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Search results for: structural strength
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PROBLEMY ZWIĄZANE Z ZASTOSOWANIEM NANOTECHNOLOGII W TERMOIZOLACJI BUDYNKÓW
PublicationBudownictwo i architektura były zawsze ściśle związane z rozwojem technologicznym a ciągły postęp w badaniach nad inżynierią materiałową pozwalał na uzyskiwanie bardziej wydajnych i wytrzymałych materiałów. Dotyczy to nie tylko elementów konstrukcyjnych budynku ale także technologii związanych z jego wykończeniem. Obecnie coraz większą rolę w budownictwie i architekturze odgrywa pojęcie nanotechnologii. Dziedzina nauki, zdawałoby...
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THE EFFECT OF NOTCH DEPTH ON CTOD VALUES IN FRACTURE TESTS OF STRUCTURAL STEEL ELEMENTS
PublicationIn elements of steel structures working at low temperatures, there is a risk of appearance of brittle fracture. This risk is reduced through the use of certified materials having guaranteed strength at a given temperature. A method which is most frequently used to determine brittle fracture toughness is the Charpy impact test, preformed for a given temperature. For offshore structures intended to work in the arctic climat e, the...
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An investigation on the role of GMA grafting degree on the efficiency of PET/PP-g-GMA reactive blending: morphology and mechanical properties
PublicationGlycidyl methacrylate (GMA) has been grafted on polypropylene (PP) with the aid of styrene (St) comonomer, by changing dicumyl peroxide initiator content, GMA level, and St concentration. The performance of the resulting PP-g-GMA reactive material towards static and dynamic mechanical properties of poly (ethylene terephthalate) (PET) was monitored in terms of grafting reaction variables and compatibilizer content. Fourier transform...
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Structural and spectroscopic analysis of a new family of monomeric diphosphinoboranes
PublicationWe present a series of amino- and aryl(diphosphino)boranes R2PB(R’’)PR’2, where R2P, R’2P = tBu2P, tBuPhP, Ph2P, Cy2P, and R’’ = iPr2N, Ph, which were obtained via the metathesis reaction of iPr2NBBr2 or PhBBr2 with selected lithium phosphides. The structures of isolated diphosphinoboranes were characterized in the solid state and in solution by means of X-ray diffraction and NMR spectroscopy, respectively. The utility of these...
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AN ALTERNATIVE WAY OF DETERMINING MECHANICAL PROPERTIES OF WOOD BY MEASURING CUTTING FORCES
PublicationThe 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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Slowly-closing valve behaviour during steam machine accelerated start-up
PublicationThe paper discusses the state of stress in a slowly-closing valve during accelerated start-up of a steam turbine. The valve is one of the first components affected by high temperature gradients and is a key element on which the power, efficiency and safety of the steam system depend. The authors calibrated the valve model based on experimental data and then performed extended Thermal-FSI analyses relative to experiment. The issue...
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Determination of Thermophysical Parameters Involved in The Numerical Model to Predict the Temperature Field of Cast-In-Place Concrete Bridge Deck
PublicationThe paper dealswith a concept of a practical computationmethod to simulate the temperature distribution in an extradosed bridge deck. The main goal of the study is to develop a feasible model of hardening of concrete consistent with in-situ measurement capabilities. The presented investigations include laboratory tests of high performance concrete, measurements of temperature evolution in the bridge deck and above all, numerical...
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Influence of Heat Treatment Temperature on Fatigue Toughness in Medium-Carbon High-Strength Steels
PublicationCurrent research has demonstrated that the tempering temperature affects the martensitic transformation of medium-carbon high-strength steels. This temperature plays an important role in the final microstructure, percentage ratios of martensite to ferrite phases and, consequently, in the mechanical properties and the fatigue response. So far, the relationship between the martensitic tempering temperature and the cyclic deformation...
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Application of Shape Memory Alloys in Retrofitting of Masonry and Heritage Structures Based on Their Vulnerability Revealed in the Bam 2003 Earthquake
PublicationFor decades, one of the most critical considerations of civil engineers has been the construction of structures that can sufficiently resist earthquakes. However, in many parts of the globe, ancient and contemporary buildings were constructed without regard for engineering; thus, there is a rising necessity to adapt existing structures to avoid accidents and preserve historical artefacts. There are various techniques for retrofitting...
