Evaluation Of Mechanical Performance Research Articles

Enhancing surface properties of AISI P20 + Ni mold steel via boronizing: Evaluation of mechanical, tribological, and corrosion performance

Enhancing surface properties of AISI P20 + Ni mold steel via boronizing: Evaluation of mechanical, tribological, and corrosion performance

Study on Evaluation and Prediction Model of Long-term Mechanical Properties of Fine-grained Saline Soil Subgrade

In this thorough examination, we dive deep into the long-lasting mechanical characteristics of fine-grained saline soil subgrades, aspiring to establish a precise and reliable collection of predictive models. Our objective is to provide a solid scientific footing for the design and ongoing upkeep of road networks within saline soil environments. Analyzing prolonged monitoring data across diverse highway subgrades within a prototypical saline soil locale, we unveil the intricate temporal fluctuations and environmental sensitivities of the soil’s mechanical properties under continuous load. Precisely, the subgrade’s compressive modulus dwindled by 15%, while shear strength declined by 8% over a five-year period. These trends intensify during rainy and scorching seasons, with drops surpassing 20% and 12% respectively. Leveraging this intricate data, we deploy nonlinear regression analysis and sophisticated machine learning algorithms to construct a predictive model tailored for the long-term mechanical properties of fine-grained saline soil roadbeds. This model integrates a multitude of factors, including load duration, temperature, humidity, and more, delivering accurate forecasts of key subgrade indicators like compressive modulus, shear strength, and beyond. In the verification stage, compared with the measured data, the error rate of the model prediction results is controlled within 5%, showing high prediction accuracy and stability. In addition, we also carried on the sensitivity analysis to the model, found that the load size and the duration of the impact on the mechanical properties of the roadbed is the most significant. Therefore, in the design of road engineering in saline soil areas, the influence of these factors should be fully considered, and reasonable engineering measures should be taken to ensure the safety and durability of roads. This study not only provides effective data support for the long-term mechanical performance evaluation of fine-grained saline soil roadbed, but also provides an important theoretical reference for engineering practice in related fields.

Development of calculation methods for the uncertainty of special mechanical characteristics of structural steel

Understanding of an accuracy related to the evaluation of special mechanical performances of materials is an essential part of the quality control system providing for safe operation of modern structures in severe climatic conditions in far locations where any emergency and repair activities are hindered. In absence of a priori known values of such performances the methodic basis of uncertainty calculation procedures should be developed. Relevance of the problem is supported by the requirement of Russian Accreditation Agency regarding the availability and due application of the corresponding methods in test laboratories as for directly measured parameters as for ones calculated from the test results. Uncertainty calculation procedures are suggested as a background for the developed specialized software.

Mechanical characterization and performance evaluation of twisted Jute-Kevlar hybrid composites with varied fiber orientations

Abstract Composite materials play a vital role in developing new materials in engineering and technology. Composites show how the properties of the matrix and reinforcement work together to create more robust, more rigid materials than would be possible from the individual components working alone. They consist of two or more component materials combined with notably dissimilar physical or chemical characteristics. Two categories of composite coupons have been developed in this research work: the first category (C1) is made up of jute twisted-Kevlar twisted jute fiber (0/90 degree), and the second category (C2) is made up of jute twisted-Kevlar twisted jute fiber (0/45 degree). The nano-silica is reinforced with the matrix with a weight percentage of 0%,5%,10% and 15%. The necessary interfacial adhesion and bonding between fiber layers have been accomplished using a 10:1 mixture of epoxy resin (LY556) and hardener (HY951). According to ASTM guidelines, the tensile, flexural, impact, double shear, wear, and hardness tests were carried out. This study uses two natural and synthetic fibers—twisted Jute and Kevlar fibers—as reinforcement. The Jute fibers have a high strength since they are high in cellulose. Efforts have been made to create a composite material with completely different twisted fiber orientations and to assess the mechanical properties of the composites. This involved various mechanical tests, analysis of wear surfaces, as well as DMA, DSC, FEA testing, and ultimately, the machining of the composites studied. The machining parameters used in waterjet machining have been carefully analyzed.

