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As an environmentally friendly and renewable energy solution, wind power is rapidly gaining favour worldwide due to its gentle impact on the environment. Nevertheless, the potential environmental risks posed by discarded wind turbine blades still need to be brought to our attention. Therefore, exploring ways to recycle and reuse discarded wind turbine blades has become an urgent task in the field of environmental protection. This study focuses on the incorporation of recycled glass fibres from crushed wind turbine blades into concrete to assess their benefits in engineering practice. In this study, we used four different particle sizes of recycled glass fibres, 0-5mm, 5-10mm, 10-15mm and 15-20mm, and incorporated them into the concrete at four different admixture levels of 0.2%, 0.4%, 0.6% and 0.8%. By comprehensively examining its workability, mechanical properties and microstructure, we found that although the incorporation of glass fibres reduced the apparent density, slump and compressive strength of the concrete to a certain extent, it significantly improved the split tensile and flexural strengths of the concrete, as well as effectively improved the brittleness of the material and enhanced its toughness. These findings reveal the feasibility of recycling glass fibres from decommissioned wind turbine blades and applying them to concrete. This study not only opens up a new path for environmentally friendly recycling and reuse of wind turbine blades, but also provides a valuable reference for practical engineering applications, with significant social and economic benefits.

The elaborated paper presents a series of methodologies with which the dynamic characteristics (damping coefficient, damping factor) can be determined, depending on the working conditions, of a hyperelastic material using vibration theory. These methodologies can be extended to characterize any type of hyperelastic material. The main aim of this work is to develop experimental technology and methodology to characterize this type of materials like rubber to establish a series of dynamic factors like damping factor, transmissibility at resonance, pulsation at resonance, dynamic elastic constant. These characteristics are variable, depending on composition, request, etc. In conclusion, they are not available in specialized literature as are the characteristics of linear-elastic materials. The application of numerical calculation programs in carrying out resistance calculations, in the case of structures made of such materials, is also impossible to achieve, having as an impediment the lack of knowledge of the values of the material characteristics.

To optimize the infill parameters and improve the tensile properties of 3D printed polyethylene terephthalate-1,4-cyclohexanedimethanol ester (PETG) models, this study explored the effects of infill thickness, infill flow rate, and infill overlap length on the tensile properties of 3D printed PETG models via the one-way test combined with the Taguchi test. The results of the one-way test showed that the tensile strength and elastic modulus of the PETG models increased with the increase of infill thickness, infill flow rate, and infill overlap length. The results of Taguchi`s test showed that the influence of infill parameters on the tensile properties of PETG models was as follows: infill thickness ] infill flow rate ] infill overlap length; the optimized infill parameters were: infill thickness of 1.2 mm, infill flow rate of 120%, and infill overlap length of 2.8 mm, and the tensile strength of the 3D printed PETG models with optimized parameters was 20.13 MPa, and elastic modulus was 1.32 GPa, which gave the best tensile properties.

Plastics have light weight and excellent performance, which are widely used in all kinds of automobiles. Polypropylene (PP) and its reinforcing materials are used in automotive components, where the surfaces of bumpers and fenders are coated with paint. Traditional recycling can frequently generate various pollutants, such as paint sludge. Microwave pyrolysis is a more environmentally friendly pyrolysis method with a higher heating coefficient than traditional electric pyrolysis. This study first explores the elemental composition of two types of automotive PP plastics and uses thermo-gravimetric analysis and the Kissinger-Akahira-Sunose method to preliminarily calculate the activation energy of automotive PP. The calculation results show that the activation energy of PP containing paint ranges from 189.145 kJ/mol- 199.513 kJ/mol, with an average value of 193.903 kJ/mol. The activation energy of PP without paint is between 215.506 kJ/mol-265.794 kJ/mol, with an average value of 242.425kJ/mol. Then, pyrolysis experiments on PP for vehicles without paint are conducted using a microwave atmosphere tube furnace at different temperatures and microwave powers. The experimental results showed that, when the pyrolysis temperature increased from 500oC to 620 oC, the total proportion of gas products rose from 0.75 wt.% to 4.81 wt.%, and the content of alkanes in the liquid products improved from 26.21 wt.% to 34.37 wt.%; when the microwave power increased from 900 W to 1100 W, the gas product rose to 20.77 wt.%, and the content of aromatic compounds in the liquid product improved to 17.78 wt.%. In addition, the pyrolysis experiment of automotive PP containing paint showed that paint had a relatively minor effect on the pyrolysis products of automotive PP. This study shows that using microwave pyrolysis to treat automotive PP and PP with paint is feasible, which provides a reference for the clean treatment of automotive polymers.

