Wyniki wyszukiwania dla: cracks
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Continuous and discontinuous modeling of cracks in concrete elements
PublikacjaW artykule przedstawiono różne sposoby modelowania rys w elementach betonowych w warunkach mieszanego sposobu obciążenia przy zastosowaniu modeli ciągłych i nieciągłych. Symulacje wykonano przy zastosowaniu 3 różnych modeli ciągłych: modelu sprężysto-plastycznego, modelu w ramach mechaniki zniszczeniowej i modelu rys rozmytych z rysami obracającymi się oraz 1 modelu nieciągłego przy zastosowaniu stref kontaktu..
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The influence oil additives on spread cracks in silicon nitride
PublikacjaThe paper presents an experimental study of the influence of oil additives (Cl, S, P, cerium dioxide (CeO2)) on spread cracks in silicon nitride. The additives Cl, S, P are bound in molecules in liquid form soluble in the base oil. The CeO2 is purely in powder form in suspension. The use of CeO2 powder was made based on the good results of polishing of silicon nitride. A ceramic angular contact ball bearing was modelled using a...
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Mechanism of the fatigue cracks development in bearing slide layer
PublikacjaNa podstawie literatury przedstawiono wybrane problemy dotyczące powiązania wytrzymałości zmęczeniowej łożysk ślizgowych ze strukturą i charakterystyką materiału tworzącego warstwę ślizgową panwi.W szczególności analizowano mechanizm inicjacji i propagacji pęknięć zmęczeniowych jako zależną nie tylko od wzorca obciążenia dynamicznego, lecz również od geometrii i struktury warstwy ślizgowej.Wyróżniono dwa typy pęknięć: strukturalne...
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Damage of a post-tensioned concrete bridge – Unwanted cracks of the girders
PublikacjaThe cracking of a post-tensioned T-beam superstructure, which was built using the incremental launching method, is analyzed in the paper. The problem is studied in detail, as specific damage was observed in the form of longitudinal cracks, especially in the mid-height zone of the girder at the interface of two assembly sections. The paper is a case study. A detailed inspection is done and non-destructive testing results of the...
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Guided waves for monitoring of plate structures with linear cracks of variable length
PublikacjaDamage occurring at the work of plate structures may grow to a considerable size. The joint action – the detection of a defect at the earliest possible stage, the monitoring of its growth and the determination of its critical size in the context of structural reliability allows optimizing the cost of the maintenance and repair of structural elements. Thus the development of monitoring systems for permanent observation of fault...
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J. FE modelling of cracks in concrete elements within continuum mechanics.
PublikacjaW artykule przedstawiono wyniki symulacji rys zakrzywionych w elementach betonowych w warunkach mieszanego sposobu obciążenia. Symulacje wykonano przy zastosowaniu 3 różnych modeli: modelu sprężysto-plastycznego, modelu w ramach mechaniki zniszczeniowej i modelu z rysami obracającymi się.
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Analysis of ring cracks in ceramic rolling elements using the boundary element method
PublikacjaCeramic materials have been increasingly used in bearing technology for over a dozen years. This is due to the characteristic properties of ceramic materials such as: high hardness, corrosion resistance, the possibility of use in aggressive chemical environments, as well as due to the lower specific weight compared to steel materials. However, the use of ceramic materials is connected with many limitations. The main disadvantages...
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Nondestructive methods complemented by FEM calculations in diagnostics of cracks in bridge approach pavement
PublikacjaNondestructive methods of road pavement diagnostics are an alternative to traditional approach to pavement failure investigation. The article presents a detailed multidisciplinary inspection carried out using ground-penetrating radar (GPR), laser scanning technology and finite element method (FEM) calculations. It was done in order to assess the factors that contributed to occurrence of premature cracks of a bridge approach pavement....
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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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Wady powierzchniowe ceramicznych elementów tocznych = Surface cracks of ceramic rolling elements
PublikacjaMateriały ceramiczne posiadają kombinację optymalnych własności, które są niezbędne w zastosowaniach na wysoko obciążone elementy maszyn. Podstawowym problemem związanym z wytrzymałością zmęczeniową materiałów ceramicznych są wszelkiego rodzaju wady powierzchniowe będące efektem procesu wytwarzania lub wynikające z defektów struktury materiału ceramicznego. W artykule przedstawiono badania doświadczalne dwutlenku cyrkonu ze sztucznie...
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Simulations of Shear Zones and Cracks in Engineering Materials Using eXtended Finite Element Method
PublikacjaNumerical simulations of cracks and shear zones in quasi-brittle materials are presented. Extended Finite Element Method is used to describe both cracks and shear zones. In a description of tensile cracks, a Rankine criterion is assumed. A discrete Mohr-Coulomb law is adopted for simulations of shear zones. Results of simple numerical tests: unixial tension, bending and biaxial compression are demonstrated.
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Size effect in concrete beams under bending – influence of the boundary layer and the numerical description of cracks
PublikacjaIn the paper the size effect phenomenon in concrete is analysed. The results of numerical simulations of using FEM on geometrically similar un-notched and notched concrete beams under bending are presented. Concrete beams of four different sizes and five different notch heights under three-point bending test were simulated. In total 18 beams were analysed. Two approaches were used to describe cracks in concrete. First, eXtended...
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Comparison of low-temperature cracks intensity on pavements with high modulus asphalt concrete and conventional asphalt concrete bases
PublikacjaHigh modulus asphalt concrete (HMAC) base courses provide very good resistance to rutting and fatigue but they can increase the risk of low-temperature cracking as compared with conventional asphalt concrete (AC). The article presents the comparison of these two road materials in terms of low-temperature cracking. The statistical method based on the ordered logistic regression model was used. The analysis was based on results of...
