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Recently, composite PVDF membranes with good performance have triggered enormous interest because of their great potential application. However, the uncertainty of mechanical properties limits their application. Herein, this paper reveals the elastic modulus properties of the loading angle between warp and tensile direction using the uni-axial tensile test of SH-1050P membrane textile. In addition, the bi-axial tensile test with different loading ratios was implemented. Both uni-axial and bi-axial ductile load-displacement/stress-strain curves are featured. It is the first to establish a relationship between the elastic modulus and the loading angle using a theoretical method based on the assumption that there is no slippage and crease between yarns and matric. Furthermore, simulations with different textile parameters were carried out to verify the theoretical results. The key finding is that the elastic modulus under uni-axial load can be divided into two stages, which are elasticity and plasticity. Both of which are proportional to the sine function applied to two times the loading angle. The Poisson's ratio of SH-1050P textile can be considered as a fixed value of 0.11. This conclusion can be extended to similar textiles. The outcome of this paper contributes to a deeper understanding of the PVDF memrane's mechanical behavior and presents a novel insight into its response to different loading conditions. [ABSTRACT FROM AUTHOR]

This paper aims to valorize the excavated earth (ExE) generated from the tunnel digging works, to elaborate excavated earth-based plasters for masonry walls. Excavated earth is an admixture of water, gravel, sand, and fine particles. A small amount of gravel (<4% by weight) was removed, and the tunnel-excavated earth is used to elaborate plasters. Cement and slag are used as stabilizers in ExE-based plasters and reinforced with natural hemp fibers. The physical, mechanical, thermal, and hydric properties of ExE-based plasters are investigated. The increase in cement content affects the workability of ExE-based plasters in a fresh state, while the addition of natural hemp fibers has no significant effect on the workability. It has been demonstrated that the mechanical performances (compressive strength, flexural strength, and dynamic modulus) of ExE-based plasters increase with the increase of cement content and decrease with the increase in slag content. The hemp fiber addition (0.8% by weight) shows no considerable effect on the ExE-based plaster's mechanical performance. As for the thermal properties, the increase of cement and slag contents negatively affects the thermal conductivity. The increase in cement content decreases the water absorption of earth-plasters. Except for some tests (shrinkage, main cohesion, and cracking tests), which have not been done in this study, the results of cement-stabilized ExE-based plasters (7% and 9%) are in accordance with the recommendation of the DIN 18947 standard, indicating that the tunnel excavated earth can be used as earth-plasters. [ABSTRACT FROM AUTHOR]

Fabric/unsaturated polyester composites have garnered significant attention due to their lightweight properties and superior mechanical characteristics. Despite these advantages, the strength of joints within these composites remains a crucial aspect requiring thorough investigation. This paper presents a study focused on comprehending the factors that influence joint strength in fabric/polymer composites, emphasizing the importance of effective load transfer and robust adhesion within the fabric/polymer matrix. The objective is to minimize stress concentration and enhance load distribution within the joint. The failure mechanism involves a combination of Bearing Failure and shear-out failure, particularly in single-fabric layer composites. The study establishes a linear relationship between composite bending stiffness and the enforcement fabric's flexural rigidity. A comparison of tensile properties across various joining methods, such as bolts, adhesive bonding, and tongue grooves, reveals that bolt joints exhibit the highest strength and elongation, followed by tongue groove joints. Notably, bolt joints demonstrate elevated toughness, efficiency, and stiffness in samples of two-layer twill fabric when the twill lines are oriented perpendicular to each other. Under these conditions, joint properties are measured at 0.89%, 14804.65 Nm, and 20.46 J, respectively. Increased fabric flexural rigidity yields advantages in terms of load distribution, load transfer efficiency, and dimensional stability. This study deepens the understanding of factors influencing joint strength, contributing valuable insights for the development of optimized joint designs and manufacturing processes. These advancements aim to enhance the performance and reliability of fabric/unsaturated polyester composites in applications requiring high strength and structural integrity. [ABSTRACT FROM AUTHOR]

