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This study presents the optimization of the friction stir welding (FSW) process using polynomial regression to predict the maximum tensile load (MTL) of welded joints. The experimental design included varying spindle speeds from 600 to 2200 rpm and welding speeds from 100 to 350 mm/min over 28 experimental points. The resulting MTL values ranged from 1912 to 15,336 N. A fifth-degree polynomial regression model was developed to fit the experimental data. Diagnostic tests, including the Shapiro-Wilk test and kurtosis analysis, indicated a non-normal distribution of the MTL data. Model validation showed that fifth-degree polynomial regression provided a robust fit with high fitted and predicted R 2 values, indicating strong predictive power. Hill-climbing optimization was used to fine-tune the welding parameters, identifying an optimal spindle speed of 1100 rpm and a welding speed of 332 mm/min, which was predicted to achieve an MTL of 16,852 N. Response surface analysis confirmed the effectiveness of the identified parameters and demonstrated their significant influence on the MTL. These results suggest that the applied polynomial regression model and optimization approach are effective tools for improving the performance and reliability of the FSW process.

This article presents an investigation of the use of machine learning methodologies for the prediction of surface roughness in milling operations, using sensor data as the primary source of information. The sensors, which included current transformers, a microphone, and displacement sensors, captured comprehensive machining signals at a frequency of 10 kHz. The signals were subjected to preprocessing using the Savitzky-Golay filter, with the objective of isolating relevant moments of active material machining and reducing noise. Two machine learning models, namely Elastic Net and neural networks, were employed for the prediction purposes. The Elastic Net model demonstrated effective handling of multicollinearity and reduction in the data dimensionality, while the neural networks, utilizing the ReLU activation function, exhibited the capacity to capture complex, nonlinear patterns. The models were evaluated using the coefficient of determination (R²), which yielded values of 0.94 for Elastic Net and 0.95 for neural networks, indicating a high degree of predictive accuracy. These findings illustrate the potential of machine learning to optimize manufacturing processes by facilitating precise predictions of surface roughness. Elastic Net demonstrated its utility in reducing dimensionality and selecting features, while neural networks proved effective in modeling complex data. Consequently, these methods exemplify the efficacy of integrating data-driven approaches with robust predictive models to improve the quality and efficiency of surface.

The aim of this study was to compare the mechanical properties of carbon-fiber-reinforced polymer (CFRP) composites produced using three popular technologies. The tests were performed on composites produced from prepregs in an autoclave, the next variant is composites produced using the infusion method, and the third variant concerns composites produced using the vacuum-assisted hand lay-up method. For each variant, flat plates with dimensions of 1000 mm × 1000 mm were produced while maintaining similar material properties and fabric arrangement configuration. Samples for testing were cut using a plotter in the 0° and 45° directions. Non-destructive tests (NDTs) were carried out using the active thermography method, demonstrating the correctness of the composites, i.e., the absence of structural defects for all variants. Static peel strength tests were carried out for samples with different directional orientations. The tests were carried out at temperatures of +25 °C and +80 °C. At room temperature, similar strengths were demonstrated, which for the 0° orientation were 619 MPa, 599 MPa and 536 MPa for the autoclave, vacuum and infusion variants, respectively. However, at a temperature of +80 °C, only the composite produced in the autoclave maintained the stability of its properties, showing a strength of 668 MPa. Meanwhile, in the case of the composite produced by the infusion method, a decrease in strength at an elevated temperature of 46.5% was demonstrated, while for the composite produced by the hand lay-up method, there was a decrease of 46.2%. For the last two variants, differential scanning calorimetry (DSC) analysis of epoxy resins constituting the composite matrices was carried out, showing a glass transition temperature value of 49.91 °C for the infusion variant and 56.07 °C for the vacuum variant. In the three-point static bending test, the highest strength was also demonstrated for the 0ᵒ orientation, and the bending strength was 1088 MPa for the autoclave variant, 634 MPa for the infusion variant and 547 MPa for the vacuum variant. The fatigue strength tests in tension at 80% of the static strength for the infusion variant showed an average fatigue life of 678.788 × 10 3 cycles for the autoclave variant, 176.620 × 10 3 cycles for the vacuum variant and 159.539 × 10 3 cycles for the infusion variant.

Titanium alloys, particularly Ti-6Al-4V, are widely used in many industries due to their high strength, low density, and corrosion resistance. However, machining these materials is challenging due to high strength at elevated temperatures, low thermal conductivity, and high chemical reactivity. This study investigates Recurrence Plot (RP) and Recurrence Quantification Analysis (RQA) to analyze tool wear during the finish turning of Ti-6Al-4V. The tests were conducted under Minimum Quantity Lubrication (MQL). Three inserts (two coated, one uncoated) were tested, and tool life was evaluated based on material removal volume. The issue of tool exploitation and process reliability is crucial, as it directly impacts machining performance. Results show that the uncoated insert outperformed the coated ones. RQA parameters indicated a stable-to-unstable transition in coated inserts but not in the uncoated insert. This suggests that recurrence analysis can monitor cutting dynamics in coated insert machining, but further research is needed for uncoated tools. This paper's novelty lies in applying RP and RQA to diagnose tool wear in titanium alloy machining under MQL conditions, a method not previously explored in this context.

This article presents a new parametric method for shaping flat transverse frame structural systems supporting thin-walled roofs made of flat sheets folded unidirectionally and transformed elastically to various shell forms. The parameterization was limited to one independent variable, that is the stiffness of the support joints. For different discrete values of simulated stiffness, the surface areas of the cross sections of the tensile and compressed elements and the section modulus of the bending elements were calculated so as to obtain the optimized work of the frame and its elements in the assumed load environment. The developed method allows for optimizing the work of frames considered as flat bar structural systems of building halls, taking into account the ultimate and serviceability limit states. The operation of the method is illustrated with an example concerning the formation of a flat frame working under a load characteristic for buildings located in a lowland area in a moderate climate. The authors intend to successively extend the method with new types of frame systems so as to obtain increasingly accurate and universal models defined by means of an increasing number of independent variables. These parameters are related to different forms and inclinations of columns and girders, and different external load types. The successive increase in the parameters defining the computational parametric model of the frame requires the use of increasingly advanced artificial intelligence algorithms to describe the static and strength performance of the buildings shaped, which makes the proposed method universal and the created structural systems effective in various external environments.

Resistance spot-welded joints are crucial parts in contemporary manufacturing technology due to their ubiquitous use in the automobile industry. The necessity of improving manufacturing efficiency and quality at an affordable cost requires deep knowledge of the resistance spot welding (RSW) process and the development of artificial neural network (ANN)- and machine learning (ML)-based modelling techniques, apt for providing essential tools for design, planning, and incorporation in the welding process. Tensile shear force and nugget diameter are the most crucial outputs for evaluating the quality of a resistance spot-welded specimen. This study uses ML and ANN models to predict shear force and nugget diameter responses to RSW parameters. The RSW analysis was executed on similar and dissimilar AISI 304 and grade 2 titanium alloy joints with equal and unequal thicknesses. The input parameters included welding current, pressure, welding duration, squeezing time, holding time, pulse welding, and sheet thickness. Linear regression, Decision tree, Support vector machine (SVM), Random forest (RF), Gradient-boosting, CatBoost, K-Nearest Neighbour (KNN), Ridge, Lasso, and ElasticNet machine learning algorithms, along with two different structures of Multilayer Perceptron, were utilized for studying the impact of the RSW parameters on the shear force and nugget diameter. Different validation metrics were applied to assess each model's quality. Two equations were developed to determine the shear force and nugget diameter based on the investigation parameters. The current research also presents a prediction of the Relative Importance (RI) of RSW factors. Shear force and nugget diameter predictions were examined using SHapley (SHAP) Additive Explanations for the first time in the RSW field. Trainbr as the training function and Logsig as the transfer function delivered the best ANN model for predicting shear force in a one-output structure. Trainrp with Tansig made the most accurate predictions for nugget diameter in a one-output structure and for shear force and diameter in a two-output structure. Depending on validation metrics, the Random forest model outperformed the other ML algorithms in predicting shear force or nugget diameter in a one-output model, while the Decision tree model gave the best prediction using a two-output structure. Linear regression made the worst ML predictions for shear force, while ElasticNet made the worst nugget diameter forecasts in a one-output model. However, in two-output models, Lasso made the worst predictions.

