Search

This study ascertained the physico-mechanical and anatomical properties of Terminalia superba tension wood, in comparison with its normal counterpart. Tension wood recorded higher green moisture content (75 ± 2%), and lower basic density (562 ± 11 kg/m3) than normal wood (71 ± 2.8% and 576 ± 7.9 kg/m3, respectively). The modulus of elasticity, modulus of rupture, and compression parallel to grain (11293 ± 227.5, 106 ± 4.5 and 65 ± 1.8 MPa, respectively) for normal wood were greater than tension wood (7276 ± 443.7, 50 ± 0.4 and 50 ± 3.5 MPa, respectively). The double wall thickness (66 µm) and diameter (37 µm) of normal wood were greater than those of tension wood (65.68 and 33.24 µm, respectively). Normal wood also recorded greater fibre length (1.4 mm) than tension wood (1.2 mm). However, fibre-lumen diameter (32.24 µm) and vessel diameter (156.80 µm) were wider for tension wood than for normal wood (29.34 and 147.93 µm, respectively). With their comparable properties besides strength, T. superba tension wood would substitute its normal counterpart for light construction works to maximise total recovery and efficient use of T. superba and other timbers with such strains. [ABSTRACT FROM AUTHOR]

A huge amount of fruits and vegetables is being produced and processed in India and therefore the waste is also generated in high quantities. These wastes are good sources of vitamins, enzymes, cellulose, and many other essential compounds. The non-utilization of these bio-wastes leads to economic loss and also environmental problems. Plastic is versatile and very convenient material to use as packaging material. Plastic is a non-biodegradable material which is not only hazardous to human health but also affecting environment. To overcome such problems, the study was conducted to utilize plant-based waste to develop biodegradable packaging containers. Among the various alternatives, plant-based waste like peels of orange along with wheat flour and tamarind seed kernel flour at varying levels were used to develop acceptable quality biodegradable packaging containers. The studies involved obtaining the optimized formulation by using Response Surface Methodology (RSM) for creating biodegradable containers with desired mechanical and chemical properties. The independent variables used were Orange Peel Powder (OPP), Wheat Flour (FL) and Tamarind Seed Powder (BA) as binding agent. The dependent variables were water activity and compression strength. The optimized formulation obtained from the RSM is 50.28% OPP, 35.71% FL, and 14.01% BA along with process parameters 1310C for 64 min. This optimized formulation produced biodegradable container with 12.63kgf compression strength and 0.21 water activity. [ABSTRACT FROM AUTHOR]

The potential to utilize ZrB2 based ceramics for high-temperature space applications requires excellent thermal shock resistance. Therefore, the present study describes the use of water quenching method to determine the thermal shock resistance of microwave sintered ZrB2-25 SiC (vol. %) and ZrB2-25 SiC-2 MgO (vol. %) composites at 400 °C, 800 °C and 1200 °C. The MgO incorporation enhanced the ability of ZrB2-25 SiC (vol. %) composite to withstand thermal shock due to the higher fracture toughness and flexural strength. The crack deflection was observed as the primary toughening mechanism after thermal shock. The ZrB2-SiC-MgO composite demonstrated outstanding thermal shock resistance with a critical thermal shock temperature difference of 974.41 °C, surpassing that of ZrB2-SiC composite by 1.6 times. Post thermal shock test at 1200 °C, the maximum microhardness of 14.99 ± 1.29 GPa, maximum compression strength of 769.01 ± 36.66 MPa, maximum fracture toughness of 5.98 ± 0.39 MPa.m0.5 and maximum critical energy release rate of 76.05 ± 9.89 J/m2 were observed for ZrB2-25 SiC-2 MgO (vol. %) composition. The addition of MgO to ZrB2-SiC resulted in exceptional performance in microhardness, compression strength, and fracture toughness following thermal shock testing at 1200 °C. Specifically, the ZrB2-SiC-MgO composite retained 94.16%, 91.28%, and 95.52% of its pre thermal shock values for these mechanical properties, emphasizing its thermal stability and resistance to degradation under high-temperature conditions. [ABSTRACT FROM AUTHOR]

The Knoop hardness (HK) and compression strength (σc) of 23 advanced ceramics were measured to determine if an overarching HK/σc relationship could be identified for ceramics, or if one exists for a specific class of ceramics, similar to the hardness/yield strength relationship (H/Y ≈ 3) identified by Tabor for metals. Compression strength was determined using a dumbbell‐shaped specimen that virtually eliminates the end splitting that occurs when cylinders or cuboids are tested and provides a more representative compression strength value. HK values were obtained over a range of indentation loads between 0.98 and 98N. Four HK values, HK2, load‐independent HK, the hardness from the proportional specimen resistance model, and a brittleness parameter, were obtained and plotted against compression strength. An overarching relationship could not be identified for ceramics in general and the only class of ceramics that had a consistent relationship was tungsten carbide/cobalt that had a HK/σc of approximately 2.5. The consistent relationship for the WC/Co materials is due to the cobalt plastically deforming during the loading processes, something that does not occur in the other ceramics evaluated. [ABSTRACT FROM AUTHOR]

