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Search results for: CONSTANT STRAIN-RATE TESTS
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Hydrogen induced degradation of structural steel exposed to the technical liquid hydrocarbons
PublicationSusceptibility of the differently heat treated 26H2MF steel to stress corrosion cracking has been evaluated in the constant strain rate tension tests done at the strain rate 10-6s-1 and in the constant load tests done at the 0,98 of fracture load. The boiler fuel and the aged mineral oil at 135C and 80C respectively, have been used as the aggressive environments.
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Fracture in Asymmetric Bonded Joints
PublicationAdhesion was studied in asymmetric bonded joints using fracture mechanics tests. The asymmetric bonded joints consist of two different type and/or thickness materials bonded by an adhesive. Mentions of asymmetric bonded joint tests employed so far are rare in the literature. They are imperfect and therefore are not standardized. Accordingly three new tests were introduced in this work to study bonded joints. The new metrological...
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Application of the Bodner-Partom constitutive equations for modelling of the technical fabric Valmex used for the hanging roof of the Forest Opera in Sopot
PublicationThe study of an inelastic properties of the technical fabric Valmex used for 20 years as the roof structure of the Forest Opera in Sopot (Poland) is presented. The uniaxial tensile laboratory tests with constant strain rate have been conducted and analysed. Parameters of the Bodner-Partom constitutive model have been identified and verified by numerical simulations. Two approaches of the parameters identification have been proposed:...
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Sulfate‐reducing bacteria‐assisted hydrogen‐induced stress cracking of 2205 duplex stainless steels
PublicationThe paper presents the results of a laboratory investigation of the microbiologically assisted hydrogen‐induced stress cracking (HISC) of 2,205 duplex stainless steel (DSS). The testing of susceptibility toward HISC was performed with two different methods. Precharged in sulfate‐reducing bacteria (SRB), inoculated medium samples were subjected to slow strain‐rate testing in artificial seawater. In situ constant load tests were...
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The fracture behaviour of notched PMMA specimens under simple loading conditions – Tension and torsion experimental tests
PublicationThis paper presents the results of experimental testing of flat PMMA specimens during uniaxial loading conditions. Two separate tests were conducted: tensile and torsion. The specimens were weakened with V-type edge notches with different root radii: 0.5; 2 and 10 mm. The specimens were made in two thickness variants: 5 and 15 mm. Monotonic tensile and torsion tests were carried out while keeping the averaged strain rate constant,...
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Strain sequence effect on fatigue life and fracture surface topography of 7075-T651 aluminium alloy
PublicationThe paper studies the effect of strain-loading sequence on fatigue lifetime and fracture surface topographies in 7075-T651 aluminum alloy specimens. Fatigue tests were performed in two ways: (i) constant-amplitude loading and (ii) two series of variable amplitude loading with non-zero mean strain values. The topography of the fatigue fractures was measured over their entire surfaces with the help of an optical confocal measurement...
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Hydrogen degradation of pre-oxidized zirconium alloys
PublicationThe presence of the oxide layers on Zr alloys may retard or enhance the hydrogen entry and material degradation, depending on the layer features. This research has been aimed to determine the effects of pre-oxidation of the Zircaloy-2 alloy at a different temperature on hydrogen degradation. The specimens were oxidised in laboratory air at 350°C, 700°C, and 900°C. After, some samples were tensed at 10-5 strain rate and simultaneously...
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Process zone in the Single Cantilever Beam under transverse loading. - Part II: Experimental
PublicationThis paper describes an experimental arrangement to evaluate stress/strain fields in the process zone of asymmetric adhesively bonded joints. A transparent polycarbonate flexible beam was bonded to an aluminium alloy rigid block with an epoxy adhesive in a Single Cantilever Beam (SCB) configuration. The flexible adherend was loaded in the direction parallel to the initial crack front at constant rate. To monitor strains induced...
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Właściwości niskotemperaturowe betonów asfaltowych o wysokim module sztywności (AC-WMS) w badaniach trzypunktowego zginania
PublicationArtykuł 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 –...
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Identification of Bodner-Partom model parameters for technical fabrics
PublicationThe thorough analysis of modeling technical fabrics behavior with the viscoplastic Bodner-Partom constitutive law is presented. The study has been focused on differences between the warp and weft direction of the material. To obtain the model’s parameters only the uniaxial tensile laboratory tests with three different, but constant strain rates are required. The parameters have been found for polyester fibers PVC coated fabrics:...