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Anion–water interactions of weakly hydrated anions: molecular dynamics simulations of aqueous NaBF4 and NaPF6
PublicationIn aqueous ionic solutions, both the structure and the dynamics of water are altered dramatically with respect to the pure solvent. The emergence of novel experimental techniques makes these changes accessible to detailed investigations. At the same time, computational studies deliver unique possibilities for the interpretation of the experimental data at the molecular level. Here, using molecular dynamics simulations, we demonstrate...
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Effect of rPET Content and Preform Heating/Cooling Conditions in the Stretch Blow Molding Process on Microcavitation and Solid-State Post-Condensation of vPET-rPET Blend: Part II—Statistical Analysis and Interpretation of Tests
PublicationThis research explores how varying proportions of virgin polyethylene terephthalate (vPET) and recycled polyethylene terephthalate (rPET) in vPET-rPET blends, combined with preform thermal conditions during the stretch blow molding (SBM) process, influence PET bottles’ microscopic characteristics. Key metrics such as viscosity, density, crystallinity, amorphous phase relaxation, and microcavitation were assessed using response...
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Thermal properties of a cement composite containing phase change materials (PCMs) with post-pyrolytic char obtained from spent tyres as a carrier
PublicationThis work examines the possible use of post-pyrolysis char made from spent vehicle tyres as a carrier for phase change materials (PCM), which could be used as an additive to cement mortar. Because of the ability of PCM to accumulate heat, the cement composite obtained from it, apart from its structural and strength properties, will acquire an additional energy storage function, which can be very important for energy-saving construction. In...
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Microcracking monitoring and damage detection of graphene nanoplatelets-cement composites based on acoustic emission technology
PublicationThis 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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Failure mode prediction for composite structural insulated panels with MgO board facings
PublicationSandwich panels are readily used in civil engineering due to their high strength to weight ratio and the ease and speed of assembly. The idea of a sandwich section is to combine thin and durable facings with a light-weight core and the choice of materials used allows obtaining the desired behaviour. Panels in consideration consist of MgO (magnesium oxide) board facings and expanded polystyrene core and are characterized by immunity...
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Shaking table experimental study on damage mechanism of the disconnecting switch under seismic excitation
PublicationThe efficiency of the energetic network is a very import safety issue in the region experienced by the earthquake. High voltage disconnecting switches are important elements of the energetic infrastructure used to separate electric circuits (i.e. during repairs), which should not be damaged remaining fully operational. The aim of the paper is to show the results of the shaking table experimental investigation focused on damage...
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Role of buttering layer composition on microstructural heterogeneity and mechanical properties of Alloy 617 and P92 steel dissimilar welded joints for future Indian AUSC program
PublicationRestrictive operating conditions (even exceeding 700 °C) of materials in advanced ultra super critical (AUSC) power plants and the need to minimize manufacturing and maintenance costs require the production of dissimilar metal welded joints (DMW). Significant differences in the physical and chemical properties of welded materials lead to phenomena that reduce the weldability of the metals used and force the search for solutions...
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Aerodynamic Shape Optimization for Delaying Dynamic Stall of Airfoils by Regression Kriging
PublicationThe phenomenon of dynamic stall produce adverse aerodynamic loading which can adversely affect the structural strength and life of aerodynamic systems. Aerodynamic shape optimization (ASO) provides an effective approach for delaying and mitigating dynamic stall characteristics without the addition of auxiliary system. ASO, however, requires multiple evaluations time-consuming computational fluid dynamics models. Metamodel-based...
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Knowledge Sharing and Organizational Culture Dimensions: Does Job Satisfaction Matter?
PublicationThe aim of this study is to examine how job satisfaction influences the relationship between company performance, knowledge sharing, and organizational culture, perceived through the prism of Hofstede’s cultural dimensions, controlled by company size and staff position. A survey of 910 Polish employees (mainly knowledge workers) with different roles and experiences across different industries was conducted. The data were analyzed...
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Cast iron in the 19th-century building equipment
PublicationCast iron is a material, characteristics of which enable to receive extremely artistic elements. It maintains good strength properties at the same time. That combination of these seemingly contrary traits makes it a commodity that was widely used in the 19th century industry and architecture. These usages were not only as decorative elements, technical and structural ones. The production of new household utilities started, which...