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Quantitative assessment of the influence of tensile softening of concrete in beams under bending by numerical simulations with XFEM and cohesive cracks
PublikacjaResults of the numerical simulations of the size effect phenomenon for concrete in comparison with experimental data are presented. In-plane geometrically similar notched and unnotched beams under three-point bending are analyzed. EXtended Finite Element Method (XFEM) with a cohesive softening law is used. Comprehensive parametric study with the respect to the tensile strength and the initial fracture energy is performed. Sensitivity...
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Finite element models used in diagnostics of transverse cracks in bridge approach pavement
Dane BadawczeTransverse cracks in the asphalt pavement were observed on bridge structures next to single-module expansion joints with a 5 meter approach slab set at the depth of 1 m. The finite element (FE) models of the approach pavement were created to investigate the reasons of premature cracking and crack initiation mechanism over the back edge of the abutment...
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Investigation of low-temperature cracks on selected national roads and motorways in Poland 2020
Dane BadawczeThe dataset contains video investigation and records of 68 road sections in various parts of Poland. Videos were recorded with the use of two cameras: 1) mounted in front of measurement vehicle, which was focused on overall view of road and 2) which was focused on pavement surface. The records are categorized according to the ID of the section given...
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Patryk Ziółkowski dr inż.
OsobyAbsolwent Wydziału Inżynierii Lądowej i Środowiska Politechniki Gdańskiej, w specjalności Konstrukcje Budowlane i Inżynierskie. Pracuje na stanowisku adiunkta w Katedrze Konstrukcji Inżynierskich. Brał udział w projektach międzynarodowych, w tym projektach dla Ministerstwa Transportu stanu Alabama (2015), jest także laureatem grantu Fundacji Kościuszkowskiej na prowadzanie badań w USA, który zrealizował w 2018 roku. Współautor...
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Calculations of notch stress factor of a thin-walled spreader bracket fillet weld with the use of a local stress approach
PublikacjaPresence of geometric notches in welded joints causes concentration of strains and stresses, therefore reducing fatigue strength of such joints. This article presents an analysis of stress concentrations in a fillet weld of a spreader mounting bracket on a small sailing yacht. The aim of this article is to direct the attention of designers, manufacturers and regulatory bodies to issues of fatigue cracks that form in brackets fastening...
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Terrestrial Survey Images - 3D Exterior Model - Zukowo Church - Canon
Dane BadawczeDataset description: Raw images from photogrammetric survey. Object: Parafia Wniebowzięcia Najświętszej Maryi Panny w ŻukowieLocation: Żukowo, Pomorskie, Kartuski County, PolandDrone type: n/a (Teresstrial images)Flight plan: CircleTarget Product: 3D ModelDate: 21.04.2018Direct georeferencing: yesMetadata data: NoGCP: NoCamera Name: Canon EOS 500DModel...
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Detection of Closing Crack in Beam Based on Responses Induced by Harmonic Excitation
PublikacjaThe non-linear contact model was chosen to simulate the closed crack in the cantilever beam. The study examines the shape and characteristics of the phase diagram of a cantilever beam with closed cracks. It investigates how various crack properties influence the geometry of the phase diagram and proposes a method for identifying cracks based on their features. The area of each closed curve in the phase diagram is determined using...
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NONLINEAR VIBRATION ANALYSIS OF BEAM AND PLATE WITH CLOSED CRACK: A REVIEW
PublikacjaThe effect of nonlinearity is high sensitivity in damage detection, especially for closed cracks and delamination. This review illustrates the results of several researchers dealing with nonlinear effects caused by the closure of cracks in the structure, i.e., beam and plate structures. Early detection of damage is an important aspect for the structure and, therefore, continuous progress is being made in developing new and effective...
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The Impact of Homogeneity of High Modulus Asphalt Concrete Layer on Low-Temperature Cracking
PublikacjaDuring winter season of 2012 numerous transverse cracks developed in high-modulus asphalt concrete (HMAC) base of newly constructed motorway. Pavement cracked both in transverse joint locations and in the area between them. Research which was conducted during investigation of the causes and mechanisms of cracking consisted of: field examination, laboratory testing of specimens cored out of the existing pavement, computational analyses...
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Crack propoagation in MgO-PSZ ceramic materials
PublikacjaThe properties of ceramic materials such as elevated hardness, high temperature capability, low coefficient of thermal expansion are of interest for rolling element materials. Widely used ceramic materials in engineering applications are silicon nitride, zirconia and alumina. The paper presents an experimental study of the fatigue life of MgO-PSZ ceramic material in lubricated contact with defined types of cracks. A ceramic angular...
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Analysis of ultimate compressive strength of cracked plates with the use of DOE techniques
PublikacjaThe objective of this work is to investigate the structural compressive response of plates with locked cracks accounting for all relevant factors and correlation between them. The nonlinear FE model considering both geometric and material nonlinearities is employed herein, and the FE model of the structural response of intact plates is validated with the available experimental data. In the common studies, based on One Factor at...
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Dawid Ryś dr hab. inż.
OsobySZKOLENIA Szkolenie dotyczące metodyki zarządzania projektami PRINCE 2. Certyfikat kwalifikacji. Szkolenie dotyczące Mikromechaniki Pracy Mieszanek Mineralno-Asfaltowych Szkolenie doyczące interakcji koło pojazdu-nawierzchnia
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Field investigation of low-temperature cracking and stiffness moduli on selected roads with conventional and high modulus asphalt concrete
PublikacjaHigh Modulus Asphalt Concrete (HMAC) was introduced in Poland as a one of the solutions to the problem of rutting, type of deterioration common in the 1990s. After first encouraging trials in 2002 HMAC was widely used for heavily loaded national roads and motorways. However some concerns were raised about low-temperature cracking of HMAC. This was the main reason of the studies presented in this article were started. The article...
