This study evaluates the flexural behavior of pultruded glass fiber (GF) reinforced thermoplastic composites at elevated temperatures, based on polyphenylene sulfide (PPS), polyamide (PA6), and polypropylene (PP) matrix. The profiles were produced from preconsolidated composite tapes which were fabricated through the melt-impregnation process and then consolidated using pultrusion. Flexural tests conducted within the range of 21 °C to 280 °C showed distinct differences in thermal-mechanical performance of tested profiles. The GF/PPS composite profiles showed the highest thermal stability, maintain the flexural strength of 34.6 MPa at 260 °C, and over 50% of initial stiffness at 160 °C. The GF/PA6 profiles exhibited superior strength performance at room temperature which reached a value of 447.7 MPa and displayed moderate high-temperature resistance to test conditions. The GF/PP profiles showed performance decline which occurred at temperatures beyond 120 °C. The thermogravimetric analysis TGA and dynamic mechanical analysis DMA demonstrated that GF/PPS composites exhibited superior thermal resistance because they retained their original decomposition point until 374 °C and their glass transition point until 109 °C. Mahieux and Bosze models accurately described GF/PPS and GF/PA6 composite behavior whereas the Ha-Springer and Gibson models showed better results for GF/PP composite rapid degradation. The results underscore the importance of proper matrix selection and modeling accuracy for high-temperature composite design.

The paper investigates the microstructure of bidirectional pultruded thermoplastic (E-glass reinforced polypropylene) composites, defects (fibre misorientation and voids) and their effect on the mechanical properties. The pultruded profile with transversely reinforced plies meets the EN 13,706-3 requirements to mechanical performance of profiles for structural purposes. High pressure and deformations in the die create a danger of fibres distortions, which can compromise mechanical properties, putting them below the requirements. The purpose of the present work is evaluation of these distortions and the level of downgrading of the properties. The research uses X-ray computed tomography of 0 degrees/90 degrees reinforced pultruded plates with different ratio between the 0 degrees and 90 degrees layers. The following features are analysed: orientation of the fibres; void percentage, size; resin pockets; local fibre volume fraction. The specified fibre directions are well realised in the final profile, with a deviation of 90 degrees fibres at the profile edges up to similar to 30 degrees for the sample with 5:6 proportion of 0 degrees and 90 degrees layers. Misalignment of 0 degrees fibres is within 2 degrees - 4 degrees range. The stiffness of the profiles was estimated with orientation averaging method. The calculations show that the deviations from the ideal bidirectional microstructure bring significant changes of the laminate stiffness only for 5/6 laminate (drop in 0 degrees stiffness about 20 %); for 7/4 and 9/2 laminates the effect of the fibre misalignment and other imperfections on the plate stiffness is not significant. The uncertainty in the mechanical properties is recommended to be used in quality assessment and parts design.

Today, composite profiles of constant cross section are widely used in advanced engineering structures. The use of composite profiles in window and door structures can reduce thermal bridging and reduce energy consumption for heating and cooling. This article focuses on the production of new, thermoplastic-based structural pultruded profiles and their application in a PVC (polyvinylchloride) window structure as a reinforcement. The heat transfer model was developed to determine die temperature and pulling speed for pultrusion of the 30 × 20 × 3.5 mm tube and a 31.5 × 25.0 × 3.5 mm channel from tapes. The microscopy results demonstrated full consolidation of all tapes in the material, thus confirming proper selection of pultrusion parameters. The mechanical tests results of the welded angle joint show that the window structure with composite reinforcement can be twice as strong as the steel reinforced one. This was achieved by welding the composite reinforcement simultaneously with welding of the PVC frame on a butt welding machine. The results of the hot box test show that the U-value of the window sash and frame with the composite reinforcement is 12% lower than that of a window with a steel reinforcement. The U-value of the window with composite reinforcement is 1.47 W/(m2·K), and that of the steel reinforced window is 1.55 W/(m2·K). Thus, the windows with composite reinforcement have low thermal transmittance complying with building regulations in various countries, and their use is permitted in northern climatic zones.

