2024 - Repozytorium publikacji - Politechnika Gdańska

Pokaż publikacje z roku

Publikacje z roku 2024

Pokaż wszystkie

Effect of AlF3 and KF addition on the structure and luminescent properties of P2O5 – K2O – Nb2O5 – Bi2O3 glasses doped with Eu3+
- Michał Maciejewski
- Karolina Milewska
- Anna Synak
- Marcin Łapiński
- Wojciech Sadowski
- Barbara Kościelska
2024 JOURNAL OF LUMINESCENCE
Based on the developed phosphate glasses P2O5–K2O–Bi2O3–Nb2O5 doped with Eu3+, the influence of AlF3 and KF on the structural and luminescent properties was investigated. For this purpose, three series of glasses containing from 5 to 15 mol% fluorides were synthesized. Two of the series included the KF additive, which was introduced in two ways - proportionally and disproportionately at the expense of the K2O share. The structural characterization (XRD, FTIR) allowed us to determine the evolution of the internal structure of the glasses caused by changes in the type and content of the introduced additives and the presence of the Eu dopant. Similarly, using DSC/DTA, the thermal properties of undoped matrices were defined. The luminescence enhancement caused by the addition of ≥10 mol% fluorides was confirmed by the obtained fluorescence spectra. The presented studies not only expand the state of knowledge about the effects of fluorides on phosphate glasses but also demonstrate the ease of obtaining materials with improved properties suitable for use as phosphor in LEDs.
Effect of applied standard wood machining fluid on colour and chemical composition of the machined wood surface
- Daniel Chuchała
- Agata Sommer
- Kazimierz Orłowski
- Hanna Staroszczyk
- Szymon Mania
- Jakub Sandak
2024 Pełny tekst European Journal of Wood and Wood Products (HOLZ ALS ROH-UND WERKSTOFF)
Appropriate monitoring of wood machining processes is a key issue to ensure the expected quality of the processed wood, expected efficiency and minimize energy consumption of production processes. A new trend is the design of environmentally friendly machining fluids. In this paper, as a preliminary study in this field, the effect of applied standard wood machining fluid on changes in the colour and chemical composition of the machined wood surface is presented. Scots pine wood (Pinus sylvestris L.) was used for this research. Colour measurements were carried out based on the three-axis CIELab system test in time intervals and coefficients such as: colour chroma (Cab*), colour saturation (Sab*), colour hue (h°), and total colour changes (ΔE*). Changes in chemical composition were analysed on the Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR FT-IR). The results confirmed that standard machining fluids cause a significant change in the colour of the treated pine surface, which decreases over time but is still present even after 24 h. For the spectral analysis, no chemical changes were observed between the machining fluid and the wood. However, the fluid particles remained in the wood after 24 h. In order to reduce the effect of the machining fluid on the colour of the wood, its composition should be changed to allow and/or accelerate the evaporation of their components from the treated wood surface.
Effect of bio-polyol molecular weight on the structure and properties of polyurethane-polyisocyanurate (PUR-PIR) foams
- Adam Olszewski
- Paulina Kosmela
- Laima Vevere
- Mikelis Kirpluks
- Ugis Cabulis
- Łukasz Piszczyk
2024 Pełny tekst Scientific Reports
The increasing interest in polyurethane materials has raised the question of the environmental impact of these materials. For this reason, the scientists aim to find an extremely difficult balance between new material technologies and sustainable development. This work attempts to validate the possibility of replacing petrochemical polyols with previously synthesized bio-polyols and their impact on the structure and properties of rigid polyurethane-polyisocyanurate (PUR-PIR). To date, biobased polyols were frequently used in the manufacturing of PU, but application of bio-polyols synthesized via solvothermal liquefaction using different chains of polyethylene glycol has not been comprehensively discussed. In this work, ten sets of rigid polyurethane foams were synthesized. The influence of bio-polyols addition on foam properties was investigated by mechanical testing, thermogravimetric analysis (TGA), and cone calorimetry. The structure was determined by scanning electron microscopy (SEM) and a gas pycnometer. The tests revealed a significant extension of foam growth time, which can be explained by possible steric hindrances and the presence of less reactive secondary hydroxyl groups. Moreover, an increase average size of pores and aspect ratio was noticed. This can be interpreted by the modification of the cell growth process by the introduction of a less reactive bio-polyol with different viscosity. The analysis of foams mechanical properties showed that the normalized compressive strength increased up to 40% due to incorporation of more cross-linked structures. The thermogravimetric analysis demonstrated that the addition of bio-based polyols increased temperature of 2% (T2%) and 5% (T5%) mass degradation. On the other hand, evaluation of flammability of manufactured foams showed increase of total heat release (HRR) and smoke release (TSR) what may be caused by reduction of char layer stability. These findings add substantially to our understanding of the incorporation of bio-polyols into industrial polyurethane systems and suggest the necessity of conducting further research on these materials.