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EXPERIMENTAL AND THEORETICAL FLOW OF THE FORCES IN DEEP BEAMS WITH CANTILEVAR
PublikacjaThis article presents the results of experimental research carried out on deep beams with cantilever which was loaded throughout the depth. The main deep beam was directly simply supported on the one side. On the other side the deep beam was suspended in another deep member situated at right angles. All deep beams created a spatial arrangement. The paper is focused on the analysis of the cracks morphology and flow of the internal...
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Damage detection in plates based on Lamb wavefront shape reconstruction
PublikacjaMany of the current studies in the area of damage detection using elastic wave propagation are based on deploying sensor networks with a large number of piezoelectric transducers to detect small-size cracks. A major limitation of these studies is that cracks are usually larger and have different shapes in real cases. Moreover, using a large number of sensing nodes for damage detection is both costly and computationally intensive....
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Effects of CO2 and Nd:YAG Laser Remelting of the Ti6Al4V Alloy on the Surface Quality and Residual Stresses
PublikacjaThe 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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Vibration-Based Investigation of a Historic Bell Tower to Understand the Occurrence of Damage
PublikacjaABSTRACT The paper presents a survey of the historic Arch-cathedral bell tower in Vilnius induced by the appearance of cracks in the structure after a new bell system installation. An attempt is undertaken to identify the reason for the crack occurrence and to check a possible crack influence on global structural behaviour. The research is based on dynamic measurements made in the tower during ambient vibrations and during vibrations...
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Assessment of crack resistance of ship steels according to SEP 1390 standard
PublikacjaThe aim of the study was to evaluate the weldability of E36 nd NVE-36 steels by bending test according to SEP 1390. In the case of the specimen from E36 steel 9 external cracks were found, 5 of which were stopped in the fusion line and 4 in heat affected zone. In the case of the specimen from NVE-36 steel 8 external cracks were found, 4 of which were stopped in the fusion line and 4 in heat affected zone. Results of bending test...
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Ultrasound monitoring for evaluation of damage in reinforced concrete
PublikacjaThe paper deals with automated monitoring of damage evolution in concrete elements subjected to three-point bending tests. The monitoring is based on the nonlinear interactions of traveling ultrasonic waves with micro-crack zones inside the concrete specimens and surface-breaking cracks. The developed procedure assumes semi-continuous ultrasonic testing during the element full loading cycle and generation of the power spectral...
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Assessment of damage causes of a 17 m long wind turbine blade model
PublikacjaThe subject matter is to verify the stiffness of the steel supporting structure and assess the causes of cracks in the 17 m long wind turbine blade model
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Opinion about causes of framing of Kingston chest (box cooler) damage, on PSV vessel VS4411 DF-PSV (B-855)
PublikacjaThe subject of analysis is a damage of welded connection of box cooler framing segments, made as separate bars 50mm thickness, connected by the welds in corners. Studies of documents delivered by Customer shows cracks on the fusion of filet welds and twisting of box cooler frame. The subject of analysis is a damage of welded connection of box cooler framing segments, made as separate bars 50mm thickness, connected by the welds...
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Analysis of Ceramic Elements with Ring-Crack Defects in Lubricated Rolling Contact
PublikacjaThe properties of ceramics, specifically low density, high hardness, high temperature capability and low coefficient of thermal expansion are of most interest to rolling element manufacturers. Surface ring cracks on lubricating rolling contact fatigue failure has been studied using numerical fracture analysis. Such cracks are very often found on ceramic bearing balls and decrease fatigue life rapidly. The numerical calculations...
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Degradation of Gel-Coat Layer in Glass/Polyester Laminate in Seawater Environment
PublikacjaGlass/polyester laminate coated with gelcoat layer of different thickness 0,5; 1,5; 3 mm was studied in terms of blistering behaviour and water sorption in hot water environment. Blistering was found to be accelerated for thin (0,5 mm) gel-coat layer compared to the thick (1,5; 3 mm), however no significant difference in blistering behaviour was observed between the laminates with gel-coat thickness 1,5 and 3 mm which may suggest...
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Microstructure and Electrical Properties of Fe,Cu Substituted (Co,Mn)3O4 Thin Films
PublikacjaIn this work, thin films (~1000 nm) of a pure MnCo2O4 spinel together with its partially substituted derivatives (MnCo1.6Cu0.2Fe0.2O4, MnCo1.6Cu0.4O4, MnCo1.6Fe0.4O4) were prepared by spray pyrolysis and were evaluated for electrical conductivity. Doping by Cu increases the electrical conductivity, whereas doping by Fe decreases the conductivity. For Cu containing samples, rapid grain growth occurs and these samples develop cracks...
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EFFECT OF SURFACE STATE AND STRESS ON AN OXIDATION OF THE ZIRCALOY-2 ALLOY
PublikacjaZr alloys are widely used as materials for nuclear fuel pellets in the nuclear industry. In the case of the LOCA or RIA happen, a temperature may locally reach high values. Even if the high temperature maintains shortly, the zirconium oxides may become permeable, absorb hydrogen appearing in cooling water from decomposition reaction and crack because of formation and brittle failure of hydrides. Such model cannot so far take into...