The lifecycle of wind turbine blades is around 20-25 years. This makes studies on the reuse of dismantled blades an urgent need for our generation; however, their recycling is very difficult due to the specific makeup of their composite material. In this study, the authors determined a concept for the reuse of turbine blade sections filled with concrete for geotechnical structures, retaining the walls, piles, or parts of their foundations. Working out detailed structural solutions to the above problem should be preceded by the identification of material parameters. In particular, getting to know the interface stress-strain characteristics is crucial. Therefore, this research focuses on the cooperation between recycled FRP composites and concrete in load-carrying, including experiments and numerical analyses. Regarding the two types of destructive stress, which may occur at the interface under both compression and bending, two types of tests were executed: the 'push-out test', modelling the interface's answer to shear stress, and the 'pull-off test', demonstrating the interface's reaction to normal stress. Additionally, the strength parameters of the materials used were tested. The numerical model for the push-out process was calibrated on the basis of the tests, and this way the shear bond strength and the coefficient of friction between the concrete and the recycled FRP laminate were assessed.

The influence of the addition of ground buckwheat hulls on the properties of biocomposite on the basis of 3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) is presented here. The changes in the material after repeated reprocessing-up to five recycling cycles-are written in the paper. Analysis of the shrinkage, water adsorption, selected mechanical properties, tensile impact strength, hardness and the microstructure of the surface layer was performed. The results show that the application of the buckwheat hulls into the biopolymer decreases the material shrinkage. It improves the material dimensional stability, as well as increases the water adsorption in the wake of the hydrophobic properties of the filler. The addition of the natural filler also leads to an increase in composite stiffness. The decrease in the tensile impact strength and the elongation at break is also noted. The reprocessing of the biocomposite initially led to a decrease in its mechanical properties, but the results stabilized after further processing cycles. This indicates the improvement of the microstructure homogeneity. The microscopic analysis shows that buckwheat hull particles were better embedded in the matrix after recycling. The increase in hardness was also noted. The PHBV-ground buckwheat hull biocomposite is characterized by stable mechanical properties and by recycling resistance, which makes it a promising material in terms of the sustainable development.

The use of the minimum quantity lubrication (MQL) method during machining leads to the reduced consumption of cooling and lubricating liquids, thus contributing to sustainable machining. To improve the properties of liquids used under MQL conditions, they are enriched with various types of micro- and nanoparticles. The purpose of this study was to investigate the effect of the addition of graphite micropowder (GMP) on tool life, cutting force components, and selected surface roughness parameters during the finish turning of the Ti-6Al-4V titanium alloy under MQL conditions. The addition of 0.6 wt% of GMP to the base liquid in machining under MQL conditions leads to an extension of tool life by 7% and 96% compared to machining with a liquid without the addition of GMP and dry machining, respectively. Mathematical models of the cutting force components and surface roughness parameters were developed, taking into account the change in cutting speed and feed. It was found that the use of a liquid with the addition of GMP extends the range of cutting parameters for which the shape of chips obtained is acceptable in terms of work safety. The novelty of this study lies in the use of a cutting fluid composed of bis(2-ethylhexyl) adipate and diester, enriched with graphite micropowder, which has not been extensively investigated for machining titanium alloys under MQL conditions.

In the first part of this publication, selected technological and strength properties of synthetic molding sand bound with sodium bentonite with the addition of a new lustrous carbon carrier (R c w , R m w , R k , W f , P w , Z, P D , P S , S LS , ρ 0 ) were determined. The introduction of polyethylene as a substitute for hydrocarbon resin, and shungite as a replacement for coal dust, demonstrated the achievement of an optimal molding sand composition for practical use in casting technology. The sand containing a new lustrous carbon carrier (SH/PE) demonstrates the highest permeability and flowability. Based on the analysis of the obtained results, it should be concluded that to achieve the desired level of the measured properties in the sand with the mixture of precursors SH/PE, the moisture content should be in the range of 1.5% to 1.7%.

By volume, cement concrete is one of the most widely used construction materials in the world. This requires a significant amount of Portland cement, and the cement industry, in turn, causes a significant amount of CO 2 emissions. Therefore, the development of concrete with a reduced cement content is becoming an urgent problem for countries with a significant level of production and consumption of concrete. Therefore, the purpose of this article is to critically investigate the possibility of using inert granite dust in combination with highly active silica fume in reactive powder concrete. The main physical and mechanical properties, such as the compressive strength at different curing ages and the water absorption, were studied using mathematical planning of experiments. The consistency and microstructure of the reactive powder concrete modified with granite dust in combination with silica fume were also analyzed. Mathematical models of the main properties of this concrete are presented and analyzed, and the graphical dependencies of the influence of composition factors are constructed. A more significant factor that affects the compressive strength at all curing ages is the silica fume content, increases in which to 50 kg/m 3 lead to a 25-40% increase in strength at 1 day of age, depending on the granite dust content. In turn, an increase in the amount of granite dust from 0 kg/m 3 to 100 kg/m 3 in the absence of silica is followed by an increase in strength of 8-10%. After 3 days of curing, the effect of granite dust becomes more significant. Increases in the 28-day strength of 25%, 46% and 56% were obtained at a content of 50 kg/m 3 of silica fume and 0 kg/m 3 , 100 kg/m 3 and 200 kg/m 3 of granite dust in concrete, respectively. It is shown that the effect of inert granite dust is more significant in combination with silica fume at its maximum content in the range of variation. The pozzolanic reaction between highly active silica and Ca(OH) 2 stimulates the formation of hydrate phases in the space between the grains and causes the microstructure of the cement matrix to compact. In this case, the granite dust particles act as crystallization centers.

High-entropy alloys are of interest to many researchers due to the possibility of shaping their functional properties by, among other things, the use of alloying additives. One approach to improving the wear resistance of the AlCoCrFeNi alloy is modification through the addition of titanium. However, in this study, an alternative solution was explored by adding vanadium, which has a completely different effect on the material's structure compared to titanium. The effect of vanadium additives on changes in the microstructure, hardness, and wear resistance of the Al 0.7 CoCrFeNi alloy. The base alloys Al 0.7 CoCrFeNi and Al 0.7 CoCrFeNiV 0.5 were obtained by induction melting. The results showed that the presence of vanadium changes the microstructure of the material. In the case of the base alloy, the structure is biphasic with a visible segregation of alloying elements between phases. In contrast, the Al 0.7 CoCrFeNiV 0.5 alloy has a homogeneous solid solution bcc structure. The presence of vanadium increased hardness by 33%, while it significantly reduced friction wear by 73%. Microscopic observations of friction marks indicate differences in the wear mechanisms of the two materials.

