Mechanical Strength Characteristics Research Articles

Nanotransfer Printing for Synthesis of Vertically Aligned Carbon Nanotubes with Enhanced Atomic Penetration

AbstractVertically aligned carbon nanotubes (VACNTs) exhibit outstanding mechanical strength, chemical stability, and electrical characteristics; however, their constrained mechanical elasticity and chemical responsiveness spurred research on atomic decoration techniques for enhancing their mechanochemical attributes. Nevertheless, achieving uniform atomic decoration on the VACNT surface is difficult because of the high density and large aspect ratio of VACNT. Herein, a strategy to design and apply nanopatterned VACNTs (nVACNTs) based on a nanotransfer printing process is proposed to improve atomic penetrability. Nanopatterns inherent to nVACNTs facilitate atomic penetration, allowing for the more consistent and higher quality deposition of functional materials such as zinc oxide and alumina by atomic layer deposition. Furthermore, physical vapor deposition provides an improved coating of metal catalysts such as gold. The uniform deposition of ceramic layers on the entire surface of nVACNTs strengthens its mechanical resilience, owing to the diminished van der Waals forces of CNTs. Surface‐decorated nVACNTs display an increased sensitivity to NO2 gas, which is attributed to the enhanced quality of the reactive catalyst deposition and augmented permeability. This strategy achieves a larger decorated area while increasing a catalytically active reaction area. The obtained results promise that the enhanced nVACNTs will expand the industrial applications of carbon nanotubes.

Deterioration evolution mechanism and damage constitutive model improvement of sandstone–coal composite samples under the effect of repeated immersion

Underground reservoirs in coal mines, consisting of goafs (By goaf, we mean the space that remains underground after the extraction of valuable minerals), are commonly utilized for mine water storage and drainage, with their primary load-bearing structures being the “roof–coal pillar” systems. Consequently, this structure must endure the repeated immersion behavior resulting from fluctuations in the mine water level, resulting in the risk of geological disasters. This paper analyzes the variation in mechanical properties of sandstone–coal composite samples after repeated immersion cycles through axial loading tests. The results indicate that the water content of the sample exhibits a notable and rapid increase with each successive immersion cycle. This corresponds to a decrease in the stress threshold and modulus parameters of the samples. Moreover, the acoustic emission signals serve as indicators of the softening characteristics of the samples. With the increase in immersion cycles, there is an augmentation in both the frequency and extent of shear cracks. The non-linear failure characteristics of the samples become more pronounced. Consequently, water significantly weakens the cementing material between rock grains. Both sandstone and coal display a decrease in deformation resistance capabilities at a macroscopic level. The constitutive model of the composite sample was improved based on the degradation characteristics of mechanical strength and strain energy parameters, which offers enhanced accuracy in analyzing the degradation process caused by water immersion. This paper offers a crucial theoretical foundation for comprehending the deterioration evolution characteristics of the “roof–coal pillar” bearing structure affected by repeated immersion.

Experimental Study on the Mechanical Strength, Deformation Behavior and Infiltration Characteristics of Coral Sand

In this investigation, coral sand is presented as a sustainable substitute for conventional river and machine-manufactured sand. This study comprehensively investigated the macro-scale strength, deformation, and permeability characteristics of coral sand, alongside analyzing the mechanical behavior, deformation, and permeability under various conditions and in relation to distinct particle characteristics. It revealed that coral sand primarily consists of biotite and high-Mg calcite, featuring abundant internal pore space. Its compressive properties resemble clayey soils, displaying minimal unloading rebound and predominant plastic deformation during compression. In direct shear tests, the stress–strain relationship follows an approximate hyperbola, with no pronounced strain softening. Describing particle fragmentation in the process proves challenging, making indicators like internal friction angle less applicable in engineering. Triaxial tests indicate a rapid initial bias stress increase, followed by a gradual decrease post-stress peak, suggesting a strain softening phenomenon. As surrounding pressure rises, the axial strain needed to reach peak strength also increases. The permeability coefficient of coral sand correlates linearly with pore ratio increase, represented by 10e. The complex interaction of multiple factors influences the strength, deformation, and permeability of coral sand blown fill mixes, with specimen porosity having the greatest impact. The design and construction of high-weight foundation elements in coral sand blown fill projects should consider porosity effects.

