacjaIn this paper, a comparison of accuracy modeling of gas turbine cycles between the basic (classical) model and the in-house COM-GAS code has been presented. The basic model uses a semi-perfect gas and well known projecting assumption. On the other hand, the computational flow mechanics (CFM) basis on a real gas by using thermodynamic tables. The thermodynamic analysis of thermal cycles, simply gas cycle GT8C and gas turbine cycle...
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Experimental and theoretical study on high-temperature creep of VT6 titanium alloy under multi-axial loading conditions
PublikacjaIn the framework of damage mechanics, we discuss a new mathematical model that describes the kinetics of the stress–strain state and damage accumulation during material degradation by the mechanism of long-term strength under complex multiaxial stress state. An experimental and theoretical technique is proposed for determination of material parameters and scalar constitutive functions for damaged media based on specially set experiments...
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Drop-coating deposition surface-enhanced Raman spectroscopy on silver substrates for biofluid analysis
PublikacjaUtilization of surface-enhanced Raman spectroscopy as a measurement technique is of particular interest in biodetection due to its superb chemical specificity and high sensitivity. The use of SERS substrates further improve this method by massive enhancement of the molecule Raman spectrum, permitting very low levels of detection. Therefore it is important to seek for new ways to develop reliable substrates, which are quickly and...
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Application of Fracture Mechanics for Energetic Effects Predictions While Wood Sawing
PublikacjaIn the classical approach, energetic effects (cutting forces and cutting power) of wood sawing process are generally calculated on the basis of the specific cutting resistance, which is in the case of wood cutting the function of more or less important factors. On the other hand, cutting forces (or power - more interesting from energetic point of view) could be considered from a point of view of modern fracture mechanics. Cutting...
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Towards Understanding of Mechanics of Hernia Managed by Synthetic Mesh in Laparoscopic Operation: A Single Case Study
PublikacjaIn this paper a research towards understanding of mechanics of ventral hernia operated with the use of Physiomesh Open image in new window implant and SecureStrap Open image in new window staples is described. Experimental and numerical studies are conducted for that purpose. Experimental works cover uni-axial tension tests of the implant samples and of the implant-staples-tissue system. Also experiments on implant-staples-tissue...
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Sawing Processes as a Way of Determining Fracture Toughness and Shear Yield Stresses of Wood
PublikacjaA 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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Modelling of Abdominal Wall Under Uncertainty of Material Properties
PublikacjaThe paper concerns abdominal wall modelling. The accurate prediction and simulation of abdominal wall mechanics are important in the context of optimization of ventral hernia repair. The shell Finite Element model is considered, as the one which can be used in patient-specific approach due to relatively easy geometry generation. However, there are uncertainties in this issue, e.g. related to mechanical properties since the properties...
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A constitutive law for concrete with smooth transition from continuous into discontinuous cracks’ description
PublikacjaPaper presents a constitutive model for concrete that combines a continuous and discontinuous crack’s description to simulate the concrete under tensile dominated loads. In a continuum regime, two different constitutive laws were used. First, a plasticity model with the Rankine failure criterion and an associated flow rule was used. Second, a constitutive law based on isotropic damage mechanics was formulated. Both model alternatives...
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Influence of meniscus shape in the cross sectional plane on the knee contact mechanics
PublikacjaWe present a three dimensional finite element analysis of stress distribution and menisci deformation in the human knee joint. The study is based on the Open Knee model with the geometry of the lateral meniscus which shows some degenerative disorders. The nonlinear analysis of the knee joint under compressive axial load is performed. We present results for intact knee, knee with partial and complete radial posterior meniscus root...
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A design framework and a digital toolset supporting the early-stage explorations of responsive kinetic building skin concepts
PublikacjaIn this paper we present the first phase of our research on the development of a framework for early-stage responsive kinetic building skin design. The aims of this study were: to formulate a methodological and instrumental basis for the construction of the framework, to conduct an initial pre-assessment of its features, and finally to provide the first example of how the framework could be applied in practice. Importantly, at...
