Increase In Tensile Strength Research Articles

Effect of silane coupling agent grafted glycidyl methacrylate on hollow microsphere/natural rubber composites

AbstractTo improve the interfacial bonding between hollow microspheres (RiM01) and natural rubber (NR), the silane coupling agents γ‐aminopropyltriethoxysilane (KH550) and γ‐methacryloyloxypropyltrimethoxysilane (KH570) are used in this study as intermediate reaction platforms for the modification of (RiM01) with glycidyl methacrylate (GMA), respectively. In the process, GMA reacts with KH550 and KH570 through epoxy group ring‐opening and free radical polymerization, respectively. Different NR/RiM01@GMA composites are prepared by a mechanical blending method. The results show that the addition of GMA improves the interfacial bonding between RiM01 and NR, and enhances the vulcanization rate and cross‐linking degree of the rubber composites. When KH550 is used as the reaction platform, the tensile strength of the rubber composites increases by 24% compared to composites with unmodified RiM01, while when KH570 is used, the tensile strength increases by 18%. Additionally, the tear strength and abrasion resistance of the rubber composites increase by 13% and 15%, respectively, when KH570 is used as the reaction platform. At the same time, the filler‐matrix interaction is strongest when KH570 is used as the reaction platform, and the rubber composites exhibit the lowest rolling resistance and the best resistance to heat and oxygen aging.Highlight Modification of hollow microspheres by grafting GMA with KH550 and KH570, respectively. Improvement of rubber composite properties after modification GMA improves the interfacial bonding between hollow microspheres and rubber.

Microstructural, texture, and crystallographic analysis of SiC particle incorporation in double-sided friction stir welding of dissimilar aluminium alloys

This paper investigates the impact of incorporating SiC nanoparticles into the welded interface joint of dissimilar aluminium alloys 2024 and 7075. Double-sided friction stir welding (DS-FSW) was performed to investigate the impact of added nanoparticles on the joint's mechanical properties and crack growth rate. Microstructural analysis of the fractured surface was conducted to assess the influence of nanoparticles on crack propagation, while field emission scanning electron microscopy (FESEM) was utilized to examine the grain size distribution across different weld zones. On analyzing the DS-FSW joint with SiC-reinforced particles using electron backscattered diffraction (EBSD), predominant shear texture components such as B/B̅ and C are observed. Additionally, there are deformed textures like Rotating cube (H) {001} <110> and F {111} <112>, along with recrystallization texture elements such as Goss {110} <001>, P {011} <112>, and Cube {001} <101>. Mechanical properties, determined through hardness and tensile tests, were compared between nanocomposite weldments and base metal to assess the improvement in mechanical properties following the inclusion of SiC particles. Crack growth tests were performed using compact test (CT) specimens at a maximum load of 5 kN and a stress ratio of R = 0.1. The addition of SiC nanoparticles to the joint area led to a significant decrease in grain size and an increase in hardness within the stir zone, compared to the base metal and samples without the powder. The tests revealed an approximately 62 % increase in tensile strength and a notable increase in microhardness of the weld zone of the aluminium alloy metal matrix composite (AAMMCs).

Macro- and microstructural evolution of cement paste modified with MWCNTs under thermal shock conditions

The study investigates the influence of multi-walled carbon nanotubes (MWCNTs) on the macro- and microstructure of cement paste (CP) subjected to thermal shock conditions. CPs with 0–0.3 % MWCNTs content, exposed to a sudden temperature load in a range 50–600 °C, were analyzed in terms of mechanical properties, chemical and phase composition, air pore structure, and microstructure of cement hydration products (Si/Ca, Al/Ca, portlandite, unhydrated part of cement). The research found the optimum MWCNT range to be 0.05–0.1 %, enhancing CP's thermal performance by strengthening cement hydration products and their cohesion, by more the nucleation effect than bridging effect. With the application of MWCNTs, the density of the solid cement phase increased, and the amount of the unhydrated part of cement decreased by up to 21.5 %, at 0.1 % MWCNTs content. Unfortunately, the increase in the MWCNTs content resulted in an increase in the pore volume in the worst case, up to 12.7 %, but it did not negatively affect the strength parameters. The MWCNTs effect caused an increase in tensile strength (fcf) by up to 41.0 % at temperatures above 400 °C, where in the most favorable case improvement in compressive strength reached 16.7 %. The study showed that MWCNTs as an admixture to cement composites is suitable for environments where there is a high variability in terms of thermal loads.