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X-Ray Computer Tomography Study of Degradation of the Zircaloy-2 Tubes Oxidized at High Temperatures
PublikacjaThe investigations of high-temperature oxidation of zirconium alloys, applied for fuel pellets in nuclear power plants, are usually limited to oxidation kinetics, phase transformations and microstructural characterization. The purpose of this research was to characterize the degradation phenomena occurring within oxide layer and at the interface oxide/metal, on internal and external Zircaloy-2 tube...
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High temperature corrosion of evaporator tubes with thermal sprayed coatings
PublikacjaDegradation examinations of outer surface of low-emission steam boiler evaporator tubes are presented in the paper. Metallographic evaluation of scale morphology, its micro sites chemical composition analysis and distribution of elements on cross sections have been performed. Water-wall tubes were exposed in steam boiler for up to two years period. Common tubes made of 16Mo3 steel suffered sulphide and molten salts corrosions....
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Internal imaging of concrete fracture based on elastic waves and ultrasound computed tomography
PublikacjaThe condition assessment of concrete structures belongs to the greatest challenges of non-destructive testing. Monitoring the fracture process of concrete and detecting cracks at the earliest possible stage is a vital aspect to ensure the safety of civil engineering objects. The use of ultrasound tomography enables imaging the internal structure of a tested element. This study aims at the visualization of fracture damage in concrete...
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CORROSION TESTING OF SAMPLES ACCORDING TO ASTM G36
PublikacjaAt the end of the study, samples were found to have structures characteristic for intercrystalline corrosion. This indicates that the samples provided (fragments of the whole) were sensitized before starting the study in boiling MgCl2.On cross sections, fine cracks are observed on all samples tested.
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The influence of reinforcement on load carrying capacity and cracking of the reinforced concrete deep beam joint
PublikacjaThe paper presents the results of experimental research of the spatial reinforced concrete deep beam systems orthogonally reinforced and with additional inclined bars. Joint of the deep beams in this research was composed of the longitudinal deep beam with a cantilever suspended at the transversal deep beam. The cantilever deep beam was loaded throughout the depth and the transversal deep beam was loaded at the mid-span by longitudinal...
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A study on fibre-reinforced concrete elements properties based on the case of habitat modules in the underwater sills
PublikacjaHydrotechnical constructions are mostly objects functioning in extreme conditions and requiring a custom-made construction project. In the case of using prefabricated elements, it is required to develop production, transport, assembly, conservation and repair technology. Concerning the problem of concrete cracks, modern repair systems allow positive effects to be achieved in many cases of concrete elements repair. In this work...
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Design of novel highly sensitive sensors for crack detection in metal surfaces: theoretical foundation and experimental validation
PublikacjaThe application of different types of microwave resonators for sensing cracks in metallic structures has been subject of many studies. While most studies have been focused on improving the sensitivity of planar crack sensors, the theoretical foundation of the topic has not been treated in much detail. The major objective of this study is to perform an exhaustive study of the principles and theoretical foundations for crack sensing...
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Assessment of crack resistance of S355J2+N steel according to SEP 1390 standard
PublikacjaThe aim of the study was to evaluate the weldability of S355J2+N steel by bending test according to SEP 1390. In the specimen from S355J2+N steel 3 external cracks were found, 1 of which were stopped in the fusion line and 2 in heat affected zone. Results of bending test for investigated grade of steel are positive.
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Ultrafast high-temperature sintering (UHS) of cerium oxide-based compound
PublikacjaUltrafast high-temperature sintering (UHS) is an innovative sintering technique that can densify ceramics in a few seconds, dramatically reducing the carbon footprint and firing costs. In this work, the feasibility of applying UHS in Gd-doped ceria (GDC) and GDC-Er-stabilized bismuth oxide (ESB) composite powders was investigated. At high UHS currents (22-24 A), a fully dense GDC sample with a large grain size was obtained. Nonetheless,...
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Settlement of a historic building due to seepage-induced soil deformation
PublikacjaThe research paper reviews issues associated with the impact of groundwater flow on soil characteristics and parameters, hence, the entire structure of a building set on it. Water seepage through the ground, building subsoil or structural elements of buildings made of soil affects the soil skeleton and may lead to changes in the arrangement of individual grains relative to each other, i.e., a modified soil structure. Soil solid...
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Applying molecular dynamics simulation to take the fracture fingerprint of polycrystalline SiC nanosheets
PublikacjaGraphene-like nanosheets are the key elements of advanced materials and systems. The mechanical behavior of the structurally perfect 2D nanostructures is well documented, but that of polycrystalline ones is less understood. Herein, we applied molecular dynamics simulation (MDS) to take the fracture fingerprint of polycrystalline SiC nanosheets (PSiCNS), where monocrystalline SiC nanosheets (MSiCNS) was the reference nanosheet....
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Effects of the preheating laser treatment on microstructure and corrosion resistance of Ti6Al4V bioalloy
PublikacjaThe laser remelting of the Ti6Al4V alloy was made on specimens pre-heated at elevated temperatures. The laser treatment effected in change of microstructures of surface layers and an appearance of blisters and numerous cracks. The corrosion tests demonstrated the decrease in corrosion resistance for each preheating temperature. The observed effects were attributed to negative influence of excessive compressive stresses with no...
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Direct shear stress vs strain relation for fiber reinforced composites
PublikacjaThe majority of fiber reinforced composites exhibit strong non-linear behavior in in-plane shear state. The effect is attributed to the micro-cracks appearing in the matrix and can be modeled on the micro and macro level. In this work the author proposes constitutive laws describing the non-linear in-plane shear response, which can be alternative for the relations commonly considered in the literature. The proposed equations are...