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A hyperelastic model for soils with stress-induced and inherent anisotropy
PublicationIn this paper, modelling of the superposition of stress-induced and inherent anisotropy of soil small strain stiffness is8presented in the framework of hyperelasticity. A simple hyperelastic model, capable of reproducing variable stress-induced9anisotropy of stiffness, is extended by replacement of the stress invariant with mixed stress–microstructure invariant to10introduce constant inherent cross-anisotropic component. A convenient...
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Two tests for adhesive bonding long term characterization: principles and applications
PublicationThis article describes recent refinement of the traditional wedge test technique used to characterize durability of the adhesive joints. We propose two types of measuring protocols to monitor precisely and continuously the propagation of an "effective" crack during long term mode I fracture mechanic test. First method is directly derived from the traditional wedge test technique and consist in monitoring the surface strain of adherent...
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Modelling tunnelling-induced deformation in stiff soils with a hyperelastic–plastic anisotropic model
PublicationIn this paper, the tunnelling-induced deformation in anisotropic stiff soils is analysed using FE modelling. The influence of material description is investigated rather than an advanced simulation of the tunnelling method. A new hyperelastic– plastic model is proposed to describe the anisotropic mechanical behaviour of stiff highly overconsolidated soil. This model can reproduce the superposition of variable stress-induced anisotropy...
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Artificial Thermal Ageing of Polyester Reinforced and Polyvinyl Chloride Coated Technical Fabric
PublicationArchitectural fabric AF9032 has been subjected to artificial thermal ageing to determine changes of the material parameters of the fabric. The proposed method is based on the accelerated ageing approach proposed by Arrhenius. 300 mm x 50 mm samples were cut in the warp and fill directions and placed in a thermal chamber at 80 °C for up to 12 weeks or at 90 °C for up to 6 weeks. Then after one week of conditioning at ambient temperature,...
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Influence of soil anisotropic stiffness on the deformation induced by an open pit excavation.
PublicationIn this paper, the problem of deformation induced by an open pit excavation in anisotropic stiff soils is analysed by FE modelling. The presented research is focused on the influence of material model with anisotropic stiffness on the accuracy of deformation predictions as compared with the field measurements. A new hyperelastic-plastic model is applied to simulate anisotropic mechanical behaviour of stiff soils. It is capable...
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Pile Model Tests Using Strain Gauge Technology
PublicationOrdinary pile bearing capacity tests are usually carried out to determine the relationship between load and displacement of pile head. The measurement system required in such tests consists of force transducer and three or four displacement gauges. The whole system is installed at the pile head above the ground level. This approach, however, does not give us complete information about the pile-soil interaction. We can only determine...
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Effect of surface on the flexomagnetic response of ferroic composite nanostructures; nonlinear bending analysis
PublicationOur 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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The dependence of linear viscoelasticity limits of cold-recycled mixtures on time of curing and compaction method
PublicationCold-recycled mixtures are currently among the most widely used and investigated methods that enable recycling of old pavement structures in an environmentally friendly manner. Upon milling, the old pavement structure – whose gradation can be improved with addition of virgin aggregate – is mixed and compacted at ambient temperature. The main binding agents are bituminous emulsion and cement. Due to their dual binding behaviour,...
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Non-linear strain rate analysis of earthquake-induced pounding between steel buildings
PublicationPast and recent earthquakes have shown that ground motions may cause severe structural damage to civil engineering structures. Earthquake-induced pounding between adjacent buildings has been identified as one of the reasons which intensifies damages. The aim of this paper is to show the results of the detailed nonlinear FEM analysis of earthquake-induced pounding between two steel buildings. The elastic – perfectly plastic material...
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Experimental Study of Flow Rate in Hydraulic Satellite Motor with the Rotating Case at a Low Constant Rotational Speed
PublicationIn this article was described the methodology for the experimental study of flows in the prototype of a satellite hydraulic motor with a rotating body. The experimental tests of the motor were carried out at a low constant rotational speed in a wide range of pressure drop in this motor. The constant rotational speed of the motor was kept by a worm gear. Based on the test results, the leakage characteristics in the flat gaps of...