Effect of composition on the thermal properties and structure of M-Al-Si-O-N glasses, M = Na, Mg, Ca
- Sharafat Ali
- Natalia Wójcik
- Abbas Saeed Hakeem
- Yann Gueguen
- Stefan Karlsson
2024 PROGRESS IN SOLID STATE CHEMISTRY
The primary objective of this study is to explore the relationship between the composition, structure, and thermal characteristics of M-Al-Si-O-N glasses, with M representing sodium (Na), magnesium (Mg), or calcium (Ca). The glasses were prepared by melting in a quartz crucible at 1650 °C and AlN precursor (powder) was utilized as a nitrogen source. The measured thermal properties studied were glass transition temperature (Tg), crystallization temperature (Tc), glass stability, viscosity, and thermal expansion coefficient (α). The findings indicate that increasing the aluminum content leads to higher glass transition, crystallization temperatures, and viscosities. In contrast, fragility values increase with the Al contents, while modifier elements and silicon content influence thermal expansion coefficient values. FTIR analysis revealed that in all glasses, the dominant IR bands are attributed to the presence of Q2 and Q3 silicate units. The effect of Al is observed as a progressive polymerization of the silicate network resulting from the glass-forming role of Al2O3. In most samples, the Q4 silicate mode was also observed, strongly related to the high Al content. Overall, the study shows that the complexity of composition-property correlations where the structural changes affect the properties of Mg/Ca-based oxynitride glasses has potential implications for their use in various technological fields.
Effect of copper and silver modification of NH2-MIL-125(Ti) on the photoreduction of carbon dioxide to formic acid over this framework under visible-light irradiation
- Mateusz Baluk
- Aleksandra Pieczyńska
- Paweł Mazierski
- Malwina Kroczewska
- Kostiantyn Nikiforow
- Alicja Mikolajczyk
- Joanna Dołżonek
- Justyna Łuczak
- Adriana Zaleska-Medynska
2024 Pełny tekst APPLIED CATALYSIS B-ENVIRONMENTAL
Cu and Ag enhance the photocatalytic activities of metal–organic frameworks (MOFs) toward CO2 conversion because of their CO2 adsorption capacities and effects on the lowest unoccupied molecular orbital (LUMO) overpotentials of MOFs. However, to date, targeted introduction of metals into MOFs to achieve visible (Vis)- light-active photocatalysts for CO2 photoconversion has not been realized. Herein, a series of aminefunctionalized Ti MOF (NH2-MIL-125(Ti))-based photocatalysts were successfully synthesized using metalation, incorporation, and photodeposition, allowing Cu and Ag incorporation into NH2-MIL-125(Ti) and attainment of ultraviolet- and Vis-light-active photocatalysts. Notably, the most active photocatalyst obtained by post-synthetic metalation of NH2-MIL-125(Ti) by Cu2+ (MOF_met_0.5%Cu) demonstrated excellent performance in photoreducing CO2 to HCOOH: a conversion rate of 30.1 umolg− 1 h− 1 and quantum yield of 1.18% at 380 nm. Photoconversion of CO2 to HCOOH was further confirmed using 13CO2. The novel approach proposed herein is a significant step toward clean energy production and environmental pollutant elimination
Effect of ectoine on hydration spheres of peptides–spectroscopic studies
- Aneta Panuszko
- Marek Szymczak
- Julia Dłużewska
- Julia Godlewska
- Anna Kuffel
- Piotr Bruździak
2024 SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
In this paper, we use FTIR spectroscopy to characterize the hydration water of ectoine, its interactions with two peptides–diglycine and NAGMA, and the properties of water molecules in the hydration spheres of both peptides changed by the presence of the osmolyte. We found that the interaction of ectoine with the peptide hydration shells had no effect on its own hydration sphere. However, the enhanced hydration layer of the osmolyte influences the hydration shells of both peptides and does so in a different way for both peptides: (1) the interfacial interaction of the NAGMA peptide and ectoine hydration spheres strengthened the hydration shell of this peptide; (2) the inclusion of water molecules from the ectoine hydration sphere into the diglycine hydration sphere had only a marginally enhancing effect. Since ectoine is being used in more and more biopharmaceutical products and cosmetics, knowledge of the properties of its hydration shell and its effect on the hydration shell of other molecules is extremely relevant to understanding its protective mechanism.