Microstructure evolution and mechanical properties analysis in dissimilar ultrasonic metal welding of aluminum to copper

Ultrasonic metal welding is a solid-state welding process being widely employed for joining the interconnections of lithium-ion batteries in hybrid and plug-in hybrid vehicles. Examining the microstructure of the joint is of crucial importance to evaluate the performance. This analysis allows a comprehensive understanding of the phenomena influencing the joint strength. In this study, ultrasonic welding was utilized to join copper to aluminum sheets of 0.3 mm thickness, and then the macro- and microstructural characteristics of the weld cross-section and interface were thoroughly investigated. Finally, the microstructural changes at different values of ultrasonic welding parameters were correlated with the mechanical strength characteristics. This research identified mechanical interlocking and interface diffusion as the primary welding mechanisms. With an increase in welding time from 0.2 to 0.8 s, the bond density rose, the post-weld thickness decreased, and the average Vickers hardness at various points along the weld interface decreased by 10%.

Characteristics of Mechanical Strength and Flexibility of Shallots Leaf

When operating drone sprayer, such as to distribute pesticides, downwash is the major cause of damage on the plants. Therefore, understanding the mechanical properties of plants are important to be able select the proper drone to use. In this research, characteristics of leaf strength and flexibility of two types of shallots were investigated, namely the Batu Ijo and Birma varieties. Research on the characteristics of the strength and flexibility of shallots was carried out from the 3rd to the 8th week for the Batu Ijo and 9 varieties of Birma, 100 samples each week. The strength of the leaf was measured by pulling the leaf until it breaks by attaching a thread to the base of the leaf which is pulled by a force gauge device. Then to measure its flexibility by pulling the top of the leaf with the thread that is pulled until it touches the ground surface. From this research, data on the strength characteristics of the leaves of the Birma variety 29 N that is much stronger than the Batu Ijo variety 8.9 N got obtained. Meanwhile, for the flexural characteristics, the Batu Ijo variety was 5 N with pressure P 0,113 N/cm2 more flexible than the Birma variety 3.3 N with pressure P 0,087 N/cm2. The minimum bending strength of the leaves for the two varieties F is almost the same, where for the Batu Ijo variety F 0.044 N with P 0.005 N/cm2 and for Birma varety F 0.041 N with pressure P 0.009 N/cm2. Based on the characteristics of this minimum bending, it becomes the basis for optimizing the design of the drone sprayer blade.

Sustainable pervious concrete incorporated with graphene oxide: a comprehensive analysis of mechanical, infiltration and microstructure performance

ABSTRACT This study is a novel coalescence of using laboratory-based self-synthesised Graphene Oxide (GO) in pervious concrete (PC). The study aims to determine the effect of GO on the workability, paste drain down, porosity using CT scanning, hardened density, mechanical, infiltration and microstructural properties of previous concrete. Six mixes were designed with GO incorporation by cement weight (0, 0.02, 0.04, 0.06, 0.08 and 0.1 wt%). At 0.1 wt% of GO, the compressive strength of PC was 31.03 and 32.89 MPa at 28 and 56 days, respectively. Regarding splitting tensile strength, values were 3.68 and 3.9 MPa, and shear strength measured 4.88 and 5.12 MPa for the corresponding periods. Significant increment of 52.1% and 57% in compressive strength was observed at 28 and 56 days. The infiltration rate of all the mixes has shown a declining trend with an increase in GO percentage, and the maximum decrement was observed in the mix containing 0.1% of GO with 11.67% reduction of infiltration compared to control PC, but was within the standard permeable range as per American Concrete Institute (ACI 522R-10). Microstructural analysis revealed improved GO-modified PC performance, enhancing mechanical strength and infiltration characteristics, offering a promising and innovative solution for sustainable pavement development.

Effects of S substitution on the structural, optoelectronic, and thermomechanical properties of KTaO3 through density functional theory