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AN ALTERNATIVE WAY OF DETERMINING MECHANICAL PROPERTIES OF WOOD BY MEASURING CUTTING FORCES
PublikacjaThe cutting force is an energetic effect of splitting material, and might be therefore considered from a point of view of modern fracture mechanics. The dedicated mathematical model developed for description of the wood cutting has been developed here on the base of fracture theory, and includes work of separation (fracture toughness) in addition to the material plasticity and friction. The effect of the cutting edge dullness is...
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THE THERMODYNAMIC ANALYSIS OF THE SZEWALSKI HIERARCHIC VAPOUR CYCLE COOPERATED WITH THE SYSTEM OF HEAT RECOVERY
PublikacjaIn this paper, thermodynamic analysis of the Szewalski hierarchic vapour cycle cooperated with the system of heat recovery from exhaust gases are presented. According to that purpose, the CFM (Computation Flow Mechanics [1,3]) approach has correctly been used. The whole system consists of the first traditional steam cycle, the second organic Rankine cycle (ORC) and system of heat recovery with use of water with temperature 90...
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Fracture surface formation of notched 2017A-T4 aluminium alloy under bending fatigue
PublikacjaThe effect of cyclic loading on facture surface topology in notched components made by aluminium alloys is not completely clear. Fractogra-phy and fracture mechanics can help to understand this interdependency. This paper aims to study the distribution of the fracture surface roughness of notched 2017A-T4 aluminium alloy after bending fatigue using an optical focus-variation surface measurement technique by applying the fracture...
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Modelling and FE-simulation of plastic ductile damage evolution in plates and shells
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Effect of a characteristic length on crack spacing in a reinforced concrete bar under tension
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Experimental and numerical studies of guided wave damage detection in bars with structural discontinuities
PublikacjaPraca dotyczy analizy propagacji fal podłużnych i poprzecznych w elementach prętowych z nieciągłościami strukturalnymi. Symulacje numeryczne przeprowadzone przy zastosowaniu metody elementów spektralnych zostały porównane z wynikami badań eksperymentalnych dla pręta w stanie nienaruszonym oraz dla prętów z rysą, spawem oraz dodatkową masą.
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Buckling of frame braced by linear elastic springs
PublikacjaIn the design codes and specifications, simplifed formulae or diagrams are given for determining the buckling lengths of frame columns based on the ruling criterion of considering frames as sway or non sway. Due to the fact that, the code formulae utilize onlylocal stifness distributions, these formulae may yield in certain cases rather erroneous results. In most code formulas a case of weakly braced frames is usually not considered.In...
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Modelling of in-plane wave propagation in a plate using spectral element method and Kane–Mindlin theory with application to damage detection
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Modelling of in-plane wave propagation in a plate using spectral element method and Kane-Mindlin theory with application to damage detection
PublikacjaThis paper presents results of experimental and numerical analyses of in-plane waves propagatingin a 5 mm-thick steel plate in the frequency range of 120-300 kHz. For such a thickness/frequency ratio,extensional waves reveal dispersive character. To model in-plane wave propagation taking into account thethickness-stretch effect, a novel 2D spectral element, based on the Kane-Mindlin theory, was formulated. Anapplication of in-plane...
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Beam on elastic foundation with anticlastic curvature: Application to analysis of mode I fracture tests
PublikacjaA first order correction is proposed taking into account both interface elasticity and transverse anticlastic curvature of flexible substrate(s) in the DCB (and related tests). Adherends are represented by Kirchhoff-Love plates, and the interface by Winkler-type elastic foundation. Two functions are introduced, representing evolution of beam deflection along the sample midline and anticlastic curvature along the plate. A method...
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A new insight into understanding the Crow and Champagne preferred mode: a numerical study
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Buckling Analysis of Cold Formed Silo Column
PublikacjaThe paper is devoted to stability analysis of different models of steel cold formed silo column. The steel cylindrical silos are often composed of corrugated walls and vertical open-sectional columns uniformly placed along the silo circumference. Both the whole 3D silo, a simplified model consisting of one column with a part of the silo walls, and a single column resting on elastic foundation provided by the silo walls were analyzed....