In this research, dissimilar welding of the nickel-based superalloy Inconel 59 and austenitic stainless steel AISI 904L steel was successfully done with double-pulsed gas metal arc welding (DP-GMAW) using the filler ERNiCrMo-13. Macroscopic analysis showed a defect-free weld with an aspect ratio of 2.4, attributed to the efficient heat delivery (0.642 kJ/mm) in DP-GMAW. The microstructure of the weld joint was examined through both optical microscopy and scanning electron microscopy. Examination of the microstructure of the weld interface exposed grain coarsening near the heat-affected zone on the AISI 904L side. In contrast, the weld fusion zone contained fine equiaxed dendrites. Microsegregation and alloying element migration across the entire weld area were assessed through energy dispersive X-ray spectroscopy point analysis and line mapping, revealing controlled microsegregation across the region. X-ray diffraction (XRD) analysis was used to ascertain the average grain size (38.41 nm) and secondary phase composition. The XRD-cosα method was used to assess the residual stress of the weld joint, revealing tensile residual stress in the weld zone and compressive residual stress in other regions. Tensile, Charpy impact, and Vickers hardness tests were conducted in the study to evaluate the strength, toughness, and hardness of a dissimilar weld. The impact of two cryogenic treatments, namely shallow and deep, on tensile and toughness characteristics was investigated in this study. The cryogenic treatments significantly enhanced the mechanical properties of weld samples compared to their as-welded condition, leading to an 11.5% increase in tensile strength and a 10% improvement in toughness. [ABSTRACT FROM AUTHOR]

This research was done to investigate third-generation Advanced High-Strength Steel (AHSS) to improve mechanical properties and reduce production costs in the automotive industry. The potential of TRIP-assisted steel has been studied to address this issue, with a special focus on δ-TRIP steels. This research studied the δ-TRIP samples, which were micro-alloyed with 0.05 and 0.30 wt.% Mo, with isothermal bainitic transformation (IBT) time parameters. Microstructural analyses were conducted using optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectrometry (EDX). The volume percentage of retained austenite (RA) phase, critical to achieving the requisite mechanical characteristics, was determined using X-ray diffraction (XRD). The analysis of the samples revealed a complex, multi-phased structure comprising δ-ferrite matrix, α-ferrite, bainite, RA, and martensite. The quantity and morphology of RA significantly influenced the resulting mechanical characteristics. The experimental results demonstrated yield stresses (YS) of 400–440 MPa, ultimate tensile strength (UTS) of 790–870 MPa, and total elongations to failure (TEL) of 24–34% in δ-TRIP steels containing 0.05 and 0.30 wt.% Mo alloy. The optimal combination of UTS and TEL (UTS × TEL) is achieved at an impressive 850 MPa × 32% (27200 MPa.%). This remarkable achievement was made possible by adding only 0.30 wt.% Mo and IBT, which were carried out at 450°C for 10 min. Focusing on the effects of Mo-alloy content and heat treatment duration on microstructure and mechanical characteristics, this study provided insights into enhancing the quality of δ-TRIP steel while decreasing manufacturing costs. [ABSTRACT FROM AUTHOR]

A novel composite tandem sandwich structure made of aramid fabric and aramid honeycomb, impregnated in a matrix of epoxy resin combined with poly (vinyl butyral), PVB, is proposed. The composite was additionally reinforced with a small concentration of titanium diboride nanoparticles, TiB2, to study its effect on impact resistance. Sandwich composite samples were fabricated by impregnating the aramid fabrics and honeycomb in subsequent layers with the system epoxy/PVB/TiB2. Their mechanical behavior was examined through three-point bending test, Charpy impact test, and compressive test. The chemical reaction between PVB and epoxy resin, and chemical inertness between the nanoparticles and the other constituents were confirmed by FTIR analysis. The flexural strength and stiffness increased by 27.6% and 62.5%, respectively, in the presence of TiB2 reinforcement. Impact tests showed increase of 104% in impact toughness in the case of samples with TiB2. Nano TiB2 did not increase compressive strength of the proposed sandwich structure, but it improved its stiffness and reduced the permanent deformation. The achieved improvements in mechanical resistance make this new composite structure a promising candidate for automotive, airspace, naval, civil engineering, sports equipment industry, and for use in defense technologies. [ABSTRACT FROM AUTHOR]