Effect of free water on the quasi‑static compression behavior of partially‑saturated concrete with a fully coupled DEM/CFD approach.
- Marek Krzaczek
- Andrzej Tejchman-Konarzewski
- Michał Nitka
2024 GRANULAR MATTER
The work aims to numerically investigate the quasi-static response of partially fluid-saturated concrete under two-dimensional uniaxial compression at the mesoscale. We investigated how the impact of free pore fluid content (water and gas) affected the quasi-static strength of concrete. The totally and partially fluid-saturated concrete behavior was simulated using an improved pore-scale hydro-mechanical model based on DEM/CFD. The fluid flow concept was based on a fluid flow network made up of channels in a continuous region between discrete elements. A two-phase laminar fluid flow was postulated in partially saturated porous concrete with very low porosity. Position and volumes of pores/cracks were considered to correctly track the liquid/gas content. In both dry and wet conditions, a series of numerical simulations were performed on bonded granular specimens of a simplified spherical mesostructure that mimicked concrete. The effects of fluid saturation and fluid viscosity on concrete strength and fracture, and fluid pore pressures were investigated. It was found that each of those effects significantly impacted the hydro-mechanical behavior of concrete. Due to the rising fluid pressure in pores during initial specimen compaction under compressive loading that promoted a cracking process, the compressive strength increased as fluid saturation and fluid viscosity decreased.
Effect of lag screw on stability of first metatarsophalangeal joint arthrodesis with medial plate
- Karol Daszkiewicz
- Magdalena Rucka
- Krzysztof Czuraj
- Angela Andrzejewska
- Piotr Łuczkiewicz
2024 PeerJ
Background: First metatarsophalangeal joint (MTP-1) arthrodesis is a commonly performed procedure in the treatment of disorders of the great toe. Since the incidence of revision after MTP-1 joint arthrodesis is not insignificant, a medial approach with a medially positioned locking plate has been proposed as a new technique. The aim of the study was to investigate the effect of the application of a lag screw on the stability and strength of first metatarsophalangeal joint arthrodesis with medial plate. Methods: The bending tests in a testing machine were performed for models of the first metatarsal bone and the proximal phalanx printed on a 3D printer from polylactide material. The bones were joined using the locking titanium plate and six locking screws. The specimens were divided into three groups of seven each: medial plate and no lag screw, medial plate with a lag screw, dorsal plate with a lag screw. The tests were carried out quasi-static until the samples failure. Results: The addition of the lag screw to the medial plate significantly increased flexural stiffness (41.45 N/mm vs 23.84 N/mm, p = 0.002), which was lower than that of the dorsal plate with a lag screw (81.29 N/mm, p < 0.001). The similar maximum force greater than 700 N (p > 0.50) and the relative bone displacements lower than 0.5 mm for a force of 50 N were obtained for all fixation techniques. Conclusions: The lag screw significantly increased the shear stiffness in particular and reduced relative transverse displacements to the level that should not delay the healing process for the full load of the MTP-1 joint arthrodesis with the medial plate. It is recommended to use the locking screws with a larger cross-sectional area of the head to minimize rotation of the medial plate relative to the metatarsal bone.