Ultra-high-performance concrete (UHPC) has gained worldwide popularity due to its high mechanical performance. This research studied the influence of adding a mixture of two fibers (steel and PVA) on the compressive strength, modulus of elasticity, and flexural tensile strength of UHPC. The mixtures were prepared by adding steel fibers and PVA fibers using a standard procedure defined in the research, which is the time to mix the dry materials and the time to mix the admixture and water. The Central Composite Rotational Design (CCRD) methodology was used for the experimental design of the compressive strength and longitudinal deformation modulus tests. The results were analyzed using statistical software to investigate the influence of fibers on these two mechanical properties of UHPC. With this technique, an optimized design for the study of flexural tensile strength was arrived at. It was found that the standardized equations for the modulus of elasticity, directed to conventional concrete and high-strength concrete, are inadequate for estimating the modulus of UHPC in this research. Statistical analysis indicated that the range of fiber amounts analyzed did not significantly affect the compressive strength and modulus of elasticity. Regarding the optimized mixture, its flexural tensile strength indicated that the fiber content should be higher for UHPC to be suitable for structural use. [ABSTRACT FROM AUTHOR]

Composites have an improved property compared to their base alloy materials, thus demanding applicability in many industrial segments. The present research emphasis was made to improve the mechanical property of base alloy AA7075 with the supplication of Silicon mono nitride and zirconium carbide as hard ceramic reinforcements. Powder metallurgy route was used for the development of the composites. Later the composites were compacted, followed by sintering under optimum conditions. Mechanical property investigation is derived for compression strength and microhardness. A compression strength of 169 MPa with the AA7075 matrix was significantly enhanced by the addition of SiN up to 7 wt%. Further addition of ZrC into the SiN-reinforced composite enhanced this to a peak strength of 198 MPa with the addition of 3 wt% ZrC. This study further showed that while an increase in SiN content higher than 7 wt% raised the porosity and correspondingly lowered the mechanical properties, the optimum composition of 7 wt% SiN and 3 wt% ZrC balanced the strength and porosity rather well. The AA7075/SiN/ZrC developed hybrid composites in the present work have evidenced considerably improved mechanical properties; thus, they could find varied high-performance applications in the aerospace, automotive, defense, and industrial machinery sectors. The current findings have significant implications in the design and optimization of hybrid composites for advanced engineering applications. [ABSTRACT FROM AUTHOR]

Ti-6Al-4Nb-4Zr (mass%) was prepared by selective laser melting (SLM) under various conditions, and the microstructure evolution resulting from SLM processing and subsequent heat treatments was investigated. The effects of the unique SLM-induced microstructure on the high-temperature compressive strength and creep properties of the samples were then elucidated. Under rapid cooling conditions, the martensitic structure formed in a scale--like pattern, with a 100µm in size, consistent with the laser scanning pattern. By contrast, under slow cooling conditions, the α/β lamellar structure formed in β grains with a 300µm grain size instead of in a scale-like pattern. The martensitic structure drastically changed to a Widmanstätten structure during heat treatment. The equiaxed α phase also formed at the interface of the scale-like patterns. By contrast, the α/β lamellar structure did not exhibit a change in response to heat treatment. The compressive strength of the SLM samples was governed by the martensite α size and the grain size, both of which depended on the cooling rate. The dominant creep deformation mechanism at 600°C and under a loading stress of 137 MPa was grain boundary sliding. The creep life depended on the grain size. The HIP treatment improved the creep life because it eliminated pores introduced by the SLM process. [ABSTRACT FROM AUTHOR]

In the building industry, concrete is widely utilised as a foundation. In the construction of superstructures, structural concrete, slab construction, stair construction, and architectural components are all utilised. The most frequent components of concrete are cement, fine aggregate, coarse aggregate made of shattered stones or gravels, chemical admixtures, and water. During the curing or hardening process, concrete will shrink slightly. This shrinkage generates strain in the freshly poured concrete, resulting in shrinkage fractures. To rule out this problem, bioconcrete was employed, which is made up of microorganisms that can precipitate calcium carbonate and aid in crack sealing, giving it a self-healing capacity. These are considered to be more cost-effective, eco-friendly, and require less maintenance. Due to the formation of the microcracks leads to the failure of the structure due to corrosion. The importance and efficiency of bioconcrete madding using four different microorganisms—Bacillus subtilis, Brevibacillus sp., Bacillus megaterium, and Microvirga sp. are discussed in this paper. It has been found that the bioconcrete made using Bacillus subtilis had higher compressive strength of 50.37 N/mm2 followed by Brevibacillus sp. with the compressive strength of 42.81 N/mm2 [ABSTRACT FROM AUTHOR]