The influence of ball burnishing on friction and wear at elevated temperatures under fretting conditions has not yet been reported. Fretting experiments were conducted using the Optimol SRV5 tester (Optimol Instruments, Munich, Germany) under dry gross fretting conditions. A ball of WC ceramic was pressed against a disc from the titanium alloy Ti6Al4V. Experiments were carried out at elevated temperatures of 100, 200, and 300 °C. The displacement frequency was 50 Hz, the stroke was 0.1 mm, and the test duration was 15 min. The normal loads used were 40, 60, and 80 N. Ball burnishing led to a substantial reduction in the roughness height and an increase in the microhardness of samples from the titanium alloy. Burnishing, in most cases, caused an improvement in the friction resistance of sliding assemblies. Ball burnishing also led to wear reduction compared to the turned disc sample. The best tribological performance of the sliding pair was achieved for the disc sample burnished with the highest pressure of 40 MPa. An increase in temperature from 100 to 200 °C caused small changes in disc wear volumes and coefficients of friction. A further increase in temperature to 300 °C led to an increase in disc wear rates and friction coefficients.

In recent years, global climate change has caused worldwide trends in science and industry toward a focus on the development of modern technologies with reduced environmental impact, including reduced CO 2 emissions into the atmosphere. The technology for producing asphalt mixtures (AM) at lower temperatures (WMA-warm asphalt mix) using zeolite materials for the bitumen foaming process fits perfectly into these trends. Therefore, towards the development of this technology, the research presented in this paper presents the modification process of zeolite NaP1 from fly ash with silanes of different chemical structures (TEOS, MPTS, TESPT) and their application in the foaming process of bitumen modified with polymers (PMB 45/80-55). The scope of the work includes two main novelty elements: (1) the use of zeolite-silane composites in bitumen foaming and (2) polymer-modified bitumen foaming. Chemical characterisation carried out by EDS-XRF, FTIR, and XPS analysis clearly demonstrated the success of the zeolite matrix modification process, which directly resulted in textural changes. Simultaneously, mineralogical analysis carried out by XRD showed the complete retention of the initial phase composition of zeolite matrix. Further studies have shown that the application of zeolite-oxide composites results in less PMB 45/80-55 stiffening without imposing negative effects on its softening point and dynamic viscosity.

The paper presents results of experimental investigations of the influence of temperature on the effectiveness of passive vibration isolation. Two types of viscoelastic materials (butyl rubber and bituminous material) were tested. In the performed vibration analysis, the Oberst beam made out of aluminum alloy with a damping material in a Free Layer Damping (FLD) configuration was used. The experimental modal analysis was performed using the Unholtz-Dickie UDCO TA-250 vibration system. To investigate the influence of temperature on the effectiveness of passive vibration isolation, an isothermal cooling chamber (using Peltier cells) was designed and constructed. The tests were carried out in a wide frequency range from 40 Hz to 4000 Hz, at a constant sweep rate, in a temperature range from -2 °C to 22 °C. Miniature piezoelectric acceleration sensors were used to determine the acceleration of the beam and the exciter head. The analysis of accelerations of both the object and the shaker head allowed for the determination of a Frequency Response Function (FRF) for the beam. The course of FRF was used to determine the resonance frequencies and the vibration amplitudes of the beam damped with bituminous material and butyl rubber at various temperatures. The loss factor η, calculated for each resonance using the generalized half-power method (n-dB method), was used as an indicator of damping intensity. The research results presented in this work (important from scientific point of view) also have utilitarian significance and can be used in the design of more quiet and comfortable motor vehicles, railway wagons and aircraft structures.

This paper presents the properties of an SMA LA (stone matrix asphalt Lärmarmer) mixture based on the polymer-modified binder PMB 45/80-55, formed by the addition of zeolites (synthetic zeolite type Na-P1 and natural zeolite-clinoptilolite). The compositions of the SMA 11, SMA 8 LA and SMA 11 LA mixtures based on modified bitumen with PMB 45/80-55 (reference mixture) or PMB 45/80-55 with Na-P1 or clinoptilolite were determined. Their resistance to permanent deformation, water sensitivity, water permeability and susceptibility to changes in texture and skid resistance during the period of use were verified. Adding zeolites reduced the production temperature by as much as 15 °C for the SMA 11 LA mixtures and 20 °C for SMA 8 LA. The addition of zeolites did not significantly affect the resistance to permanent deformation, the water permeability or the mass loss. The mixtures with clinoptilolite were resistant to the harmful effects of water, while the mixtures with Na-P1 proved more sensitive to water. Water permeability tests showed a higher permeability for SMA 11 LA compared to SMA 8 LA due to the higher nominal aggregate size. The Cantabro test showed greater particle loss for SMA 11 LA than for SMA 8 LA. A skid resistance and macrotexture analysis indicated that the SMA LA layers required special maintenance on the road due to the clogging of pores in the mix structure.

Polymeric materials are widely used in medical engineering, and with the dynamic development of additive manufacturing (AM) technology, increasing attention is being paid to research on the mechanical strength of composite polymer structures. At the same time, the impact of sterilization on, for example, surgical templates and the influence of the sterilization process on the geometry of these parts have not been sufficiently studied. In this work, the effect of steam sterilization on samples made of polymer materials for medical applications was presented. This research was carried out on samples with normative geometry made of polyetheretherketone (PEEK) polymers produced using the Material Extrusion (MEX) AM process and acrylic formulation (MED610) produced by Jetting Modeling Technology (JMT). These materials provide biocompatibility, which makes them suitable for potential medical applications. Steam sterilization was performed in an autoclave at temperatures of 121 °C and 134 °C. The three-point bending strength properties were determined according to ISO 178 standards. An INSTRON 5967 strength testing machine was used for those tests. Surface roughness analysis (according to ISO 21920) was performed and presented in 2D and 3D surface views using the Mountains Map Software (version 6.0).

Nanocomposite flexible polyurethane foams (nFPUfs) were obtained by modifying the polyurethane formulation by adding a halloysite nano-filler in the amount of one to five parts by weight per hundred parts of used polyol (php). Flexible polyurethane (PU) foams with an open-cell structure and with a beneficial SAG factor were obtained. Premixes with nano-filler had a lower reactivity than the reference PU system. This favored the production of smaller cells, but with a more rounded shape in comparison with the REF foam without the nano-filler. During the study, the morphology and physical and mechanical properties were characterized, including apparent density, compressive stress, rebound flexibility, SAG factor, closed-cell content, and thermal stability, and compared with the properties of the unmodified reference foam. Scanning electron microscopy (SEM) showed that the cell structures of all prepared foams were open, and the cell size decreased with increasing nano-filler content. Apparent densities, SAG factors and rebound flexibilities of the foams increased with the increase of nano-filler content, while the resistance to permanent deformation showed the opposite trend. The proper selection of raw materials and optimally developed polyurethane formulations allow for obtaining environmentally friendly foams with favorable functional properties, taking into account price and the needs of sustainable development in the synthesis of flexible foams dedicated to the upholstery industry.

Magnesium alloys are an important group of materials that are used in many industries, primarily due to their low weight. Constantly increasing quality requirements make it necessary to improve the accuracy of manufactured products. In this study, the precision milling process for AZ91D and AZ31B magnesium alloys was investigated, and the results obtained with uncoated and TiB 2 -coated end mills were compared. The impact of variable cutting parameters was also investigated. Specifically, the study focused on the dimensional accuracy of the machined parts. The results showed that even though the dimensional accuracy obtained in milling both magnesium alloys was comparable, it was higher in the case of the AZ31B alloy by up to 22%. The study also demonstrated that the use of the TiB 2 coating did not have the desired effect and that higher dimensional accuracy up to 27% was obtained with the uncoated tool.