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The use of chain extenders as processing aids in the valorization of single-use polylactide (PLA) products by rotomolding
PublicationBiodegradable plastics in single-use products have increased in popularity as a way to reduce the negative environmental impact of conventional plastics and meet the tightening law regulations. However, their recyclability needs to be assessed, as the environmental behavior of single-use plastics, even if compostable, is not negligible. Polylactide (PLA) is susceptible to thermal, oxidative, hydrolytic, and mechanical degradation...
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Naprawa po pożarze stalowej wielokondygnacyjnej wieży produkcyjnej z zastosowaniem sprężanych elementów wzmocnienia
PublicationPożar we wnętrzu wielokondygnacyjnego obiektu produkcyjnego o stalowej konstrukcji ramowej spowodował znaczne uszkodzenia w zakresie stalowych stropów międzykondygnacyjnych oraz części głównych słupów nośnych obiektu. Pomimo dużych strat w obrębie konstrukcji i lekkiej obudowy obiektu oraz długiej akcji gaśniczej udało się uratować w całości baterię technologicznych silosów magazynowych zlokalizowanych na jego dachu. Wydane bezpośrednio...
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Improving Thermal Insulation Properties for Prefabricated Wall Components Made of Lightweight Aggregate Concrete with Open Structure
PublicationPorous concrete is commonly used in civil engineering due to its good thermal insulation properties in comparison with normal concrete and high compression strength in comparison with other building materials. An extremely porous concrete, called ‘lightweight aggregate concrete with open structure’ (LAC), is used in some German plants to produce prefabricated wall components. They are used mainly in hall buildings, e.g. supermarkets....
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Impact of laser beam welding on mechanical behaviour of 2.25Cr–1Mo (P22) steel
PublicationThe use of welding processes in the manufacturing and repair of structures intended for the energy industry plays a key role in the guarantee of a continuous supply of fossil fuels, which is the basic condition for ensuring energy security. A square butt joint of 10 mm thick plate of 2.25Cr–1Mo (P22) steel was fabricated by autogenous laser beam welding process and then post-weld heat treatment (PWHT) for two sets of process parameters...
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Load Testing of GFRP Composite U-Shape Footbridge
PublicationThe paper presents the scope of load tests carried out on an innovative shell composite footbridge. The tested footbridge was manufactured in one production cycle and has no components made from materials other than GFRP laminates and PET foam. The load tests, performed on a 14-m long structure, were the final stage of a research program in the Fobridge project carried out in cooperation with: Gdańsk University of Technology (leader),...
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Structural Changes and Their Implications in Foamed Flexible Polyurethane Composites Filled with Rapeseed Oil-Treated Ground Tire Rubber
PublicationThe utilization of post-consumer car tires is an essential issue from an ecological andeconomic point of view. One of the simplest and the least harmful methods is their material recyclingresulting in ground tire rubber (GTR), which can be further applied as fillers for polymer-basedcomposites. Nevertheless, insufficient interfacial interactions implicate the necessity of GTR modi-fication before introduction into polymer matrices....
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Analysis of floor-to-column pounding of buildings founded on different soil types
PublicationThe aim of this study is to investigate the effect of the soil type on buildings experiencing floor-to-column pounding during earthquakes. Five buildings with 4-storeys, 6-storeys, and 7-storeys were considered. Three types of the 4-storey building with different total heights were taken into account which leads to floor-to-column pounding at 1/3, 1/2 and 2/3 of the height of the impacted column. Two pounding scenarios were considered,...
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Synthesis, structural characterization, and thermal properties of Ca‐ and La‐doped soda‐lime glasses by laser melting
PublicationLaser melting techniques have been used in the preparation of unconventional glass compositions with high melting temperatures. Thus, we wanted to test the feasibility of using a CO2 laser in the preparation of nitrogen-rich oxynitride glasses and nitride silicate glasses. Melting from oxides and metallic raw materials, we wanted to study first glass formation and possible evaporation losses of the glass components. Two glass series...
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Simple Computational Methods in Predicting Limit Load of High-Strength Cold-Formed Sections due to Local Buckling: A Case Study
PublicationCold-formed thin-walled sections are prone to local buckling caused by residual stresses, geometrical imperfections and inconsistency of material properties. We present a real case of buckling failure and conduct a numerical and experimental study aimed to identify methods capable of predicting such failures. It is important because designers of structures are getting more FEA-oriented and tend to avoid lengthy procedures of cold-formed...