Driven by a curiosity of how sulfur (S) alters the physical properties of KTaO3, we embarked on a computational journey using the WIEN2k code and the insights of density functional theory (DFT). We aim to unravel the influence of S-substitution on the material's structure, electronic behavior, optical responses, mechanical strength, and thermodynamic characteristics of KTaO3. Our investigation has unveiled a remarkable structural transformation, wherein the cubic phase of KTaO3 undergoes a shift to a tetragonal configuration for KTaO2S and KTaOS2, eventually returning to a cubic phase in KTaS3. Significantly, the band gap values have undergone substantial alterations, presenting energy gaps of 1.808 eV, 0.264 eV, and 0.078 eV for KTaO2S, KTaOS2, and KTaS3, respectively, diverging from the original band gap of 3.572 eV in KTaO3. Importantly, all these compounds have exhibited mechanical and dynamical stability. Furthermore, these compounds have displayed promising optical features characterized by high absorption coefficients (∼105 cm−1), minimal reflectivity (<30%), and robust optical conductivity within the visible spectrum, making them ideal candidates for a range of optoelectronic technologies. Our comprehensive investigation has reinforced the stability of all computed phases, showcasing exceptional electronic, optical, and thermo-mechanical properties, including semiconducting behavior, hardness, ductility, anisotropy, high absorptivity, and low reflectivity. The modified band gap and optical characteristics of KTaO2S indicate considerable potential for its application in solar cells, presenting promising opportunities to improve solar energy conversion efficiency. The thermal conductivity of KTaO3 is fascinating and shows substantial promise for applications as a heat sink material.

Experimental study on mechanical strength and acoustic emission characteristics of waste rock cemented backfill

Experimental study on mechanical strength and acoustic emission characteristics of waste rock cemented backfill

Modified Mechanical Strength, Thermal Decomposition, and Combustion Characteristics of Nitroguanidine Propellant with Graphene Nanosheets as Reinforcement

Modified Mechanical Strength, Thermal Decomposition, and Combustion Characteristics of Nitroguanidine Propellant with Graphene Nanosheets as Reinforcement

EXPERIMENTAL INVESTIGATION AND INTELLIGENT PREDICTION OF MECHANICAL STRENGTH OF PERVIOUS CONCRETE

This study determines the mechanical strength characteristics of pervious concrete using fuzzy logic. During construction, the process of determining the quality of concrete produced takes about 28 days before testing, training the fuzzy logic model through the research data gotten from the laboratory experiments in order to intelligently predict the mechanical strength of pervious concrete. Crushed granite was used in this experiment to ensure the pervious concrete has a little degree of fine aggregates and the maximum size of coarse aggregate used was 20 mm. Compressive, flexural and split tensile strength tests were carried out on pervious concrete of mixing ratios 1:4, 1:5 and 1:6 with each of the mixing ratios having varying water to cement ratios of 0.4, 0.5, 0.6 and 0.7. The developed fuzzy logic model was applied to predict the mechanical strengths of the concrete by using data obtained from experimental results, with input parameters of water content, crushing value, weight and density and the mechanical strengths as the output parameters employing the triangular membership function. The model was calibrated using the error measures of the root mean square error (RMSE), mean absolute percentage error (MAPE) and R squared were computed for the model. In this study, it was observed that higher water to cement ratio slightly reduces the mechanical strength of PC but increases the workability compared to increase in cement to granite ratio which notably increases the strength and reduced the workability, alternatively, higher water to cement ratio causes a notable decrease in permeability of the pervious concrete. The correlation between the experimental and predicted values was excellent. This shows that fuzzy logic can be used to predict the mechanical properties of pervious concrete, and fuzzy logic can also be used to appropriately deduce missing values in the mechanical properties of PC subject to further research

Graphene and its composites: A review of recent advances and applications in logistics transportation

AbstractThe research boom regarding graphene and its composites since its great discovery has continued to mount. Due to its superior electrical and thermal conductivities, high mechanical strength and lightweight characteristics, it has become a hugely potential candidate in hydrogen storage, aerospace, high‐performance composite, sensors, new energy batteries, etc. Here we provide a review of the application of graphene composites and extend into the field of transportation packaging to explore the possibilities of their application. The preparation process, mechanical properties and research methods of graphene structure are introduced, and the practical application of graphene‐reinforced composites is listed. The application prospects of graphene composites in packaging and transportation are presented.

TiO2 bonded SiO2-alkyl-NH2 grafted cellulose for improving thermal stability, mechanical strength characteristics, and water adsorption capacity

TiO2 bonded SiO2-alkyl-NH2 grafted cellulose for improving thermal stability, mechanical strength characteristics, and water adsorption capacity

Sustainability in the Manufacturing of Eco-Friendly Aluminum Matrix Composite Materials