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Nutrient transport and acquisition by diatom chains in a moving fluid
PublikacjaThe role of fluid motion in delivery of nutrients to phytoplankton cells is a fundamental question in biological and chemical oceanography. In the study of mass transfer to phytoplankton, diatoms are of particular interest. They are non-motile, are often the most abundant components in aggregates and often form chains, so they are the ones expected to benefit most from enhancement of nutrient flux due to dissipating turbulence....
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Multistage Coupling of Eight Mistuned Bladed Discs on Solid Shaft with 1% Mistuning
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3D Buckling Analysis of a Truss with Horizontal Braces
PublikacjaThe present research is devoted to the study of out–of–plane buckling of a truss with horizontal braces. The truss is a model of real roof truss scaled by factor 1=4. A linear buckling and a non–linear analysis with geometric and material non–linearity were carried out. The truss buckling and limit load for different stiffnesses and number of braces are found. Numerical analysis are verified by experiment. Threshold bracing stiffness condition...
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Elastoplastic law of Cosserat type in shell theory with drilling rotation
PublikacjaWithin the framework of six-parameter non-linear shell theory, with strain measures of the Cosserat type, we develop small-strain J2-type elastoplastic constitutive relations. The relations are obtained from the Cosserat plane stress relations assumed in each shell layer, by through-the-thickness integration employing the first-order shear theory. The formulation allows for unlimited translations and rotations. The constitutive...
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Doświadczalne badania wytrzymałości zmęczeniowej stopów łożyskowych
PublikacjaW pracy przedstawiono wyniki badań nad wytrzymałością zmęczeniową warstw ślizgowych wykonanych z wybranych materiałów stosowanych w cienkościennych panwiach łożyskowych współczesnych maszyn. Badania przeprowadzono za pomocą urządzeń badawczych skonstruowanych i zbudowanych w Politechnice Gdańskiej. Przedstawiono zaobserwowane pęknięcia zmęczeniowe badanych próbek oraz oszacowano odpowiadające im krytyczne wartości naprężeń w warstwach...
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Procedura kontrolowanego wywrócenia żurawia stoczniowego
PublikacjaPrzedstawiono procedurę złomowania żurawia stoczniowego, wyposażeniowego. Procedurę tę przeprowadzono w przypadku żurawia uszkodzonego w wyniku katastrofy suwnicy bramowej. Może być również stosowana w przypadkach planowego złomowania wielkich dźwignic.
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Experimental Validation of Numerical Model within a Flow Configuration of the Model Kaplan Turbine
PublikacjaThis paper investigates validation of flow within a model Kaplan turbine. This includes comparison of various turbulence models and their influence on torque and power generated by the turbine. Numerical results were compared with experimental data.
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The experimental and numerical investigation of fracture behaviour in PMMA notched specimens under biaxial loading conditions – Tension with torsion
PublikacjaThis paper presents the results of experimental fracture test of flat PMMA specimens under biaxial loading condition tension with torsion (proportional). The specimens were made in two thicknesses: 5 and 15 mm and were weakened with V-type edge notches with different root radii: 0.5; 2 and 10 mm. Thanks to the ARAMIS 3D 4 M non-contact vision system, measurement of the elongation and twist angle were recorded. During experimental...
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Response to David Steigmann’s discussion of our paper
PublikacjaWe respond to David Steigmann's discussion of our paper "A general theory for anisotropic Kirchhoff-Love shells with in-plane bending of embedded fibers, Math. Mech. Solids, 28(5):1274-1317" (arXiv:2101.03122). His discussion allows us to clarify two misleading statements in our original paper, and confirm that its formulation is fully consistent with the formulation of Steigmann. We also demonstrate that some of our original statements...
