Mechanical Performance Tests Research Articles

Preparation of high strength and rigidity carbon layer on SiO material surface by dynamic CVD method using gas carbon source C2H2

The main issue in the application of silicon-based negative electrode materials is the inevitable volume expansion, leading to negative electrode material fracture, which severely impacts the performance of batteries. This study employed Chemical Vapor Deposition (CVD) (C2H2@SiO), solid-phase coating method (Pitch@SiO), and liquid-phase coating method (RGFQ@SiO) to coat the surface of SiO materials with a dense amorphous carbon structure. Material property analysis revealed that C2H2@SiO has a relatively small specific surface area (1.8 m2 g−1) and surface carbon increment (2.4 %). It exhibited high reversible specific capacity (1563.4 mAh g−1), high initial Coulombic efficiency (81.45 %), and low volume expansion rate (9.3 %). Mechanical performance testing indicated that the surface carbon layer Young's modulus of C2H2@SiO was the highest (35 GPa), suggesting that using the CVD method to obtain a dense carbon layer can enhance the structural strength of the material. Based on the electrochemical-mechanical coupling theory simulation analysis of the stress during the charge-discharge process of electrode materials, the evolution of concentration and stress field during lithium insertion process was obtained, showing that the coating can further improve the electrochemical and mechanical performance of the negative electrode materials effectively. Additionally, the negative electrode sheets fabricated using sample C2H2@SiO were assembled into 18650 cylindrical batteries, exhibiting excellent cycling performance in 1000 cycles at 25 °C with a capacity retention rate of 85.7 %, along with good rate capability and high/low-temperature performance. The conclusions of this study provide certain guidance for the design and optimization of negative electrode materials for battery electrodes.

Investigation into the long-term alkali resistance of basalt fibers

To more accurately simulate the alkaline environment of basalt fiber in cement-based materials, this study innovatively employs the benchmark cement supernatant as the alkaline solution for the long-term corrosion testing of basalt fiber (BF). Additionally, through mechanical performance testing of mortar containing basalt fiber at different ages, the study reveals the corrosion behavior of basalt fiber in an alkaline environment. The results indicate that basalt fiber undergoes corrosion in the benchmark cement supernatant, where the OH− ions in the solution react with SiO2 in the basalt fibers, thereby disrupting the silicate framework of the fibers and causing pitting corrosion on the fiber surface. The black and white binarization analysis of the SEM images of BF7 after 360d erosion revealed that the corrosion pits covered 31.50 % of the fiber surface area, indicating severe corrosion. Furthermore, the study on the long-term mechanical properties of basalt fiber mortar demonstrated an initial increase in performance, followed by a gradual decline as the curing age progressed. Notably, after 360d of curing, the flexural strength of basalt fiber mortar was lower than that at 30d. For instance, the 360d flexural strength of BF1-0.1 and BF7-0.1 decreased by 18.85 % and 14.54 %, respectively, compared to 30d. This decline is primarily attributed to the corrosion of basalt fibers in alkaline environments, leading to a decrease in their mechanical properties. Therefore, it is essential to enhance the alkali resistance of basalt fibers when used in cement-based materials.

State-of-the-art of mechanical properties of 3D printed concrete

The utilization of 3D printing in civil engineering has expedited the progression of intelligent construction and building industrialization. A plethora of studies in recent years have contributed to the advancement of 3D printed concrete technology. In contrast to traditional concrete construction techniques, 3D printed concrete technology offers additional benefits such as cost-effectiveness, reduced environmental impact, and a simpler process. The mechanical properties of 3D printed concrete are crucial for its application in building structures. This article provides a comprehensive review of the latest research endeavors in 3D printed concrete, covering both research and application. Firstly, this manuscript examines the size parameters and fabrication methods of the specimens utilized for mechanical performance tests. Subsequently, the mechanical properties of 3D printed concrete are described, and the effect of time-gap as a significant parameter on the performance of 3D printed concrete is discussed. Finally, the existing 3D printed concrete reinforcement technologies and their applications are summarized and categorized based on fibers and steel bars. Moreover, the key technical obstacles in the application of 3D printed concrete in building structures are identified. The ultimate objective of this article is to chart a course for the development and implementation of 3D printed concrete in building structures.