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Underwater wet welding of S1300 ultra-high strength steel
PublikacjaMarine Structures Volume 81, January 2022, 103120 Underwater wet welding of S1300 ultra-high strength steel Author links open overlay panelJacekTomkówGrzegorzRogalski https://doi.org/10.1016/j.marstruc.2021.103120 Get rights and content Under a Creative Commons licenseopen access Highlights • Technological method of S1300 steel underwater weldability improving was proposed. • Number of cracks and hardness of welded joints was...
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Microcracking monitoring and damage detection of graphene nanoplatelets-cement composites based on acoustic emission technology
PublikacjaThis study aims to identify the micro-cracking pattern and structural applications of cement composites replaced with 0 wt%, 0.04 wt%, and 0.08 wt% contents of graphene nanoplatelets (GNPs) over cement weight through acoustic emission (AE) monitoring under mechanical degradation. The ultraviolet-visible spectroscopy (UV–vis) results showed that at 60 min sonication period, GNP-4 showed maximum absorbance rate of 16.15% compared...
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Fatigue behaviour of SLM maraging steel under variable-amplitude loading
PublikacjaOne of the most challenging issues for additive manufactured materials is fatigue endurance. Engineering components often operate under complex, variable amplitude loadings, in which existing technological imperfections promote fatigue cracks growth and damage of elements eventually. In this study the effects of different variable-amplitude strain levels on fatigue life, 18Ni300 steel was tested. The work presents various behaviours...
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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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On some problems in determining tensile parameters of concrete model from size effect tests
PublikacjaThe paper presents results of numerical simulations of size effect phenomenon in concrete specimens. The behaviour of in-plane geometrically similar notched and unnotched beams under three-point bending is investigated. In total 18 beams are analysed. Concrete beams of four different sizes and five different notch to depth ratios are simulated. Two methods are applied to describe cracks. First, an elasto-plastic constitutive law...
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Factors affecting low-temperature cracking of asphalt pavements: analysis of field observations using the ordered logistic model
PublikacjaAccurate identification of factors that primarily affect the number of low-temperature cracks is crucial for selection of road materials and planning of pavement maintenance. Field investigations of lowtemperature cracks were performed in the years 2014 and 2020 on the same 68 road sections being in service in typical traffic conditions. The collected data were statistically analysed using the ordered logistic regression model....
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Weldability of high strength steel in underwater environment
PublikacjaThe article describes the problems with weldability of high-strength steels in the aquatic environment. The tendency of steel S355J2G3 and S500M to form cold cracks when welded in wet welding conditions has been experimentally evaluated. It was found that the tested steels have a high propensity to cracking. An experiment has been proposed and tested to evaluate the usefulness of the tempering bead technique as a method of improving...
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Non-uniqueness of fracture parameter choice in simulations of concrete cracking at mesoscale level
PublikacjaIn the paper a non-uniqueness of fracture parameter choice in simulations of cracking process in plain concrete specimens at mesoscale level under monotonic static loading is analysed. The Finite Element Method is used, where cracks are defined in a discrete way using interface cohesive elements with nonlinear material law including softening. The concrete mesostructure (such as: cement matrix, air voids, aggregates, and Interfacial...
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Coda wave interferometry in monitoring the fracture process of concrete beams under bending test
PublikacjaEarly detection of damage is necessary for the safe and reliable use of civil engineering structures made of concrete. Recently, the identification of micro-cracks in concrete has become an area of growing interest, especially using wave-based techniques. In this paper, a non-destructive testing approach for the characterization of the fracture process was presented. Experimental tests were made on concrete beams subjected to mechanical...
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Operational causes of fatigue failures within the passages of gas turbine engines
PublikacjaThe short profile of a fatigue wear process of gas turbine engine's constructional elements has been introduced in the article. The primary causes of a fatigue cracks formation within the mechanical system as well as within the passages of the engine have been showed. Especial attention was devoted to the low-cycle fatigue, what is associated with unsteady thermal-flow processes being worked out in the passages.The selected damages...
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Causes of damage and methods of repairing floor made on polystyrene concrete
PublikacjaThe paper describes damages, tests and repair of the floor made on existing ceiling and expanded polystyrene concrete underlay. The floor was built on a reinforced concrete ceiling with an area of about 1050 m2. Significant damage in the form of cracks, detachments and unevenness was found in the floor. In order to determine the causes of damage, in situ tests and laboratory tests were carried out. It was found that the damage...
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Innowacyjny moduł ultradźwiękowy systemu monitoringu technicznego mostu podwieszonego w Rzeszowie
PublikacjaW artykule przedstawiono system monitoringu technicznego konstrukcji mostu podwieszonego nad rzeką Wisłok. System będzie wyposażony w dodatkowy moduł ultradźwiękowy umożliwiający śledzenie degradacji mechanicznej betonu w pylonie mostu. Wczesne wykrywanie stref mikropęknięć, przed pojawieniem się widocznych rys, umożliwia monitorowanie amplitud propagującej fali ultradźwiękowej oraz analizę sygnałów w dziedzinie częstotliwości.
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Uszkodzenia wielowarstwowych posadzek betonowych
PublikacjaPosadzki wielowarstwowe to często projektowane elementy wewnętrznego wykończenia budowli. Mają bardzo duży wpływ na kształtowanie architektoniczne wnętrz oraz zapewnienie właściwych warunków użytkowania. W artykule przedstawiono przyczyny wystąpienia uszkodzeń posadzki w postaci rys i spękań. Górna trudno ścieralna warstwa posadzki grubości ok. 20 mm została wykonana metodą „mokre na suche”.