The growing demand for products made of polymeric materials, including the commonly used polypropylene (PP), is accompanied by the problem of storing and disposing of non-biodegradable waste, increasing greenhouse gas emissions, climate change and the creation of toxic products that constitute a health hazard of all living organisms. Moreover, most of the synthetic polymers used are made from petrochemical feedstocks from non-renewable resources. The use of petrochemical raw materials also causes degradation of the natural environment. A potential solution to these problems is the use of biopolymers. Biopolymers include biodegradable or biosynthesizable polymers, i.e., obtained from renewable sources or produced synthetically but from raw materials of natural origin. One of them is the poly(3-hydroxybutyrate) (P3HB) biopolymer, whose properties are comparable to PP. Unfortunately, it is necessary to modify its properties to improve its processing and operational properties. In the work, hybrid polymer nanobiocomposites based on P3HB, with the addition of chain, uncross-linked polyurethane (PU) and layered aluminosilicate modified with organic salts (Cloisite ® 30B) were produced by extrusion process. The introduction of PU and Cloisite ® 30B to the polymer matrix (P3HB) influenced the processing parameters beneficially and resulted in a decrease in the extrusion temperature of more than 10 °C. The influence of the simultaneous addition of a constant amount of PU (10 m/m%) and the different amounts of nanoadditives (1, 2 and 3 m/m%) on the compatibility, morphology and static mechanical properties of the resulted nanobiocomposites were examined. The component interactions by Fourier transformation infrared spectroscopy (FTIR) analysis, nano- and microscale structure studies using small-angle X-ray scattering (SAXS) and morphology by scanning electron microscopy (SEM) were carried out, and the hardness and tensile strength of the obtained polymer nanobiocomposites were determined. FTIR analysis identified the compatibility of the polyester matrix, PU, and organomodified montmorillonite, the greatest being 3 m/m% Cloisite30B content. The addition of PU to the polyester elasticizes the material and decreases the material's strength and ductility. The presence of nanoclay enhanced the mechanical properties of nanobiocomposites. The resulting nanobiocomposites can be used in the production of short-life materials applied in gardening or agriculture.

This paper presents a study on the use of cold plasma to reduce the roughness of the working surface of center plates of railway cars. The use of cold plasma is a promising method of surface treatment which allows for a significant reduction in roughness without changing the mechanical and chemical properties of the material. As part of the study, experiments were conducted on the treatment of center plates with cold plasma, the surface roughness was measured before and after the treatment, and the microhardness, microstructure, and chemical composition of the material were analyzed. The results of our experimental studies show that the use of cold plasma can reduce roughness by 1.4-1.6 times. At the same time, the roughness parameters Ra are reduced by 29.1-37.4%, and Rz by 29.3-39.6%. A slight increase of 2.81-3.31% in the roughness parameter Sa is also obtained after cold plasma treatment compared to the base samples. Thus, the use of cold plasma for the treatment of center plates of railway cars can significantly increase their durability and reduce the costs of manufacture or repair, making this method promising for use in the railway industry.

The high-energy ball milling process was applied to fabricate a composite material from 7075 aluminium alloy milling chips, silicon carbide, and titanium dioxide powders. Raw materials were ground, and the obtained powders were cold pressed and sintered. It was demonstrated that this method can be used in the recycling of aluminium alloy scrap characterised by a high surface-to-volume ratio, and also that chemical removal of the oxide layer from chips is not necessary. The finest particles, with 50 vol.% of their population below 36 μm, were obtained after grinding for 60 min at a 1000 rpm rotational speed. Such an intensive grinding was necessary to fabricate the compact composite material with a homogeneous microstructure and a low porosity of 0.7%. The corrosion resistance of the composites was studied in 3.5 wt.% NaCl solution using cyclic voltammetry and electrochemical impedance spectroscopy, and corrosion rates in the range of ca. 342 and 3 μA∙cm -2 were obtained. The corrosion mechanism includes aluminium alloy dissolution at the matrix/reinforcement interphase and around intermetallic particles localised within the matrix grains.

One of the key trends affecting the future of the construction industry is the issue of ecology; therefore, current activities in construction aim to reduce the use of raw materials, which is made possible by including recycled materials in composites, among other methods. This article describes the results of tests conducted using four types of epoxy composites, i.e., composites modified with waste rubber (WR), composites modified with waste polyethylene (PE) agglomerate, glycolysate obtained using polyethylene terephthalate (PET) waste, and control unmodified mortars (CUM). Selected properties of the mortars were monitored during their maturation under laboratory conditions, as well as after post-curing at elevated temperatures in the range of 60 °C-180 °C. With the increase in the reheating temperature, an increase in the flexural strength of all types of mortars was noted, with the highest more than twofold stronger than the unmodified composites. The compressive strength increased up to a temperature of 140 °C, and then decreased slightly. The highest value of 139.8 MPa was obtained using PET mortars. Post-curing also led to a slight loss of mass of all samples in the range of 0 to 0.06%. Statistical methods were employed, which made it possible to determine the post-curing temperature and composite composition for which the determined properties are simultaneously the most beneficial, especially for the prefabricated elements.

This paper presents the process of manufacturing mechanical joint components using additive manufacturing (AM) techniques such as Material Extrusion (Fused Deposition Modelling (FDM)), Material Jetting (PolyJet), and Vat Photopolymerization (VAT)/Stereolithography (SLA). Using the PolyJet technique and a photopolymer resin, spline and threaded joint components were produced. For comparative analysis, the threaded joint was also fabricated using FDM and SLA techniques. PLA material was used for the FDM technique, while photopolymer resin was utilized for the SLA process. The components produced underwent a surface analysis to evaluate the accuracy of the dimensions in relation to the nominal dimensions. For the spline connection components, the dimensional deviations recorded by a 3D scanner ranged from -0.11 to +0.18 mm for the shaft and up to 0.24 mm for the sleeve. Measurements of screw and nut diameters showed the highest accuracy for screws produced using the PolyJet technique, while the nuts exhibited the best accuracy when fabricated with the SLA method. The profile of the screw threads using a contour gauge revealed the most accurate thread profile on the screw manufactured with the PolyJet technique.

Measurements of areal (3D) surface texture using optical methods are very popular because of the short measurement time compared to the stylus tip technique. However, they are very sensitive to measurement errors. In some cases, optical measurements are not recommended. The stylus measurement method is well known and can be the reference technique for surface texture measurement. The main disadvantage is the long measuring time. This time can be shortened using higher speeds of measurement. The effect of the speed of the measurement of stylus profilometer on changes in surface texture parameters was studied. Fifty surface topographies were measured using the stylus profilometer at speeds 0.5, 1, 2, 3, 4, and 5 mm/s in the same places. Surfaces after lapping, polishing, grinding, milling, laser texturing, and two-process random surfaces were measured and analyzed. Changes in parameters caused by the increase in the traverse speed depend on the characteristics and parameters of the surfaces. The random surfaces changed more than the deterministic ones. The increase in the traverse speed from 0.5 to 1 mm/s caused small changes in the parameters.

This article presents the results of an experimental study carried out to assess the possibility of using waste wind turbine blades as retaining wall structures for slopes and trenches. The use of Vestas and LM-type blades as retaining wall components was assumed, based on 'columns' made of Vestas-type closed profiles filled with concrete and 'slabs' of fragments extracted from LM-type blades. The results of the tests and comparisons of the displacement and strain values of the components obtained using different measurement methods are presented in this paper. The force-strain and force-displacement relationships obtained from the tests were used to validate numerical models of slope protection walls and excavations designed from used wind turbine blades. According to our research, there is a high degree of variability in the strength parameters and deformation of the composite elements made from the wind turbine blades. Therefore, in the case of this type of material, characterized by a significant variation in carrying capacity, deformability, and the nature of the failures, the use of different measurement methods makes it possible to obtain much of the data necessary for assessing the reusability of wind turbine blades in building.