Tribological properties of graphene oxide reinforced aramid paper-based composites

Self-lubricating paper-based composites can provide technological solutions such as low friction and extended service life for the aerospace airframe kinematic mechanical components. To improve the tribological properties of aramid short fibers, this study chemically combined graphene oxide (GO) with aramid nanofibers (ANF) through intermolecular forces, creating a self-lubricating GO-reinforced aramid paper-based composite GO/ANF. Mechanical performance tests have shown that the introduction of GO can significantly improve the fracture strength, Young's modulus, and toughness of paper-based composites. The frictional performance test results show that compared with ANF, the GO/ANF paper-based composites can maintain the lowest coefficient of friction (COF) and wear under high load and high sliding rate conditions. When the amount of GO added is 1 wt%, the COF and volume wear rate of GO/ANF paper-based composites are reduced by 23 % and 89 %, respectively. Mechanism analysis indicates that synergistic effects and friction transfer films are important factors contributing to the excellent performance of paper-based composites. This GO/ANF paper-based composite has good application prospects as a good anti-wear liner material in self-lubricating sliding bearing.

Water-soluble polysaccharides extracted from Enteromorpha prolifera/PVA composite film functionalized as ε-polylysine with improved mechanical and antibacterial properties

The issue of environmental protection has received sustained and widespread attention. In order to reduce environmental pollution related to traditional plastics, it is an incessant demand to design novel environment-friendly food packaging materials with excellent performance. Sulfated polysaccharide extracted from the “green tide” marine pollution Enteromorpha prolifera (SPE) has been innovatively transformed into a film-forming material for better utilization. The insufficient mechanical properties and limited functionalities, however, hinder its wide application. In this study, polyvinyl alcohol (PVA) was blended to enhance its mechanical properties and ε-polylysine (ε-PL) was incorporated to endow it with antimicrobial performance. A novel and biodegradable film composed of SPE, PVA, and ε-PL was fabricated by casting method. We further determined the physicochemical properties of composited films. Mechanical performance test revealed the tensile strength of SPE-PVA-PL films increased from 5.56 MPa to 6.65 MPa and the E% increased from 128.8 % to 246.9 % compared with that of SPE-PVA films. Antimicrobial tests showed the excellent antibacterial activity of SPE-PVA-PL films against representative microbial species, Staphylococcus aureus and Escherichia coli. The results of this study suggested that the SPE-based composite film has the potential to be used as a potential food packaging and wound dressing materials.

Mechanical behavior and microscopic damage mechanism of hybrid fiber-reinforced geopolymer concrete at elevated temperature

Geopolymer concrete (GPC) that is prepared from eco-friendly materials exhibits much more excellent resistance on high temperature compared with ordinary Portland cement concrete. In this study, hybrid fibers containing varying proportions of steel fiber (0.5%-2.0%) and polyvinyl alcohol (PVA) fiber (0.2%-0.8%) were incorporated in GPC. The hybrid fiber-reinforced geopolymer concrete (HFRGC) was subjected to temperatures ranging from 200 °C to 800 °C. The physical properties tests, mechanical properties tests, and microstructure tests of HFRGC were carried out at elevated temperatures, while the environmental impact and cost-effectiveness of HFRGC were assessed. The results of physical properties tests showed that the appearance and mass loss of the HFRGC were mainly affected by temperature, while hybrid fibers had a negligible effect on both. The appearance of HFRGC gradually transformed from gray to brick red with increasing temperature, and the mass loss of HFRGC at 800 °C was as high as 9.4%. The mechanical performance test results indicated that the mechanical strength of HFRGC increased at 200 °C and then decreased with elevated temperature. At 200 °C, the compressive strength, splitting tensile strength, and flexural strength of HFRGC containing 1.5% steel fibers and 0.6% PVA fibers were respectively increased by 13.1%, 14.7%, and 4.4% as compared with ambient conditions. The microstructure test results showed that further geopolymerization at 200 °C promoted the densification of the matrix. The matrix was damaged at higher temperatures violently while the porosity of HFRGC was dramatically increased from 13.35% at 25 °C to 27.83% at 800 °C. Based on the thermal behavior, environmental impact, and cost-effectiveness of HFRGC, a reference for future research in the fire prevention of GPC was provided.