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Bitumen Aging—Laboratory Simulation Methods Used in Practice and Selected Directions of Research on New Methods
PublikacjaChanges in the properties of bitumen binders that occur as a result of aging have a huge impact on the durability of products produced from them. In particular, asphalt pavements, which constitute the most common use of petroleum bitumen, are susceptible to damage resulting from the increasing stiffness of the bitumen during its life cycle. Increased stiffness of asphalt pavements reduces the pavement resistance to low-temperature...
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Restoration and preservation of the reinforced concrete poles of fence at the former Auschwitz concentration and extermination camp
PublikacjaThe objective of this study was to assess the present state of the reinforced concrete poles of fence at the former Auschwitz I and Auschwitz II-Birkenau concentration and extermination camp. The poles were subjected to renovation about 10 years ago. After this time some deficiencies of applied renovation method were noticed. Cracks appeared between fresh and original part of concrete cover. Analysis of the reasons of these failures...
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Weldability of high strength steels in wet welding conditions
PublikacjaIn this paper are characterized problems of high strength steel weldability in underwater wet welding conditions. Water as a welding environment intensifies action of unfavourable factors which influence susceptibility to cold cracking of welded steel joints. The susceptibility to cold cracking of S355J2G3 steel and S500M steel in wet conditions was experimentally estimated (by using Tekken test). It was concluded that the steels...
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Restoration and preservation of the reinforced concrete poles of fence at the former Auschwitz concentration and extermination camp
PublikacjaThe objective of this study was to assess the present state of the reinforced concrete poles of fence at the former Auschwitz I and Auschwitz II-Birkenau concentration and extermination camp. The poles were subjected to renovation about 10 years ago. After this time some deficiencies of applied renovation method were noticed. Cracks appeared between fresh and original part of concrete cover. Analysis of the reasons of these failures...
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Właściwości stali S460M napawanej pod wodą metodą lokalnej komory suchej
PublikacjaW artykule przedstawiono wyniki badań próbek ze stali S460M wykonanych pod wodą metodą lokalnej komory suchej. Pomiary twardości oraz analiza strukturalna wykazały, że dla określonych ilości wprowadzonego ciepła możliwe jest wykonanie złączy bez niezgodności spawalniczych. Stwierdzono formowanie się w pewnych warunkach pęknięć zimnych w SWC wywołanych procesami odprowadzania ciepła z materiału, które są charakterystyczne dla spawania...
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Review and evaluation of cold recycling with bitumen emulsion and cement for rehabilitation of old pavements
PublikacjaThe article presents Polish experience with cold recycling of asphalt pavements with theusage of bituminous emulsion and cement. In the 1990s numerous roads in Polandrequired immediate reinforcement due to their significant degradation. Implementation ofthe cold recycling technology was one of the solutions to this problem. Cold recycledmixtures containebeside the recycled asphalt pavement and aggregateetwo differenttypes of binding...
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Field Evaluation of High Modulus Asphalt Concrete Resistance to Low-Temperature Cracking
PublikacjaHigh-modulus asphalt concrete has numerous advantages in comparison to conventional asphalt concrete, including increased resistance to permanent deformations and increased pavement fatigue life. However, previous studies have shown that the construction of road pavements with High Modulus Asphalt Concrete (HMAC) may significantly increase the risk of low-temperature cracking. Those observations were the motivation for the research...
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Numerical analysis of crack propagation in silicone nitride
PublikacjaThe properties of ceramics, specifically low density, high hardness, high temperature capability and low coefficient of thermal expansion are of most interest to rolling element manufacturers. The influence of ring crack size on rolling contact fatigue failure has been studied using numerical fracture analysis. Such cracks are very often found on ceramic bearing balls and decrease fatigue life rapidly. The numerical calculation...
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Analysis of the dynamic influences on the Lowland Gate in Gdańsk
PublikacjaThe Lowland Gate has been built in 1626. It is one of the best-preserved historical buildings in Gdansk. The structure is still of the city's infrastructural importance as through it goes a road connecting two districts. The Gate is now so neglected that it is hard to appreciate its value. The main purpose of the investigation carried out was to determine the harmfulness of the traffic on the structure as well as the reasons of...
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Investigation of low-temperature cracking in newly constructed high-modulus asphalt concrete base course of a motorway pavement
PublikacjaThe paper presents the issue of low-temperature transverse cracks which have developed in newly constructed base courses made of high-modulus asphalt concrete mix (HMAC). Numerous transverse cracks developed in the analysed HMAC base during the winter season before the pavement was actually completed, both at the transverse joint locations and in the areas between them. This had not happened so far on such a scale during road construction...
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Modeling, simulation, and validation of a TB41 crash test of the H2/W5/B concrete vehicle restraint system
PublikacjaThe paper addresses numerical simulations of a concrete vehicle restraint system. The model is described in detail. The advanced material law of the continuous surface cap model was used to analyze the damage locations in concrete barrier segments. The results were validated against the TB41 full-scale crash test. The test was conducted in compliance with European standard EN 1317, and the validation was performed in accordance...
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Experimental investigations of damage evolution in concrete during bending by continuous micro-CT scanning
PublikacjaThe paper describes experimental investigation results of fracture in notched concrete beams under quasi-static three-point bending. To visualize 3D fracture in concrete under bending, an extended X-ray micro-computed tomography system was used, i.e. the tomography system SkyScan 1173 was connected to the loading machine ISTRON 5569. This combined system enabled to shot images of deforming concrete beams during a continuous deformation...
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Influence of bitumen type on cracking resistance of asphalt mixtures used in pavement overlays
PublikacjaCracking is one of the predominant distresses occurring in flexible pavements, especially in old pavements that were rehabilitated with an asphalt overlay. In such cases asphalt mixtures should be designed to ensure high resistance to reflective cracking because new asphalt layers are exposed to existing cracks of the old pavement. The nature of these cracks can be various (transverse, longitudinal as well as crazy cracking). One...