Flexural properties of fiber-reinforced concrete using hybrid recycled steel fibers and manufactured steel fibers

This study investigates the flexural properties of fiber-reinforced concrete (FRC) using a hybrid mix of recycled steel fibers (RSF) from waste tires and manufactured steel fibers (MSF). The aim of this study is to demonstrate hybrid steel fiber reinforcement as a more environmentally sustainable alternative to traditional single-fiber systems, by assessing whether hybrid reinforcement can achieve or surpass the performance of conventional single-manufactured steel fiber reinforcement. Using a novel four-stage methodology, this paper presents a comprehensive and detailed evaluation of mechanical and ductility performance through three-point bending tests, digital image correlation (DIC), CT-scans, and scanning electron microscopy (SEM). The results from flexural stress-deflection curves were used to evaluate the flexural strength and toughness. This was followed by an in-depth eight-stage DIC analysis and Surface Damage Index (SDI) curves throughout the test. CT-scan images were used to quantify the proportion of fibers classified as pulled-out, ruptured, or bridging the crack, while SEM analyzed the efficiency of fiber reinforcement through microstructural evaluations, further validating the findings of this study. Results show that hybrid reinforcement significantly enhances both toughness and ductility while reducing surface damage. MSFs in the hybrid system improve post-peak ductility and energy absorption by bridging large cracks, while RSFs prevent micro-cracks, increasing pre-peak rigidity. CT-scan analysis reveals that the inclusion of RSFs reduces pulled-out MSFs by 26%, further boosting flexural performance. SEM confirms the superior bond of MSFs with the concrete matrix in hybrid samples. Additionally, higher fiber content in FRC enhances toughness and ductility while reducing surface damage. This research advances our understanding of hybrid fiber-reinforced concrete and promotes more sustainable construction practices through the use of recycled steel fibers. By leveraging the combination of new methodologies, the study effectively targets gaps in the current research landscape, offering a comprehensive approach to improving performance and sustainability in construction materials.

Prediction of mechanical properties of manufactured sand polymer-modified mortar based on swarm intelligence algorithm

Because polymer-modified mortar (PMM) exhibits a complex and diverse composition, there is a complex nonlinear relationship between its mechanical properties and mix proportions that is challenging for conventional mechanical performance prediction methods to accurately predict. Consequently, in this study, a predictive model utilizing a backpropagation neural network (BPNN) was formulated, featuring a structure of 6–14-2. Simultaneously, three swarm intelligence algorithms were integrated—the ant colony optimization algorithm, grey wolf optimization algorithm, and bat optimization algorithm (BAT)—to collectively refine the optimization process of the BPNN prediction model. The model's input layer included cement (OPC), cellulose ether (CE), dispersible polymer powder (DPP), antifoam (AF), fly ash (FA), and tuff stone powder (SP), and the output layer consisted of the compressive and bond strengths. The model dataset comprised 520 samples (260 × 2), with 60 % (312) used for model establishment and 40 % (208) used for validation. Correlation matrix and principal component analyses were conducted on the dataset, along with a comparative analysis of the factors influencing the mechanical performance evaluation indicators. The results indicate that at 7 and 28 d, there was a positive correlation between the DPP and AF with the development of PMM mechanical properties. At 7 d, the SP and FA were negatively correlated with the compressive and flexural strength, whereas the CE was positively correlated with the bond strength. At 28 d, the OPC was negatively correlated with the compressive, bond, and flexural strengths, and positively correlated with the SP and FA. C3 represents the optimal mix proportion for the PMM, and considering the influence of all raw materials, F3 was identified as the comprehensive optimal mix proportion. The predictive performance evaluation indicators of the BAT–BPNN for the compressive and bond strengths were R2 = 0.980 and 0.942, MAE = 5.967 and 1.958, MAPE = 0.071 and 0.041, and RMSE = 4.686 and 1.594, respectively. BAT significantly improves the predictive accuracy of the BPNN model, enabling the prediction of PMM mechanical properties and providing a scientific basis for its mix proportion design.