Failure analysis and optimization design of CFRP automotive seat back under multiple conditions

This study explores the adoption of carbon fiber reinforced plastic (CFRP) in automotive seat backrests, aiming to improve compliance with regulatory standards and enhance performance. By replacing conventional materials with CFRP, and employing mechanical performance tests alongside the principle of equal stiffness, the study tackles material failure issues. A novel multi-criteria decision-making method, coupled with an optimal Latin hypercube experimental design, is used to optimize the layup sequence. The optimized design not only meets regulatory requirements but also significantly enhances driver and passenger safety and comfort during collisions.

Preparation and Performance Study of Ultraviolet-Responsive Self-Healing Epoxy Asphalt.

In this study, a self-healing epoxy asphalt material was developed by incorporating coumarin groups. This material achieved microcrack self-repair under UV irradiation at 50 °C. Fluorescence microscopy observations and mechanical performance tests demonstrated significant advantages in crack filling and mechanical property recovery after repair, with the fracture toughness of the repaired epoxy asphalt reaching 69% of that in its original state. Furthermore, the synergistic effect of temperature and UV irradiation in the self-healing process enhanced the material's durability and service life. This research offers new insights and methods for developing more durable and long-lasting self-healing asphalt materials, showcasing the great potential of smart materials in infrastructure applications.

Mechanical properties study of fiberglass reinforced flexible pipeline in marine applications

ABSTRACT A mechanical properties study of fibereglass reinforced flexible pipe (FGRFP) in marine applications is proposed based on the reinforced layer interface structure design, the anisotropic layer section mechanical performance test, and the structural strength analysis under the laying operation condition. Based on laboratory tests and referencing ASTM and DNV regulations, the technical design indexes of flexible marine pipe that meet strength requirements have been provided. Through tests, the maximum yield tension of FGRFP is 89.8kN, the ultimate curvature is 3.3 rad/m, the bending moment is 2312.2Nm, the torsion angle is 0.32 rad, and the torque is 2610.4Nm. Based on numerical simulation, static analysis can identify weak points in flexible pipelines. Especially, the feasibility of FGRFP structural section design was verified through dynamic analysis under the combined action of waves and currents. Finally, parameter sensitivity studies were conducted, including the effects of wave/flow direction, wave height, and period.

Fabrication of small-diameter in situ tissue engineered vascular grafts with core/shell fibrous structure and a one-year evaluation via rat abdominal vessel replacement model

A high vascular patency was realized in the bulk or surface heparinized small-diameter in situ tissue-engineered vascular grafts (TEVGs) via a rabbit carotid artery replacement model in our previous studies. Those surface heparinized TEVGs could reduce the occurrence of aneurysms, but with a low level of the remodeled elastin, whereas those bulk heparinized TEVGs displayed a faster degradation and an increasing occurrence of aneurysms, but with a high level of the regenerated elastin. To combine the advantages of the bulk and surface graft heparinization to boost the remodeling of elastin and defer the occurrence of aneurysms, a coaxial electro-spinning technique was used to fabricate a kind of small-diameter core/shell fibrous structural in situ TEVGs with a faster degradable poly(lactic-co-glycolic acid) (PLGA) as a core layer and a relatively lower degradable poly(ε-caprolactone) (PCL) as a shell layer followed by the surface heparinization. The in vitro mechanical performance and enzymatic degradation tests revealed the resulting PLGA@PCL-Hep in situ TEVGs possessing not only a faster degradation rate, but also the mechanical properties comparable to those of human saphenous veins. After implanted in the rat abdominal aorta for 12 months, the good endothelialization, low inflammation, and no calcification were evidenced. Furthermore, the neointima layer of regenerated new blood vessels was basically constructed with a well-organized arrangement of elastin and collagen proteins. The results showed the great potential of these in situ TEVGs to be used as a novel type of long-term small-diameter vascular grafts.

