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In view of its combination of distinctive qualities, including strong tensile and tearing strength along with exceptional dynamic capabilities, which make it a strategic and irreplaceable material to produce bigger tyres, rubber is among the most used polymer in the world. The most widely employed sealing material in mechanical components is rubber. Failing of the rubber sealing in structural parts that seal could result in disastrous mishaps. Rubber seals serve to eliminate scratches brought on by direct contact between the piston and the cylinder block's inner walls and stop the flow of hydraulic oil. Due to the challenging work environment and discomfort of replacing rubber, it is important to suggest greater standards for its dependability. The rubber's reliability may be impacted by several variables over its life cycle, including load fluctuations, environmental factors, and heat treatment. In the current study, polyvinyl-nitrile rubber was subjected to heat treatment. The heat treatment was conducted with varying four different parameters such as curing time, curing temperature, post curing temperature, and post curing time. Based on these four parameters, sixteen samples were heat-treated. The microhardness, tensile properties, and fracture behavior of the tensile samples were analyzed by using Vicker's microhardness tester, universal testing machine, and scanning electron microscope. The outcomes revealed that the curing temperature and curing time has a significant effect on the hardness and tensile properties, and the samples' strength increased by 25% for curing temperature of 170 °C. The fracture analysis revealed that the minimal variation in the fractured micrographs was seen during the heat-treated cycle, showing that the environment seems to have less impact on the rubber matrix's ability to adhere. [ABSTRACT FROM AUTHOR]

In this study, the 3D printing technology was adopted to produce carbon fiber-reinforced polylactic acid and polyethylene terephthalate glycol composites. Fused deposition modeling process was conducted at different settings of printing parameters, specifically, raster angle, printing speed, and extrusion temperature. Each of the selected printing parameters has a key role in making the best-printed part in terms of layer-by-layer deposition quality and mechanical performance. To examine how these process parameters affect the behavior of the printed parts, tensile tests were performed and mechanical properties were assessed. It was reported that the printing orientation, characterized by the raster angle, can be identified as the determining factor to define the fracture mode. Composite parts printed with 0° raster angle, aligning with the tensile loading path, exhibit the highest levels of stiffness and ductility. Ductile and brittle fractures corresponding to 0° and 90° raster angles, respectively, were illustrated through optical observations of failure profiles. Furthermore, the tensile test indicates that higher printing speed leads to a significant deterioration in mechanical performances, notably reducing the stiffness of the printed structures. Scanning electron microscopy analysis confirmed that increasing the printing speed results in greater porosity within the structure, thereby weakening its mechanical strength. Regarding the extrusion temperature, it was shown that elevating it enhances the mechanical characteristics of the printed parts, particularly in terms of strength and ductility. Referring to microstructural observations, this outcome is attributed to the improved adhesion between the deposited layers and the reduction in porosity at high extrusion temperature. [ABSTRACT FROM AUTHOR]

Using Shimadzu AGS-100KN universal tensile testing machine, tensile tests were conducted on copper containing antibacterial stainless steel at 25 °C, −20 °C, −60 °C, −100 °C, and −140 °C. The fracture morphology and microstructure evolution of the material were then analyzed using various techniques including scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. The experimental findings showed that with the decrease of deformation temperature, the ultimate tensile strength(UTS) increased by about 49.7 %, the yield strength (YS) increased by about 35.5 %, and the elongation(EI) decreased by about 27.3 %, showed obvious low temperature strengthening effect. The High-angle grain boundaries (HAGBs) increased with decreasing temperature, while low-angle grain boundaries (LAGBs) decreased. The plasticity gradually decreased and the strength gradually increased, resulting in an increase in its ability to resist deformation. The number of precipitated phases gradually increased, and the size also gradually becomes larger, and the interaction between the diffusely distributed precipitated phases and dislocations led to precipitation strengthening. With the decrease of temperature, the stacking fault energy gradually decreased, the SFE was 21.26 mJ/m2 at the temperature of −140 °C. The main plastic deformation mechanism of copper-containing austenitic stainless steel in the low-temperature tensile process was transformed from deformation twins to strain-induced martensitic phase transformation.

This study explores a novel approach to quenching and partitioning (Q&P) heat treatment applied to AISI 9260 spring steel, comprising Fe-0.65C-1.58Mn-1.05Si-0.41Cr (wt.%). Our research focuses on balancing strength and ductility through optimized Q&P pathways, leading to a diverse microstructure that includes martensite, bainite, carbide, and retained austenite. Advanced X-ray diffraction and scanning electron microscopy techniques were employed to analyze the complexities of this microstructure. A key aspect of this study is the precise control of partitioning temperature and time, crucial for modulating lattice distortion and dislocation density within martensitic and bainitic structures. Optimal partitioning temperature promotes carbon distribution into austenite, tempering lattice distortions, and dislocation densities. Concurrently, carbide precipitation and segregation contribute to the refinement of the bainite phase. The sample quenched at 125 °C and partitioned at 350 °C (Q&P-125/350) demonstrates notable mechanical properties: a yield strength of 950 ± 15 MPa, an ultimate tensile strength of 1710 ± 15 MPa, and an elongation of approximately 9.7%. These results are partly attributed to the effect of silicon in preventing cementite coarsening and the effective distribution of carbide. Our findings highlight the potential of Q&P heat treatment in developing tailored microstructures with enhanced mechanical properties in steel, without relying on costly alloying elements. This approach presents new avenues for the design and application of high-performance materials. [ABSTRACT FROM AUTHOR]

Abstract Hexagonal boron nitride (h-BN) is a semiconductor material with a wide band gap, which has great potential to serve as a nanoresonators in microelectronics and mass and force sensing fields. This paper investigates the mechanical properties and natural frequencies of bilayer h-BN nanosheets under five different stacking modes, which have been rarely studied, using molecular dynamics simulations. The mechanical properties, including Young’s modulus, the ultimate stress, ultimate strain, Poisson’s ratio and shear modulus, are studied for all five stacking modes. And the effects of strain rate, crystal orientation and temperature to bilayer h-BN nanosheets’ tensile properties have also been studied. Our findings suggest that bilayer h-BN nanosheets are basically an anisotropic material whose tensile properties vary substantially with stacking modes and temperature. Moreover, the natural frequencies are proposed in an explicit form based on the nonlocal theory. The differences of the fundamental natural frequencies among different stacking modes are affected by the constraint condition of bilayer h-BN sheet. The theory results match well with the simulation results. These findings establish elementary understandings of the mechanical behavior and vibration character of bilayer h-BN nanosheets under five different stacking modes, which could benefit its application in advanced nanodevices.