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Strain-dependent behaviour of cold recycled material mixtures in cyclic compression tests
PublicationThe purpose of the study is to evaluate strain-dependent behaviour of Cold Recycled Material (CRM) mixtures using three frameworks typically applied for Hot Mix Asphalt (HMA): linear viscoelastic (LVE) limits; non-linearity directions; changes in rheological model parameters. To this aim, the complex modulus of three CRM mixtures with different bitumen-to-cement ratio (0.2, 0.6 and 1.8) was measured in cyclic compression mode,...
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Erroneous GNSS Strain Rate Patterns and their Application to Investigate the Tectonic Credibility of GNSS Velocities
PublicationThe paper concerns investigation of the credibility of tectonic interpretation of GNSS strain rates. The analysis was focused on stable regions, where the crustal deformations are small and the reliability of GNSS velocities is questionable. We are showing how the unreliable motion of stations affects calculated strains around them. We expressed distribution of local principal strains by a sinusoidal function and used them to investigate...
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Dependence of bimolecular recombination rate constant on different experimental parameters
PublicationZ otrzymanych wzorów analitycznych oraz przeprowadzonych obliczeń numerycznych wynika, że dla wysokich natężeń pola elektrycznego stała szybkości rekombinacji bimolekularnej jest funkcją zewnętrznego pola elektrycznego oraz koncentracji nośników ładunku. Szczególnie interesujący jest wynik dotyczący obniżania się stałej szybkości rekombinacji wraz ze wzrostem natężenia pola elektrycznego, który różni się zupełnie od przewidywań...
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Numerical simulation of cold flow and combustion in a swirl stabilized combustor
PublicationA numerical simulation model was developed to investigate the cold flow and combustion using Ansys FLUENT 2021R1. The governing equations were solved using the pressure-based method, and pressure–velocity coupling was performed using the SIMPLE method. To model the turbulent process, the RSM model was used. Non-premixed model is chosen to solve the chemical kinetics between fuel and oxigen. Radiation heat transfer was calculated...
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Thermal buckling of functionally graded piezomagnetic micro- and nanobeams presenting the flexomagnetic effect
PublicationGalerkin 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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Caring for Children with Dravet Syndrome: Exploring the Daily Challenges of Family Caregivers
PublicationWhile Polish studies focus on the symptoms, causes and treatment of people suffering from Dravet syndrome (DS), much less is known about the situation of the family caregivers of DS children. This study was designed to explore the experiences, daily challenges and needs related to caring for DS children. An anonymous self-administered online questionnaire was developed. Thesurvey was completed by 75 family caregivers affiliated...
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Experimental studies on the impact of changing the pipe material on the propagation of the pressure wave during water hammer
PublicationAim of the paper is to present the results studying the water hammer phenomenon in pipes made of different materials, and to show the impact of changing the type of material of the pipe on the velocity of the pressure wave during the transient flow in the pipes. In terms of research material and methods, pipes made of galvanized steel and high-density polyethylene were tested. Measurements were made using strain gauges with a high...
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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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Estimation of autotrophic maximum specific growth rate constant-experience from the long-term operation of a laboratory-scale Sequencing Batch Reactor System
PublicationW pracy wykorzystano wyniki badań z długookresowej eksploatacji laboratoryjnego reaktora typu SBR do estymacji stałej szybkości przyrostu bakterii nitryfikacyjnych. Badania obejmowały zarówno pomiary empiryczne (doświadczenia przy niskim stosunku substratu do biomasy) oraz symulacje komputerowe. Do symulacji dynamicznych wykorzystano jedną wartość współczynnika = 1,2 1/d, pomimo różnych wartości mierzonych jednostkowych szybkości...
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White light thermoplasmonic activated gold nanorod arrays enable the photo-thermal disinfection of medical tools from bacterial contamination
PublicationThe outspread of bacterial pathogens causing severe infections and spreading rapidly, especially among hospitalized patients, is worrying and represents a global public health issue. Current disinfection techniques are becoming insufficient to counteract the spread of these pathogens because they carry multiple antibiotic-resistance genes. For this reason, a constant need exists for new technological solutions that rely on physical...
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The effect of strain rate on the passive layer cracking of 304L stainless steel in chloride solutions based on the differential analysis of electrochemical parameters obtained by means of DEIS
PublicationOkreślono wpływ szybkości rozciągania w zakresie 10-5s-1 ÷ 16∙10-5s-1 na niestacjonarny proces elektrochemiczny pękania warstwy pasywnej. Badania przeprowadzono na stali wysokostopowej 304L w temperaturze pokojowej w środowisku chlorków za pomocą dynamicznej elektrochemicznej spektroskopii impedancyjnej (DEIS). W rezultacie uzyskano zestaw chwilowych widm impedancyjnych odzwierciedlających dynamikę badanego układu korozyjnego....