Experimental investigation of face mask fiber-reinforced fully recycled coarse aggregate concrete

To address the challenges associated with the disposal of construction and demolition waste (C&DW) and discarded personal protective equipment, this study investigates the feasibility of using face mask (FM) fibers to enhance fully recycled coarse aggregate (FRCA) concrete. The current study uses six FM fiber volume fractions (0, 0.1 %, 0.2 %, 0.3 %, 0.4 %, 0.5 %) for FRCA concrete reinforcement. According to the mechanical performance test results, adding FM fibers can enhance the splitting tensile strength (up to 8.22 % contents 0.1 % FM fiber) and flexural strength (up to 26.92 % contents 0.2 % FM fiber) of FRCA concrete. While excessive FM fibers (over 0.3 %) affect compressive strength negatively, the damaged concrete retains integrity due to the bridging action of FM fibers combined with scanning electron microscopy (SEM) analysis. Comparatively, the hydrophilic inner layer of disposable medical masks features a better microstructural fiber arrangement, increasing tensile strength by 14.51 % and 111.68 % compared to the filter and outer layers, respectively, making it ideal for enhancing FRCA concrete. All samples achieved a "Good" rating in the UPV tests, confirming the feasibility of FM fiber-reinforced FRCA concrete. The calculation method for FRCA concrete mechanical properties prediction considers the contribution of fibers in addressing the disparate effects of FM fiber incorporation, with correlation coefficients of 0.904 and 0.827 for splitting tensile strength and flexural strength, respectively. Environmental and economic impact analysis indicates that FM fiber-reinforced FRCA concrete can reduce carbon emissions by 71.25 % and save 29.05 % of economic costs.

Electrospun PLGA composite hydrogel scaffold loaded with 3D extracellular vesicles for nasal septal cartilage defect repair

The nasal septum plays an important role in the growth and support of the human nose, and defects can cause nasal deformities. Extracellular vesicles (EVs) have shown great potential in tissue repair, especially cartilage repair, and stem cell EVs are widely used in the repair of articular cartilage defects but have not been reported in the repair of nasal septal cartilage defects. At the same time, due to the low yield of EVs, which are easy to lose during in-situ injection, better preparation methods are needed to obtain EVs and more suitable carriers for the sustained release of EVs in wounds. Firstly, swelling and degradation experiments were conducted on the scaffold, as well as mechanical performance testing, including observation of the scaffold morphology under SEM. Subsequently, in vitro cell experiments were conducted to evaluate the ability of 3D EVs to promote chondrocyte proliferation, migration, and extracellular matrix formation. Finally, Gel-PLGA loaded with EVs was implanted into the nasal septum defect site of rabbits in vivo animal experiments to observe the repair effect on the defect. In vitro experiments showed that the biological scaffold exhibited good biocompatibility and could effectively promote the proliferation and migration of chondrocytes. In vivo, a composite biological scaffold loaded with EVs was implanted into the nasal septum defect of rabbits, and the tissues were tested at 6 and 12 weeks after surgery. The results indicate that composite scaffolds loaded with EVs can effectively promote the repair of defect sites. The results showed that 3D EVs could promote tissue repair and healing, which provided a new idea for the clinical treatment of nasal septal defects.