SiCf/Ti2AlNb-reinforced Ti17 (SiCf/Ti2AlNb/Ti17) composites were fabricated through hot isostatic pressing. The designed SiCf/Ti2AlNb/Ti17 composites exhibited excellent tensile properties, with tensile strengths of 1657 MPa at room temperature and 1830 MPa at 450 °C. The microstructure, fracture morphology, and longitudinal section of the composites were characterized by X-ray diffraction, scanning electron microscopy, and electron backscatter diffraction techniques. The fracture process of SiCf/Ti2AlNb/Ti17 composites during room-temperature tensile tests was as follows: the SiCf/Ti2AlNb reaction layer first fractured, the crack extended into the Ti2AlNb matrix, the Ti2AlNb matrix crack extended to the adjacent reaction layer and promoted fiber fracture, the crack extended to the Ti2AlNb/Ti17 interface, ultimately the Ti17 capsule fractured. The fracture process of SiCf/Ti2AlNb/Ti17 composites during 450 °C tensile tests was as follows: the SiCf/Ti2AlNb reaction layer first fractured, multiple fiber fractures occurred, and the crack in the reaction layer entered the Ti2AlNb matrix, the crack extended to the Ti2AlNb/Ti17 interface, eventually the Ti17 capsule fractured. The room-temperature tensile fracture was fitted to the LLS model, while the tensile fracture at 450 °C was fitted to the GLS model. The different fracture processes indicated that the SiCf/Ti2AlNb/Ti17 composites were suitable for exploiting fiber strength at 450 °C and therefore exhibited excellent tensile strength.

With the increasing popularity of fused deposition modelling (FDM), an improved understanding of the interdependence between process-structure-property (P-S-P) of FDM manufactured (FDMed) parts is imperative. This paper proposes models for linking the microstructure and degradation of properties during the FDM process with the mechanical properties. Through careful and elaborate finite element (FE) modeling, it is demonstrated that there is definite material degradation during the FDM process, which cannot be attributed only to extra voids generated during printing. A novel hybrid multiscale model is proposed to estimate the degradation parameter and utilize this information to predict the printed coupons' properties. Additionally, two methods for generating representative volume element (RVE) are demonstrated using scanning electron microscope (SEM) imaging and density data. For the experimental validation, polyamide (PA) and polylactic acid (PLA) filaments and dogbone samples with multiple raster orientations were tested. The use of degradation parameter during modeling leads to very accurate results for both PLA and PA. Also, it presents insights into the limitations of the FDM process and possible improvements. [ABSTRACT FROM AUTHOR]

Additive manufacturing of duplex (DSS) and super duplex stainless steel (SDSS) has been successfully demonstrated using laser powder bed fusion (LPBF) in recent years. Owing to the high cooling rates, as-built LPBF-processed DSS and SDSS exhibit close to 100% ferritic microstructures and require heat treatment at 1000–1300 °C to obtain the desired duplex microstructure. In this work, the mechanical properties of DSS and SDSS processed via LPBF were investigated in three building directions (vertical, horizontal, diagonal) and three processing conditions (as-built, stress-relieved, annealed, and quenched) using uniaxial tensile testing. As-built samples exhibited tensile and yield strength greater than 1000 MPa accompanied by less than 20% elongation at break. In comparison, the water-quenched samples and samples annealed at 1100 °C exhibited elongation at break greater than 34% with yield and tensile strength values less than 950 MPa. Stress relief annealing at 300 °C had a negligible impact on the mechanical properties. Austenite formation upon high-temperature annealing restored the reduced ductility of the as-built samples. The as-built and stress-relieved SDSS showed the highest yield and tensile strength values in the horizontal build direction, reaching up to ≈1400 and ≈1500 MPa (for SDSS), respectively, as compared to the vertical and diagonal directions. Fractographic investigation after tensile testing revealed predominantly a quasi-ductile failure mechanism, showing fine size dimple formation and cleavage facets in the as-built state and a fully ductile fracture in the annealed and quenched conditions. The findings in this study demonstrate the mechanical anisotropy of DSS and SDSS along three different build orientations, 0°, 45°, 90°, and three post-processing conditions. [ABSTRACT FROM AUTHOR]

AbstractThe Textile Reinforced Engineering Cementitious Composite (TRECC) is a cementitious composite material reinforced with short polyvinyl alcohol (PVA) or polyethylene (PE) fibers, possessing exceptional ductility. This unique attribute enhances the utilization of the textile grid’s strength and significantly improves the load-bearing and deformation capabilities of ECC members reinforced with textile grids. In this study, the effects of fiber textile grids and steel wire mesh on the tensile properties of ECC were investigated. The test results showed that the carbon textile grid significantly improved the peak strength of specimens. On the other hand, the glass textile grid significantly improved the ultimate strain of specimens. The carbon combined with glass textile grids can integrate effectively the advantages of both carbon and glass textile grids. When compared with single textile grids, the combination uses of steel wire mesh and fiber textile grids resulted in a significant improvement in ultimate strain and post-peak energy absorption values. Finally, based on the test data, this study proposed the peak strength calculation of TRECC and provided the stress–strain expressions of the initial non-linear strain hardening phase and the tensile softening phase and a related analytical model to describe the stress–strain behavior of TRECC. [ABSTRACT FROM AUTHOR]

Due to their exceptional properties and diverse applications, including to magnetic devices, thermoelectric materials, catalysis, biomedicine, and energy storage, nanoscale metallic multilayer composites (NMMCs) have recently attracted great attention. The alternating layers of two or more metals that make up NMMCs are each just a few nanometers thick. The difficulties in producing and synthesizing new materials can be overcome by using nanoscale multilayer architectures. By adjusting the layer thickness, composition, and interface structure, the mechanical properties of these materials can be controlled. In addition, NMMCs exhibit unusually high strength at thin layer thicknesses because the multilayers have exceptionally high strength, as the individual layer thicknesses are reduced to the nanoscale. The properties of NMMCs depend on the individual layers. This means that the properties can be tuned by varying the layer thickness, composition, and interface structure. Therefore, this review article aims to provide a comprehensive overview of the mechanical properties and the application of high-performance NMMCs. The paper briefly discusses the fabrication methods used to produce these composites and highlights their potential in various fields, such as electronics, energy storage, aerospace, and biomedical engineering. Furthermore, the electrical conductivity, mechanical properties, and thermal stability of the above composite materials are analyzed in detail. The review concludes with a discussion of the future prospects and challenges associated with the development of NMMCs. [ABSTRACT FROM AUTHOR]