Multi‐objective optimization of 3D printing process parameters using gray‐based Taguchi for composite PLA parts

AbstractThis study investigates the additive manufacturing (AM) process of 30% ceramic‐reinforced composite PLA material using the fused deposition modeling (FDM) technique. The effects of various printing parameters on tensile strength, build time, and material consumption are comprehensively analyzed through a combination of the Taguchi method, analysis of variance (ANOVA), and gray relational analysis (GRA). Experimental design parameters include nozzle diameter, infill density, infill pattern, wall line count, print speed, and layer height. Statistical analyses reveal significant contributions of these parameters to mechanical properties and production efficiency. Single and multi‐objective optimizations of the responses were performed. The single optimization resulted in a significant increase in tensile strength from 39.9 to 48.10 MPa. Production time was reduced from 16 to 9 min; material consumption decreased from 4.95 to 2.43 g for tensile test specimens. The use of GRA in multi‐objective optimization has led to a significant improvement of 8.31% in the gray relational grade (GRG) when compared to the initial parameter settings. These findings provide valuable insights for optimizing FDM processes in the fabrication of composite PLA materials. This contributes towards the advancement of additive manufacturing technology and its applications across various industries. and its applications across various industries.Highlights Tensile strength increased while reducing build time and material consumption. Optimal printing parameters were identified for a composite PLA material. Layer height and nozzle diameter were effective parameters.

A study of mechanical properties and performance of bamboo fiber/polymer composites

In recent years, bamboo seems to have attracted the attention of researchers due to its advantages over synthetic polymers including being renewable, environmentally friendly, and fully biodegradable. Bamboo fibers at (9, 13, and 18 wt%) are filled with epoxy resin and the effects of mixing the bamboo fibers on mechanical properties were studied. In this paper, the tensile properties and performance of natural bamboo fiber powder-reinforced epoxy polymer matrix-based composites were investigated at three different curing temperatures ranging from T26 °C, T38 °C, and T50 °C. The results showed that the tensile strength and Young's modulus of the bamboo fiber/epoxy composites increased at T26 °C are 41.6 MPa and 2.84 GPa, respectively, for particle size 0.52 μm at a weight loading of 13 %. The increase in tensile strength is due to the excellent fiber matrix interface adhesion. However, it was found that the samples tested under T26 °C for bamboo fiber-reinforced epoxy composites acquired better tensile strength than those tested under the high temperatures of T38 °C and T50 °C. According to the analysis of the flexural characteristics of bamboo particle/epoxy composites, the composite with 1.5 μm particle size has the highest flexural strength at 13 wt% weight loading, measuring 105 MPa. The composite with a 1.5 μm particle size at 18 wt% loading records the maximum impact strength of, 5593 J/m2. This work provides a new approach for the development of lightweight and high-strength composite from natural fiber and polymer.

The three-dimensional stability analysis of piled slopes in unsaturated and inhomogeneous soils with nonlinear failure criterion

Under the nonlinear Mohr-Coulomb (MC) failure criterion, based on the upper-bound limit analysis theorem, the three-dimensional(3D) stability of piled unsaturated inhomogeneous slopes is analyzed. By incorporating the nonlinear strength parameters c t and φ t, the energy balance equation is established, and the explicit expression of slope safety factor (F S) is derived by the gravity increase method (GIM). In addition, a genetic algorithm (GA) is used to calculate the minimum F S. The results obtained were compared with those of existing literature to verify the effectiveness of the method used in this paper. The influence of nonlinear parameters on slope stability was studied through parameter analysis. The results show that the nonlinear parameters of soil have a significant influence on the stability of piled slopes. The F S increases with the increase of nonlinear coefficient and uniaxial tensile strength and decreases with the increase of initial cohesion of soil. In addition, the critical slip surface of the slope becomes shallower with the weakening of soil nonlinearity. Furthermore, ignoring the suction effect will overestimate the slope stability, and the slope stability intensified with decreased soil inhomogeneity.