The utilization of natural fibers in polymer biocomposites is on the rise owing to their ready availability, lightweight nature, excellent mechanical strength and eco-friendly characteristics. In this study, a solution casting method was performed to synthesize biodegradable composite films based on polyvinyl alcohol (PVA) with 10 to 30% polyethylene glycol loading (PEG, matrix) and 10% untreated or alkali treated coir fiber (reinforcement). SEM, FTIR, XRD, mechanical properties and contact angle studies were used to examine how the alkaline treatment affected the structure and characteristics of the synthesized films. Alkali treatment on coir fiber removed hemicellulose, lignin, and pectin and significantly improved its crystalline nature from 38.3% to 69.5%, confirmed by the XRD test. Adding 10 wt% polyethylene glycol with alkali treated coir fibers attained the highest tensile strength which was 38.6% greater than untreated coir fiber and demonstrated the best reinforcing effects of treated coir on these biocomposite films. According to our research, coir fiber's alkali treatment considerably enhances its ability to interact with polyvinyl alcohol polymer and polyethylene glycol polymer blends, making it possible to fabricate composite films with improved mechanical properties. [ABSTRACT FROM AUTHOR]

BSK 46 is a low alloy structural steel with excellent mechanical and corrosion properties and is widely used in many applications, including tipper bodies of heavy-duty trucks. Optimizing the welding parameters to reduce defects and improve productivity is critical for the users. The present work addresses optimizing the welding process parameters to improve productivity with adequate weld quality during the pulsed gas metal arc welding (P-GMAW) process. Three BSK 46 weldments (weld-1, weld-2 and weld-3) were fabricated by varying the root gap, root face, filler pass and heat input. The metallographic and mechanical characterization of P-GMAW weldments were done through microstructures, Vickers micro-hardness, transverse tensile strength, Charpy toughness and three-point bend test. Subsequently, a correlation has been developed between the microstructural features and mechanical properties of the weld joints. The hardness was found to be incremental in nature from the base metal to the fusion zone. Maximum hardness of 215.81 ± 10 HV was observed in the weld-3 fusion zone. Tensile test results reveal that weld-3 weldments exhibit a higher tensile strength of 547.48 ± 2 MPa than weld-1 (537.46 ± 7 MPa) and weld-2 (533.67 ± 9 MPa) weldments. Maximum impact toughness of 136.33 ± 14 J was observed in the weld-3 weldments. Post-bend testing showed no cracks on the weld surfaces, indicating defect-free weld joints with good ductility. It is observed that weld-3 showed relatively better mechanical properties than weld-1 and weld-2 in lesser welding time and lower welding cost [ABSTRACT FROM AUTHOR]

Titanium/steel bimetallic sheets are extensively employed in engineering applications due to their excellent cost performance and high corrosion resistance. However, the interface defect is easy to form due to significant differences in physical and chemical properties between titanium and iron, which need to be improved through effective repair techniques. The wire and laser additive manufacturing (WLAM) method is implemented to repair TA1/Q235 bimetallic sheets. The addition of a copper interlayer plays a crucial role in the repair process. According to the results, S201 copper wire is used as the interlayer material, while TA1 wire serves as the deposit material in the repair process using the WLAM technique. Under the conditions of a laser power setting of 1500 W, a defocusing amount of −40 mm, a deposition speed of 1 mm/s and an argon flow rate of 23 L/min, the interface defects are effectively addressed, leading to successful repair. The WLAMed copper interlayer avoids direct contact between the titanium repaired layer and the steel base layer, improving the interface bonding characteristics. The interior of the repair region of TA1-Q235 bimetallic sheets is made of the pure copper layer, Cu2Ti + Cu4Ti3 layer, CuTi layer, CuTi2+β-Ti layer and pure titanium layer. The copper-titanium compound region exhibits a pronounced increase in hardness, with the repair region achieving a tensile strength of 436 MPa. Notably, the fracture position occurs within the repair region, with the titanium side exhibiting brittle fracture and the steel side displaying ductile fracture. [ABSTRACT FROM AUTHOR]