Effect of multi-walled carbon nanotubes properties on the photocatalytic activity of bismuth-based composites synthesised via an imidazolium ionic liquid
- Aleksandra Bielicka-giełdoń
- Patrycja Wilczewska
- Monika Paszkiewicz
- Anna Malankowska
- Karol Szczodrowski
- Jacek Ryl
- Ewa Siedlecka
2024 Pełny tekst APPLIED SURFACE SCIENCE
The use of various types of multi-walled carbon nanotubes in the synthesis of bismuth oxybromide semiconductors via imidazolium ionic liquid was studied in detail. The effect of the MWCNT shape, specific surface area, and various diameters on the morphology, surface properties and photoactivity of the Bi-based composites has been investigated for the first time. So far, the literature has only shown the enhancement of photocatalytic activity of composites containing MWCNT; however, our research shows a broader view of the issue. The photocatalytic activity of the individual composites under UV–Vis irradiation was assessed by the degradation of various micropollutants, showing the diversity of properties of the obtained composites. It is also significant that in the composite system, the imidazolium ionic liquid played a crucial role in the formation of microspheres and acted as a dispersing agent, leading to an even distribution of MWCNTs on the surface of the spherical bismuth oxybromide.
Effect of rPET Content and Preform Heating/Cooling Conditions in the Stretch Blow Molding Process on Microcavitation and Solid-State Post-Condensation of vPET-rPET Blend: Part I—Research Methodology and Results
- Paweł Wawrzyniak
- Waldemar Karaszewski
- Artur Różański
2024 Materials
Polyethylene terephthalate (PET) is widely used in bottle production due to its costeffectiveness and low environmental impact. The first part of this article describes the research and statistical analysis methodology of the influence of the virgin PET (vPET) and recycled PET (rPET) content in the vPET-rPET blend, as well as the preform heating/cooling conditions in the stretch blow molding (SBM) process on the microscopic bottle properties. Microscopic properties such as crystallinity, density, viscosity, relaxation degree of the amorphous phase, and microcavitation in PET were examined. This study reveals that microcavity and solid-state post-condensation effects occur during PET deformation in the SBM process. The increase in free volume, indicating microcavitation, was confirmed by measuring positron annihilation lifetime spectroscopy (PALS). PALS and density of the amorphous phase studies prove a reduction in the dimensions of the free volumes, with a simultaneous significant increase in their number and ellipsoidization. It can be associated with crystallite rotation in a temperature-dependent non-crystalline matrix. The occurrence of solidstate post-condensation effects was confirmed by measuring the intrinsic viscosity. The conclusions resulting from the analysis of the microstructure affecting the mechanical strength of the material were validated by pressure resistance tests of the bottles.
Effect of strain level on the stiffness of cold recycled bituminous mixtures
- Vittoria Grilli
- Andrea Grilli
- Andrea Graziani
- Mariusz Jaczewski
2024
Cold recycling is a sustainable technology for the rehabilitation of bitumi-nous pavements. This study investigates the stiffness response of cement-bitumen treated materials (CBTM)manufactured with 80% reclaimed asphalt and treated with 2.0% Portland cement and 4.0% bitumen emulsion. Indirect tensile stiffness modulus tests were carried out to assess the strain dependence of stiffness at target horizontal deformation levels between 2 and 15 micrometers. Ultrasonic pulse velocity was also measured to evaluate stiffness at very low strain level. The tests were carried out at three temperatures (5, 20, 35C) on CBTMspecimens with 14 % of voids. The results showed that the CBTM stiffness decreased with increasing deformation level. Small-strain results can be used to estimate the linear viscoelastic response whereas damage can be observed when the deformation level is increased
Effect of the ex situ physical and in situ chemical modification of bacterial nanocellulose on mechanical properties in the context of its potential applications in heart valve design
- Alicja Stanisławska
- Marek Szkodo
- Hanna Staroszczyk
- Kinga Dawidowska
- Magdalena Kołaczkowska
- Piotr Siondalski
2024 Pełny tekst INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
Bacterial nanocellulose (BNC) is a promising material for heart valve prostheses. However, its low strength properties limit its applicability in cardiovascular surgery. To overcome these limitations, the mechanical properties of BNC can be improved through modifications. The aim of the research was to investigate the extent to which the mechanical properties of BNC can be altered by modifying its structure during its production and after synthesis. The study presents the results of various analyses, including tensile tests, nanoindentation tests, X-ray diffraction (XRD) tests, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy, conducted on BNC chemically modified in situ with hyaluronic acid (BNC/HA) and physically modified ex situ through a dehydration/rehydration process (BNC 25DR, BNC105DR, BNC FDR and BNC/HA 25DR, BNC/HA 105DR, BNC/HA FDR). The results demonstrate that both chemical and physical modifications can effectively shape the mechanical properties of BNC. These modifications induce changes in the crystalline structure, pore size and distribution, and residual stresses of BNC. Results show the effect of the crystalline structure of BNC on its mechanical properties. There is correlation between hardness and Young’s modulus and Iα/Iβ index for BNC/HA and between creep rate of BNC/HA, and Young’s modulus for BNC vs Iα/Iβ index.