Researchers have been engaged in the study of high-ductility concrete (HDC) due to its excellent ductility and cracking control ability. This study combines the concepts of HDC and alkali-activated composites (AAC) to develop high-ductility alkali-activated composites (HDAAC) using polyethylene terephthalate (PET) powder. Experimental investigations were conducted to assess the compressive and tensile properties of HDAAC, focusing on the impact of varying PET powder content (0%, 15%, 30%, and 45%) and fly ash/slag ratios (FA/GGBS, 6:4, 7:3, and 8:2). The results indicated that the compressive strength of HDAAC ranged from approximately 30 MPa to about 100 MPa, with the specimens maintaining good integrity after axial compression failure due to the bridging action of PE fibers. The replacement of quartz powder (QP) with PET powder slightly decreased the compressive strength and elastic modulus of HDAAC, albeit mitigating its brittleness under compression. An increase in GGBS content enhanced the compressive strength and elastic modulus of HDAAC due to the increased formation of the C-A-S-H reaction products, leading to reduced porosity and a denser microstructure. Under axial tension, HDAAC exhibited typical multiple-cracking behavior with significant pseudo-strain hardening. Increases in the PET content and FA/GGBS ratio resulted in finer cracks, indicating excellent crack control and deformation capabilities. The initial cracking strength, tensile strength, and ultimate tensile strain ranged from 3.0 MPa to 4.6 MPa, 4.2 MPa to 8.2 MPa, and 4.1% to 7.2%, respectively. Despite a decrease in the initial cracking strength and tensile strength with higher PET content, the ultimate tensile strain of HDAAC slightly increased. Observations under a scanning electron microscope revealed a distinct interfacial transition zone near the PET powder, leading to poor bonding with the alkali-activated matrix. In contrast, QP dissolved on the surface in highly alkaline environments, forming better interface properties. These variations in interface properties can be used to interpret the variations in the mechanical performance of HDAAC. [ABSTRACT FROM AUTHOR]

Modeling the mechanical behavior of different materials has been always one of the challenging topics and among them, the modeling of textile materials such as fabrics or composites due to their unique structure has attracted the attention of many researchers. In this study, it was tried to model the tensile behavior of woven fabrics with the plain, twill and customized patterns using the finite element modeling (FEM) by considering the yarn progressive damage. The trial and error method was used to find the damage parameters such as the effective plastic displacement for the warp and weft yarns based on the behavior of ductile materials. The obtained error in predicting the rupture force of warp and weft in FEM was less than 8%. After that, the defined yarns were used to model the unit cell of the woven fabrics based on the Pierce's model. Then, the tensile test of the fabrics in the warp and weft directions was simulated using FEM on the unit cell. Comparing the FEM outputs and corresponding experimental data, it was found that the larger the unit cell dimensions, the less uniform the fabric, so the simulation behavior would be less similar to the experimental one. Finally, the lowest errors of FEM in predicting the fabric rupture force in two directions of the warp and weft were equal to 5% and 15%, respectively, which was related to the plain samples (fully interlaced fabric). [ABSTRACT FROM AUTHOR]

The microstructure of high-entropy alloys with refractory elements and Al as constituents can be considered to be analogous to superalloys. These so-termed refractory high-entropy superalloys (RHSAs) can show remarkable compressive strength up to temperatures exceeding 1200 °C. Here, we examine the microstructure and properties - compressive, tensile, and fracture toughness - of a precipitation-hardened, body-centered cubic, RHSA, Al0.5Nb1.25Ta1.25TiZr, at ambient temperature (RT) to 1200 °C. Two dual-phase microstructures comprising ordered B2 (brittle) and disordered A2 (ductile) phases were produced in this alloy - one with B2 as the matrix, the other with A2 - for evaluation of the mechanical properties. Under compression, both microstructures display RT compressive strengths above 1.5 GPa and considerable ductility exceeding 40% at elevated temperatures; the alloy with the A2 matrix has ∼15% compressive ductility even at RT. However, properties are very different under tensile loading; at all temperatures, both microstructures fail predominately in an intergranular mode in the elastic regime at a fracture stress less than 200 MPa and ductility below 0.15%. The microstructure with the A2 matrix has a KIc fracture toughness of ∼15 MPa√m at RT, although at all temperatures above 800 °C, measured KIc values for both dual-phase microstructures are less than 5 MPa√m. In this study, we investigate the microstructural origin of these mechanical properties, and emphasize the importance of evaluating these alloys in tension.

ABSTRACTThe research conducted focused on examining the unique properties of Agave Americana Flower Stem fiber (AAFS), particularly its behavior under quasi-static tensile conditions. A total of 200 AAFS fibers were subjected to tensile tests using a standard gauge length of 40 mm. Tests spanned seven groups with quantities (N) ranging from 30 to 200. The study aimed to understand the fibers’ mechanical traits, as tensile resistance and modulus of elasticity, and to see how different test quantities influence these properties. A significant observation was the dispersion of the tensile characteristics of AAFS fibers, a common trait of natural fibers. To understand this, we applied rigorous statistical tools, including the Weibull distribution at a 95% confidence interval and one-way ANOVA. A mathematical model was produced utilizing data from experiments regarding the tensile behavior of AAFS fibers. The ANN provided correlation coefficients (R2) of 0.9897, 0.9971, 0.9993, and 0.9939 for training, validation, testing, and all datasets respectively, which were able to accurately predict the experimental data. The proposed model would be of tremendous assistance to engineers and designers in obtaining green composite materials that are based on natural fibers and thereby more durable. These methods illuminated the patterns in our results, enriching our understanding of AAFS fiber mechanics.