High-manganese steels, due to their unique combination of strength and elongation, have been widely used in aerospace, petrochemical and rail transportation. However, a prevalent challenge in advancing the utilization of high-manganese steel is the need for corresponding welding consumables. The deformation mechanism of high-manganese steel encompasses three primary mechanisms: martensitic phase transformation, twinning and dislocation movement. The stacking fault energy (SFE) is a critical factor in determining the dominant deformation mechanism in high-manganese austenitic steels. Furthermore, the magnitude of the SFE is principally influenced by the alloying elements present and the temperature at which deformation occurs. Alloying elements can significantly influence the microstructure and mechanical properties of wire arc additive manufacturing (WAAM) of high-manganese steels. The metal powder-cored wire of high-manganese steel with full austenitic microstructure was designed in this paper. The effects of C, Mn and Cu on the microstructure, solute segregation and properties of WAAM of high-manganese steels were systematically investigated by optical microscopy, electron microscopy and mechanical testing. The influence of SFE on the microstructure characteristics and work hardening behaviour were also studied. The results showed that as an increase of the C content, the tensile strength and elongation of deposited metals were improved. The corresponding low-temperature impact toughness increased at first and then decreased. The highest value of impact toughness was 68.5 J with 0.79%C. As the Mn increased, the strength decreased, the elongation increased and the low-temperature impact toughness value displayed an initial increase followed by a subsequent decrease. With the increase of Cu, the yield strength and elongation improved significantly. The tensile strength exhibited a marginal initial increase followed by a decrease, whereas the change was not substantial. In contrast, the low-temperature impact toughness value showed a substantial increase followed by a decrease. The developed M3 wire containing 1.10%C-21%Mn-0.3%Cu possessed the optimum performance (yield strength of 551 MPa, tensile strength of 909 MPa, elongation at break of 30.2%, impact toughness value of 57.5J), with the good mechanical stability and low solidification cracking sensitivity. [ABSTRACT FROM AUTHOR]

The ever-increasing usage of ceramic materials in restorative dentistry necessitates a simple and effective method to evaluate flexural strength σF and fracture toughness K C. We propose a novel method to determine these quantities using a bilayer specimen composed of a brittle plate adhesively bonded onto a transparent polycarbonate substrate. When this bilayer structure is placed under spherical indentation, tunneling radial cracks initiate and propagate in the lower surface of the brittle layer. The failure analysis is based on previous theoretical relationships, which correlate σF with the indentation force P and layer thickness d, and K C with P and mean length of radial cracks. This work examines the accuracy and limitations of this approach using a wide range of contemporary dental ceramic materials. The effect of layer thickness, indenter radius, load level, and length and number of radial cracks are carefully examined. The accuracy of the predicted σF and K C is similar to those obtained with other concurrent test methods, such as biaxial flexure and 3-point bending (σF), and bending specimens with crack-initiation flaws (K C). The benefits of the present approach include treatment for small and thin plates, elimination of the need to introduce a precrack, and avoidance of dealing with local material nonlinearity effects for the K C measurements. Finally, the bilayer configuration resembles occlusal loading of a ceramic restoration (brittle layer) bonded to a posterior tooth (compliant substrate). [ABSTRACT FROM AUTHOR]

This study investigates the performance degradation and prediction of polyvinylidene fluoride (PVDF) membrane materials under natural aging conditions (2 MPa prestress) and artificially accelerated aging conditions. Initially, the tensile strength, elongation at break, elastic modulus, tear strength, and apparent properties (transmittance, reflectivity, and conjugated double bond absorption area) of the membrane material were measured through uniaxial tensile testing, trapezoidal tear testing, and ultraviolet (UV) testing. These measurement results were then compared and analyzed in relation to tear strength and apparent properties under artificially accelerated aging conditions. The results indicate that UV irradiation and 2 MPa prestress play a crucial role in the degradation of PVDF membrane material properties. Finally, an enhanced Arrhenius equation, accounting for the triple effects of irradiation, oxygen pressure, and temperature, and Schwarzschild's law, were employed to establish a correlation between natural (2 MPa prestress) and artificially accelerated aging performance of PVDF. The results demonstrate that the enhanced Arrhenius equation provides a more accurate prediction compared to Schwarzschild's law. [ABSTRACT FROM AUTHOR]