Effect of ultrasound on the physicochemical, mechanical and adhesive properties of micro-arc oxidized coatings on Ti13Nb13Zr bio-alloy
- Balbina Makurat-Kasprolewicz
- Marcin Wekwejt
- Luca Pezzato
- Anna Ronowska
- Jolanta Krupa
- Sławomir Zimowski
- Stefan Dzionk
- Agnieszka Ossowska
2024 Pełny tekst Scientific Reports
Implant surgeries are increasingly challenging due to their rising number. Achieving the desired biomaterial surface properties to ensure a strong bond with human tissue is a significant issue. This study investigates the influence of ultrasound (US) during the micro-arc oxidation (MAO) process on Ti13Zr13Nb bio-alloy, an area not previously explored, to enhance titanium alloy coatings’ properties for biomedical applications. Porous calcium-phosphate-based coatings were successfully deposited on Ti13Zr13Nb using MAO and ultrasound micro-arc oxidation (UMAO). Various properties such as morphology, chemical composition, topography, wettability, surface free energy, thickness, adhesion to the substrate, as well as mechanical and corrosion characteristics were thoroughly analyzed. Cytocompatibility was assessed using human osteoblasts. Using US during the MAO process increased coating roughness (up to ~ 17%), core height (up to 22%), isotropy (up to 17%), thickness (up to ~ 46%), and hardness (up to ~ 18%), depending on MAO parameters and US mode. Optimal coating performance was achieved at 136 mA, 600 s, and a sinusoidal US setting, resulting in the highest isotropy (~ 79%) and rutile quantity (2.6%), the lowest elastic modulus (~ 57 GPa), and the contact angle of ~ 70°, all of which could have contributed to enhancing osteoblast viability in vitro. This study, for the first time, underscores the importance of using the US during the MAO in tailoring the Ti13Zr13Nb for specific biomedical applications.
Effect of underwater friction stir welding parameters on AA5754 alloy joints: experimental studies
- Anna Janeczek
- Dariusz Fydrych
- Jacek Tomków
- Hamed Aghajani Derazkola
- Katarzyna Łyczkowska
2024 INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
The water as a welding environment may generate serious technological and metallurgical problems but in certain cases, the physicochemical properties of water can be used effectively, e.g., to impart the specific properties of welded materials. The purpose of the work was verification of effectiveness of the water cooling of aluminium alloy AA5754 for various sets of technological parameters of underwater friction stir welding (UFSW). For the joints performed with the range of parameters of rotational speed: 475–925 rpm and welding speed: 47.5–95 mm/min, the following examinations were carried out: visual tests, radiographic tests, static tensile test, fractography (SEM, scanning electron microscope) analysis, and surface texture analysis performed with 3D measurement system. All of the joints were characterized with some amount of flash. Besides, depending on the values of selected parameters, the defects arising from inadequate stirring were found—tunnel defects and melting. The best appearance of the joint was obtained for the set of parameters of 925 rpm and 47.5 mm/min. The samples of the same joint were found to be of the highest mechanical properties—ultimate tensile strength (UTS) of 194 MPa and elongation (A) of 9.2%. The results were confirmed by the fractography analysis, which in this case indicated the ductile fracture mode. Dynamic plastic behaviour strongly depends on the process parameter values, which was reflected in the results of surface texture analysis. The parameter selection resulted in significant changes in the roughness results (from 8 to 14.2 µm depending on the sample) as well as the flow ring distance of the weld (from 20 to 50 µm depending on the sample).