Correct design of the sheet metal forming process requires knowledge of the friction phenomenon occurring in various areas of the drawpiece. Additionally, the friction at the drawbead is decisive to ensure that the sheet flows in the desired direction. This article presents the results of experimental tests enabling the determination of the coefficient of friction at the drawbead and using a specially designed tribometer. The test material was a DC04 carbon steel sheet. The tests were carried out for different orientations of the samples in relation to the sheet rolling direction, different drawbead heights, different lubrication conditions and different average roughnesses of the countersamples. According to the aim of this work, the Features Importance analysis, conducted using the Gradient-Boosted Regression Trees algorithm, was used to find the influence of several parameter features on the coefficient of friction. The advantage of gradient-boosted decision trees is their ability to analyze complex relationships in the data and protect against overfitting. Another advantage is that there is no need for prior data processing. According to the best of the authors' knowledge, the effectiveness of gradient-boosted decision trees in analyzing the friction occurring in the drawbead in sheet metal forming has not been previously studied. To improve the accuracy of the model, five MinLeafs were applied to the regression tree, together with 500 ensembles utilized for learning the previously learned nodes, noting that the MinLeaf indicates the minimum number of leaf node observations. The least-squares-boosting technique, often known as LSBoost, is used to train a group of regression trees. Features Importance analysis has shown that the friction conditions (dry friction of lubricated conditions) had the most significant influence on the coefficient of friction, at 56.98%, followed by the drawbead height, at 23.41%, and the sample width, at 11.95%. The average surface roughness of rollers and sample orientation have the smallest impact on the value of the coefficient of friction at 6.09% and 1.57%, respectively. The dispersion and deviation observed for the testing dataset from the experimental data indicate the model's ability to predict the values of the coefficient of friction at a coefficient of determination of R 2 = 0.972 and a mean-squared error of MSE = 0.000048. It was qualitatively found that in order to ensure the optimal (the lowest) coefficient of friction, it is necessary to control the friction conditions (use of lubricant) and the drawbead height.

In this work, a laminate based on bioresin and natural fibers was produced. Flax fabric was selected as the natural fiber. The biocomposite was subjected to strength tests. Stress-strain characteristics and strength indicators were determined. The workability of the laminate produced was also tested using milling technology. The tests were carried out using five carbide shank cutters for different purposes. The cutters with the geometry used in the processing of polymer materials and composites, general purpose cutters, and cutters with the geometry for aluminum and with different numbers of blades were analyzed. In order to obtain information on the workability of the prepared material, machining tests with different configurations of technological parameters were carried out. For each cutter, the effect of cutting speed and feed rate on the quality of the machined surface was tested. Due to the small thickness of the laminate, the machining was carried out in one pass, as a result of which the cutting depth in each case was constant. Changes in cutting speed and feed were evenly distributed over five levels. The quality of machining was assessed in two stages. The first stage included a visual assessment of the machined surface, involving a preliminary qualification of the machining parameters. The criterion was the amount of chips, frays, burrs, etc., remaining after machining that adhered to the surface. The next stage was the measurement of the geometric structure of the surface, during which the roughness parameters were analyzed using an optical microscope with a roughness analysis attachment. Quantitative analysis was performed for the best quality composite surfaces from each measurement series. The studies showed a dependence of the quality of machining on the technological parameters used. High tool speed, regardless of the type, especially at low feed, led to the sticking of chips, which had a very delicate form. In turn, low tool speed and high feed, due to the chip thickness, favored the formation of burrs. Machining with different types of tools showed that the process progresses better for tools with sharp blade geometry. Machining with a regular and polished cutter did not show any differences in the scope of the process progress.

In the present paper, we present an electron magnetic resonance (EMR) study of Ni50.2Mn28.3Ga21.5 powders obtained from melt-spun ribbons in the milling process. We registered EMR spectra in various temperatures at the X-band. In the EMR spectra recorded for the samples taken at the beginning of the milling process, the "training effect" was observed. After 2 h of milling, this phenomenon was no longer observed. To determine the basic EMR parameters, such as linewidth, resonance field, and asymmetry parameters, the experimental data were fitted using a single metallic Lorentz line. In high-temperature regions, we observed the influence of dispersion on the shape of the spectra, but as the temperature decreased, the asymmetry of line was reduced. The shift in the resonance field value at high temperatures and the temperature dependence of the linewidth below Curie temperature indicate that the investigated samples exhibited a characteristics of a spin-glass alloy.

One of the intensively developed tools for cancer therapy is drug-releasing matrices. Polyamidoamine dendrimers (PAMAM) are commonly used as nanoparticles to increase the solubility, stability and retention of drugs in the human body. Most often, drugs are encapsulated in PAMAM cavities or covalently attached to their surface. However, there are no data on the use of PAMAM dendrimers as a component of porous matrices based on polyurethane foams for the controlled release of drugs and biologically active substances. Therefore, in this work, porous materials based on polyurethane foam with incorporated third-generation poly(amidoamine) dendrimers (PAMAM G3) were synthesized and characterized. Density, water uptake and morphology of foams were examined with SEM and XPS. The PAMAM was liquefied with polyether polyol (G441) and reacted with polymeric 4,4'-diphenylmethane diisocyanate (pMDI) in the presence of silicone, water and a catalyst to obtain foam (PF1). In selected compositions, the castor oil was added (PF2). Analogs without PAMAM G3 were also synthesized (F1 and F2, respectively). An SEM analysis of foams showed that they are composed of thin ribs/walls forming an interconnected network containing hollow bubbles/pores and showing some irregularities in the structure. Foam from a G3:G441:CO (PF2) composition is characterized by a more regular structure than the foam from the composition without castor oil. The encapsulation efficiency of drugs determined by the XPS method shows that it varies depending on the matrix and the drug and ranges from several to a dozen mass percent. In vitro biological studies with direct contact and extract assays indicated that the F2 matrix was highly biocompatible. Significant toxicity of dendrimeric matrices PF1 and PF2 containing 50% of PAMAM G3 was higher against human squamous carcinoma cells than human immortalized keratinocytes. The ability of the matrices to immobilize drugs was demonstrated in the example of perspective (Nimesulide, 8-Methoxypsolarene) or approved anticancer drugs (Doxorubicin-DOX, 5-Aminolevulinic acid). Release into the culture medium and penetration of DOX into the tested SCC-15 and HaCaT cells were also proved. The results show that further modification of the obtained matrices may lead to their use as drug delivery systems, e.g., for anticancer therapy.

The Pb, Cr, Cd, Ni, Zn, Cu, Co, As, Sr, Ba, and Zr content has been determined in the tested rock raw materials. The concentration of cadmium (Cd) was found to be elevated in all types of rock materials and was found on average to be: 1.39 mg/kg in limestones, 0.86 mg/kg-sandstones, 0.44 mg/kg-diatomites, 0.55 mg/kg-opoka rocks, 0.89 mg/kg-marls, 0.21 mg/kg-gaizes 0.42 mg/kg-kaolin clays, and 2.13 mg/kg-decalcified opoka rocks. Higher concentrations of arsenic (As) have also been recorded in sandstones and diatomites, as well as lead (Pb) in limestones and sandstones. The results obtained indicate that the anomalous level of elements is of natural origin and the results of identified secondary mineralisation processes that have affected the tested materials. Pyritization and sulfatization processes have been detected. Mineralogical research has shown that these processes can be associated with the activity of biochemical processes caused by the decomposition of the soft tissues of animal organisms and the organic substances of plant origin that fill the stylolites. It has been shown that the content of strontium (Sr) increases in geologically older Jurassic formations compared to younger Cretaceous formations, which can be used in the monitoring of building materials.