FORMABILITY CAPABILITIES AND MECHANICAL PROPERTIES OF TITANIUM TAILOR-WELDED BLANKS

Titanium alloys have many applications in aerospace, nuclear and automotive industries and in most parts are in sheet form and require joints of high integrity to meet the design requirements and achieve reliable welds. For weight and cost reduction, the technology of tailor-welded blanks (TWBs) is a promising technology in various components. TWBs are usually semi-finished metallic sheets made of different strengths, materials, and/or thicknesses and a forming process is often needed to manufacture the final components. In this paper, Grade-2 and Grade-5 titanium alloy sheets (Ti-TWBs) were laser welded and subjected to a forming process in U-profile geometry at elevated temperatures. The deformation behaviors of the weld joints after forming process were analyzed by mechanical tests such as tensile and hardness tests. The formability of the welded blanks is assessed based on variations in the geometric changes related to the springback angles. The results showed that there was significant increase in tensile strength with forming temperature increase and the failure mode was changed at 850 °C. The formability of the Ti-TWBs was found to be strongly dependent on the applied process temperatures and forming at 850 °C leads to the lowest springback angle.

Characterization and Implementation of Cocoa Pod Husk as a Reinforcing Agent to Obtain Thermoplastic Starches and Bio-Based Composite Materials.

When the cocoa pod husk (CPH) is used and processed, two types of flour were obtained and can be differentiated by particle size, fine flour (FFCH), and coarse flour (CFCH) and can be used as a possible reinforcement for the development of bio-based composite materials. Each flour was obtained from chopping, drying by forced convection, milling by blades, and sieving using the 100 mesh/bottom according to the Tyler series. Their physicochemical, thermal, and structural characterization made it possible to identify the lower presence of lignin and higher proportions of cellulose and pectin in FFCH. Based on the properties identified in FFCH, it was included in the processing of thermoplastic starch (TPS) from the plantain pulp (Musa paradisiaca) and its respective bio-based composite material using plantain peel short fiber (PPSF) as a reinforcing agent using the following sequence of processing techniques: extrusion, internal mixing, and compression molding. The influence of FFCH contributed to the increase in ultimate tensile strength (7.59 MPa) and higher matrix-reinforcement interaction when obtaining the freshly processed composite material (day 0) when compared to the bio-based composite material with higher FCP content (30%) in the absence of FFCH. As for the disadvantages of FFCH, reduced thermal stability (323.57 to 300.47 °C) and losses in ultimate tensile strength (0.73 MPa) and modulus of elasticity (142.53 to 26.17 MPa) during storage progress were identified. In the case of TPS, the strengthening action of FFCH was not evident. Finally, the use of CFCH was not considered for the elaboration of the bio-based composite material because it reached a higher lignin content than FFCH, which was expected to decrease its affinity with the TPS matrix, resulting in lower mechanical properties in the material.

The effect of mixing sequence on synthesis of PP-g-GMA compatibilizer for multilayer packaging (MLP) compounding

Melt recycling Multilayer Packaging (MLP) waste is difficult due to challenging separation procedures. However, blending techniques with compatibilizers can simplify MLP waste melt recycling. PP-g-GMA is a common compatibilizer in polyolefin and PET blends. PP-g-GMA compatibilizer was synthesized by utilizing an internal mixer at 175℃, 50 rpm, and 10 min using styrene as a comonomer. Titration was a method to examine effect of three different sequences of adding the BPO initiator on GMA grafting. Each sequence's PP-g-GMA samples were compounded with MLP waste using a twin-screw extruder and injection molded to make tensile test specimens. FTIR analysis shows that the GMA and Styrene monomers had grafted onto the PP polymer backbone, with the GMA grafting degree by varying mixing sequence. Sequence 3, which introduced initiator, GMA, and styrene simultaneously to PP melt, yielded PP-g-GMA with the most significant GMA grafting degree of 5.11%. Adding PP-g-GMA produced from sequence 3 into the MLP melt enhanced the highest increase in tensile strength and elongation at break of the MLP/PP-g-GMA compound.