Welded steel plates are widely used in various structural applications, and the presence of inclined welds is often encountered in practical scenarios. Carbon fiber reinforced polymer (CFRP) has been proven to be effective for strengthening steel structures. However, the behavior of CFRP-strengthened welded steel plates with inclined welds, particularly considering the influence of welding residual stress, is limited. This paper aims to investigate the tensile behavior of CFRP-strengthened welded Q355 steel plates with inclined welds considering welding residual stress (WRS). First, WRS data were obtained by the X-ray diffraction (XRD) method at different locations. The maximum tensile and compressive residual stresses are 0.39 and 0.14 times the yield strength of the steel, respectively. Then, finite element models were established to investigate the effects of weld angles, weld width, and height on the WRS distribution of welded steel plates. Finally, the tensile performance of CFRP-strengthened welded plates with WRS was studied by numerical simulation. The results showed that the weld angles have little effect on the distribution pattern of residual stress but significantly affect the peak tensile WRS. When the weld angle changes from 0° to 60°, the peak tensile WRS decreases significantly from 0.32 to 0.06 times the yield strength of steel; furthermore, the influence of weld width and height on WRS is relatively limited. Under tension loading, the maximum stress occurs near the weld. The ends of the weld enter the yielding state later than the middle part of the weld due to the distribution of the WRS. As the weld angle increases and the length of the weld increases, the stress in the weld zone decreases, while the stress in the base material zone correspondingly increases. In addition, CFRP strengthening can reduce the magnitude of stress. This study provides preliminary references for understanding the tensile behavior of CFRP-strengthened welded steel plates with inclined welds. [ABSTRACT FROM AUTHOR]

To enhance the mechanical properties and cost-effectiveness of conventional polyvinyl alcohol fiber reinforced strain hardening cementitious composite (PVA-SHCC), a modified version called multiscale hybrid fiber reinforced SHCC (MsHySHCC) was developed. This new composite incorporates a combination of steel fiber, PVA fiber and calcium carbonate (CaCO3) whisker. Uniaxial direct tensile behaviors (stress-strain relationship, tensile strength, tensile deformation capacity and tensile toughness) of designed MsHySHCCs were investigated and evaluated. The results show that the PVA fibers dominate the ductile behavior and the steel fibers and CaCO3 whiskers effectively affect the strength of MsHySHCCs. The PVA fibers can be partially replaced by CaCO3 whisker and steel fiber, along with an increase in tensile strength and ductility of designed composites. The findings suggest that the configuration of MsHySHCC proves to be a viable approach in simultaneously enhancing the strength and ductility of PVA-SHCC. A semi-theoretical prediction model for tensile constitutive relationship was derived. The comparison of the theoretical results with the experimental data shows that this semi-theoretical model is applicable for determining the tensile constitutive relationship of PVA-SHCCs and MsHySHCCs. [ABSTRACT FROM AUTHOR]

The bolted joint is widely used to connect different composite structures in the aerospace field, and the joint is usually the weakest part, and its performance is widely influenced by temperature. This paper aims to investigate the static tensile behavior of the composite‐aluminum four‐nailed joint structure at different temperatures. Carbon fiber epoxy resin matrix composites with a layup of [(0/45)2s]2 are selected to fabricate specimens, and the test temperatures are room temperature (RT, 25 °C), 60 °C, 100 °C, and 150 °C, respectively. The surface strain field and damage evolution inside the specimens are monitored at different stages of the loading process by combining the digital image correlation (DIC) and X‐ray computed tomography (CT) techniques. During the loading process at RT, a sudden drop in load occurs after structural yielding, and the following secondary bearing is observed; however, at higher temperatures, the load continuously decreases until final failure after it reaches the peak value. Moreover, the rearrangement of stress distribution around the bolts at higher temperatures relieves the asymmetric secondary bending of the joint. The experimental findings in this study provide valuable guidance for the structural design and safety assessment for composite‐aluminum bolted joints at different temperatures. Highlights: The loading process shows five stages at RT and four stages at higher temperatures.Extrusion damage led by shear cracks appears earlier at higher temperatures.Load on the upper and lower bolts is closer as the temperature increases.Higher temperatures relieve the asymmetric secondary bending of the joint. [ABSTRACT FROM AUTHOR]

Clay-rich rocks such as mudstone have a great affinity for water due to the formation of a diffuse double layer around the negatively charged minerals. This makes the behavior of this rock type unique when exposed to different temperatures. Therefore, the tensile, compressive, and shear mechanical behaviors of mudstone were investigated under the coupling effect of temperature and confining pressure. Results indicated that the mudstone can sustain a temperature of up to 500 °C without the appearance of thermal cracks. By increasing the temperature from room temperature (RT) to 500 °C, the mechanical properties improved due to thermal expansion that causes the closure of pre-existing micro-cracks. Tensile strength increased by about 92.3% after thermal treatment at 500 °C, while the tensile modulus of elasticity (ET) increased from 14.2 GPa under RT to 16.1 and 20.5 GPa after thermal treatment at 250 and 500 °C, respectively. The compressive behavior of the mudstone was greatly influenced by the coupling of temperature and confining pressure. Comparing between initial (T = RT and σ3 = 0.0 MPa) and extreme (T = 500 °C and σ3 = 10 MPa) conditions in this study, compressive strength, axial and transverse moduli of elasticity increased by about 150%, 59%, and 148%, respectively. However, Poisson's ratio decreased from 0.387 to 0.248, indicating an increase in the brittle behavior of the mudstone between initial and extreme conditions. Regarding shear behavior, the linear Mohr–Coulomb criterion was in good agreement with test data to represent the shear behavior of the mudstone before and after thermal treatment. A little reduction of about 4% in the peak friction angle was observed after thermal treatment at 500 °C, while the cohesion increased by about 47%. This indicates a significant improvement in the peak shear strength of the mudstone with increasing temperature. The experimental findings of this study offer valuable insights into the mudstone behavior when exposed to thermal effect. The obtained parameters play a critical role in the governing equations that describe how the rock material responds to thermal effect in terms of compressive, tensile, and shear behavior. Highlights: Clay-rich rocks such as mudstone have unique behaviour under thermal effect. The influence of coupling temperature and confining pressure was considered. Tensile strength and modulus of elasticity were measured as temperature function. Compressive behavior including elastic moduli and Poisson's ratio was investigated. The shear behavior of intact mudstone versus temperature effects was analyzed. [ABSTRACT FROM AUTHOR]