Carbon fiber-reinforced polymer composites are widely used materials in the aircraft industry, automotive sector, marine applications, civil engineering, and daily consumer goods, due to their superior mechanical properties at a relatively low density compared to metallic materials. The studied composites are composed of an epoxy resin matrix in which three layers of carbon fiber fabric are embedded, oriented at 0 and 90 degrees. Carbon fiber-reinforced polymer composites were manufactured using the Vacuum Assisted Resin Transfer Molding technique. The tensile failure mechanism in carbon fiber-reinforced polymer composites is an extremely complex phenomenon influenced by numerous factors. This study aims to evaluate the mechanical behavior of carbon fiber-reinforced composites through tensile testing and to compare experimentally obtained results with those calculated using the mixture rule. Additionally, the behavior of the materials under tensile stress was analyzed using the digital image correlation method. Estimating mechanical properties based on the mixture rule is a common practice in the design phase of polymer composites. This study`s novelty and originality lie in its anticipation of the tensile strength and modulus of elasticity of the studied composites. This anticipation was achieved using a virtual instrument developed in the LabVIEW graphical programming environment. The experimentally obtained results for the tensile characteristics of the studied materials are suitable for this type of composite. These results were compared with estimates derived from the mixture rule, and the absolute error was determined.

Acrylonitrile-butadiene-styrene (ABS) material is widely used as a protective rigid shell and impact absorber in bike helmets, providing vital protection against head injuries under specific working conditions. However, ABS aging in helmets could affect the safety factor of helmets and shorten the service life. Exploring the transformation during aging process for real assembled helmets made of ABS out shells is crucial for the investigation and fabrication of high performance helmets. Herein, the effect of long-term aging on the physical properties of practical helmets made of ABS outer shells has been discussed systematically. Four different types of helmets were subjected to different aging conditions, i.e., outdoor environment, ultraviolet exposure, hot air, and humid-heat conditions. The impact property and stiffness tests were carried out as a function of aging time and aging conditions. The measured helmets were capable of meeting engineering tolerances when aged under outdoor, ultraviolet, and hot air conditions, and could deliver competitive mechanical performance to their pristine helmets. Yet, after aging under humid-heat for 800 h, the helmets showed an obvious decrease in impact strength, gloss, and stiffness. The influence of different aging conditions was further investigated by thermal and spectral characterizations. The study might provide some valuable advice for helmet performance evaluation.

This study investigated the effects of different solutions (artificial saliva, Listerine Cool Mint-alcohol containing and Colgate Plax-alcohol free) on the nanohardness, elastic modulus and surface roughness of enamel surface and composite materials (Admira Fusion, Clearfil Majesty Esthetic and Mosaic Universal). Specimens of 2 mm depth and 5 mm diameter were stored in solutions for 12 h at 37°C. Baseline and final measurements were obtained using a HYSITRON TI 950 TriboIndenter testing machine. The applied force to each specimen increased from 0 to 1000 µN. For SEM images, one sample in each group was covered with a thin layer of mix of gold and palladium using a sputter coater (Quorum Q150R ES, UK). Scanning electron microscopy (SEM) images were taken at 5000× magnifications to evaluate the surface morphology. Statistical analysis for hardness, elastic modulus and roughness was performed by Two-way ANOVA, Benferroni and Tukey HSD at a significance level 0.05. The results of this study showed that the highest value of surface roughness and lowest hardness and elastic modulus were presented by Admira (p[0.001). Listerine caused significantly increased surface roughness (p[0.001) and decreased hardness and elastic modulus parameters (p[0.001). The mouthrinse containing alcohol caused more significant changes in the nanohardness, elastic modulus, surface roughness values of enamel and composite surfaces.