This contribution presents the results of research focused on changes in selected properties of organic-coated steel sheets in a corrosive environment of salt mist. The aim of this study was to characterise coated sheets and to analyse the influence of elevated temperature on changes in their selected properties. The methodology and experiments were chosen to simulate the accelerated ageing and to evaluate the surface of organic-coated steel sheets. During the research, the effect of artificial ageing due to increased temperature on changes in mechanical properties of coated sheets was monitored, which were determined by tensile testing according to STN EN 10002-1. The fracture surface of the test samples was analysed using a SEM. The following observations were made for the evaluation of coating by cross-cut tests according to EN ISO 2409. Corrosion tests were carried out by conducting salt spray corrosion tests according to EN ISO 9227. The test specimens were artificially sectioned using a laser beam. The results of the research experiments confirmed the assumption that the utilisation of the laser beam was convenient for the creation cross-cut test of the material. After the ageing test, only small significant changes in the basic mechanical properties of the tested materials were observed. It is necessary to take into account that there were changes in the appearance of the coating. The cross-cut test confirmed the results that the plastic-coated sheets could be utilised in salt corrosion environments.

The development of materials and the products made from them should respond to new challenges posed by market changes and also by climate change. Therefore, the objective of this investigation was to develop a method that supports the sustainable development of materials and the products made from them based on an aggregated indicator of quality and environmental load in the life cycle (QLCA). The testing and illustration of the QLCA method included a passenger car tyre and nine prototypes. These prototypes were described using eight quality criteria: season, class, size of the load index, speed index, rolling, adhesion, and external noise. Then, customer expectations regarding the importance of the criteria and satisfaction with the indicators in the current and modified states were obtained. Based on the customer assessment, the quality indicators of the prototypes were assessed. This assessment was supported by the weighted sum model (WSM) and the entropy method. Then, life cycle assessment for the reference tyre was performed using the Ecoinvent database in the OpenLCA program. LCA indicators were modelled for other prototypes, taking into account quality changes. As a result of the verification of the method, an aggregated QLCA indicator was estimated, based on which it was possible to select the most favourable (qualitatively and environmentally) prototype out of nine. This was the P4 prototype (QLCA = 0.57). The next position in the ranking was taken by P7 (QLCA = 0.43). The QLCA method can be used to determine the direction of development of materials and products in terms of their sustainable development.

The aim of this article is to provide an analysis of the influence of the type of hard anti-wear coatings on the friction behaviour of DC01 deep-drawing steel sheets. DC01 steel sheets exhibit high formability, and they are widely used in sheet metal forming operations. The tribological properties of the tool surface, especially the coating used, determine the friction conditions in sheet metal forming. In order to carry out the research, this study developed and manufactured a special bending-under-tension (BUT) friction tribometer that models the friction phenomenon on the rounded edges of tools in the deep-drawing process. The rationale for building the tribotester was that there are no commercial tribotesters available that can be used to model the phenomenon of friction on the rounded edges of tools in sheet forming processes. The influence of the type of coating and sheet deformation on the coefficient of friction (CoF) and the change in the topography of the sheet surface were analysed. Countersamples with surfaces prepared using titanium + nitrogen ion implantation, nitrogen ion implantation and electron beam remelting were tested. The tests were carried out in conditions of dry friction and lubrication with oils with different kinematic viscosities. Under dry friction conditions, a clear increase in the CoF value, with the elongation of the samples for all analysed types of countersamples, was observed. Under lubricated conditions, the uncoated countersample showed the most favourable friction conditions. Furthermore, oil with a lower viscosity provided more favourable conditions for reducing the coefficient of friction. Within the entire range of sample elongation, the most favourable conditions for reducing the CoF were provided by uncoated samples and lubrication with S100+ oil. During the friction process, the average roughness decreased as a result of flattening the phenomenon. Under dry friction conditions, the value of the Sa parameter during the BUT test decreased by 20.3-30.2%, depending on the type of countersample. As a result of the friction process, the kurtosis and skewness increased and decreased, respectively, compared to as-received sheet metal.

This work focused on obtaining a low-temperature powder coating characterized by self-healing properties. To achieve this, acrylic resin, blocked polyisocyanates (bPICs) with 1,2,4-triazole, and unsaturated commercial resin were used. The synthesis of bPICs with triazole enabled the low-temperature curing and reversible Diels-Alder (DA) reaction at 160 °C. The chemical structure of bPICs was confirmed using 1 H-NMR. The occurrence of the DA and retro-DA (rDA) reactions in the crosslinked polymer, at temperatures of 60-85 °C and 90-130 °C, respectively, was confirmed using Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and FT-IR spectroscopy. The self-healing properties of the powder coating were examined using polarized optical microscopy. Additionally, the occurrence of the DA and rDA reactions between triazole and unsaturated polyester resin was investigated through repeated self-healing tests.

The growing use of aluminum and its compounds has increased the volume of aluminum waste. To mitigate environmental impacts and cut down on manufacturing expenses, extensive investigations have recently been undertaken to recycle aluminum compounds. This paper outlines the outcomes of a study on fabricating standard EN AW-2007 alloy using industrial and secondary scrap through continuous casting. The resultant recycled bars were analyzed for their chemical makeup and examined for microstructural features in both the cast and T4 states, undergoing mechanical property evaluations. The study identified several phases in the cast form through LM, SEM + EDS, and XRD techniques: Al 7 Cu 2 Fe, θ-Al 2 Cu, β-Mg 2 Si, Q-Al 4 Cu 2 Mg 8 Si 7 , and α-Al 15 (FeMn) 3 (SiCu) 2, along with Pb particles. Most primary intermetallic precipitates such as θ-Al 2 Cu, β-Mg 2 Si, and Q-Al 4 Cu 2 Mg 8 Si 7 dissolved into the α-Al solid solution during the solution heat treatment. In the subsequent natural aging process, the θ-Al 2 Cu phase predominantly emerged as a finely dispersed hardening phase. The peak hardness achieved in the EN AW-2007 alloy was 124.8 HB, following a solution heat treatment at 500 °C and aging at 25 °C for 80 h. The static tensile test assessed the mechanical and ductility properties of the EN AW-2007 alloy in both the cast and T4 heat-treated states. Superior strength parameters were achieved after solution heat treatment at 500 °C for 6 h, followed by water quenching and natural aging at 25 °C/9 h, with a tensile strength of 435.0 MPa, a yield strength of 240.5 MPa, and an appreciable elongation of 18.1% at break. The findings demonstrate the feasibility of producing defect-free EN AW-2007 alloy ingots with excellent mechanical properties from recycled scrap using the continuous casting technique.

In this article, an attempt was made to join DP600 steel and Ti6Al4V titanium alloy sheets by resistance spot-welding (RSW) using an interlayer in the form of Cu and Au layers fabricated through the cold-spraying process. The welded joints obtained by RSW without an interlayer were also considered. The influence of Cu and Au as an interlayer on the resulting microstructure as well as mechanical properties (shear force and microhardness) of the joints were determined. A typical type of failure of Ti6Al4V/DP600 joints produced without the use of an interlayer is brittle fracture. The microstructure of the resulting joint consisted mainly of the intermetallic phases FeTi and Fe 2 Ti. The microstructure of the Ti6Al4V/Au/DP600 joint contained the intermetallic phases Ti 3 Au, TiAu, and TiAu4. The intermetallic phases TiCu and FeCu were found in the microstructure of the Ti6Al4V/Cu/DP600 joint. The maximum tensile/shear stress was 109.46 MPa, which is more than three times higher than for a welded joint fabricated without the use of Cu or Au interlayers. It has been observed that some alloying elements, such as Fe, can lower the martensitic transformation temperature, and some, such as Au, can increase the martensitic transformation temperature.