High-performance co-polyimide (co-PI) fibers derived from 3,3'4,4'-biphenyldianhydride (BPDA), p-phenylenediamine (p-PDA) and 2-(4-aminophenyl)-5-amino-benzimidazole (BIA) were prepared via the wet spinning and dry-jet wet spinning method, respectively. The distinctions between wet spinning and dry-jet wet spinning processes on the structures and properties of co-PI fibers were systematically investigated. The co-PI fibers prepared by dry-jet wet spinning exhibited smoother surface morphology and higher mechanical properties than those of co-PI prepared by wet spinning. Wide-angle X-ray diffraction (WAXD) results showed that the co-PI fibers prepared by dry-jet wet spinning exhibited highly oriented structure along the fiber direction along with a low degree of lateral packing order in the transverse direction. Small-angle X-ray scattering (SAXS) revealed that the radius, length, misorientation and internal surface roughness of the microvoids in the co-PI fibers prepared by the dry-jet wet spinning are lower than those in co-PI fibers prepared by wet spinning. Moreover, the effect of air layer height, as well as the heat treatment on the structure and properties of fibers during the dry-jet wet spinning process, was also studied. The tensile strength and modulus of co-PI fibers prepared by dry-jet wet spinning reached 2.72 GPa and 114.29 GPa, respectively, with an air layer height of 10 mm and a heat stretching temperature of 440°C. [ABSTRACT FROM AUTHOR]

The contemporary agricultural natural fiber is effectively used for fabricating composites because of its economical, ample availability, and biodegradability. In this way, the potential material for the reinforcement of hybrid (paddy straw and pineapple leaf) fiber- and ortho-laminated polyester composites was conducted. This research article is focused on the hybridization of untreated, treated, and paddy pulp fiber-reinforced polyester composite laminates. The unidirectional paddy straw fiber and pineapple leaf fiber (PALF) were used in the fabrication process of laminate using a compression molding machine with the mold dimensions of 300 × 300 × 5 mm is used and the investigation of mechanical (tensile, flexural, impact, hardness, shear) behaviors are conducted in the samples as per the standard. Five samples were prepared by varying the fiber content in the matrix in which sample S1 pure polyester plate without any addition of reinforcement. Out of these five samples, sample 4 (S4) produced better tensile, flexural, impact, hardness, and shear values of 28 MPa, 61 MPa, 3.46 Joules, 64 HR L, and 68.7 MPa, respectively. Comparing the laminate samples of S1 and S4 there is a 35.2% increase in the tensile value of S4, similarly, other values also resulted in better hikes. In addition to that, the water absorption properties of the laminate were also evaluated and fiber breakage, fiber pullout, fiber orientation, crack propagation, and voids on the fractured specimens were identified with help of a scanning electron microscope (SEM). Overall, the fabricated hybrid composite laminates were lightweight and has good fiber-matrix bonding with improved mechanical and morphological properties for commercial and home need applications. [ABSTRACT FROM AUTHOR]

This study involves the characterization and analysis of a Chinese red clay obtained from Hunan province to determine its suitability for manufacturing ceramic products. X-ray fluorescence analysis showed the clay has high silica (63.25 weight percent) and alumina (21.38 weight percent) content along with iron oxide, alkalis, and calcium acting as fluxes. X-ray diffraction (XRD) confirmed the presence of quartz, kaolinite, illite, and hematite as the major mineralogical phases. Scanning electron microscopy revealed loosely stacked, plate-shaped kaolinite particles exhibiting pseudohexagonal morphology. Particle size distribution shows a d50 of 12.7 μm and specific surface area is 21.3 m2 /g. Differential thermal analysis-thermogravimetric analysis showed mass losses between 450–600°C and 950–1050°C corresponding to dehydroxylation and formation of a liquid phase, respectively. Dilatometry traced the onset of viscous flow sintering around 1000°C. Test bars produced from the clay were fired at 800°C, 900°C, 950°C, 1000°C, and 1050°C. The firing shrinkage increased from 2.5% at 800°C to 12.8% at 1050°C. Strength improved from 11.2 megapascals at 800°C to 42.3 megapascals at 1050°C due to densification and mullite formation. Hematite content caused the color to change from orange-red at 950°C to dark red at 1050° C. XRD analysis of fired specimens confirmed the presence of hematite and newly formed mullite and cristobalite phases. The results indicate the suitability of the clay for manufacturing bricks, roof tiles, and wall tiles using appropriate firing temperatures and cycles. [ABSTRACT FROM AUTHOR]