Despite the advantages of thermoplastic resin, pultrusion process has struggled to create bidirectional laminates, resulting in weaknesses in joint connections and transverse properties. To tackle this issue, the study focuses on developing a methodology for pultruding bidirectional laminates. Initially, two types of sheet thermoplastic prepreg of glass fiber and polypropylene were produced: one with transverse (90°) orientation of fibers and another with longitudinal (0°) orientation of fibers. These sheets are then integrated into a single pack where fibers are oriented both transversely and longitudinally, and fed into the pultrusion machine. The resulting strip profiles (75 × 3.5 mm) demonstrate threefold increase in pin-bearing strength and transverse properties, showing a considerable promise for applications that demand robust joint connections and dimensional stability. The addition of transversely reinforced plies makes it possible for the pultruded profile to meet the EN 13706-3 requirements to mechanical performance. The bidirectional thermoplastic profiles produced in this study demonstrated high mechanical properties and are suitable for use in composite structures with bolted joints.

The design of lightweight composite structures is often limited by the performance and weight of joining methods, yet their long-term fatigue behavior remains largely unexplored. This study experimentally investigates the static and fatigue behavior of composite joints fastened with pultruded glass fiber/polypropylene (GF/PP) rivets, comparing their performance to bolted, adhesively bonded, and hybrid joints under tension–tension loading. While riveted joints showed lower absolute strength than bolted and hybrid joints, they offered the highest specific joint strength, nearly three times that of their bolted counterparts. This presents a clear design advantage for mass-sensitive applications. In fatigue, the riveted joints exhibited superior relative performance, reflected in a significantly flatter normalized F-N curve slope and thus a lower damage rate compared to the adhesive and hybrid joints. The hybrid configuration demonstrated a synergistic effect in static strength; however, its fatigue performance was dominated by the adhesive’s high damage rate. Riveted joints reached an endurance limit of one million cycles at 50% of their ultimate load. Typical failure modes were rivet head debonding or rivet body shear. Crucially, this behavior enables a fail-safe design philosophy by protecting the primary composite structure, a distinct advantage over the laminate-damaging failure modes of bolted joints.

The electric and magnetic frequency rearrangement of a Bragg resonance in the spectrum of spin waves in a magnonic crystal in the form of 100-nm-thick yttrium iron garnet film with attached 10-nm-thick platinum strips is reported. The effect of the spin current on the position of the Bragg band gap depends on the polarity of the voltage applied to the platinum strips. The positive voltage does not affect the band gap position, while the applied negative voltage lowers the band gap by about of 5 MHz. At frequencies outside the band gap, depending on the polarity of the voltage applied to platinum, either the enhancement or suppression of the spin wave is observed.

This study investigates the long-term durability of polyamide (PA) based pultruded thermoplastic composites reinforced with basalt and glass fibers. Composite profiles were manufactured by pultrusion and subjected to hydrothermal aging in distilled water and in alkaline solutions for up to 120 days at temperatures of 20 °C and 40 °C. Mechanical properties were evaluated by way of flexural strength and interlaminar shear strength (ILSS) testing. Moisture absorption was evaluated using a Fickian model. Initial testing revealed superior mechanical performance of basalt fiber reinforced polyamide (BFRPA) composite, with flexural strength and ILSS values reaching 518 MPa and 40.2 MPa, respectively, compared to 385 MPa and 28.3 MPa for glass fiber reinforced polyamide (GFRPA). Following extended immersion in alkaline solution at 40 °C, the flexural strength of BFRPA was maintained at 164 MPa, corresponding to nearly 32 % of its original value (518 MPa), while that of GFRPA declined to 136 MPa, equivalent to about 35 % of its initial 385 MPa. Basalt fiber reinforced polyamide composite absorbed water faster but retained less moisture at equilibrium, likely due to its porous structure and presence of stable oxides improving its chemical resistance in adverse environments. These results demonstrate superior durability of basalt fiber reinforced polyamide composites in chemically aggressive environments and attest to their suitability for long-term structural applications in marine, civil, and industrial sectors.

Nonlinear-optical effects in magnetic composite nanostructures are of fundamental and practical interest. Here we study, on the micro- and macro-scales, the nonlinear-optical and magnetooptical response of metasurfaces made of arrays of magnetic Co/Au plasmonic particles on the crystalline garnet layer. We find a manyfold enhancement of the efficiency of the optical second harmonic generation as well as a strong modification of the magnetooptical response of this metasurface as compared to the pure garnet film. Numerical modelling of the local electromagnetic field confirms these findings.