The purpose of this work was to consolidate the eco-friendly Al–SiC composites prepared with various weight fractions of ceramic particles (0; 2.5; 5; 10; 15 wt.% SiC) in the energy-saving sintering process under vacuum and in a nitrogen atmosphere at 600 °C. The density of the manufactured composites was determined using Archimedes’ method. The mechanical properties and strength characteristics of the metal–ceramic interface were measured using three-point flexural and uniaxial compression tests, as well as the Brinell hardness measurement. The tribological properties were evaluated by determining the coefficients of friction and weight losses of the tested materials and identifying the tribological wear mechanisms. Advanced microstructural observation methods, such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM), were used to analyze the microstructure of the composites in detail, including the identification of the phase composition using X-ray analysis methods. Low-cost composites with a porosity not exceeding 7% were successfully produced via energy-saving production routes. Simultaneously, owing to the formation of aluminum nitrides during sintering in a nitrogen atmosphere, these composites exhibited mechanical and tribological properties superior to those of materials sintered under vacuum.

Experimental and modeling study of shear strength of unsaturated fine-grained soils with bi-modal water-retention characteristics

The mechanical behavior and strength characteristics of unsaturated fine-grained soils with dual-porosity are of crucial importance in geotechnical designs. Nanyang fine-grained soils have been selected as typical dual-porosity structure soils to perform experimental tests under a wide range of suction and different initial densities while studying its stress-strain-strength properties constitute the main scope of this study. Axial translation and vapor equilibrium techniques are jointly employed to apply a wide suction range. Our data suggest that soil behavior transits from strain-hardening with shear-induced contraction to strain-softening with shear-induced dilation as suction and density increase. By exploiting a bi-modal soil–water retention curve (SWRC) explicitly separating capillarity and adsorption mechanisms, the shear strength is allowed to be analyzed in the capillary suction stress-shear stress space. The strength envelop exhibits bi-linear characteristics. Based on these findings, we propose a bi-linear shear strength criterion specifically for dual-porosity fine-grained soils. We utilize the obtained test data to evaluate existing strength criteria based on effective stress and dual stress variables that consider the bi-modal SWRC characteristics. The comparison indicates that the proposed bi-linear shear strength criterion can more reasonably represent the variation of shear strength under a wide range of suction for unsaturated dual-porosity fine-grained soils.

An investigation of the efficacy of nanoemulsions as alternative treatment for a marginal quality pavement material

Stabilisation of road materials that do not meet specified requirements is a common practice in road construction. Cement and lime are among the most commonly used products for stabilisation. However, these products pose challenges in particular conditions, including rigidity and proneness to cracking, incompatibility with certain materials types and susceptibility to particular environmental conditions. In this regard, alternatives have been considered and nanotechnology-based materials have emerged as a viable option. For this study, the efficacy of Nano-Modified Emulsion (NME) for stabilisation of gravel material was investigated. The gravel material, stabilised with up to 1.5% NME was evaluated in the laboratory for mechanical strength characteristics and resistance to moisture damage. Results obtained for Static Triaxial Tests (STT) show that the NME improves the cohesion of the material by up to 54% but has no significant effect on the friction angle. Significant improvements are also noted in the results for California Bearing Ratio (CBR), Unconfined Compression Strength (UCS) and Indirect Tensile Strength (ITS) tests. The results also show that NME stabilisation improves the gravel material's resistance to moisture damage. Further investigations are recommended for repeated load triaxial tests, field trials, environmental risks and life cycle costs.

Separable and Inseparable Silk Fibroin Microneedles for the Transdermal Delivery of Colchicine: Development, Characterization, and Comparisons.

Colchicine is the first-line option for both the treatment and prophylaxis of gout flares. However, due to potentially severe side effects, the clinical use of colchicine is limited. A well-tolerated and safe delivery system for colchicine is widely desired. For this purpose, colchicine-loaded inseparable microneedles were fabricated using silk fibroin. Additionally, separable microneedles made of silk fibroin as the needle tips and PVP K30 as the base material were developed. Both types of microneedles were evaluated for their mechanical strength, swelling and dissolution characteristics, insertion abilities, degradation properties, in vitro penetration, skin irritation, and in vivo anti-gout effects. The results demonstrated that separable microneedles had greater mechanical strength and insertion ability. Moreover, the separable microneedles separated quickly and caused little skin irritation. In the pharmacodynamic test, mice with acute gouty arthritis responded significantly to treatment with separable microneedles. In conclusion, the separable silk fibroin-based microneedles provide a promising route for colchicine delivery.