Effect of hygrothermal aging on mechanical properties of continuous flax fiber composites

AbstractThe influence of hygrothermal aging on the mechanical properties of flax fiber‐reinforced polymer (FFRP) composites was studied by examining the mechanical properties and failure mechanism of the composite laminates exposed in distilled water at different temperatures. The resin transfer molding (RTM) process was used to manufacture FFRP laminates, which were then subjected to accelerated aging tests in distilled water at different temperatures. The moisture absorption characteristics of FFRP were analyzed by a water absorption test. Tensile, bending, and low‐velocity impact tests of laminates after different aging conditions were performed. Combined with DSC and FTIR tests, the failure mechanism of FFRP exposure to hygrothermal aging was analyzed. The result indicated that the increase in temperature will accelerate the moisture absorption process of FFRP, and the hygroscopic behaviors at different temperatures conform to Fick's law. In the early stage of hygrothermal aging, the composites undergo post‐curing, and the tensile and bending strengths increase. After that, the tensile and bending strengths are decreased because of the thermo‐oxygen aging of materials and fiber/matrix interface damage. After hygrothermal aging, the impact peak force of FFRP decreases obviously while the absorbed energy increases due to the increase of internal defects and plasticization of composites. The increase of hygrothermal aging temperature aggravates the aging of materials, resulting in a more obvious decline in the tensile, bending, and impact properties of the composites.Highlights The effect of hygrothermal aging on the mechanical properties of FFRP is investigated. With the increase of hygrothermal aging time, the tensile and bending strength of FFRP increased at the early stage of aging and then decreased. After hygrothermal aging, the impact peak force of FFRP decreases and the absorbed energy increases due to the increase of internal defects and plasticization of composites.

Characterizing thermo-hydro-mechanical behavior of rock using a grain interface-based discrete element model (GIB-DEM)

Understanding the meso-structure evolution and macro-mechanical property changes in rocks under thermo-hydro-mechanical (THM) treatment is crucial for advancing and managing deep geological projects. However, due to complex discontinuity networks in rocks, achieving an accurate characterization that quantitatively correlates the micro-macro mechanical behaviors under THM conditions remains challenging. This study introduces a groundbreaking multi-scale analysis method called the grain interface-based discrete element model (GIB-DEM) to tackle this issue. By utilizing digital imaging processing (DIP) and meso-mechanical measurements, the GIB-DEM directly determines the meso-mechanical parameters of bonds, eliminating the need for complex calibration found in traditional methods. After validating the GIB-DEM through experimental and numerical Brazilian Splitting tests, we investigate the macro- mechanical behaviors of rock under different THM conditions. Our results indicate that the increase in the tensile strength at 75 °C is attributed to the tensile strength increase of quartz grain interfaces. The development of micro-cracks on the interfaces of feldspar and feldspar-quartz accounts for the decrease in tensile strength of rock under thermal and hydraulic treatment. Overall, this pioneering research provides valuable insights for optimizing Enhanced Geothermal System (EGS) projects and effectively managing Hot Dry Rock (HDR) resources.