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Investigations on fracture in reinforced concrete beams in 3-point bending using continuous micro-CT scanning
PublikacjaThis study explores a fracture process in rectangular reinforced concrete (RC) beams subjected to quasi-static three-point bending. RC beams were short and long with included longitudinal reinforcement in the form of a steel or basalt bar. The ratio of the shear span to the effective depth was 1.5 and 0.75. The focus was on the load–deflection diagram and crack formation. Three-dimensional (3D) analyses of the size and distribution...
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Badania spawalności stali S460N w środowisku wodnym z wykorzystaniem próby Tekken
PublikacjaSpawanie w środowisku wodnym niesie ze sobą wiele problemów, wśród których najważniejszym jest skłonność stali do powstawania pęknięć zimnych. O ile w przypadku spawania na powietrzu istnieje wiele metod zapobiegania tym pęknięciom, o tyle pod wodą zastosowanie tych metod jest ograniczone. Z tego powodu konieczne jest określenie skłonności danego materiału do pękania zimnego. W pracy oceniono spawalność drobnoziarnistej...
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Opracowanie technologii naprawy nieciągłości metalicznych w połączeniach spawanych, w konstrukcji podpór przednich pras filtracyjnych położonych na terenie Grupowej Oczyszczalni Ścieków Dębogórze
PublikacjaCelem niniejszej pracy jest opracowanie wytycznych technologicznych, których wdrożenie pozwoli na usunięcie istniejących pęknięć, co przyczyni się do stabilizacji wymiarowej podpór oraz całej konstrukcji pras. Osiągniecie tego celu wymaga podjęcia następujących działań: - ocenę stanu technicznego naprawianego komponentu- podpór przednich trzech pras filtracyjnych, - określenie własności spawalniczych materiału naprawianego, -...
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Traffic-induced vibrations. The impact on buildings and people
PublikacjaTraffic-induced vibrations have recently been of major concern to engineers as one of the aspects of so called physical environmental pollution. The interest is related to the observations of serious negative effects of such kind of vibrations on buildings and their inhabitants. Traffic-induced vibrations may cause plaster cracks, structural damage and even failure and collapse of the structure. They may also be the reason of serious...
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Experimental study on static and dynamic properties of polymer mass
PublikacjaA new method of repairing damaged structures by filling the cracks with a specially prepared polymer mass has been recently proposed. This new and innovative technique, known as the Flexible Joint Method (FJM), is mainly dedicated to masonries and historical objects, where minimum intervention is permitted. The flexible joint bonds the disrupted elements and ensures further safe exploitation of a damaged structure. The aim of the...
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Structural design and sensitivity analysis of semi-rigid pavement of a motorway
PublikacjaThis paper presents application of mechanistic-empirical methods in design of semi-rigid pavement for a section of a motorway in Poland. The stage construction was assumed. Three fatigue criteria were applied in the design. For asphalt fatigue cracking and subgrade soil the criteria from the Asphalt Institute (USA) were applied. For fatigue cracking of cement stabilized bases the Dempsey (USA) and De Beer (South Africa) criteria...
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Experimental examination of an elastomeric polymer
PublikacjaA new method of repairing damaged structures by filling the cracks with a specially prepared elastomeric polymer mass has been recently proposed. This new and innovative technique, known as the Flexible Joint Method (FJM), is mainly dedicated to masonries and historical objects, where minimum intervention is permitted. The flexible joint bonds the disrupted elements and ensures further safe exploitation of a damaged structure....
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Assessment of Tensile Strength Reserve of Asphalt Mixtures at Low Temperatures
PublikacjaDuring winter conditions, low-temperature cracks develop at the surface of the asphalt pavement when tensile thermal stress induced in the asphalt layer during cooling equals and exceeds the tensile strength of the material. The paper presents the results of tensile strength reserve assessment of asphalt mixtures with neat and SBS-polymer modified bitumen application. The tensile strength reservewas calculated as difference between...
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Using the ultrasonic tomography method to study the condition of wooden beams from historical buildngs
PublikacjaThe need to evaluate the integrity of wooden structural elements is constantly increasing. Non-destructive methods are becoming more popular in this field of research. One type of non-destructive testing is the ultrasonic imaging method, which allows the analysis of internal wood structures without disturbing their state and integrity. In this study, we are interested in assessing the effect of wood condition on the ultrasound...
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Study on Microstructure and Mechanical Properties of Laser Welded Dissimilar Joint of P91 Steel and INCOLOY 800HT Nickel Alloy
PublikacjaThis investigation attempts to explore the weld characteristics of a laser welded dissimilar joint of ferritic/martensitic 9Cr-1Mo-V-Nb (P91) steel and Incoloy 800HT austenitic nickel alloy. This dissimilar joint is essential in power generating nuclear and thermal plants operating at 600–650 °C. In such critical operating conditions, it is essential for a dissimilar joint to preserve its characteristics and be free from any kind...
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An experimental study on polymer mass
PublikacjaA new method of repairing damaged structures by filling the cracks with specially prepared polymer mass has been recently proposed. The technique is mainly dedicated to historical objects where minimum intervention is permitted. The flexible joint bonds the disrupted elements and ensures further safe exploitation of a damaged structure. The aim of the present paper is to show the results of an experimental study on polymer mass...