Copyright of Modern Urban Transit is the property of Modern Urban Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Test specimens with smaller sizes seem to be preferable because using standard specimen sizes for ultra-high-performance concrete (UHPC) can lead to issues owing to the current testing equipment’s capacity limitations. Therefore, the size effect investigation of the UHPC specimens is necessary. In this paper, the UHPC mix was used to explore the size effect on the compression and flexural response of the cylinder and beam specimens, respectively. The UHPC mix was cast into various-sized cylinders and beams with diameters ranging from 50 to 150 mm and heights/widths from 50 to 150 mm, respectively. A nonlinear 3D finite element (FE) model has been created in ABAQUS software for all UHPC specimens. Additionally, validation was done using the experimental findings of this study. The findings clearly revealed that the compressive and flexural strength decreases with increasing the size of the specimen. The larger specimens revealed a slight reduction in compressive strength between 1.4% and 9.5%, while a considerable reduction was recorded in flexural strength, where the larger specimens showed reduction ratios between 19.1% and 35.6%. Furthermore, the experimental and FE findings were in satisfactory agreement and exhibited virtually identical overall trends.

Friction Stir Extrusion (FSE) was employed to convert cylindrical LM13 ingots into pipes, utilizing three distinct designs of rotating tool heads. This study examined the influence of process variables, consisting of tool rotational speed and plunging speed, on key properties of the resulting products. The properties investigated encompassed the size of Si precipitates, microhardness, wear resistance, and ultimate compressive strength (UCS). To effectively establish the relationships between the process input variables and the resulting mechanical and microstructural characteristics of the produced pipes, an artificial neural network (ANN) was used. This established correlation was integrated into a hybrid multi-objective optimization framework to identify the optimal process parameters. The investigation determined the ideal configuration: a plunging rate of 31 mm/min, a rotational rate of 653 rpm, and tool design number 3.

This study investigates the properties of waste steel fiber reinforced recycled concrete (RC-WSF) aiming to develop sustainable concrete using demolition debris and steel fibers from machining chips. The research has two primary. To assess the impact of various percentages of recycled aggregates (RA) as replacements for natural aggregates (NA) in conventional concrete and to evaluate the effect of incorporating waste steel fibers (WSF) into recycled concrete mixes. The experimental methodology involved producing and testing standard specimens in two phases: first, evaluating different RA percentages (25%-RC25, 50%-RC50, 75%-RC75) in natural concrete; second, studying the addition of WSF (0.4%, 0.6%, 0.8%) to selected recycled concrete mixes (RC25, RC50) from the initial phase. The tests included compressive and flexural tests with particular attention to the workability of fresh concrete. The results showed that replacing NA with RA decreased compressive strength, flexural strength, and Young's modulus. However, for 25% and 50% RA replacements, the reduction in mechanical properties was less than 25% in general. Low volume fractions of WSF (< 0.8%) significantly improved the mechanical performance of recycled concrete under compression and increased ductility in flexure. Higher WSF content did not lead to further improvements. Flexural tests on notched beams showed more than 30% increase in fracture energy for RC25 and RC50 reinforced with 0.4–0.6% WSF. These new results underscore the viability of RC-WSF in promoting sustainable building practices, offering significant insights into the adaptive behavior of recycled concrete and the advantageous roles of waste steel fibers in enhancing structural integrity. [ABSTRACT FROM AUTHOR]

The structural performance was tested for two plywood products distributed in South Korea: Plywood for roof (RP) and plywood for concrete form (CP), in accordance with ASTM standards. The evaluation included tests for tensile-shear strength under wet conditions, bending performance, compressive strength, and rolling shear strength. Results indicated that the CP specimens exhibited a compressive strength of 37 MPa, surpassing that of structural cross-laminated timber (CLT) with comparable specific gravity. The bending performance of CP plywood was also notable, with a modulus of rupture of 56.8 MPa and a modulus of elasticity of 12 GPa. The rolling shear strength was measured at 2.4 MPa, which is favorable compared to the rolling shear strengths of European structural wood species. Notably, the failure pattern was ideal. Furthermore, the CP specimens demonstrated excellent adhesive strength in the tensile-shear test after cyclic boiling, both meeting and exceeding the Korean standards for structural plywood in all evaluated aspects. In contrast, the RP specimens did not fully meet some of the Korean standards, indicating areas for improvement in structural applications.

Identification of suitable polymeric materials to fabricate microneedles (MNs) for the collection of interstitial fluid (ISF) is a challenge. Here, characterization of different carrageenan‐biopolymer composites for MN patch fabrication intended for ISF collection is reported. Systematic oscillatory rheological studies of composites containing iota‐carrageenan mixed with alginate, gelatin, or pectin are performed to determine the linear viscoelastic region, gel point, tan delta, complex viscosity, and flow transition index. A polynomial equation is derived by relating flow transition index of biopolymer composites and compression strength of fabricated MNs. The biopolymer composite of iota‐carrageenan and gelatin at 2% and 14%, respectively, and CaCl2 crosslinker (80 mm) shows the greatest compression strength sufficient for MNs insertion into the excised porcine skin. MNs swell up on application in an agarose gel model and the ex vivo excised porcine skin model to collect 36 ± 5 and 14 ± 1 µL of fluid within 10 min, respectively. Taken together, it is demonstrated that rheological analysis can be performed to select suitable polymer composites that possess sufficient strength for the skin insertion and swellability for ISF collection. [ABSTRACT FROM AUTHOR]