In the present work, an as-cast strip of novel high entropy alloy (Fe48.8Co26.9Cr9.7Ni5.7V8.3N0.6 at.%) was successfully produced by twin-roll casting technology. Then, the as-cast strip with or without primary annealing was cold-rolled and annealed. The directly cold-rolled and annealed samples consisted of single-phase FCC and they were easier to recrystallize. While many granular VN particles precipitated during primary annealing. Besides, after secondary annealing, the dual phases microstructure of FCC+BCC was obtained. The BCC phase made the alloy have high recrystallization resistance and inhibited grains growth, causing refined grains in secondary annealed samples. The grain size was refined to 1.26 µm when annealed at 800 °C, the corresponding recrystallization fraction was only 60.9%. When annealing at 1000 °C, the content of BCC decreased, resulting in larger grain size (~ 8.13 µm) and fully recrystallized structure. The secondary annealed sheets showed excellent tensile properties, the ultimate tensile strengths were 770-898 MPa and corresponding total elongations were 32-46%. [ABSTRACT FROM AUTHOR]

The demand for weight reduction, cost savings, more fuel efficiency, and reduced greenhouse gas has led to the increasing application of tailor welded blanks (TWBs) in the automotive industry. The purpose of this study is to investigate the strain rate effect on the tensile behavior of TWB consisting of dissimilar thickness sheets. Hence, a fiber laser was used for welding St14 steel sheets. The weld zone was examined using metallographic and microhardness tests. For investigating the tensile properties, uniaxial tensile tests were performed at strain rates ranging from 0.001 to 10 s−1. It has been found that the presence of Bainitic microstructure in the weld zone increases its hardness. Tensile test results indicate that yield strength and ultimate tensile strength of base metals and TWB enhanced with increasing strain rate. The yield and ultimate tensile strength of TWB are higher than base metals at different strain rates. As the strain rate increases, the total elongation of the TWB decreases, but in base metals, it decreases first and then increases at higher strain rates. In TWB and base metals, by increasing strain rate, uniform elongation decreases, but post-uniform elongation increases. For analysis of plastic deformation of thick and thin parts of TWB, indexes of limiting thickness ratio and difference of ratios (DR) were used. DR decreases with increasing strain rate, which indicates a decrease in the plastic deformation of the thick part of TWB and is consistent with the experimental findings. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of a post-weld intercritical annealing (PWIA) on the microstructure and tensile behavior of a friction stir (FS)-welded DP600 steel. Results showed that in the FS-welded sample, tempering of the pre-existing martensite in the sub-critical heat-affected zone (HAZ) and formation of ferrite and pearlite in the fine-grained HAZ led to the formation of a softened zone and a significant decrease in the ultimate tensile strength (UTS) with a joint efficiency of 87%. After PWIA, a dual phase microstructure was developed throughout the weldment, which resulted in the elimination of the softened zone and full recovery of the UTS. Measurements by digital image correlation revealed that localization of strain in the softened zones after yielding resulted in the early fracture. However, the strain localization was significantly reduced after PWIA. All samples exhibited features of ductile fracture mode during tensile testing. Ferrite-martensite interface decohesion was the main void nucleation mechanism in the DP600 steel and PWIA sample, while in the FSW sample a fraction of voids were also formed as a result of martensite necking. [ABSTRACT FROM AUTHOR]

Among the failure forms of fiber reinforced materials, interface failure caused by fiber debonding is the most common but complex failure mode. This research proposed a fiber layering modeling method based on the different mechanical properties of the outer and inner parts of fiber yarn, then investigated the mechanical behavior of fiber reinforced materials under dynamic loads with different loading speeds. Two pullout models were established, considering the layering feature of fiber caused by the matrix penetration. The simulated results were compared with the existing experimental data to determine reliable parameters values of the fiber-matrix interface. Based on the values, another pullout model and tensile model were built. Distribution and development of stress in the loading process were discussed. Results show that fiber modeling with inner and outer parts, as well as the cohesive property with reliable parameters, could effectively represent the interface characteristics of fiber reinforced materials under dynamic load. [ABSTRACT FROM AUTHOR]

This study explores the impact of resin-missing defects on the mechanical properties of composite laminates through experimental and finite element methods. Specimens with varying defect contents (5.3%, 8.0%, 10.7%, 13.3%, and 16.7%) were prepared via Vacuum Assistant Resin Infusion process. Experimental tests were conducted with the assistance of Digital Image Correlation measurements to illustrate the impact of resin-missing defects on failure characteristics. The experimental results indicate that the existence of resin-missing defects altered the stress distribution, increased the local stress, and reduced the tensile strength of the composite laminate. The DIC results indicate that the presence of defects weakens the matrix, leading to premature damage and deterioration. Numerical modeling with a progressive damage analysis method was developed to simulate the failure process and the influence of the resin-missing defects. The simulation results agree well with the experimental results, and the maximum error was 3.06%. The failure modes obtained from finite elements are consistent with the experimental and DIC results. Furthermore, a study was conducted on how the location of resin-missing defects affects the mechanical properties of composite laminates. The findings suggest that defects situated at the edges or on the surface of the material have a more significant impact on the tensile strength. [ABSTRACT FROM AUTHOR]

The objective of this paper is to propose a fiber-level modeling method for simulating tensile fracture of 3D needled composite. The complex fiber structure of 3D needled nonwoven preform is reproduced using virtual fibers. Micro-scale model of the composite is established by embedding virtual fiber structure into the voxel meshes of matrix material. The novel stiffness correction method is developed to solve the problems of volume redundancy and loss of reinforcing effect in transverse and shearing directions of the virtual fiber embedded element. The stiffness of the virtual fiber is not changed by the stiffness correction, ensuring that the stress of the virtual fibers is accurate. Damage initiation and evolution for fiber and matrix materials are characterized by the development of damage constitutive models. The tensile behavior of 3D needled composite is simulated. Influence of modeling parameters, including virtual fiber diameter and voxel mesh density on calculation accuracy is analyzed. Experimental tests are conducted to verify the simulation results. It is indicated that the predicted stress–strain response, strength, and fracture mode all agree well with the experimental results.