Influence of high temperatures on the mechanical and microstructural properties of hybrid steel-basalt fibers based ultra-high-performance concrete (UHPC)

One of the major problem in ultra-high-performance concrete (UHPC) after exposure to high-temperatures is explosive spalling. Adding a single type of fibers alone is insufficient sometimes for suppressing such spalling, and therefore, hybridization of fibers has been adopted, particularly steel with organic fibers. However, the degradation of organic fibers at ambient and elevated temperatures is a significant challenge in the long term and needs to be addressed. Recently, inorganic basalt fibers have been considered as an alternative to organic fibers due to their better mechanical strength and high-temperature resistance characteristics. In this study, hybridizing steel with basalt fiber is proposed as a potential solution to the aforementioned problem. The spalling behavior, residual compressive strength, microstructure, porosity, hydration kinetics, phase decomposition, and quantification of hydration products were evaluated for hybrid steel-basalt fiber reinforced UHPC after exposure to high-temperatures. The study results indicated that hybrid steel-basalt fiber reinforced UHPC successfully prevented explosive spalling behavior. The use of inorganic mineral basalt fibers offers a promising solution for developing UHPC with superior high-temperature resistance.

Experimental Contribution to Study the Physico-Mechanical and Thermal Properties of Lightweight Cellular Concrete Prepared With Different Types of Sand and Waste Marble Powder

Abstract Algeria is currently undergoing an evolution in civil engineering, which has resulted in a higher use of aggregates, especially sand. This study contributes to the development of locally produced materials. Its goal is to explore how the type of sand and waste marble powder (WMP), which can be used as a partial replacement of cement and aluminum powder (Al) with different percentages as an expansive agent, can affect physico-mechanical properties such as the bulk density and mechanical strength at 28 and 90 days, as well as the thermal conductivity of lightweight cellular concrete. Non-autoclaved cellular concretes (CC) were investigated based on three types of sand, i.e., sea sand (SS), river sand (RS), and waste marble sand (WMS); a hydraulic binder (a mix of cement and waste marble powder), and aluminum powder. The experimental results indicate that the nature and particle size distribution of the sand used had an impact on the properties of the CCs. Furthermore, it can be seen that the increased aluminum contents decrease the density, mechanical strength, and thermal characteristics of the CCs. Using 10-15% WMP as a cement substitute improves the mechanical strength, offers better thermal conductivity values, and contributes to sustainable development by developing a new class of environmentally friendly cellular concrete.

Bending Behavior Analysis of Box Beams with the Reinforcement of Composite Materials for Wind Turbine Blades

Wind turbine blades in excessive wind conditions present extreme deflection problems. For this reason, an analysis of the structural response of composite reinforced box beams is developed. For this purpose, reinforced box beams were fabricated to improve the bending strength in the flapwise direction of the wind turbine blades. The box beams were analyzed with three-dimensional models using the Finite Element Method (FEM) and validated with bending tests at four-points and two-points. The box beam meets the characteristics of lightness and mechanical strength. Experimental four-point bending results showed that reinforced cross-sections decrease displacements by 30.09% and increase their stiffness to 43.41% for a box beam without structural reinforcement. In addition, the two-point bending results showed a difference of 18.98% between the displacements of the beams with structural reinforcements. In the FEM analysis, a maximum error of 11.24% was obtained when correlating the maximum displacement value with the experimental results of the beams.

Stretchable, Adhesive, and Biocompatible Hydrogel Based on Iron-Dopamine Complexes.

Hydrogels' exceptional mechanical strength and skin-adhesion characteristics offer significant advantages for various applications, particularly in the fields of tissue adhesion and wearable sensors. Herein, we incorporated a combination of metal-coordination and hydrogen-bonding forces in the design of stretchable and adhesive hydrogels. We synthesized four hydrogels, namely PAID-0, PAID-1, PAID-2, and PAID-3, consisting of acrylamide (AAM), N,N'-methylene-bis-acrylamide (MBA), and methacrylic-modified dopamine (DA). The impact of different ratios of iron (III) ions to DA on each hydrogel's performance was investigated. Our results demonstrate that the incorporation of iron-dopamine complexes significantly enhances the mechanical strength of the hydrogel. Interestingly, as the DA content increased, we observed a continuous and substantial improvement in both the stretchability and skin adhesiveness of the hydrogel. Among the hydrogels tested, PAID-3, which exhibited optimal mechanical properties, was selected for adhesion testing on various materials. Impressively, PAID-3 demonstrated excellent adhesion to diverse materials and, combined with the low cytotoxicity of PAID hydrogel, holds great promise as an innovative option for biomedical engineering applications.