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Wpływ kierunku rozchodzenia się fali detonacyjnej oraz współczynnika asymetrii na rozkład prędkości odkształceń w kotlinie walcowniczej podczas asymetrycznego walcowania pasma Al-Cu. The influences of the direction of explosion wave and asymetrical coefficient at the distribution of strain rate in the roll cap of bimetallic plate Al-Cu of rolling process.
PublicationPrzedstawiono symulacje komputerowe walcowania blach Al-Cu łączonych wybuchowo. Symulacje przeprowadzono dla procesu walcowania w walcarce o średnicy walców D=150 mm z indywidualnym napędem walców roboczych. W ramach badań numerycznych określony został wpływ kierunku rozchodzenia się fali detonacyjnej na rozkład prędkości odkształcenia w kotlinie walcowniczej asymetrycznie walcowanej blachy bimetalowej Al-Cu.
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ENVIRONMENTAL DEGRADATION OF DISSIMILAR AUSTENITIC 316L AND DUPLEX 2205 STAINLESS STEELS WELDED JOINTS
PublicationThe paper describes structure and properties of dissimilar stainless steels welded joints between duplex 2205 and austenitic 316L steels. Investigations were focused on environmentally assisted cracking of welded joints. The susceptibility to stress corrosion cracking (SCC) and hydrogen embrittlement was determined in slow strain rate tests (SSRT) with the strain rate of 2.2 × 10–6 s–1. Chloride-inducted SCC was determined in the...
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Corrosion monitoring by harmonic analysis in aqueous environments
PublicationThis paper presents tests concerning the rate of corrosion in non-alloy steel (type S235JR) in an aqueous environment, with an additive of sodium chloride by means of polarization resistance measurements and harmonic analysis. The tests have been carried out for steel samples exposed to the testing environment for six weeks, in order to obtain a constant rate of corrosion in the function of time. The measurements have aimed at...
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Właściwości mechaniczne tworzywa PET - przegląd literatury
PublicationThe article describes the influance of the microstructure and environment conditions on the mechanical properties of PET material. From the microskopic point of view, mechanical and thermal properties of PET material have the biggest influance on orientation and crystallization processes of material. From the macroskopic point of view mechanical properties can be described by parameters derived from strees-strain mechanical answers...
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Degradation of ferritic X10CrAlSi18 stainless steel caused by slurry
PublicationThe slurry erosion tests of ferritic X10CrAlSi18 steel were carried out using a slurry pot device. In order to investigate the erosion process, two series of tests were performed: first one with a constant impact velocity of 5 m/s, 7 m/s and 9 m/s and the second one, during which the impact velocity was changed after every exposure. During each test, an influence of test conditions on volume loss, surface hardness and roughness...
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Experimental study on polymer mass used to repair damaged structures
PublicationA 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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Adhesive Monitoring with Instrumented Wedge Test
PublicationThe wedge test (sometimes called the Boeing wedge test) is amongst the most readily exploitable techniques for assessment of the rate-dependent fracture energy of adhesive materials when used to bond relatively rigid substrates. With its siblings: the double cantilever beam (DCB), and the tapered double cantilever beam (TDCB), a force is applied, essentially in cleavage, to provoke substrate separation perpendicularly to the bondline...
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The energy approach to fatigue crack growth of S355 steel welded specimens subjected to bending
PublicationThe study presents the results of the research on the rate of fatigue crack growth subjected to bending in the ferritic-pearlitic structure. The studies were carried out at a constant amplitude of the moment and at various values of the load ratios R and at the operating frequency of the machine of 28.4 Hz. Flat specimens made of S355 steel and with fillet welds and with double-sided blunt external notches as well as concave...
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On the crack front curvature in bonded joints
PublicationStandard tests of adhesively bonded specimens are likely to produce heterogeneous stress distribution along the crack front and its vicinity. High separation rate mode I dominated fracture test is performed.Observation of post mortem fractured surfaces with an optical microscope reveals characteristic features of mixed mode I/III fracture near the sides of the specimen but not in the middle. At first, finite elements calculations...