Novel semiconductor material with both high strength and ductility is urgently needed to meet the demands of increasing complex applications for electronic components. However, overcoming the inherent trade-off between strength and ductility has remained a longstanding challenge in materials science research. Herein, we proposed a three-dimensional carbon allotrope, oc-C24 with pure sp2 hybridization. This structure comprises arrays of carbon chains in an “8”-shape helix configuration, in between the C-chains which interlinked by the oriented ethylene with a planar π-conjugation. The distinctive structural unit imbues oc-C24 with remarkable tensile behavior, characterized by multi-stage chemical bond rearrangements and structural phase transitions along [010] crystallographic direction, displaying multi-level stress re-enhancement phenomena. A tensile strength of 104.2 GPa and a record strain of 1.05 are observed along [010] direction. Electronic band analysis reveals that oc-C24 is a semiconductor with an indirect band gap of 2.91 eV. The impressive tensile resistance and ductility of oc-C24 suggest its strong potential applications in electronic devices under extreme conditions. Our findings offer valuable insights and methodological strategies for designing novel carbon allotropes with unique mechanical responses.

High-entropy alloys (HEAs) demonstrate superior mechanical properties at room temperature, highlighting potential for engineering applications. With the increasing demand for advanced materials, especially in modern applications facing rigorous conditions, it becomes imperative to gain profound insights into the dynamic behavior of HEAs. In this study, the (FeCoNi)86Al7Ti7 HEA, renowned for exceptional printability and room-temperature mechanical properties, has been fabricated by selective laser melting (SLM), and its tensile and impact behaviors at ambient and cryogenic temperatures are systematically investigated. Experimental results reveal enhanced tensile properties as temperature decreases, achieving a high ultimate strength of 1313.6 MPa and impressive ductility of 24.8 % at 77 K. This improvement is attributed to the synergistic deformation mechanisms, including dislocation slip, stacking faults, Lomer and Lomer-Cottrell locks, which maintain a high strain-hardening rate and thus suppress strain localization. In contrast, impact properties deteriorate due to constrained dislocation mobility at high strain rates and low temperatures, with Charpy impact energy decreasing from 8.1 J at 293 K to 5.1 J at 77 K. Consequently, cracks readily initiate at cellular boundaries or defects, propagating in an intergranular manner and inducing localized deformation. This study provides valuable insights for the future applications of 3D-printed HEAs in extreme operational environments.

This study was aimed at analyzing the properties of the deposited material and interface on a substrate containing an inner lattice structure, layered using directed energy deposition (DED). The substrate with the lattice structure was fabricated using powder bed fusion (PBF) and then layered using a heterogeneous material through DED. Subsequently, the temperature changes of the substrate were monitored during layering, and its correlation with the properties of the deposited material were investigated. The results revealed that the lattice substrate exhibited a high heating and cooling rate during layering. Moreover, the temperature near the deposited region of the substrate was higher than that of the solid sample. This heat transfer property of the substrate resulted in a thick fusion or transition zone at the substrate-deposits interface. Owing to the rapid cooling rate of the lattice substrate, the microstructure of the deposited region was predominantly cellular grain, and the formation of the Laves phase was suppressed. In the tensile test, the lattice samples showed fractures within the substrate region. This was attributed to the formation of a transition zone in the interface of the lattice sample, where the compositions of the two heterogeneous materials gradually fused. In contrast, the interface of the solid sample had a narrow transition zone, leading to non-convergent fracture locations and tensile properties due to inadequate fusion at the interface. Additionally, the dominant Laves phase in the deposited region of the solid sample was identified as a factor contributing to the delamination near the interface.

The stress drop and strain localization behaviors of Ti–6Al–4V titanium alloy under the action of single pulse were investigated using electrically-assisted (EA) tension tests in this study. It is found that the flow stress drop gradually increases with the increase of current density and pulse width during EA tension. The digital image correlation (DIC) technology was adopted to analyze the strain distribution evolution and fracture regulation in EA micro-tension process. It turn out that the EA tensile sample will suddenly form two new intersecting high-strain bands at the moment of applying a pulse. With the increase of strain, the two high-strain bands converge toward the center and gradually evolve into a crossed localized flow zone, which makes the EA tensile sample exhibit a high local plastic deformation compared with room temperature tension. Furthermore, with the increase of current density, the temperature gradient in the tensile direction of the sample increases gradually, resulting in the narrowing of localized flow zone. The transformation of the localized flow zone eventually leads to the increase of fracture angle and the formation of a sawtooth shape fracture morphology. Finally, a material flow model for the single-pulse EA tension process was established. The calculation results show that about 11 % of the stress drop comes from the contribution of non-thermal electroplastic, the main mechanism of stress drop is thermal softening and thermal expansion induced by Joule heat during EA tension.

In this study, a new composition of HEA ((Fe50Mn30Co10Cr10)91Al9, at.%) was designed, and the microstructure evolution and tensile behavior of hot-rolled (Fe50Mn30Co10Cr10)91Al9 (at.%) high-entropy alloy (HEA) were investigated after annealing at various temperatures. The HEA exhibited a three-phase structure of the FCC phase, BCC phase, and a small amount of HCP phase after hot rolling and annealing. Annealing at lower temperatures led to a higher fraction of BCC phase and sub-crystalline grains in the recovery state, making the HEA have high strength. After annealing at high temperatures, the fraction of FCC phase increased. The fraction of recrystallized grains and twin boundaries in the HEA also increased, improving the ductility of the HEA. The HEA exhibited a multistage strain-hardening mechanism during deformation, which was rarely seen in traditional HEAs. The relationship between the microstructure and mechanical properties was discussed from the lattice frictional stress, solid solution strengthening, phase fractions, grain sizes, and dislocation. [ABSTRACT FROM AUTHOR]

In recent years, Fabric-Reinforced Cementitious Mortar (FRCM) has gained widespread application for strengthening reinforced concrete and masonry structures. This research investigated the influence of microfibre parameters on the tensile characteristics of FRCM, focusing on the fibre type, length, and volume fraction. Three distinct types of microfibres were scrutinized: amorphous metallic (AM) fibres, polyvinyl alcohol (PVA) fibres, and nylon fibres. FRCM coupons were designed and fabricated based on the AC434 standard. A tensile experimental program, following RILEM TC232-TDT, revealed the pronounced advantage of employing AM fibres in the pre-cracking stage by significantly improving the crack stress up to 226% and pre-cracking stiffness of FRCM. Conversely, synthetic fibres such as nylon and PVA were beneficial in the post-cracking stage by enhancing cracked stiffness, peak stress, and tensile toughness. Additionally, it was found that using fibres with shorter lengths improved the tensile behavior of FRCM composites in the post-cracking stage due to better random distribution in the cement-based matrix. Finally, an artificial neural network (ANN) model was proposed to predict the tensile parameters of the FRCM composites incorporating microfibres. [ABSTRACT FROM AUTHOR]