We experimentally determined the decrease of residual compressive strength of the pultruded glass-fiber laminate after tension-compression cyclic loading. The adapted Arcan rig was used for tension-compression fatigue tests. The cyclic load was applied with the critical stress ratio R=−0.87. The residual compressive strength was determined after applying the predefined number of loading cycles with the stress amplitudes of 242 MPa and 173 MPa. The results indicated that the residual compressive strength was reduced about 20% at 77% of fatigue life under the stress amplitude of 242 MPa and at 83% of fatigue life under the stress amplitude of 173 MPa. The microstructural analysis showed that the crack growth path and failure mode depend on the stress amplitude.

This paper investigates innovative approaches for enhancing the structural integrity of form-found shell structures with a focus on rib-based reinforcements. It discusses the significance of ribs in enhancing stability and addressing the sensitivity of form-found structures to various loads. Traditional methods such as increasing shell thickness or introducing supports often compromise efficiency and aesthetics. A more intelligent approach involves reinforcing the shell with ribs and advanced materials. Diverse rib patterns are presented, including geometric, biomimetic, and topological optimization-inspired designs, each adhering to a 50% volume constraint, when compared to the original shell. Physical testing and numerical simulations demonstrate that these rib patterns significantly increase stiffness and buckling resistance. The findings presented in the paper suggest that combining form-finding methodologies with well-designed rib patterns can create sustainable and resilient structures, contributing to a reduction in both the consumption of materials and the environmental impact of these structures.

The paper presents the results of theoretical and experimental research aimed at improving the efficiency of blade machining of heat-resistant and heat-resistant chrome-nickel alloys on the basis of application of high-entropy coatings on metal-cutting tools obtained by using high-entropy target cathodes for their application. Methodologically, the work was carried out in several interrelated consecutive stages: development and obtaining of high-entropy coatings with subsequent study of their properties and composition; development of technology and modes of application of high-entropy wear-resistant coatings; carrying out high-temperature tribotechnical tests and carrying out wear resistance studies during milling.

The main features of the nonlinear pulse propagated in iron-yttrium-garnet magnonic crystal with thickness 100 nm and a periodic system of grooves on the surface are studied. We have demonstrated the possibility of the formation of gap solitons at a frequency inside the band gap of the magnonic crystal when the input signal power is increased. A further increase in the duration and power of the input pulse leads to the formation a series of gap solitons with a duration of about 10 ns. We have discovered that the threshold power of the gap solitons' generation is determined by the magnitude of the magnetic field.

Type 2 diabetes mellitus (T2DM) is accompanied by halogenative stress resulting from the excessive activation of neutrophils and neutrophilic myeloperoxidase (MPO) generating highly reactive hypochlorous acid (HOCl). HOCl in blood plasma modifies serum albumin (Cl-HSA). We studied the formation of neutrophil extracellular traps (NETs) in the whole blood and by isolated neutrophils under the action of Cl-HSA. It was found that Cl-HSA induces neutrophil priming and NETosis. MPO-containing as well as MPO-free NETs were found. These NETs with different composition can be a product of NETosis of one and the same neutrophil. NET formation in neutrophils with vacuolated cytoplasm was detected. In the presence of Cl-HSA, acceleration of NET degradation was observed. Accelerated NET degradation and neutrophil priming can be the factors contributing to the development of complications in T2DM.

NETosis, i.e., the formation of neutrophil extracellular traps (NET), and neutrophil autophagy are important elements in the pathogenesis and the development of complications of type 2 diabetes mellitus (T2DM). Therefore, the search of drugs that can regulate the level of NETosis and autophagy in T2DM is relevant. Here we studied an ex vivo NET formation and neutrophil death in whole blood from healthy subjects upon the addition of glucose up to a high concentration of 15 mM or/and the phorbol ester PMA (phorbol-12-myristate-13-acetate). Their individual and combined action caused neutrophil death and an increase in NET content. It can be hypothesized that this resulted from activation of NETosis and autophagy. It was also shown that this activation of NETosis and autophagy is completely prevented by daily intake of 1000 IU vitamin D3 for 14 days. Therefore, vitamin D3 supplementation can be considered as a preventive measure against the development of T2DM complications.