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Role of Fungi in Biodegradation of Imidazolium Ionic Liquids by Activated Sewage Sludge
PublicationIonic liquids (ILs), due to their specific properties, can play the role of persistent water contaminants. Fungi manifest the ability to decompose hardy degradable compounds, showing potential in the biodegradation of ILs, which has been studied extensively on sewage sludge; however, attention was drawn mainly to bacterial and not fungal species. The aim of the research was to determine the significance of fungi in ILs’ biodegradation...
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On Kinetic Nature of Hysteresis Phenomena in Stress-Induced Phase Transformations
PublicationA simplest model is developed which demonstrates that hysteresis phenomena in stress-induced phase transformations may have a kinetic nature and follow from the discrepancy between strain rate and characteristic rate of the new phase growth.
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Maturity curve for estimating the in-place strength of high performance concrete
PublicationThe paper presents the maturity curve for estimating the in-place early-age compressive strength of concrete. The development of appropriate maturity curve is a complex process. It is important to correctly determine the datum temperature and activation energy, which can be obtained in mortar tests. This paper describes an investigation of the accuracy of the maturity method to estimate the strength when different way to rate constant...
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Determination of the theoretical and actual working volume of a hydraulic motor
PublicationA new methodology of determination of the theoretical and actual working volume of a hydraulic motor based on the characteristics of the delivered flow rate into hydraulic motor vs. the rotational speed at a constant pressure drop in the working chambers is described in this paper. A new method of describing the delivered flow rate into a motor per one shaft revolution as a nonlinear function of the pressure drop in the motor working...
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Parameters’ Identification of Perzyna and Chaboche Viscoplastic Models for Aluminum Alloy at Temperature of 120◦C
PublicationThe main purpose of this paper is the parameters identification of the Perzyna and the Chaboche models for the aluminum alloy at elevated temperature. The additional purpose is comparison of the results for these viscoplastic models. The results have been verified by the numerical simulation of the laboratory tests. The material parameters have been calculated on the basis of the uniaxial tension test. The determination of the...
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Fracture of aluminium joints bonded with epoxy adhesive reinforced by mmt nanoparticles
PublicationCrack propagation behavior was studied for aluminium/aluminum adhesive joints bonded with two epoxy adhesives: pure and reinforced with clay nanoparticles. The focus was also on the novel use of the constant displacement rate test to study adhesion/adhesives efficiency. The epoxy systems studied were: Epidian E6 produced from bisphenol A and epichlorohydrin, (''Organika -Sarzyna'' Poland); pure or strengthened with montmorillonit...
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Properties of surface layers of duplex stainless steel after burnishing processes
PublicationStress corrosion cracking resistance of cold worked layers of 25 Cr duplex stainless steel grade UR52N+ has been investigated. The surface layers were performed through burnishing treatment. The residual stresses at surface layers were determined using grazing angle incidence X-ray diffraction method (g-sin2 Ψ). Corrosion tests were performed with the use of Slow Strain Rate Test technique in boiling 35% MgCl2 solution. It has...
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Effect of adhesive compliance in the assessment of soft adhesives with the wedge test
PublicationWedge tests are usually analysed assuming that the free, unbonded members may be treated as encastré cantilever beams. However, if the adhesive layer is sufficiently flexible (e.g., due to low elastic modulus), then significant strain in the bonded region may occur and lead to modification of the behaviour outside this region. Using in conjunction a sensitive strain gauge method on asymmetric wedge tests and a mathematical analysis...
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Instrumented End Notched Flexure - Crack propagation and process zonemonitoring. Part I: Modelling and analysis
PublicationAnalysis of the three-point bending, End Notched Flexure (ENF), test is presented for exploitation with a new experimental methodology using the backface strain monitoring technique. The model consists oftwo Timoshenko beams joined with a two parameter elastic foundation, to evaluate stress and strain fields in both adherends and the adhesive layer, together with the specimen compliance and energyrelease rate. This model is compared...
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Load Tests of the Movable Footbridge Over the Port Canal in Ustka
PublicationThe paper presents the acceptance tests carried out on the open footbridge over the port canal in the Port of Ustka. The steel footbridge construction is created by a single pylon to which a movable truss span is suspended with a theoretical span of 52.3 m. The studies about load test of the object included static and dynamic extortion and measurements. In static tests the ballast was of pallets with concrete blocks. Dynamic studies...