The mechanical performance evaluation of fly-ash derived geopolymer mortar for concrete patch repair

The utilization of fly-ash-based geopolymers as a primary material in patch repair mortar technology represents a significant advancement in replacing conventional cement mortar, known for its high carbon emissions. This study employs Class C fly-ash with various proportions of activators to evaluate the resulting mechanical properties of the geopolymer mortar. The research includes trial and error for mix design, selection of an effective curing temperature, fresh properties, and hardened properties of mortar. Class C fly-ash was chosen due to its high-temperature resilience, essential for geopolymerization. An effective curing temperature of 60°C was identified. The activator solution comprised NaOH and Na2SiO3 with a 14 M molarity. Results indicate the highest compressive strength at a fly-ash to activator ratio of 60:40, achieving 70.80 MPa, while the highest average flexural strength was at a 70:30 ratio, achieving 12.19 MPa. The highest splitting tensile strength was also at a 70:30 ratio, measuring 26.33 MPa. These findings suggest that fly-ash-based geopolymer mortar is suitable for use in patch repair applications for corrosion damage.

A novel approach for enhancing the mechanical behavior of additively manufactured metal matrix composite structures: Preliminary investigation

Additive Manufacturing is a promising technique for expanding the boundaries of Metal Matrix Composites. In this study, Powder Bed Fusion (PBF) technique, employing Electron Beam as the heat source, was used to print Ti6Al4V metal matrix in different geometric shapes with a new approach for MMC fabrication. Yttria Stabilized Zirconia (YSZ) powder was then incorporated into these pattern shapes, compacted, and sintered to bind the powder particles together. The findings showed that successful sintering was achieved, resulting in the formation of a flexible interface region, with the circular design achieving the best interface region among all pattern designs. Regarding the mechanical performance evaluation of the developed Metal Matrix Composites, it was found that the mechanical strength was significantly increased with the hexagonal and circular patterns achieving the best results. Future research should pay more attention to further design development for the metal matrix model to achieve outstanding performance and create a new field for Metal Matrix Composites using the developed method.

Mechanical and wear performance evaluation of natural fiber/epoxy matrix composites

Mechanical and wear performance evaluation of natural fiber/epoxy matrix composites

Mechanical response of LPBFed TI64 thickness graded Voronoi lattice structures

The possibility to realize Additively Manufactured functionally graded lattice structure based on Voronoi tessellation enormously increases the possibility in tailoring the stiffness, mechanical properties and energy absorption capacity of the samples. The work presents the design and mechanical characterization of functionally thickness graded Voronoi lattice structures in comparison with constant thickness lattice structures for the evaluation of mechanical performance and energy absorption capacity. Firstly, the design and laser power bed fusion process are detailed. The dimensional deviation between designed models and Ti6Al4V specimens is quantified to assess the samples’ quality. Their mechanical performance is analyzed by quasi-static compression experimental tests, supported by numerical analysis for the evaluation of local stress distributions and deformation modes. The average dimensional deviation between CAD models and fabricated samples is 0.09 mm, likeminded with the literature optimum. The structures exhibit Young Modulus values ranging between 10 MPa and 21 MPa, compatible with biomedical applications. The compressive force for thickness graded structures tends to increase up to densification, while uniform thickness structures present an almost constant value of force in the platform stage. Additionally, the energy storage changes according to the presence of thickness gradient: the larger the thickness gradient, the larger the energy absorption capacity.