Effect of Vascular Lumen Reduction on the Performance and Energy Consumption of an Innovative Implantable LVAD
- Ryszard Jasiński
- Krzysztof Tesch
- Leszek Dąbrowski
- Jan Rogowski
2024 Pełny tekst Applied Sciences-Basel
This paper presents the results of a study on the effect of vascular lumen reduction on the performance of an innovative implantable LVAD (left ventricular assist device). It details the pressures in the individual cardiac chambers as a function of device frequency. In addition, mass flow rates and energy consumption of the device are examined, varying with lumen reduction and operating frequency. While the lumen reduction of the vessels has little effect on energy consumption, the mass flow rates vary considerably, i.e., above 140 cyc/min, the mass flow rate increment is no longer achieved for specified initial conditions. There are also differences regarding the pressures in the heart; namely, it was found that the pressure plots look similar in all cases, leading to the conclusion that the reduction of the vessel lumen does not affect their shape, but does affect the maximum values of the left ventricular and aortic pressures. Importantly, the innovative device in the form of an intra-cardiac balloon assembly for circulatory support is based on a pulsatile flow strategy and is synchronized with the ECG signal. Other advantages of the proposed solution include a minimally invasive method of implantation, which is important for patients with end-stage heart failure. The design of the device is portable and the device itself is battery-powered, allowing for shorter hospitalization times and faster recovery, even in patients with end-stage heart failure associated with mitral regurgitation and pulmonary hypertension.
Effective sonophotocatalytic degradation of tetracycline in water: Optimization, kinetic modeling, and degradation pathways
- Ansaf Karim
- Grzegorz Boczkaj
- Amritanshu Shriwastav
2024 CHEMICAL ENGINEERING AND PROCESSING
Hybrid advanced oxidation processes (AOPs) are gaining interest in degradation of variety of recalcitrant compounds for water and wastewater treatment, due to possible synergistic effects. The present study systematically evaluated the degradation of tetracycline (TC) with a sonophotocatalytic process combining acoustic cavitation (sonocavitation) and photocatalysis based on N-doped TiO2 catalyst. The TC degradation rate constant was 2.4 × 10−2 min−1, i.e., much higher than individual sonocatalytic (0.5 × 10−2 min−1) and photocatalysis (0.6 × 10−2 min−1) processes at the optimized conditions. The synergy index was 2.14, which reveals a significant improvement in the process performance. Maximum TC degradations of 55.5 ± 1.8 % for photocatalysis, 66.4 ± 1.8 % for sonocatalysis, and 79.5 ± 0.3 % for sonophotocatalysis were observed for 10 mg L−1 initial TC concentration after 90 min of treatment. The photocatalytic experiments were extended further to 210 min to achieve a maximum degradation of 78.9 ± 0.2 % at the optimized condition. Scavenging experiments confirmed that hydroxyl radicals (•OH), electron holes (h+), and superoxide radical anions (O2−•) played a significant role in the degradation of TC. Further, the degradation intermediates for each process were identified and degradation pathways were proposed. Empirical kinetic models based on operational parameters were also developed and validated.
Effects Induced by the Temperature and Chemical Environment on the Fluorescence of Water-Soluble Gold Nanoparticles Functionalized with a Perylene-Derivative Dye
- Agnieszka Lindstaedt
- Justyna Doroszuk
- Aneta Machnikowska
- Alicja Dziadosz
- Piotr Barski
- Vittoria Raffa
- Dariusz Witt
2024 Materials
We developed a fluorescent molecular probe based on gold nanoparticles functionalized with N,N′-bis(2-(1-piperazino)ethyl)-3,4,9,10-perylenetetracarboxylic acid diimide dihydrochloride, and these probes exhibit potential for applications in microscopic thermometry. The intensity of fluorescence was affected by changes in temperature. Chemical environments, such as different buffers with the same pH, also resulted in different fluorescence intensities. Due to the fluorescence intensity changes exhibited by modified gold nanoparticles, these materials are promising candidates for future technologies involving microscopic temperature measurements.