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Structural, thermal and physico-mechanical properties of polyurethane/brewers’ spent grain composite foams modified with ground tire rubber
PublicationIn this work, brewers’ spent grain (BSG) and ground tire rubber (GTR) waste fillers were applied as low-cost reinforcement phase in rigid polyurethane foam (PUR). PUR/BSG/GTR composites were prepared by a single step method, using polyglycerol as partial substitute of commercially available petrochemical polyols. Foaming parameters, chemical structure, dynamic mechanical properties, thermal stability, physico-mechanical properties...
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DEFORMATIONS OF INNOVATIVE COLD-FORMED GEB SECTIONS
PublicationPermanent urban growth of the world of today world implies demanding challenges for the steel construction industry. Nowadays, one of the most important issues is the cost optimization of steel structures. Since the weight of building materials is a major component of the total cost, engineers and designers try to reduce structural weight, without compromising durability and sustainability of a steel structure. Therefore, light...
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Investigating Layered Topological Magnetic Materials as Efficient Electrocatalysts for the Hydrogen Evolution Reaction under High Current Densities
PublicationDespite considerable progress, high-performing durable catalysts operating under large current densities (i.e., >1000 mA/cm2) are still lacking. To discover platinum group metal-free (PGMfree) electrocatalysts for sustainable energy, our research involves investigating layered topological magnetic materials (semiconducting ferromagnets) as highly efficient electrocatalysts for the hydrogen evolution reaction under high current...
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Marcin Wekwejt dr inż.
PeopleMarcin Wekwejt holds a bachelor’s degree in Biomedical Engineering (2016; J. and J. Śniadecki Bydgoszcz University of Technology & L. Rydygier Collegium Medicum), a master’s degree in Mechanical-Medical Engineering (2018; Gdańsk University of Technology & Gdańsk Medical University), and a PhD in Materials Engineering (2021; Gdańsk University of Technology). He was awarded the title of Doctor of Engineering and Technical...
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Three-Dimensional Fractography for Conventional and Additive Manufactured Steels After Bending-Torsion Fatigue
PublicationIn this study, fracture surface topography parameters were measured to investigate the effects of multiaxial loading. In order to assess the metrological aspects of fracture for notched specimens made of high-strength steels processed by both conventional and additively manufacturing (AM) techniques, an optical surface profilometer was used. Three bending moment to torsion moment ratios (B/T) were studied, i.e. 2, 1 and 2/3. The...
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Reinforced concrete thin wall dome after eighty years of operation in maritime climate environment
PublicationThe paper presents a description of the construction elements of the Gdynia Seaport main hall dome. Firstly, it provides information about the technical condition of the dome’s structure. Secondly, it examines the strength analysis of the thin-walled reinforced concrete dome covering. Throughout the last 80 years the building has been exposed to an unfavourable marine climate. The analysis of the state of stress and deformations...
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Image-based numerical modeling of the tensile deformation behavior and mechanical properties of additive manufactured Ti–6Al–4V diamond lattice structures
PublicationThis work concerns the numerical modeling of the deformation process and mechanical properties of structures obtained by the additive method laser power bed fusion (LPBF). The investigation uses diamond structures of Ti–6Al–4V titanium implantation alloy with various relative densities. To model the process of tensile deformation of the materials, geometric models were used, mapping the realistic shape of the examined structures....
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Justifying the prolongation of the service life of the bearing structure of a tank car when using Y25 bogies
PublicationThis paper substantiates the use of Y25 bogies under tank cars in order to prolong their service life. The reported study has been carried out for a tank car with rated parameters, as well as the actual ones, registered during full-scale research. Mathematical modeling was performed to determine the basic indicators of the tank car dynamics. The differential equations of motion were solved by a Runge-Kutta method using the Mathcad...
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Muneer Ahmed Mr
PeopleLooking for an organization where I can better utilize my scientific and technical skills in the arena of research or work as a faculty person. Besides, I am also willing to work as professional engineer with dedication and diligence in dynamic environment. Likewise, I've been a committed and tenacious candidate throughout my career. I am aware of the level of commitment, dedication and strength required. Despite the fact that...