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A study on microcrack monitoring in concrete: discrete element method simulations of acoustic emission for non-destructive diagnostics
PublikacjaThe research is focused on the monitoring of fracture evolution in concrete beams under three-point bending using the acoustic emission technique and the discrete element method. The main objective of the study was to numerically and experimentally investigate the mechanism behind the generation of elastic waves during acoustic emission events and their interaction with micro- and macro-cracking in concrete beams under monotonic...
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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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LCF behavior of 2024AA under uni- and biaxial loading taking into account creep pre-deformation
PublikacjaThis study presents the results of experimental low-cycle fatigue (LCF) tests of aluminum 2024 alloy T3511 temper in uni- and biaxial loading states. Tests were carried out on both the as-received material (hardened extruded rods) and material with different pre-deformation histories. These deformations were carried out in the creep process at 200 °C and 300 °C for two different levels of at each temperature. The pre-deformed material’s...
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Sensitivity analysis of free torsional vibration frequencies of thin-walled laminated beams under axial load
PublikacjaThe paper addresses sensitivity analysis of free torsional vibration frequencies of thin-walled beams of bisymmetric open cross-section made of unidirectional fibre-reinforced laminate. The warping effect and the axial end load are taken into account. The consideration is based upon the classical theory of thin-walled beams of non-deformable cross-section. The first-order sensitivity variation of the frequencies is derived with...
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Improving performance of large thrust bearings through modeling and experimentation
PublikacjaLarge thrust bearings are highly loaded machine elements and their failures cause serious losses. Start ups and stoppages of the bearing under load are specially critical regimes of operation. Load carrying capacity depends on the profile of the oil gap. In transient states this profile is also changing. In the design of large thrust bearings minimizing thermo-elastic deformations is an important goal, which can be accomplished...
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Structural response of existing spatial truss roof construction based on Cosserat rod theory
PublikacjaPaper presents the application of the Cosserat rod theory and newly developed associated finite elements code as the tools that support in the expert-designing engineering practice. Mechanical principles of the 3D spatially curved rods, dynamics (statics) laws, principle of virtual work are discussed. Corresponding FEM approach with interpolation and accumulation techniques of state variables are shown that enable the formulation...
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Nonlinear finite element modeling of vibration control of plane rod-type structural members with integrated piezoelectric patches
PublikacjaThis paper addresses modeling and finite element analysis of the transient large-amplitude vibration response of thin rod-type structures (e.g., plane curved beams, arches, ring shells) and its control by integrated piezoelectric layers. A geometrically nonlinear finite beam element for the analysis of piezolaminated structures is developed that is based on the Bernoulli hypothesis and the assumptions of small strains and finite...
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Elastic distortional buckling of thin-walled bars of closed quadratic cross-section
PublikacjaIn this study a tin-walled bar with closed quadratic cross-section is considered. The elastic stability of axially compressed bar related to the cross-section distortion is investigated. The governing differential equatio is derived with aid of the principle of stationary potential energy. The critical load for simply supported bar is found in an analytical form and it is copared with the FEM solution. Sufficient accuracy of the...
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Adaptation of the arbitrary Lagrange–Euler approach to fluid–solid interaction on an example of high velocity flow over thin platelet
PublikacjaThe aim of this study is to analyse the behaviour of a thin plate with air flow velocities of 0.3–0.9 Ma. Data from the experiment and numerical tools were used for the analysis. For fluid–solid interaction calculations, the arbitrary Lagrange–Euler approach was used. The results of the measurements are twofold. The first one is the measurement of the flow before and after vibrating plate, i.e. pure flow plate, and the second consists...
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Enriched buckling for beam-lattice metamaterials
PublikacjaWe discuss two examples of beam-lattice metamaterials which show attractive mechanical properties concerning their enriched buckling. The first one considers pantographic beams and the nonlinear solution is traced out numerically on the base of a Hencky’s model and an algorithm based on Riks’ arc-length scheme. The second one concerns a beam-lattice with sliders and the nonlinear solution is discussed in analytic way and, finally,...