This paper presents the results of an experimental modal analysis of a beam covered by polymer materials used as a passive vibration isolation. The main aim of this study was to determine the damping properties of selected viscoelastic materials. In order to check the damping properties of tested materials, an experimental modal analysis, with the use of an electrodynamic vibration system, was performed. In this study, four kinds of specimens were considered. In the first step of the work, the beam made out of aluminum alloy was investigated. Afterwards, a cantilever beam was covered with a layer of bitumen-based material acting as a damper. This method is commonly known as a free layer damping treatment (FLD). In order to increase the damping capabilities, the previous configuration was improved by fixing a thin aluminum layer directly to the viscoelastic core. Such a treatment is called constrained layer damping (CLD). Subsequently, another polymer (butyl rubber) in the CLD configuration was tested for its damping properties. As a result of the performed experimental modal analysis, the frequencies of resonant vibrations and their corresponding amplitudes were obtained. The experimental results were used to quantitatively evaluate the damping properties of tested materials.

This study involved the optimization of the molded pieces manufacturing process from a poly-3-hydroxybutyrate-co-3-hydroxyvalerate biocomposite containing 30% wood flour by mass. The amount of wood flour and preliminary processing parameters were determined on the basis of preliminary tests. The aim of the optimization was to find the configuration of important parameters of the injection process to obtain molded pieces of good quality, in terms of aesthetics, dimensions, and mechanical properties. The products tested for quality were dog bone specimens. The biocomposite was produced using a single-screw extruder, whereas molded pieces were made using an injection molding process. The Taguchi method was applied to optimize the injection molding parameters, which determine the products quality. Control factors were selected at three levels. The L27 orthogonal plan was used. For each set of input parameters from this plan, four processing tests were performed. The sample weight, shrinkage, elongation at break, tensile strength, and Young's modulus were selected to assess the quality of the molded parts. As a result of the research, the processing parameters of the tested biocomposite were determined, enabling the production of good-quality molded pieces. No common parameter configuration was found for different optimization criteria. Further research should focus on finding a different range of technological parameters. At the same time, it was found that the range of processing parameters of the produced biocomposite, especially processing temperature, made it possible to use it in the Wood Polymer Composites segment.

This work presents issues related to selected errors accompanying spatial measurements of surface roughness using contact profilometry. The influence of internal heat sources, such as engines or control electronics, on the thermal expansion of the drive responsible for the measurement probe's movement in the X-axis direction was investigated. In terms of starting measurements on a thermally unstable device, the synchronization error of individual profile paths was 16.1 µm. Based on thermographic studies, the time required for full thermal stabilization of this drive was determined to be 6-12 h from when the device was turned on. It was demonstrated that thermal stabilization of the profilometer significantly reduced positioning errors of the measurement probe on the X-axis. Thermal stabilization time should be determined individually for a specific device variant. This research also determined how changes in the center of gravity caused by the measurement probe's movement affected the overall rigidity of the profilometer structure and the leveling of the tested surface. Laser interferometry was used for this purpose. The determined vulnerability of the profilometer structure was 0.8 µm for a measurement section of 25 mm. Understanding the described relationships will reduce errors associated with conducting measurements and preparing equipment for tests. Additionally, it will enable the correct evaluation of surface geometry.

Protection against fire and the corrosion of metals is necessary to ensure human safety. Most of the fire and corrosion inhibitors do not meet the ecological requirements. Therefore, effective and ecological methods of protecting metals are currently a challenge for researchers. In this work, the influence of hexakis(4-(hydroxymethyl)phenoxy)cyclotriphosphazene (HHPCP) on the characteristics of powder coatings was examined. The coatings' properties were investigated by measuring the roughness, hardness, adhesion to the steel surface, cupping, gloss, scratch resistance, and water contact angle. The thermal stability was studied by furnace test and TGA analysis. The corrosion resistance test was carried out in a 3.5% NaCl solution. The distribution of phosphazene-derived segments in the coating was examined by GD-EOS analysis. Modified coatings show better corrosion and thermal resistance and can be used for the protection of the steel surface. Their better corrosion resistance is due to the electroactive properties of the phosphazene ring and its higher concentration at the coating surface, confirmed by GD-EOS analysis. The increase in thermal resistance is due to the effect of the formation of phosphoric metaphosphoric and polyphosphoric acids during the decomposition of HHCPC, which remain in the condensed char phase and play a crucial role in surface protection.

This paper presents the long-term, holistic results of research into an innovative heat accumulator based on an organic phase-change material in the form of a mixture of aliphatic alkanes, molecular silica sieves, carbon recyclate and epoxy and cement matrices. The research included chemical testing of vacuum soaking of molecular silica sieves with a liquid phase-change material. The results proved an improvement in the heat storage efficiency of the heat accumulators due to the addition of carbon recyclate by 28%, while increasing the heat storage time by 134 min, and a reduction in PCM leakage due to the use of molecular silica sieves. In addition to its cognitive scientific value, another research objective of the work achieved was to obtain response functions in the form of approximating polynomials. They provide a useful, validated and verified tool to predict the physical and chemical characteristics of heat accumulators with different contents of individual components. As part of the ongoing research, technical problems related to leak-proofing assurance and matrix selection for organic phase-change materials were also solved. The solution presented is in line with the issues of efficient use of renewable energy, low-carbon and energy-efficient circular economy.

During co-action between contact elements in reciprocating motion, different working conditions exist in outer and inner zones of stationary elements. Because the tribological effects of surface texturing depend on the operating conditions, various dimple patterns were created in the middle part of the steel disc and near the reversal points. The behaviors of variable dimple patterns were compared with those of uniform texturing and untexturing. It was found that the dimple patterns in the middle disc zone depended on the resistance to motion. The best tribological behavior was obtained for a pit area ratio of 13% and diameter of 0.4 mm in the inner zone, and pit area ratio of 3% and diameter of 0.2 mm in the outer zones. Low resistance to motion and the smallest friction variation of all tested sliding pairs were achieved. For the same pit area ratio of 13% in a disc of 0.4 mm, the dimple diameter behaved better than in the 0.2 mm diameter disc. The greatest decrease in the coefficient of friction of 85% compared to untextured sliding pair was achieved for uniform laser texturing with a pit area ratio of 13% and dimple diameter of 0.4 mm, when the normal load was 40 N and frequency of displacement was 20 Hz., Competing Interests: The authors declare no conflict of interest.

This study addresses the critical need for efficient and recyclable photocatalysts for water treatment applications by presenting a novel approach for the synthesis and characterization of copper (I) oxide (Cu 2 O) nanoparticles modified with ascorbic acid (Cu 2 O/AA). The motivation for this research stems from the increasing concern about environmental pollution caused by organic pollutants, such as Brilliant Cresyl Blue (BCB), and the necessity for sustainable solutions to mitigate this issue. Through comprehensive characterization techniques including Ultraviolet-Visible spectroscopy (UV-Vis), Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), zeta potential measurements, and Brunauer-Emmett-Teller (BET) analysis, we demonstrate a significant modification to the electronic structure, enhancing the photocatalytic activity of Cu 2 O/AA. BET analysis revealed a mesoporous structure with a specific surface area of 2.7247 m 2 /g for Cu 2 O/AA, further emphasizing its potential for enhanced catalytic performance. The photocatalytic degradation studies showcased remarkable efficiency improvements, with degradation coefficients of 30.8% and 73.12% for Cu 2 O NPs and Cu 2 O/AA NC, respectively, within a 120 min timeframe. Additionally, recyclability experiments indicated sustained efficiency over five consecutive cycles, with both catalysts retaining crystalline integrity. These findings underscore the promising potential of Cu 2 O/AA nanoparticles as highly efficient and recyclable photocatalysts for the degradation of organic pollutants, offering superior performance compared to pure Cu 2 O NPs and addressing the pressing need for sustainable water treatment solutions.