Effects of Deck-Abutment Pounding on the Seismic Fragility Curves of Box-Girder Highway Bridges
- Seyyed Amirhossein Moayyedi
- Hossein Rezaei
- Afshin Kalantari
- Robert Jankowski
2024 JOURNAL OF EARTHQUAKE ENGINEERING
Earthquake-induced pounding in bridges is a complex contact phenomenon in which the dynamic responses of structures, including collisions between deck and abutments, are strongly related to structural properties and earthquake excitation. The goal of this study is to develop and compare the seismic fragility curves of overall system and individual components of regular and irregular box-girder highway bridges in two cases: with pounding and without pounding. For this purpose, four levels of altitudinal irregularity, ranging from regular to highly irregular, are considered. To extend the results for all bridges in the same class, different sources of uncertainties related to earthquakes, structural geometries, and material properties are taken into account. The analytical fragility curves have been developed based on nonlinear time history analyses in OpenSees finite element software for the cases with and without pounding effects. The process has been repeated for each two-, three-, and four-span classes at four irregularity levels. The fragility function parameters for the two cases with and without pounding have been compared for all classes considered in this study. Using fragility functions, this paper clarifies the interactive roles of irregularity and pounding between deck and abutments for seismic vulnerability of multi-span box-birder highway bridges. The results indicate that collisions often show an adverse effect on all structural components. It has also been observed that the detrimental effect of pounding on seismic fragility is more apparent in irregular bridges when compared with regular ones. In addition, the study introduces a conversion coefficient to clarify the effects of pounding on the fragility of bridge components and the overall system. This coefficient can be applied in both conventional analytical methods like static or simplified analysis and technical earthquake models like HAZUS, adjusting fragility values for pounding and irregularity effects.
Effects of interfacial sliding on anti-plane waves in an elastic plate imperfectly attached to an elastic half-space
- Gennadi I. Mikhasev
- Victor Eremeev
2024 INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE
We study the anti-plane shear waves in a domain consisting of an elastic layer (plate) with a coating attached to an elastic half-space (substrate). We assume an imperfect contact between the layer and the half-space, allowing some sliding. We also assume some elastic bonds between the layer and the substrate. On the free top surface we apply the compatibility conditions within the Gurtin–Murdoch surface elasticity. We found two different solutions: (i) the transversely exponential–transversely exponential (TE–TE) regime with amplitudes decaying exponentially from the free top surface and the interface in both the plate and the half-space, and (ii) the transversely harmonic–transversely exponential (TH–TE) regime with harmonic wave behaviour in the transverse direction in the plate and exponential decay in the half-space. The TE regime of anti-plane waves in an elastic half-space with non-perfect contact is also considered as a special case. A detailed analysis of the derived dispersion relations reveals a crucial influence of the interface stiffness on the phase velocities of anti-plane waves. This effect consists in the decrease of the phase velocities when the interfacial bonds are weakened. The strongest effect of the interfacial sliding on the phase velocities was observed for the long-length waves belonging to the TE–TE regime. Based on the derived lower bounds for the wave numbers from which the TE–TE regime of anti-plane waves exists, we have developed the theoretical background and methodology for assessing the bond stiffness of thin plates imperfectly bonded to an elastic substrate.
Effects of polymer sealant interlayer on quality of EN AW-2024-T3 aluminum alloy lap joint prepared by friction stir welding
- Andrzej Kubit
- Hamed Aghajani Derazkola
- Piotr Myśliwiec
- Paulina Szawara
- Ján Slota
- Wojciech Macek
2024 Archives of Civil and Mechanical Engineering
This study investigates the influence of polymer interlayers on the mechanical properties and fracture behavior of friction stir welded EN AW-2024-T3 aluminum alloy joints. Aqualock AL 6002 (Adhesive_1) and 3M Adhesion Promoter 86A (Adhesive_2) were selected as polymeric sealants for EN AW-2024-T3 aluminum alloy interfaces. Force analysis revealed that the choice of polymer interlayer significantly affects the axial force during welding, with Adhesive_1 joints showing a significant reduction in force compared to other variants. The axial force during FSW in Adhesive_1 was 18% less than in Adhesive_2. Cross-sectional analysis revealed distinct features in joint morphology and defects, with Adhesive_1 joints exhibiting favorable thermal stability and minimal defects compared to Adhesive_2 joints. Tensile strength analysis showed a significant increase in load capacity for the Adhesive_1 (9470N) joint, while the Adhesive_2 (5030N) joint exhibited reduced strength due to inadequate heat flow. The Adhesive_1 joint showed a 93% increase in tensile strength compared to Adhesive_2. The mixing of Adhesive_2 with the joint area produced hard complex particles that reduced the strength of the final joint. Fracture analysis revealed complex fracture mechanisms, with Adhesive_1 joints exhibiting ductile fracture zones and Adhesive_2 joints exhibiting quasi-cleavable intergranular cracking. Microhardness distribution analysis showed variation between the joint variants, with Adhesive_2 joints showing higher microhardness in the weld nugget.