Thermoplastic composites have become increasingly popular due to their numerous benefits. To enhance the performance of fiber-reinforced thermoplastic composites, many research efforts have been made using various types of fillers. However, the high melting temperature and viscosity of thermoplastic polymer melt present a primary challenge in achieving uniform filler dispersion. Interply strengthening is one of the simplest and most cost-effective techniques for addressing this challenge. This study utilized micro-size core-shell particles that were dispersed using a sieve. The particles were carefully sprinkled onto the sieve, facilitating their controlled dispersion at the ply interface, after which fabric and thermoplastic films were laid on top. The resulting stacked arrangement was then processed using a hot consolidation cycle via compression molding to produce composite laminate. The impact of incorporating core-shell particles on the mechanical performance of carbon fiber-reinforced polyamide 6 (CF/PA6) laminates was investigated. Results showed that adding 4 wt% core-shell particles led to a maximum improvement of 58.99%, 25.62%, 41.56%, and 47.83% in flexural strength and modulus, interply shear strength, and compression strength, respectively, compared to the pristine composites. Stress-strain curves confirmed that the core-shell particles delayed matrix and interlaminar crack propagation. Furthermore, micrographic images indicated improved interaction of CSPs at the ply interfaces. These findings can improve the interply strength of thermoplastic composites and assist designers in achieving higher performance. [ABSTRACT FROM AUTHOR]

Fused filament fabrication (FFF), a known variation of fused deposition modeling (FDM), is a fast-growing additive manufacturing technique that is widely used in various industrial and technological applications owing to its ability to build functional parts with complex geometrical features in a reasonably good time. FFF utilizes a variety of thermoplastic materials such as polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), nylon (polyamide), and polycarbonate (PC) each offering distinct properties suitable for different applications. Polycarbonate is a high-performance polymer with engineering applications, but it is a less studied material with respect to the FFF process. The mechanical properties and dimensional accuracy of FFF-built parts are influenced by several process parameters, and choosing the best set of process parameters is essential for achieving the desired properties in the built parts. This study examined the effects of four critical process parameters (layer thickness, extrusion temperature, printing speed, and extrusion width) on the mechanical properties such as the tensile, flexural, and compression strengths of FFF-printed polycarbonate specimens. Tensile, flexural, and compressive tests were performed according to ASTM standards. Mathematical models based on dimensional analysis were developed to determine the correlation between the process parameters and mechanical properties of the printed specimen. The predicted models obtained showed a good correlation with the measured values and could be used to generalize the prediction for the process conditions of the FFF process. Validation tests were conducted to verify the developed mathematical models. The developed mathematical models provide a tool for optimizing the manufacturing parameters during the fused filament fabrication process. [ABSTRACT FROM AUTHOR]

This paper summarizes the effect of replacing some cement on the mechanical properties and durability of concrete・ The analysis showed that, through the use of wollastonite to replace the right amount of cement, the compressive strength of concrete will be improved, and the small particles of wollastonite will fill the internal pores of concrete, make the internal structure of concrete more dense, and then improve the durability of concrete, prolong the service life of concrete components・ Through the elaboration of this paper, it will provide a certain theoretical basis for the future experimental research ・ The future research and development in this field is discussed. [ABSTRACT FROM AUTHOR]

Direct Contact Membrane Distillation (DCMD) uses low heat sources to separate water from urea, which was then used as a plasticizer in regolith-based cement to make it more workable. The work investigated separating potable water and urea from artificial urine using DCMD and then characterizing the products. Water was successfully separated from the artificial urine solution as characterized by density, conductivity, pH, and substance concentrations. The concentrated urine solution was used in regolith-based cement cured under vacuum at temperatures that simulated temperatures that would be expected in construction on the Moon. Workability and other properties were improved by replacing water with concentrated urine solution in the mix. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the behavior of accelerated carbonation-cured laboratory specimens using the ultrasonic non-destructive testing (UNDT) method and compare the results with the destructive testing (DT) method. The materials used in the study included a blend of lime kiln dust and ground granulated blast furnace slag (LKD-GBFS) wastes, natural fine aggregate (sand), and alternative fine aggregates from waste tires. The chemical analysis of the LKD and GBFS samples highlighted them as suitable alternatives to OPC, hence their utilization in the study. A 60:40 (LKD-GBFS) blending ratio and a 1:2 mix design (one part LKD-GBFS blend and two part sand) was considered. The natural fine aggregate was partially replaced with fine waste tire rubber crumbs (TRCs) in stepped increments of 0, 5, and 10% by the volume of the sand. The samples produced were cured using three curing regimens: humid curing (HC), accelerated carbonation curing (ACC) with no water curing (NWC) afterwards, and water curing after carbonation (WC). From the results, an exponential model was developed, which showed a direct correlation between the UNDT and DT results. The developed model is a useful tool that can predict the CS of carbonated samples when cast samples are unavailable. Lastly, a total CO2 uptake of 15,912 g (15.9 kg) was recorded, which underscores ACC as a promising curing technique that can be utilized in the construction industry. This technique will bring about savings in terms of the time required to produce masonry units while promoting a change in the basic assumptions of a safer and cleaner environment. [ABSTRACT FROM AUTHOR]