This article covers the problem of improving the wear resistance of cutting tools. This problem can be solved by modifying the surface layer of the cutting edge of the tool by synthesizing wear-resistance coatings made of high-entropy alloys. Despite the significant interest in high-entropy alloys in our country and abroad, the problems of high-entropy coating synthesis require detailed revision and experimentation. This paper presents a synthesis procedure for high-entropy coatings using the vacuum ion-plasma magnetron sputtering in the ionic escorting conditions. To obtain high-entropy coatings, the authors used a cathodic target made of a high-entropy Ti–Zr–Cr–Ni–W–Mo–Nb alloy produced with spark plasma sintering. The production processes of applying high-entropy coatings for an upgraded NNV-type unit were determined in experiments. The authors present the results of experiments confirming the possibility of obtaining high-entropy coatings using the vacuum ion-plasma magnetron sputtering method with a high-entropy cathodic target made by the spark-plasma sintering method. They studied the impacts of the vacuum ion-plasma synthesis modes on the properties and structure of high-entropy coatings. The results confirm the feasibility of producing high-entropy coatings using the vacuum ion-plasma magnetron sputtering method with a high-entropy target cathode made with the spark plasma sintering method to improve the operating properties of cutting tools.

The main goal of the work is to simulate heat transfer in structural elements of an aircraft under random temperature changes of its outer surface due to rapid changes in environmental parameters. In this case, to model the heat transfer a one-dimensional boundary value problem of the third kind is taken for the heat conduction equation. Random disturbances are specified at the boundary corresponding to the outer surface. The numerical solution is based on an application of a Galerkin method. Modeling the random disturbances of the external environment is carried out using a Wiener integral in a system of differential equations written in integral form. Calculations for a problem with a known exact solution show that when moving away from the boundary with random disturbances, the numerical solution of the boundary value problem with disturbances converges to the known exact solution of the undisturbed boundary value problem. Based on an expansion of the solution to the boundary value problem in trigonometric functions, theoretical estimates are obtained for the influence of a disturbance on the outer surface as a function of the wall thickness and the disturbance magnitude.

Multi-pulse femtosecond laser irradiation of a monolayer of polystyrene microspheres deposited on a polystyrene substrate leads to the formation of carbon nanomaterial exhibiting broadband excitation-dependent luminescence both within the microspheres and in the substrate. Initial polystyrene substrate and microspheres are transparent at the laser wavelength (800 nm). Peak intensity of the laser irradiation focusing by the microspheres reaches 1013 W/cm2, resulting in multiphoton absorption followed by ionization and further carbonization processes. Raman spectroscopy and transmission electron microscopy analysis show that carbonization products contain carbon crystalline nanoobjects.

Co/Pt multilayers with perpendicular magnetic anisotropy were locally irradiated with a focused beam of He+ ions to change the magnetic properties of the sample in strictly defined regions. Irradiated regions of 100-400-nm diameter served as pinning centers for chiral magnetic textures, resulting in the formation of magnetic skyrmions of the same diameter. The magnetization topology of such skyrmions was studied by Lorentz transmission electron microscopy. It was found that the helicity of skyrmions depended on its diameter and the ion irradiation fluence. Both Bloch-type skyrmions and N & eacute;el-type skyrmions, as well as skyrmions of the intermediate type, were observed. We assume that this behavior is due to a change in the balance of the magnetostatic energy and the Dzyaloshinskii-Moriya energy, which is confirmed by micromagnetic simulations.

A highly soluble Au(I) gold precursor is used to produce a nanocomposite material consisting of a polystyrene matrix and gold nanoparticles. Irradiation of such a material with nanosecond laser pulses at the plasmon resonance wavelength leads to the formation of highly luminescent black spots containing amorphous carbon, as confirmed by HR TEM analysis. A simple model, based on laser heating of a nanoparticle to a temperature of more than 2000 K and stabilization of this temperature by the endothermic process of polystyrene carbonization, fits well the dependence of the luminescent signal increment on the laser fluence.