Evaluation of thermal insulation capacity and mechanical performance of a novel low-carbon thermal insulating foam concrete

The use of building insulation materials is an effective measure to reduce building energy consumption. To improve the sustainability of insulation materials, desert sand (DS) was used to replace part of the binder, and rice husk ash (RHA) was incorporated to further improve the performance of foamed concrete. The fresh properties, strengths, thermal properties and thermal insulation function of DS-based foamed concrete (DSFC) were systematically investigated. The use of DS and RHA to replace part of Portland cement (PC) and fly ash reduces the flowability of the mixture when the water/binder (PC, fly ash, DS and RHA) ratio is constant. Although the incorporation of DS into foamed concrete increases its density and thermal conductivity, it improves the volume stability of the sample. The strength of specimen with DS decreases due to the low reactivity of DS, which also reduces the content of hydration products. Further incorporation of RHA not only improves the matrix strength by increasing the C-S-H content but also improves the pore structure of the DSFC by increasing the yield stress of the paste. The joint application of DS and RHA effectively reduces the heat storage coefficient and thermal inertia index of DSFC, which is beneficial to improve the thermal insulation capacity of buildings and reduce energy consumption. Incorporating DS and RHA can effectively improve the environmental and economic benefits of the foamed mixture, and the unit strength cost and carbon emission per cubic meter of the 5%–10% RHA-modified samples are reduced by 20.3%–39.1% and 20.2%–38.9%, respectively, compared with the DS35. This research provides a new approach and theoretical basis for building energy saving and external wall insulation.

Comprehensive evaluation of microstructure and mechanical performance of sustainable ambient-cured alkali-activated composites

Cement is one of the building materials that is most frequently utilized in the construction field. However, the cement industry contributes significantly to the production of greenhouse gases. Therefore, many works have focused on improving sustainable construction materials that could contribute to decreasing greenhouse gas emissions. This study aimed to design a sustainable geopolymer mortar (GPM) made of fly ash (FA) and ground-granulated blast furnace slag (GGBS), which would be suitable for repairing damaged concrete structures. The work focused on investigating the effect of GGBS percentage, alkaline activator ratio, and superplasticizer dosage on the compressive strength, setting time, and workability of an ambient-cured GPM. The results of this research indicated that the compressive strength of GPM improved with the increase in GGBS percentage until a certain limit. However, the workability and setting time deteriorated with the increase in GGBS percentage. Increasing the alkaline activator ratio contributed to improving the compressive strength, workability, and setting time of GPM up to specific levels, but then they started to reduce. Superplasticizer dosage contributed to enhancing the compressive strength, workability, and setting time of GPM. This study found that the optimum FA/GGBS-based GPM that may be used in repair applications contains 50% GGBS, 50% FA, and 5% superplasticizer. The silica sand/binder ratio and alkaline activator ratio were 2.75 and 1.0, respectively. The compressive strength at 1 day, setting time, and workability of the optimum mix were about 12.70 MPa, 20 min, and 138.75 mm, respectively. The XRF, XRD, TGA, and SEM analyses were useful tools used to interpret the effects of the alkaline activator ratio on the fresh and mechanical properties of GPM.

Anisotropic piezomagnetic behavior of wire and arc additively manufactured low carbon steel

The objective of this study is to investigate the piezomagnetic behavior corresponding to the mechanical properties of a low-carbon steel fabricated by wire arc additive manufacturing (WAAM) under tensile stress. WAAM rectangular tubes with a nominal thickness of 4 mm were fabricated with ER70S-6 wires using a continuous path with single way stacking between layers. Tests were carried out on WAAM steel specimens with three different orientations relative to the deposition direction extracted from rectangular tubes, and the evolutions of magnetic field around the specimens were recorded. The variation characteristics of piezomagnetic response at different loading stages were analyzed, highlighting the anisotropic nature of the piezomagnetic field evolution. The internal correlation between piezomagnetic field and tensile stress was explored. It is found that the piezomagnetic behavior of WAAM steel during the tensile process corresponds to the mechanical response. The Villari reversal points can be used to predict the yield strength and tensile ultimate strength of WAAM steel, and the area of the magnetic field-stress curve may be a measure of the ductility of WAAM steel. The theory of microscopic magnetic domains and the constitutive relation of ferromagnetic materials considering magnetocrystalline anisotropy were used to explain the experimental results. This study provides new insights into the anisotropic piezomagnetic properties of WAAM steel, offering potential applications in non-destructive evaluation of mechanical performance.