The risk posed by expansive soils can be lessened by placing foundations at a more deep level below the surface. Structures are able to withstand uplift forces because overburden pressure partially suppresses swelling pressure. In order to transfer the forces to a sufficiently deep depth, this study suggests introducing shafts of a low-expansion overburden material. Soil improved with cement is chosen for this purpose. This study suggests using sand with added excavated natural clay and cement. The expansive clay is added to sand in ratios of 10, 20, 30, 40 and 60%. The clay–sand mixture is then enhanced by cement of 1, 2, 4 and 8% by the weight of the mixture under four curing periods of 1, 7, 28, and 90 days. This material is recommended for use under lean concrete to transfer the loads to lower levels below the foundation depth. The thickness of this material depends on the stresses exerted, the type and the properties of the subsurface soils. The cement-enhanced clay–sand shaft's properties are examined in this work with regard to the swelling potential, compressibility, and the unconfined compressive strength for different clay contents and curing conditions. Stiff shafts were formed and found to support stresses from 600 to 3500 kPa at cement additions in the range of 1% to 8%. Clay content above 30% is found to be not suitable for Al-Qatif clay due to the compressibility and low strength of the mixture. When two percent or more of cement is added, the swelling potential is significantly reduced. This is reliant on the pozzolanic interactions of soils and cement as well as the clay mineralogy. Determining how cement affects clay–sand combinations in regions with expansive soils would facilitate the introduction of a novel, inexpensive technology to support loads applied by the superstructure. [ABSTRACT FROM AUTHOR]

This study investigates the mechanical properties of single and double-layer woven sisal mat-reinforced PP composite panels. Sisal fibers were extracted using the manual decortication method, resulting in fibers with a density of 1.43 g/cm3 and a diameter ranging from 0.4 mm to 0.6 mm. To improve the bonding between the sisal fibers and the matrix, the fibers were hand-spun into yarn and woven into mats. The study focuses on the unique material combination and the use of sisal as a natural fiber reinforcement. The 18 mm thick panels were tested for water absorption following ASTM D570, compression strength, and tensile strength following ASTM D3039 using the UTES-100 High Precision universal strength tester machine. Composite panels with single layers of 10% and 15% woven fabric mat, loaded with 8 kg and 10 kg, exhibited compressive strengths of 11.6KN and 12.5KN, respectively. Panels reinforced with two layers of 20% and 30% sisal woven fabric mat, loaded with 8 kg and 10 kg, had compression strengths of 12.2KN and 12.5KN, respectively. Moreover, composite samples with 15% single layer and 30% double-layer sisal woven fabric mat demonstrated a equal compression strength of 12.5KN, falling within the range recommended by ISO13006:2012. The tensile strength of 16.99MPa, although slightly below the recommended ISO13006 value of 20MPa for commercial-grade panels, indicates promising results. The study’s findings suggest that higher fiber content and additional reinforcement layers lead to increased compression and tensile strength. Furthermore, the moisture absorption rate of the developed composite panels was significantly lower than the 0.5% water absorption rate authorized by the American National Standard Institute.

In this research, for the first time, the effect of embedding irregular and jagged steel particles of recycled milling dendritic chips on the improvement of compressive and interlayer strength of thermoplastic polyamide6 (PA6)-based, 200 g/m2 plain weave E-glass-fabric-reinforced composite laminates was investigated. The goal here is to examine whether the sharp spikes on the particles can penetrate adjoining laminate layers to provide superior interface toughness compared to spherical toughening particles. In-plane compression tests, according to ASTM D695-15 standard, show that through thickness expansion leads to delamination and subsequent failure. Consequently, theoretical considerations suggest that enhancements in interface toughness should lead to an increase in compression strength. For this purpose, steel particles with three size ranges, 300–600 µm, 150–300 µm, and 75–150 µm, were prepared and embedded into the composite laminates using film-stacking and hot-pressing process, in four different volume fractions. The particle distribution, impregnation, and bonding with the PA6 matrix were analyzed using optical and scanning electron microscopy imaging. Overall, results demonstrate a very good mechanical bonding between the particles and the thermoplastic matrix. Some interlocks between the particles and composite laminates were observed which has led to an improvement in the compressive strength of the composite laminate. [ABSTRACT FROM AUTHOR]