Anterior skull base reconstruction is a complex surgical procedure that requires careful evaluation of the patient`s condition and the expertise of a skilled surgical team. Skull base reconstruction objectives focus on providing water-tight separation between the intracranial and extracranial contents, closing dead space, and returning reasonable form and function. Regarding the reconstruction options, the main categories are non-vascular grafts, loco-regional flaps, free tissue transfer or bony-free flaps. The major challenge in reconstructive surgery is the effective sealing of the defect due to its uneven edges and the conformation of the anterior skull base. Given this challenge, we are considering the possibility of designing a prosthetic for anterior skull base defects using the 3D printer.

Part dimensional inaccuracies serve as a barrier from adopting Additive Manufacturing (AM) processes in mass production. Fused Deposition Modeling (FDM) is a thermoplastic based low cost AM process which can create conceptual models, prototypes and end user industrial parts. The current study involves predicting the optimal parameter settings and significant parameter for reduced geometric deviations in printed part using Nylon filament reinforced with 20% carbon fiber. Five input factors such as build orientation, layer thickness, infill density, raster angle and infill pattern have been considered for preparing the experimental layout through taguchi’s mixed fractional factorial design. The changes in length, width and thickness of the printed part from CAD value have been evaluated individually through ANOVA and Signal to Noise Ratio method (Smaller the better). Layer thickness is significant only for variations in length, but build orientation affects both width and thickness dimensions. The geometric deviations are further analyzed using combined multi criteria decision making (MCDM) approaches such as Entropy-CoCoSo and PCA-TOPSIS. The optimal parameter settings obtained for reduced geometric deviations is found to be Flat orientation, 0.1mm layer thickness, 50% infill density, 0° raster angle and cubic infill pattern. Layer thickness is found to be highly significant parameter influencing the geometric deviations subsequently followed by build orientation from both the MCDM methods. The multi response performance index values obtained from Entropy-CoCoSo has been trained using classification algorithms such as decision tree, random forest and Naive Bayes. Naive Bayes algorithm outperformed other methods with highest classification accuracy of 99.4% in a training-testing split ratio of 75:25.

In this paper, new epoxy resin/rubber powder/hollow beads three-phase composites were prepared by designing the incorporation of fly ash hollow beads with different mass fractions (5%, 10%, 15%, and 20%) as new reinforcing phases into epoxy resin/rubber powder two-phase composites with 5% mass fraction of carbon black rubber powder. Quasi-static compression tests were conducted at room temperature to test the compressive properties of the oxygen resin/rubber powder/hollow beads composites. Calculate the energy absorption properties and energy absorption efficiency of the composites from the compression curves. Fracture characteristics of compressed material specimens with microscopic morphology were observed by scanning electron microscopy. By systematically analyzing the effect of fly ash hollow beads content on the mechanical properties of epoxy resin/rubber powder/hollow beads three-phase composites, it was found that fly ash hollow beads as reinforcing materials can effectively improve the brittleness and yield strength of epoxy resin/rubber powder as well as the energy-absorbing properties and efficiency of the composites. The energy absorption properties of the epoxy resin/rubber powder/hollow beads composites increased and then decreased with the increase in the mass fraction of fly ash hollow beads. In the epoxy resin/rubber powder/hollow beads composites, the most significant performance was observed when the mass fraction of fly ash was 10%.