Microstructure and mechanical properties of ZrB2 ceramic particle reinforced AlCoCrFeNi high entropy alloy composite materials prepared by spark plasma sintering

In this study, xZrB2-AlCoCrFeNi (x = 0,5,10,15) (wt%) based high entropy alloy (HEA) composites were prepared by Spark Plasma Sintering (SPS). The influence of ceramic particle ZrB2 content on the densification behavior, microstructural evolution, and mechanical properties of the composites was investigated through scanning electron microscopy, X-ray diffraction, and mechanical performance testing. The results indicate that the HEA composites undergo a phase transformation, from (FCC + BCC + B2) structure to (FCC + BCC + B2+Laves) structure with the addition of ZrB2. The incorporation of ZrB2 facilitates the emergence of the Cr precipitate phase, and the grain size of this phase enlarges as the ZrB2 content rises. Additionally, when the ZrB2 content is 10 %, the maximum compressive strength reached 2071 MPa. Furthermore, at the ZrB2 content of 15 %, the composite material achieves a maximum densification of 99.13 % and a maximum hardness of 1222.2 HV.

Development of high-strength geopolymer mortar based on fly ash-slag: Correlational analysis of microstructural and mechanical properties and environmental assessment

Given the insufficient mechanical performance of existing fly ash-based geopolymer mortars under ambient curing conditions, this study is dedicated to developing a high-strength geopolymer mortar that meets the requirements of modern structural engineering. Based on the rheological performance tests of the fresh geopolymer mortar, the evolution of its rheological characteristics was revealed. Through macroscopic mechanical performance tests, the influence of slag content on the compressive and flexural strength of geopolymer mortar was clarified. Employing microstructural performance testing methods such as Thermogravimetric and Mercury Intrusion Porosimetry, the micro-mechanisms behind the improvement of mechanical properties were revealed. Utilizing the grey relational analysis method, a framework was established to analyze the correlation between the microstructural and macroscopic mechanical properties of geopolymer mortar. Additionally, an assessment system for evaluating environmental and economic benefits was developed using statistical analysis methods. The results show that increasing slag content enhances the yield stress and plastic viscosity of geopolymer mortar. Optimizing slag content boosts the compressive strength of fly ash-based geopolymer mortar, reaching up to 88.13 MPa under ambient curing conditions. An optimal amount of slag also promotes gel formation during polymerization, improving the internal pore structure. Furthermore, the content of reaction products correlates more strongly with macroscopic mechanical properties than pore structure characteristics. Geopolymer mortar also presents significant environmental and economic advantages over traditional cement-based materials, with its carbon and economic intensity indices at only 5.50 % and 10.80 %, respectively, of those in cement-based materials.

Research on Mechanical Properties of New Aluminum Alloy Scaffold Nodes

This article explores the feasibility of using aluminum profiles to design a new type of foldable scaffolding system. To verify the ultimate bearing capacity and failure mode of structural node connectivity points, mechanical performance tests were conducted on the tensile strength of cast aluminum and angle iron nodes to clarify the ultimate bearing capacity and failure mode of the nodes, providing a reference for using aluminum profiles to make new types of scaffolding.

Study on pore structure and acoustic emission characteristics of Mg(OH)2 modified expired cement

This study investigated the preparation of cementitious mortar specimens (ECM) by blending different dosages of pure magnesium hydroxide (AR), active magnesium oxide, and nano magnesium hydroxide as external additives with expired composite Portland cement. The optimal solution was selected by comparing their “nuclear magnetic resonance” (NMR), mechanical properties, and acoustic emission characteristics. NMR experiments revealed that the addition of 4 wt% nano magnesium hydroxide to expired cement resulted in the largest decrease in harmful pore content in ECM, reaching 21.9%. Mechanical performance testing and acoustic emission monitoring results indicated that the strength of ECM reached a maximum of 21.356 MPa with the addition of 4 wt% nano magnesium hydroxide, representing a 20.2% increase compared to the control group. This suggests that adding 4 wt% nano magnesium hydroxide to expired cement is a preferable option.