The study investigated the tensile behavior of Sandwich Functionally Graded Material (SFGM) fabricated using Additive Manufacturing (AM) technology experimentally and numerically. SFGMs are characterized by a gradual variation in composition and structure with respect to the forming volume from the lower and upper surfaces of the structure toward the center, resulting in a corresponding change in material properties. Fused Filament Fabrication (FFF), a widely used AM process, was used in the present work to fabricate the thermoplastic polymer-based SFGM specimens. SFGM were produced by the FFF method using ABS and PLA materials and subjected to tensile tests according to ASTMD638. [ABSTRACT FROM AUTHOR]

A discontinuous plastic flow is detected in a single-crystal superalloy with an [001] orientation during tensile tests over a wide temperature range. Results reveals that the synergistic impact of normal γ′ precipitates and nanoscale γ′ precipitates in γ matrix on the dislocations motion is the root of the serrated flow. [ABSTRACT FROM AUTHOR]

The development of the use of natural fiber as a constituent material for FFP as an external concrete retrofit that is environmentally friendly and affordable price has been quite developed. One plant that grows massively in Indonesia and can be extracted into fiber is water hyacinth. This plant will be extracted into fiber through three variations, namely mechanical, boiling, and natural alkali, by using bio-resin to produce WHBR (Water Hyacinth and Bio-Resin) FRP in the form of rope and weave. The tensile behavior of the obtained WHBR FRP will be investigated against ASTM A931-18 and ASTM D3039 requirements. The results of the investigation are compliance with failure criteria, the impact of the tensile test result on compliance with failure criteria, and the impact of pattern-delignification on tensile strength performance. In this study, it has been found that the boiling treatment-plain woven variation of WHBR FRP has the best properties and it is recommended as an external concrete retrofit material for future studies. [ABSTRACT FROM AUTHOR]

Ultra-high-performance concrete (UHPC) is a cementitious concrete material known for its sustained post-cracking tensile performance. Various specimen geometries and different test approaches have been used to establish the tensile characteristics of UHPC. Intending to standardize a direct tension test method, this paper independently evaluates a procedure developed by the Federal Highway Administration (FHWA), which has been adopted into AASHTO T 397. To verify the reliability and repeatability of the test method, 216 tensile specimens were cast from three different UHPC types with fiber-volume fractions of 1, 2, and 3% and tested at six laboratories. The measured responses were characterized for different phases of the tensile behavior and analyzed to under)stand the scatter in the test data. It was found that testing can be executed with a 60 to 70% success rate with carefully prepared samples and some modifications to the proposed test method. The test results show an increase in both the tensile strength and multi)cracking phase with an increase in fiber-volume fraction, but the crack straining phase depends primarily on the type of UHPC. Using the test data, average and characteristic tensile responses were established, which are intended, respectively, for analysis and design purposes. [ABSTRACT FROM AUTHOR]

This work studies the tensile behavior of polyamide 6 (PA6) at different strain rates using both experimental and numerical methods. Quasi-static and dynamic tensile tests are performed using a universal testing machine and a split Hopkinson tensile bar (SHTB). The stress-strain curves and specimen morphologies are obtained over a wide range of strain rates from 2.6 × 10–4 s–1 to 900 s–1. The tensile behavior of PA6 is sensitive to strain rate, and the yield strength and yield strain both increase with an increase of strain rate. The plastic stage of PA6 exhibits strain hardening characteristics under quasi-static loading, but strain softening characteristics under dynamic loading. The strain softening characteristics become more significant with an increase of strain rate. The quasi-static tensile mechanical responses of PA6 are analyzed by a ZWT viscoelastic constitutive model, while the dynamic ones are analyzed by a ZWT model with a damage factor. The experimental stress-strain curves are well described by the constitutive model. Three-dimensional incremental expressions of the constitutive model are given, and a user-defined constitutive subroutine is written. Numerical simulations on the stress wave propagation process and the stress-strain curves of PA6 under SHTB loading are conducted, with results that are consistent with the experiments. [ABSTRACT FROM AUTHOR]

The 3D printing of composite materials especially, nanocomposites, is an essential step in exploring new perspectives for the applications of organic matrix composite materials for industrial applications. In this work, the effect of ceramic nanofillers on the mechanical properties of a thermoplastic matrix is studied using different wt% of nanofillers (AEROSIL). The results showed that the increase in the wt% of AEROSIL resulted in an increase in the mechanical properties in terms of hardness, stiffness, ductility, and tensile strength. Moreover, these samples were 3D printed and were compared with the samples prepared by conventional injection moulding. The comparison characterized the influence of the manufacturing method on the mechanical performance of materials. Although there was very little behavior difference in both samples, the 3D-printed samples showed a weight reduction. This has broadened the possible applications of this material and technique in areas where weight is of utmost significance. [ABSTRACT FROM AUTHOR]

The interest in natural fiber as reinforcement in cement composites has grown in recent decades, owing to their environmental benefits and good mechanical properties. However, the mechanical behavior of these eco-composites needs to be further investigated in order to make their use possible for repairing and strengthening existing masonry or concrete structures. In this context, this paper investigates the mechanical behavior of a Fabric Reinforced Cementitious Matrix (FRCM) system produced with flax textile embedded within a Prompt Natural Cement (PNC). A parametric study was conducted to evaluate the effect of the textile reinforcement ratio, the curing time and the water/cement ratio of matrix on the tensile behavior of flax composites. The analysis of the results presented herein allowed to understand the behavior of this type of composites and identify the parameters affecting their mechanical performance. [ABSTRACT FROM AUTHOR]