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Problems of analytical determination of journal bearing bush fatigue strength estimates
PublikacjaProblems connected with determination of stress distribution in sliding layer of thinwalled bearing bushes, investigated in bearing fatigue test rigs, have been presented. Using an example of plain bearings tested in the fatigue machine SMOK (built at the Gdask University of Technology) problems with obtaining a convergence of iterative procedure for determining the fatigue strength estimators of bearing alloy surface layer are...
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The influence of temperature on properties of the polymer flexible joint used for strengthening historical masonries
PublikacjaA new method of repairing damaged structures by filling the cracks with a specially prepared elastomeric polymer mass has been recently proposed. This new and innovative technique, known as the Flexible Joint Method (FJM), is mainly dedicated to masonries and historical objects, where minimum intervention is permitted. The flexible joint bonds the disrupted elements and ensures further safe exploitation of a damaged structure....
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Glass-ceramic joining of Fe22Cr porous alloy to Crofer22APU: interfacial issues and mechanical properties
PublikacjaThis work deals with the joining of porous Fe22Cr ferritic stainless steel to a dense Crofer22APU plate by using a silica-based, Ba-containing glass-ceramic. The chemical and interfacial stability and the mechanical properties of the joints were evaluated before and after thermal ageing at 700 ◦C for 500hrs. The sintering behaviour of the glass was assessed by using heating stage microscopy (HSM) to study the influence of a porous...
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Preliminary investigations of effect of conditions of FCAW process on diffusible hydrogen content in deposited metal
PublikacjaOne of the types of hydrogen degradation of steel welded joints is cold cracking. The direct cause of the formation of cold cracks is simultaneous presence of hydrogen, residual stresses and brittle structure. The way of preventing the occurring of degradation is to eliminate at least one of these factors. Practice has shown that the best solution is to control the amount of hydrogen in deposited metal. In this paper the state...
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Influence of High Temperature Oxidation on Hydrogen Absorption and Degradation of Zircaloy-2 and Zr 700 Alloys
PublikacjaThe present research was aimed at determining the effects of the oxide layers on hydrogen absorption, microstructure and mechanical properties of the Zircaloy- 2 and Zr 702 alloys. The oxidation was made at 350 °C, 700 °C and 900 °C for 10 to 30 min in laboratory air, followed by hydrogen cathodic charging for 72 h and annealing at 400 °C for 4 h. The slow strain rate tests were carried out on oxidized, charged and annealed specimens. The...
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Predicting the impact of traffic–induced vibrations on buildings using artificial neural networks
PublikacjaTraffic–induced vibrations may constitute a considerable load to a building, cause cracking of plaster, cracks in load–bearing elements or even a global structural collapse of the whole structure [1-4]. Vibrations measurements of real structures are costly and laborious, not justified in all cases. The aim of the paper is to create an original algorithm, to predict the negative dynamic impact on the examined residential building...
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Wzmocnienie uszkodzonej belki typu T w przęśle wiaduktu drogowego
PublikacjaW artykule opisano metodę wzmocnienia belki prefabrykowanej typu T dźwigara wiaduktu drogowego uszkodzonej przez pojazd „wozidło”. Beton belki uległ zarysowaniom w wielu miejscach. Wystąpiły też ubytki otuliny strun sprężających. Zaproponowano naprawę i wzmocnienie przez dobetonowanie dodatkowej belki. Podczas naprawy zastosowano balastowanie przęsła w celu wciągnięcia nowego dźwigara do współpracy od ciężaru własnego i sprężenia....
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The influence of the welding environment on the properties of Tekken joints made from S355J2C+N steel
PublikacjaThere are three main methods of underwater welding: dry, wet and intermediate between them, by using the local dry chamber. Due to low costs, the most common method is the wet welding with the use of covered electrodes. Water as a welding environment carries out a lot of problems. The first is limited visibility and instability of the welding arc. The biggest problem during underwater welding is high susceptibility to cold cracking,...
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Textile reinforced concrete members subjected to tension, bending, and in-plane loads: Experimental study and numerical analyses
PublikacjaTextile reinforced concrete has raised increasing research interest during the last years, mainly due to its potential to be used for freeform shell structures involving complex load situations. Yet, most experimental work has focused on test setups with primarily uniaxial loading. In the current work, such setups are complemented with a novel test setup of deep beams, including in-plane bending and shear. Further, nonlinear finite...
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Weldability of Underwater Wet-Welded HSLA Steel: Effects of Electrode Hydrophobic Coatings
PublikacjaThe paper presents the effects of waterproof coatings use to cover electrodes on the weldability of high-strength, low-alloy (HSLA) steel in water. With the aim of improving the weldability of S460N HSLA steel in water, modifications of welding filler material were chosen. The surfaces of electrodes were covered by different hydrophobic substances. The aim of the controlled thermal severity (CTS) test was to check the influence...
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Correlation between Fractal Dimension and Areal Surface Parameters for Fracture Analysis after Bending-Torsion Fatigue
PublikacjaThis paper investigates the fracture surface topography of two steel and aluminum alloys subject to bending-torsion fatigue loadings, as well as their susceptibility to fatigue performance and failure mechanisms. Using fracture surface topography data analysis, elements with different geometries were elaborated. A correlation between the fractal dimension, other selected parameters of surface topography such as areal Sx, and...
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Bio-Based Polyurethane Composites and Hybrid Composites Containing a New Type of Bio-Polyol and Addition of Natural and Synthetic Fibers
PublikacjaThis article describes how new bio-based polyol during the liquefaction process can be obtained. Selected polyol was tested in the production of polyurethane resins. Moreover, this research describes the process of manufacturing polyurethane materials and the impact of two different types of fibers—synthetic and natural (glass and sisal fibers)—on the properties of composites. The best properties were achieved at a reaction temperature...