The complex modeling and computational cost are unavoidable in analysis of finite element models (FEMs) when mechanical properties of woven composite materials are predicted. To overcome the drawbacks of FEMs, two different artificial neural network models (ANNMs) based on quasi-static axial compression experimental data of 2.5D woven composite plates (2.5DWCPs) are constructed: (1) The direct strength prediction model (DSPM) is a non-destructive way to predict strength, which is meaningful in engineering; (2) The indirect strength prediction model (ISPM) is based on stress–strain curves, which firstly proposes a simplified data processing method including the state variables (SVs). The SVs are introduced to modify the experimental stress–strain curves, which not only reduces training data size but also significantly improves prediction accuracy. Then, the performance of the DSPM and the ISPM has been evaluated by numerical examples. The results indicate that the DSPM has simple and direct expressions of input parameters (IPs) and output parameters (OPs), which makes it easier to construct and train ANNMs. The ISPM not only utilizes sufficient training data from experiments but also performs well in predicting stress–strain curve and failure strain. In short, two proposed ANNMs have ability to fast and accurately predict compression strength, which are more suitable for engineering than FEMs. To reduce experimental costs, the DSPM is proposed to produce reasonable results. If a lot of experimental data are prepared, the ISPM can produce more accurate results. [ABSTRACT FROM AUTHOR]

The main purpose of this work is to optimize the mechanical properties of tungsten–copper (W–Cu) nanocomposite fabricated by the sintering process. For this purpose, the parameters of sintering temperature, sintering time and weight percentage of copper were selected to optimize the compression strength, impact strength, hardness and corrosion resistance of the W–Cu nanocomposite using the desirability function procedure and response surface method. The analyses of transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) were also performed to examine the microstructure of W–Cu nanocomposite. The results exhibited that a rise in the sintering temperature from 1000∘C to 1150∘C significantly enhanced the impact strength of W–Cu nanocomposite, while a rise in the sintering temperature from 1150∘C to 1300∘C deteriorated the impact strength. Moreover, the compression strength and hardness of the W–Cu nanocomposite continuously improved by elevation of sintering temperature from 1000∘C to 1300∘C. A rise in the amount of Cu from 20 wt.% to 40 wt.% led to a reduction in the hardness of the W–Cu nanocomposite, while a rise of Cu content improved the impact and compression strengths. The results also indicated that the mechanical properties of W–Cu nanocomposite enhanced simultaneously by using 27 wt.% Cu at sintering temperature of 1197∘C and sintering time of 2.7 h. The samples sintered at the optimal conditions indicated a higher corrosion resistance than that sintered at the initial conditions. [ABSTRACT FROM AUTHOR]

Milti-principal cation oxide ceramics with excellent mechanical properties for potential applications in coating materials. A Multi-principal cation mullite (MPCM) ceramic is synthesized with MgO, TiO 2 , Cr 2 O 3 , ZrCl 2 O·8H 2 O and Al 2 O 3 , SiO 2 via solid state reaction at 1600 °C. It is determined that 96.9 % of the sample composition is mullite. MPCM ceramic exhibits higher compressive strength (981 ± 19 MPa) and fracture toughness (3.37 ± 0.05 MPa∙m1/2), the compressive strength has raised by 453 MPa, and the added value of solution strengthening (452 MPa) is gained by using solid-solution strengthening theory. The improvement of compressive strength is mainly due to the solution strengthening effect of the four oxides(Mg, Ti, Zr, Cr), and the improvement of fracture toughness is caused by the grain hindrance during crack propagation. Moreover, its application at the high-temperature resistant coating is verified through experimentation. The interfacial binding force, as an important mechanical property index for ceramics, is researched. In this study, pure mullite powder and MPCM powder are coated onto the refractory TaWNbV alloy matrix by slurry coating method, and the interfacial toughness of the two coatings mingled with the matrix is calculated to be 72.9 and 62.6 J·m−2, respectively. The "shrinking cylinder" model is introduced to interpret the oxidative weight gain mechanism of the two coatings. [ABSTRACT FROM AUTHOR]

This study investigates the feasibility of fabricating a dynamic foot prosthesis for lower knee amputees using a composite material composed of polypropylene (PP), fresh cow bone powder (FCBP), and silicon rubber (Si). Nine samples with variable compositions of these components were prepared and subjected to mechanical testing to evaluate their compression strength, elongation, factor of safety, impact energy, and energy storage efficiency. The results demonstrated that the innovative composite made up of 68% PP, 18% FCBP, and 14% Si has exhibited the highest foot energy storage efficiency of 67.83%, which is within the standards of 63–100%. Furthermore, the synthesised dynamic foot has obtained excellent mechanical properties and a maximum factor of safety of 2.71. Accordingly, this study proposes that the developed composite material has the potential to be utilised for the fabrication of dynamic foot prostheses, as it offers a set of improved mechanical properties and potentially enhances the mobility and quality of life for lower knee amputees. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the properties of biodegradable plantable pots made from biomaterials. Specifically, rapeseed straw and cow manure biomaterials were studied here because these biomaterials add nutrients to the soil during their biodegradation and are readily available agricultural by-products. Furthermore, the use of biomaterials helps in replacing the plastic materials which are currently used to make pots and decreases the environmental impact by producing a cleaner product. The physical and mechanical properties of biocomposites pots were investigated and optimized in the present work. The effect of mixing ratio (straw: cow manure) in the composite, straw particle size, and chemical pre-treatments of straw by 1% HCl or 2% NaOH on the physical and mechanical properties of biodegradable pots was investigated. Additionally, the Taguchi method and ANOVA statistical analyses were employed for parameters optimization. The results indicated the straw to cow manure ratio exhibited a significant effect on the compression strength (CS), penetration strength (PS), and water absorption (WA) of pots. While the CS and PS of pots decreased with increasing the ratio of straw from 2 to 10% and increasing the particle size of straw from 1.5 to 3.0 mm, these changes increased the water absorption of pots (126.52–141.21% for 1.5-mm untreated straw). Chemical pre-treatments of straw investigated here resulted in decreased CS and PS of pots. The straw ratio in the straw/manure mixture is the most significant factor affecting the characteristics of biodegradable pots. [ABSTRACT FROM AUTHOR]