The thread-anchored blind bolt (TBB) is anchored by a threaded bolt hole instead of a nut. It can only be mounted from one side, providing an alternative method to build the square hollow section column connection (SHSCC). A study on the change of mechanical behavior of a structural component after exposure to fire is the key to its reuse or repair after a fire. The tensile performance of TBB bolted SHSCC after a fire, and the effect of the internal strengthening component (ISC) was studied by experiments. The full-period method was adopted in the test to consider the influence of the load and temperature on the postfire behavior of the TBB bolted SHSCC. Two failure modes of the TBB bolted SHSCC were observed in the test, and the column wall thickness decided the failure mode. Increased load or temperature could cause the connection to fail previously in a fire but not change the failure mode. The TBB bolted SHSCC could recover most of its resistance after cooling down. Comparative tests were also conducted to assess the difference between the SHSCC bolted by TBB and standard bolt (SB). TBB and SB connections with the same configuration showed the same failure mode under the same condition. The TBB and SB connections demonstrated similar postfire performance when the column wall thickness was large. However, the SB connections showed a much better safety reserve than TBB ones when the column wall thickness was limited. The ISC improved the performance of TBB bolted SHSCC significantly when the column wall thickness was limited. The TBB bolted SHSCC strengthened by ISC could also be comparable to the TBB bolted ones. [ABSTRACT FROM AUTHOR]

In this study, a typical γ′ phase precipitation-strengthened Ni-based superalloy DZ411 was repaired using an LMD-based repairing technique with an IN738LC superalloy, and crack-free samples were acquired. The mechanical properties and microstructure of different areas inside the repair sample were investigated, including the IN738LC deposit, the DZ411 substrate, and the interface between these two parts. The differences in mechanical properties between different areas were explained via analyzing fractography and KAM maps. It was found that the coarse carbides of the DZ411 substrate might lead to rapid cracking of grain boundaries, resulting in the worst mechanical properties of the DZ411 substrate. The IN738LC deposit demonstrated significantly superior mechanical properties in comparison to the DZ411 substrate. Its tensile strength exceeded that of the substrate by over 250 MPa, while its relative elongation after fracture was twice as great as that of the substrate. The excellent mechanical properties of the IN738LC deposit could be attributed to its fine microstructure, which resisted rapid cracking and generated a large number of GNDs during the plastic deformation process. For the interface between the deposit and substrate, although its hardness before the tensile test was low, it could also generate many GNDs during the plastic deformation process, hence exhibiting commendable mechanical properties. The research results show that using an LMD-based repairing technique with IN738LC superalloy to repair γ′ phase precipitation-strengthened Ni-based superalloy DZ411 is a feasible solution. [ABSTRACT FROM AUTHOR]

This study investigates the microstructure and mechanical properties of 6082-T6 aluminum alloy base metal (BM) and repair welds (RW) made using ER5356 aluminum filler metal in the metal inert gas process. Tensile tests were carried out under constant strain rates at various temperatures to establish the tensile strength and fracture location of BM and RW samples. The test results demonstrated that the microstructure of the RW samples had a variance in grain structure due to thermal effects during welding, resulting in a reduction in the hardness and tensile strength of the test specimen. The tensile strength of the RW was roughly 78% of the BM sample at room temperature, and when the temperature of the tensile test was raised, the tensile strength of both samples decreased. The tensile fracture location of RW samples occurred in the heat-affected zone, and the fracture occurred in a ductile mode. [ABSTRACT FROM AUTHOR]

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Additive manufacturing of duplex (DSS) and super duplex stainless steel (SDSS) has been successfully demonstrated using laser powder bed fusion (LPBF) in recent years. Owing to the high cooling rates, as-built LPBF-processed DSS and SDSS exhibit close to 100% ferritic microstructures and require heat treatment at 1000–1300 °C to obtain the desired duplex microstructure. In this work, the mechanical properties of DSS and SDSS processed via LPBF were investigated in three building directions (vertical, horizontal, diagonal) and three processing conditions (as-built, stress-relieved, annealed, and quenched) using uniaxial tensile testing. As-built samples exhibited tensile and yield strength greater than 1000 MPa accompanied by less than 20% elongation at break. In comparison, the water-quenched samples and samples annealed at 1100 °C exhibited elongation at break greater than 34% with yield and tensile strength values less than 950 MPa. Stress relief annealing at 300 °C had a negligible impact on the mechanical properties. Austenite formation upon high-temperature annealing restored the reduced ductility of the as-built samples. The as-built and stress-relieved SDSS showed the highest yield and tensile strength values in the horizontal build direction, reaching up to ≈1400 and ≈1500 MPa (for SDSS), respectively, as compared to the vertical and diagonal directions. Fractographic investigation after tensile testing revealed predominantly a quasi-ductile failure mechanism, showing fine size dimple formation and cleavage facets in the as-built state and a fully ductile fracture in the annealed and quenched conditions. The findings in this study demonstrate the mechanical anisotropy of DSS and SDSS along three different build orientations, 0°, 45°, 90°, and three post-processing conditions.

Researchers have been engaged in the study of high-ductility concrete (HDC) due to its excellent ductility and cracking control ability. This study combines the concepts of HDC and alkali-activated composites (AAC) to develop high-ductility alkali-activated composites (HDAAC) using polyethylene terephthalate (PET) powder. Experimental investigations were conducted to assess the compressive and tensile properties of HDAAC, focusing on the impact of varying PET powder content (0%, 15%, 30%, and 45%) and fly ash/slag ratios (FA/GGBS, 6:4, 7:3, and 8:2). The results indicated that the compressive strength of HDAAC ranged from approximately 30 MPa to about 100 MPa, with the specimens maintaining good integrity after axial compression failure due to the bridging action of PE fibers. The replacement of quartz powder (QP) with PET powder slightly decreased the compressive strength and elastic modulus of HDAAC, albeit mitigating its brittleness under compression. An increase in GGBS content enhanced the compressive strength and elastic modulus of HDAAC due to the increased formation of the C-A-S-H reaction products, leading to reduced porosity and a denser microstructure. Under axial tension, HDAAC exhibited typical multiple-cracking behavior with significant pseudo-strain hardening. Increases in the PET content and FA/GGBS ratio resulted in finer cracks, indicating excellent crack control and deformation capabilities. The initial cracking strength, tensile strength, and ultimate tensile strain ranged from 3.0 MPa to 4.6 MPa, 4.2 MPa to 8.2 MPa, and 4.1% to 7.2%, respectively. Despite a decrease in the initial cracking strength and tensile strength with higher PET content, the ultimate tensile strain of HDAAC slightly increased. Observations under a scanning electron microscope revealed a distinct interfacial transition zone near the PET powder, leading to poor bonding with the alkali-activated matrix. In contrast, QP dissolved on the surface in highly alkaline environments, forming better interface properties. These variations in interface properties can be used to interpret the variations in the mechanical performance of HDAAC.