Damage analysis and mechanical performance evaluation of frame structures in recycling

Research on the recycling of space frame structures is beneficial to reduce the waste of resources and has important engineering application prospects. Repeated disassembly tests were carried out on a full size space frame structure with bolt-ball joints. The maximum number of cycles was 3. The test results showed that with the increase of the number of cycles, the damage of joints and tubes gradually increased, the phenomenon of false tightening increased, and the construction efficiency decreased. After three cycles, the damage of high-strength bolts accounted for 16.56 % and the damage of steel tubes accounted for 5 %. Due to the component damage and construction deviation, the deformation and stress of the structure after unloading could not be restored to that before loading. However, within three cycles, the overall displacement and stress of the frame structure under general roof loads were almost not affected by component damage and construction deviation. Furthermore, the distribution pattern of displacement and stress was independent of the number of cycles. The maximum mid-span displacement of the structure was about 80 mm and the maximum difference of the overall stress level was within 10 MPa. Finally, according to the test results, the relevant engineering suggestions for the recycling of space frame structures were put forward.

Multi-recyclability of asphalt mixtures modified with recycled plastic: Towards a circular economy

Although asphalt pavements modified with recycled plastic have demonstrated enhanced performance, their recyclability remains under-explored, which is crucial under the scope of a circular economy. To address this, the present study investigates the multi-recyclability of asphalt mixtures, both with and without a recycled plastic modifier, at a recycling rate of 50 % over two cycles using an open-loop and a closed-loop model. The research utilised an innovative recycled plastic modifier made from hard waste plastics, incorporated into the mixture via the dry method. To ensure control over consistency and variables while also considering the novelty of the recycled plastic modifier, the reclaimed asphalt pavements (RAPs) were prepared using a loose asphalt mixture ageing protocol. Additionally, a rejuvenator made of vegetal derivatives was used as the recycling agent, considering the high recycling rate over each cycle. The comprehensive evaluation of volumetric and mechanical performance revealed that asphalt mixtures containing the recycled plastic modifier performed comparably to unmodified mixtures over two recycling cycles. Furthermore, all the recycled mixtures exhibited superior performance in resistance to rutting, moisture susceptibility, and fatigue compared to the conventional asphalt mixture. Overall, it can be inferred that the asphalt mixture modified with recycled plastic is capable of being recycled over multiple life cycles without compromising its mechanical and performance characteristics.

Multiscale mechanical performance evaluation of L-DED Ti6Al4V by novel ultrasonic burnishing (UB)

Laser-directed energy deposition (L-DED), as a novel technology to produce titanium (Ti) alloys (e.g., Ti6Al4V), has potential impactful applications. However, Ti alloys by L-DED is largely compromised by defects (porosity, cracks, etc.) at or near surfaces, which prevents strength-ductility synergy. In this study, a new method for Ti6Al4V sample preparation using ultrasonic burnishing coupled with heat treatment (UB/HT) after L-DED has been suggested. The results show that UB/HT has a more positive effect than mere UB to overcome turning's disadvantages, when the roughness, porosity, microstructures, and multiscale mechanical performance of L-DED Ti6Al4V are considered. UB/HT transforms residual tensile stress into compressive stress and causes severe plastic deformation (SPD) within a depth of approximately 10 μm on the surface layer. With this, UB/HT improves multiscale mechanical properties, e.g., hardness to 428 HV and strength to 976.7 MPa, and the related failure modes and fracture features induced by the UB/HT crack inhibition effect are confirmed with the fatigue results. With these observations, this research provides a good theoretical and practical reference for multi-scale mechanical analysis and understanding of L-DED Ti6Al4V, which expand the UB/HT applications.