Expanded polystyrene (EPS) is a material used as packaging and the amount of EPS waste accumulated in landfills has driven progress in the production of biocomposite materials such as those produced from the mycelium generated by white rot fungi. The main objective of this study was the production of a biocomposite material obtained from the mycelium of Pleurotus ostreatus strain using malt bran and wheat bran as a substrate to be use as packaging material. We propose three mixtures: mixture A (50 % malt and 50 % wheat); mixture B (30 % malt and 70 % wheat) and mixture C (100 % wheat) using solid fermentations. Properties like moisture content, compressive strength, density, water absorption, electrical conductivity and pH were measured for each mixture. The best results were obtained in the mixture A with average compressive stress values of 110,04 kPa for 10 % deformation, maximum water absorption of 172,01 % (36 hours), pH of 5,88, electrical conductivity of 1860 µS/cm and density of 233,17 kg/m3. When comparing the properties with EPS, it was found that the compressive stress is similar, however, properties such as density and water absorption present remarkably high values for the biocomposite to be used in packaging. [ABSTRACT FROM AUTHOR]

Through the optimized design of the mix proportion of self-compacting concrete for steel-shell immersed tube of Shenzhen -Zhongshan Link, the effects of expansive agent and super absorbent resin on the working performance and compressive strength of self-compacting concrete were discussed, and their effects on the early shrinkage and long -term shrinkage deformation were emphatically studied. The results show that adding appropriate amount of expansive agent and super absorbent resin can improve the working performance of self-compacting concrete, but it began to have an adverse effect on the workability and the strength when the addition amount continued to increase. Compared with expansive agent, adding super absorbent resin can more effectively improve the volume stability of self-compacting concrete. [ABSTRACT FROM AUTHOR]

This article presents a study on earth bricks (adobe) used in ancient earth constructions in the region of Boussaâda, located in the southeast of northern Algeria. The objective is to evaluate the physical and mechanical properties, including compressive and shear strength, as well as the thermal characteristics of these bricks, with the aim of promoting their use on a large scale. The results of the physical and identification analyses showed that the bricks studied are silty sands. The compression tests gave an average compressive strength of 0.2 MPa. The shear tests gave an average cohesion of 172.22 kPa and an average internal friction angle of 63.92°. The average thermal conductivity is 0.7291 W/m.K. The results obtained show that Boussaâda earth bricks have satisfactory physical and mechanical characteristics. The compressive strength is low, but it is sufficient for the construction of one or two storey buildings. Cohesion and internal friction angle are satisfactory for the stability of brick walls. The thermal conductivity is low, which makes Boussaâda earth bricks good thermal insulators. The results obtained reveal that the composition of these adobes can be used to make quality bricks. [ABSTRACT FROM AUTHOR]

Hollow-strut metal lattice structures are currently attracting extensive attention due to their excellent mechanical performance. Inspired by the node structure of bamboo, this study aimed to investigate the mechanical performance of the gradient hollow-strut octet lattice structure fabricated by laser powder bed fusion (LPBF). The effect of geometrical parameters on the yield strength, Young's modulus and energy absorption of the designed octet unit cells were studied and optimized by FEA analysis. The hollow-strut geometrical parameters that deliver the best mechanical property combinations were identified, and the corresponding unit cells were then redesigned into the 3 × 3 × 3 type lattice structures for experimental evaluations. Compression tests confirmed that the designed gradient hollow-strut octet lattice structures demonstrated superior mechanical properties and deformation stability than their solid-strut lattice structure counterparts. The underlying deformation mechanism analysis revealed that the remarkably enhanced bending strength of the gradient hollow-strut lattice structure made significant contributions to its mechanical performance improvement. This study is envisaged to shed light on future hollow-strut metal lattice structure design for lightweight applications, with the final aim of enhancing the component's mechanical properties and/or lowering its density as compared with the solid-strut lattice structures. [ABSTRACT FROM AUTHOR]