Geopolymers are binder materials that are produced by a chemical reaction between silica or aluminum compounds with an alkaline activating solution. Foamed geopolymer materials are increasingly being cited as a viable alternative to popular organic insulation materials. Since the foaming process of geopolymers is difficult to control, and any achievements in improving the performance of such materials are extremely beneficial, this paper presents the effect of the addition of basalt powder on the properties of foamed geopolymers. This paper presents the results of physicochemical studies of fly ash and basalt, as well as mechanical properties, thermal properties, and structure analysis of the finished foams. The scope of the tests included density tests, compressive strength tests, tests of the thermal conductivity coefficient using a plating apparatus, as well as microstructure tests through observations using light and scanning microscopy. Ground basalt was introduced in amounts ranging from 0 to 20% by mass. It was observed that the addition of basalt powder contributes to a reduction in and spheroidization of pores, which directly affect the density and pore morphology of the materials tested. The highest density of 357.3 kg/m 3 was characterized by samples with a 5 wt.% basalt powder addition. Their density was 14% higher than the reference sample without basalt powder addition. Samples with 20 wt.% basalt addition had the lowest density, and the density averaged 307.4 kg/m 3 . Additionally, for the sample containing 5 wt.% basalt powder, the compressive strength exceeded 1.4 MPa, and the thermal conductivity coefficient was 0.1108 W/m × K. The effect of basalt powder in geopolymer foams can vary depending on many factors, such as its chemical composition, grain size, content, and physical properties. The addition of basalt above 10% causes a decrease in the significant properties of the geopolymer.

The crack resistance of concrete structures with low reinforcement ratios requires a broader examination. It is particularly important in the case of foundations working in changing subsoil conditions. Unfavorable phenomena occurring in the subsoil (e.g., ground subsidence, landslips, non-uniform settlement) can lead to unexpected cracking. Therefore, it is necessary to check the effectiveness of the low reinforcement provided. As there are limited studies on lightly reinforced concrete structures, we performed our own experimental investigation and numerical calculations. In the beams analyzed, the reinforcement ratio varied from 0.05% to 0.20%. It was found that crack resistance in concrete members depends on the reinforcement ratio and steel bar distribution. A comprehensive method was proposed for estimating the crack resistance of lightly reinforced concrete members in which both the reinforcement ratio and the reinforcement dispersion ratio were taken into account. Furthermore, the method considered the size effect and the fracture properties of concrete. The proposed method provides the basis for extrapolation of the test results obtained for small elements and conclusions for members with large cross-sections, such as foundations, which frequently use lightly reinforced concrete.

In this article, the practical issues connected with guided wave measurement are studied: (1) the influence of gluing of PZT plate actuators (NAC2013) on generated elastic wave propagation, (2) the repeatability of PZT transducers attachment, and (3) the assessment of the possibility of comparing the results of Laser Doppler Vibrometry (LDV) measurement performed on different 2D samples. The consideration of these questions is crucial in the context of the assessment of the possibility of the application of the guided wave phenomenon to structural health-monitoring systems, e.g., in civil engineering. In the examination, laboratory tests on the web of steel I-section specimens were conducted. The size and shape of the specimens were developed in such a way that they were similar to the elements typically used in civil engineering structures. It was proved that the highest amplitude of the generated wave was obtained when the exciters were glued using wax. The repeatability and durability of this connection type were the weakest. Due to this reason, it was not suitable for practical use outside the laboratory. The permanent glue application gave a stable connection between the exciter and the specimen, but the generated signal had the lowest amplitude. In the paper, the new procedure dedicated to objective analysis and comparison of the elastic waves propagating on the surface of different specimens was proposed. In this procedure, the genetic algorithms help with the determination of a new coordinate system, in which the assessment of the quality of wave propagation in different directions is possible.

The automobile industry relies primarily on spot welding operations, particularly resistance spot welding (RSW). The performance and durability of the resistance spot-welded joints are significantly impacted by the welding quality outputs, such as the shear force, nugget diameter, failure mode, and the hardness of the welded joints. In light of this, the present study sought to determine how the aforementioned welding quality outputs of 0.5 and 1 mm thick austenitic stainless steel AISI 304 were affected by RSW parameters, such as welding current, welding time, pressure, holding time, squeezing time, and pulse welding. In order to guarantee precise evaluation and experimental analysis, it is essential that they are supported by a numerical model using an intelligent model. The primary objective of this research is to develop and enhance an intelligent model employing artificial neural network (ANN) models. This model aims to provide deeper knowledge of how the RSW parameters affect the quality of optimum joint behavior. The proposed neural network (NN) models were executed using different ANN structures with various training and transfer functions based on the feedforward backpropagation approach to find the optimal model. The performance of the ANN models was evaluated in accordance with validation metrics, like the mean squared error (MSE) and correlation coefficient (R 2 ). Assessing the experimental findings revealed the maximum shear force and nugget diameter emerged to be 8.6 kN and 5.4 mm for the case of 1-1 mm, 3.298 kN and 4.1 mm for the case of 0.5-0.5 mm, and 4.031 kN and 4.9 mm for the case of 0.5-1 mm. Based on the results of the Pareto charts generated by the Minitab program, the most important parameter for the 1-1 mm case was the welding current; for the 0.5-0.5 mm case, it was pulse welding; and for the 0.5-1 mm case, it was holding time. When looking at the hardness results, it is clear that the nugget zone is much higher than the heat-affected zone (HZ) and base metal (BM) in all three cases. The ANN models showed that the one-output shear force model gave the best prediction, relating to the highest R and the lowest MSE compared to the one-output nugget diameter model and two-output structure. However, the Levenberg-Marquardt backpropagation (Trainlm) training function with the log sigmoid transfer function recorded the best prediction results of both ANN structures.

This paper presents the methodology of measuring chip temperature in the cutting zone in the rough milling of magnesium alloys. Infrared measurements are taken to determine the effect of variable cutting speed, feed per tooth, and depth of cut on the maximum temperature of chips. Thermal images of chip temperature for a generated collective frame and corresponding histograms are presented. Chip temperatures are presented in numerical terms as median and average values; maximum and minimum values; range; and standard deviation. Box plots are also shown for selected machining conditions. The problems arising during signal recording with a mean emissivity coefficient ε = 0.13, a value which is dedicated during machining magnesium alloys, are discussed in detail. Chip temperatures obtained in the tests do not exceed approx. 420 °C. Therefore, the dry rough milling process carried out with carbide tools with different blade geometries can be considered safe for a wide range of machining parameters. The proposed methodology of chip temperature measurement and result processing is a new and effective approach to safety assessment in the dry milling of magnesium alloys.

This project's objective was to create a circular economy in the composites sector by examining the possibility of using wind turbine blade composite materials to construct noise-absorbing barriers for roads. The possibility of constructing road noise barrier panels from components obtained from turbine blades was conceptually examined, and the geometry and construction of wind turbine blades were evaluated for their suitability as filler components for panels. The tensile strength parameters of two types of composites made from windmill blades-a solid composite and a sandwich type-were established based on material tests. The strength of the composite elements cut from a windmill propeller was analyzed, and a three-dimensional numerical model was created using the finite element method. The strength values of the composite used to construct the noise barriers were compared with the stresses resulting from loads operating on the road noise barriers, as determined in compliance with current standards. It was discovered that acoustic screens composed of composite materials derived from wind turbine blades may withstand loads associated with wind pressure and vehicle traffic with sufficient resistance. In order to evaluate the environmental benefits resulting from the use of composite material made from wind turbine blades to make noise barriers, this study presents the values of the embodied energy and embodied carbon for several types of road noise barriers using life cycle assessment.