Evaluation of Mechanical Joint Structural Performance through Actual Performance Testing of PC Connections

Evaluation of Mechanical Joint Structural Performance through Actual Performance Testing of PC Connections

Mechanism analysis and performance evaluation of clean and efficient recovery of N-heptanol/N-hexanol from wastewater via extractive distillation with green mixed entrainer

A clean and sustainable process for separating n-heptanol/n-hexanol/water industrial mixing system by extractive distillation via mixing organic solvent with ionic liquid as an entrainer was proposed. The mechanism of intermolecular microscopic interaction was explored by quantum chemistry calculation. By using multi-objective optimization, the optimal operating parameters of the process were obtained. In addition, process intensification technology was introduced, which improved the problems of high cost and high energy consumption in the conventional extractive distillation process. Finally, multiple performances were evaluated and analyzed for different processes. It was found that the coupled heat integration and heat pump technology to assist the extractive distillation process saved 10.45% in terms of economy, reduced gas emissions by 49.00%, and reduced energy consumption by 48.99% compared to the basic extractive distillation process. This confirmed the reliability and feasibility of implementing the process intensification technology. This work demonstrates the application of organic solvent mixed with ionic liquid as entrainer and process intensification technology in the extractive distillation process, providing guidance and reference for the design of the extractive distillation process.

Experimental Evaluation of Mechanical Properties, Thermal Analysis, Morphology, Printability, and Shape Memory Performance of the Novel 3D Printed PETG‐EVA Blends

AbstractPolyethylene terephthalate glycol (PETG) is a novel amorphous shape memory polymer with excellent printability for 4D printing. In this article, ethylene‐vinyl acetate (EVA) is used as a biocompatible and non‐toxic copolymer to improve plasticity and shape memory performance of PETG. PETG‐EVA blends are prepared and 3D printed using a melt mixing method and an upgraded fused deposition modeling (FDM) with a pneumatic feeding system. The results of the thermal analysis show that the blends exhibit two tan‐delta peaks, each related to their components, and morphology images confirm that they are biphasic and immiscible with good compatibility. The morphology of both EVA10 and EVA30 matrix droplets is observed, with the droplets being larger for EVA30. The use of a pneumatic feeding system, along with the ability to control the output melt flow, results in the best printing ability for EVA30, with minimal microholes between the grids and interlayer cracks. The tensile strength of PETG‐EVA blends ranged from 25.38 to 20.14 MPa, with the highest tensile strength achieved for EVA30. The shape memory performance of all three blends is similar; with shape recovery exceeding 90% in 20 s. Blends with higher EVA content exhibited faster shape recovery within the first 10 s.

Electric current stressing enhanced damping properties in Sn5Sb solder

PurposeThe purpose of this paper is to investigate the effects of electric current stressing on damping properties of Sn5Sb solder.Design/methodology/approachUniformly shaped Sn5Sb solders were prepared as samples. The length, width and thickness of the samples were 60.0, 5.0 and 0.5 mm, respectively. The damping properties of the samples were tested by dynamic mechanical analyzer with a cooling system to control the test temperature in the range of −100 to 100°C. Simultaneously, electric current was imposed to the tested samples using a direct current supply. After tests, the samples were characterized using scanning electron microscope, electron backscatter diffraction and transmission electron microscope, which was aimed to figure out the damping mechanism in terms of electric current stressing induced microstructure evolution.FindingsIt is confirmed experimentally that the increase in damping properties is due to Joule heating and athermal effects of current stressing, in which Joule heating should make a higher contribution. G–L theory can be used to explain the damping properties of strain amplitude under current stressing by quantitative description of geometrically necessary dislocation density. While the critical strain amplitude and high temperature activation energy decrease with increasing electric current.Originality/valueThese results provide a new method for vibration reliability evaluation of high-temperature lead-free solders in serving electronics. Notably, this method should be also inspiring for the mechanical performance evaluation and reliability assessment of conductive materials and structures serving under electric current stressing.