The European Union's initiative to reduce carbon dioxide emissions has paved the way for the exploration of innovative building materials that are environmentally friendly and meet all requirements of durability and strength. These criteria can be met by combining natural resources used in the production of building materials with waste materials that would otherwise be landfilled, having a negative impact on the environment. This study focuses on such materials and presents the results of recent research conducted at the Warsaw University of Life Sciences. The aim was to develop a new generation of materials fully compliant with the principles of the circular economy and sustainable development. Simultaneously, these materials should have no adverse effects on human health and be strong enough to carry the required loads. This study proposes the combination of a natural raw material—in the form of clay—with fly ash from the incineration of sewage sludge to produce a new generation of materials. Several samples were prepared using fly ash from two sources and then were fired at 950 °C. The resulting composites underwent physico-chemical and strength tests. These tests not only confirmed the high strength and durability of the obtained product but also the neutralization of the heavy metals originally present in the fly ash. [ABSTRACT FROM AUTHOR]

Subfossil oak (SO) wood material, originating from three different buried trunks discovered in recent years by excavations in riverbanks on Romanian territory, was analysed in this research. Aged oak recovered from constructions (AO_C) and recent/new oak wood material (NO) were also investigated to provide comparative data for the SO. The oven-dry density and the basic density, the total volumetric and linear swelling and shrinkage coefficients and the compression strength parallel to the grain were the selected physical and mechanical properties considered. The experimental results showed a lower density of SO compared to NO and AO_C tested by up to about 19–20%, alongside a trend of increased dimensional instability, with variability among the tested assortments. The compression strength parallel to the grain was reduced by 19–31% compared to NO. The properties of AO-C were closer to those of NO, but differences between wood materials from different sources and of different ages were registered. A positive linear correlation was found between compression strength parallel to grain and the basic density for all types of material and assortments tested. These comparative results have to be considered by designers and engineers in the valorisation of SO in furniture design and other applications. [ABSTRACT FROM AUTHOR]

Among the various reinforcement phases available in Cu-based composites, the unique layered structure and easy diffusion of A-layer atoms make MAX phases more suitable for reinforcing a copper matrix than others. In this study, Cu-coated Ti3AlC2 particles (Cu@Ti3AlC2) were prepared through electroless plating, and Cu@Ti3AlC2/Cu composites were fabricated via vacuum hot-press sintering. The phase composition and microstructure of both Cu@Ti3AlC2 powder and composites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results demonstrate the creation of successful electroless copper plating to obtain a Cu coating on Ti3AlC2 particles. At 850 °C, a small amount of Ti3AlC2 particles decompose to form TiCx, while Al atoms from the A layer of MAX phase diffuse into the Cu matrix to form a solid solution with Cu(Al). The test results reveal that the density of the Cu@Ti3AlC2/Cu composite reaches 98.5%, with a maximum compressive strength of 705 MPa, which is 8.29% higher than that of the Ti3AlC2/Cu composite. Additionally, the compressive strain reaches 37.6%, representing an increase of 12.24% compared to that exhibited by the Ti3AlC2/Cu composite. [ABSTRACT FROM AUTHOR]

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Peculiarities of the modern cellular concrete manufacturing technique were borrowed in the expanding glass technique at ambient temperature presented in the work. Using aluminum dust in calcium hydroxide solution and adding carboxymethyl cellulose (CMC) as a froth fixer, cellular glass specimens with excellent insulating properties with minimal energy consumption could be experimentally obtained, as an alternative solution to conventional methods industrially used. The tests presented in this article intend to improve the mechanical resistance of the cellular product under the conditions of preserving existing insulating properties by adding to the starting mixture a very effective ultrafine powder (silica fume) contributing to the increase of strength and durability. Completing the manufacturing recipe with silica fume is the originality element compared to the previously applied solutions. The results confirmed the effectiveness of the new method, the compressive strength increasing up to 4.7 MPa under conditions of density below 0.35 g·cm-3 and heat conductivity below 0.079 W·m-1 ·K-1 . [ABSTRACT FROM AUTHOR]

Self-compacting concrete, as a performing material whose casting and compacting can be made without applying the vibration technique, due to the flowability properties that allow it to flow by its own mass, was produced and tested in several versions of the material composition. Flowability gives high structural homogeneity and allows fast concrete pouring rate in a shorter time. During the experiment, four experimental versions were tested successively using coal ash, metallurgical slag, limestone dust as well as a combination of fly ash-slag as cementitious materials, that partially replaced Portland cement. Also, a water-reducing additive (polycarboxylate ether) was added in different ratios. Aggregates were chosen at low particle size (fine sand below 2 mm and granite gravel less than 12 mm). Mixing the materials together with the working water led to obtaining the paste with excellent flowability properties. The consolidated concrete had compactness and homogeneity and the mechanical characteristics were comparable to those of traditionally made concrete. Except for the remarkable flow characteristics of the paste, in this experiment it was proven that the compression strength of self-compacting concrete can reach very high values (after 28 days) of up to 60.4 MPa. [ABSTRACT FROM AUTHOR]