Design exploration of staggered hybrid minimal surface magnesium alloy bone scaffolds

Bone implant design faces multifaceted challenges, requiring the simultaneous optimization of hierarchical porous structures, large surface areas, and appropriate elastic moduli. Triply Periodic Minimal Surface (TPMS) structures show promise but are limited in their design space, making it difficult to comprehensively and precisely control these properties. This study introduces a novel implicit modeling method for reconstructing TPMS structures, breaking longstanding limitations of design freedom in bone implant design. This innovative approach uses an offset function to precisely manipulate discrete points on the isosurface, achieving unprecedented controllable freeform deformation while avoiding errors in conventional Boolean operations. Building on this breakthrough, new staggered hybrid TPMS (SH-TPMS) porous structures are developed that effectively balance and optimize volume fraction and surface area. Subsequently, magnesium alloy SH-TPMS bone scaffolds have been successfully fabricated using laser powder bed fusion (LPBF) technology. The resulting SH-TPMS structures feature multi-level controllable channel architectures. Compared to conventional TPMS structures, these staggered hybrid designs maintain consistent elastic modulus and deformation patterns through optimized mass distribution while achieving an average increase of 50 % in specific surface area at equivalent volume fractions. Mechanical performance tests confirm that the elastic moduli of the SH-Gyroid and SH-Diamond scaffolds are 4.56 GPa and 8.40 GPa, respectively, comparable to that of human bone. This work presents a promising new strategy for fabricating optimized bone implants, offering a balance between enhanced surface area and tailored mechanical properties.

Study on constitutive model and mechanical performance test simulation of 6082-T6 based on genetic optimization algorithm

Study on constitutive model and mechanical performance test simulation of 6082-T6 based on genetic optimization algorithm

Multi-scale experimental study on the failure mechanism of high-strength bolts under highly mineralized environment

High-strength bolts have become indispensable support materials in geotechnical engineering, but the incidence of safety accidents caused by bolt fractures under complex geological conditions is increasing. To address this challenge, this study focuses on a typical roadway in the Xinjulong coal mine, employing a combination of mechanical performance testing, microscopic and macroscopic analyses to investigate the failure mechanism of bolt breakage. The research indicates that the cracks in the failed bolts underground exhibit subcritical patterns, with the presence of oxides and Cl elements, and multiple intergranular fractures internally, consistent with the characteristics of stress corrosion failure. Additionally, inherent defects in the bolts are also a primary cause of failure. For instance, for type A bolts, the levels of P and S elements significantly exceed the normative requirements, forming inclusions, while the low content of elements like Si and V leads to reduced plasticity, toughness, and corrosion resistance. Furthermore, the excessive pitch in type A bolts leads to stress concentration and cracking under complex loads. The study concludes that the synergistic effect of stress corrosion cracking and inherent flaws in bolts are the main causes of failure. Therefore, it is recommended to enhance the reliability and safety of bolt support by optimizing the bolt shape and developing anti-corrosion bolts, thereby achieving long-term stability in underground engineering.

Optimization of Process Parameters and Microscopic Morphology of Multi-Walled Carbon Nanotubes/PEEK Films Using the Vacuum Suction Filtration Method

Multi-walled carbon nanotubes (MWCNTs) are a high-quality interlamination reinforcement material, but the high viscosity of polyetheretherketone (PEEK) prevents good fusion between MWCNTs and PEEK. This study proposes a method to achieve the complete integration of MWCNTs and PEEK through the preparation of a composite film using the vacuum suction filtration (VSF) method and optimizes the process parameters. An orthogonal experiment with three factors (filter paper pore size, ultrasonic dispersion time, and PEEK content) at three levels is designed, and mechanical performance testing and microscopic morphology observation are conducted. The influence of the three factors of filter paper pore size, ultrasonic time, and PEEK content on the elastic modulus and tensile strength of the film is investigated. The results are a filter paper pore size of 0.45 μm, ultrasonic time of 8.3 h, and PEEK content of 336.524 mg. The mechanical performance obtained under the optimal process parameters are an elastic modulus of 2437.5723 MPa and a tensile strength of 46.5196 MPa. This optimal process increases the elastic modulus by 12.3152% while maintaining a high tensile strength.