Mechanically robust, corrosion and impact resistance polyimide nanofiber/epoxy composite by mechanochemical fabrication

AbstractThis study aimed to explore the application of a mechanochemical method for effectively integrating polyimide nanofibers, which are widely recognized for their outstanding thermal and mechanical properties, into an epoxy resin matrix. The researchers observed an 87.5% reduction in the diameter of polyimide nanofibers after mechanical treatment. The dispersion, compatibility, and interface between the nanofibers and epoxy matrix were analyzed using molecular dynamics simulations and scanning electron microscopy. The addition of polyimide nanofibers significantly increased the binding energy of the composite, resulting in a 52.8% improvement. Moreover, compared to pure epoxy resin, the inclusion of modified polyimide nanofibers led to a 21.9% increase in tensile strength and an 18.8% increase in impact strength. The PI/epoxy composite also exhibited a 15.6% increase in tensile strength and a 16.4% increase in impact strength. Additionally, electrochemical corrosion analysis showed that the PI/epoxy composite had excellent corrosion resistance. In conclusion, due to the exceptional mechanical properties and strong interfacial adhesion of polyimide nanofibers, the PI/epoxy resin composite demonstrated significant overall performance improvement compared to pure epoxy resin.Highlights Mechanochemical method to disperse polyimide fiber, shorter and finer fibers were obtained Improve performance by adding small amounts Microscopic analysis of composites by Materials Studio, PIENFs efficiently improved the interaction on the phase interface Experiments have verified that PIENFs could make the mechanical properties and corrosion resistance

PAN-precursor to carbon fibre: An investigation of manufacture and material properties for varying comonomer composition

This study presents the conversion of polyacrylonitrile (PAN) co-polymers containing methyl acrylate (MA) and varying concentrations of itaconic acid (IA) comonomers, from precursor fibre into carbon fibre using pilot scale continuous processes. The impact of itaconic acid on fibre processability, thermal behaviour, energy consumption, and final mechanical properties during thermal oxidative stabilization (TOS) and carbonization are investigated. Itaconic acid concentration varies from 0.3 to 3 wt % and with increasing concentration of itaconic acid, the precursor fibre exhibited lower exothermicity and enhanced reactivity, resulting in 7 % less energy consumption during stabilization. Higher itaconic acid content led to improved carbon fibre properties. A 20 % increase in tensile strength was recorded for carbon fibres containing the highest amount of itaconic acid along with a higher amount of graphitic structure and carbon yield. Overall, this study explores the impact of precursor design on fibre properties as a route to the manufacture of carbon fibre with reduced embodied energy. The results of this study illustrate pathways to improve the efficiency and effectiveness of carbon fibre production, and to ultimately create high-performance, lightweight, and more sustainable carbon fibre-reinforced composites.

Experimental investigation of the properties of epoxy asphalt mastic

The research on the properties of epoxy asphalt mastic is very important due to its performance being closely related to that of epoxy asphalt mixture. This study evaluates the viscosity evolution, tensile properties, high temperature stability, low temperature crack resistance, and fatigue resistance of epoxy asphalt mastic at varying filler to asphalt ratios (F/A), and compare its performance to those of matrix asphalt mastic and SBS asphalt mastic. Besides, the surface morphology of epoxy asphalt mastic is observed through a stereo microscopy. The results show that as the F/A increases, the viscosity of epoxy asphalt mastic increases; the tensile strength increases, while the elongation at break decreases; high temperature stability first increases followed by a decrease, with optimal performance at the F/A range of 0.8–1.4; fatigue resistance first increases followed by a decrease as well, with optimal performance at the F/A range of 0.6–1.2; the rigidity increases at low temperature, but the crack resistance decreases. The optimal F/A range for best overall performance is determined as 0.8–1.2. Compared with matrix asphalt mastic and styrene-butadiene-styrene (SBS) asphalt mastic, epoxy asphalt mastic shows excellent stability at high temperature and fatigue resistance under low applied strain, except that the crack resistance of it at low temperature becomes less sensitive to changes in limestone fillers content when the F/A is greater than 0.6. Stereo microscopic imaging reveals that limestone fillers evenly disperse in epoxy asphalt at low F/A, with agglomeration occurring when F/A exceeds 1.8. This study highlights the unique performance advantages of epoxy asphalt mastic, and provides essential insights into application of epoxy asphalt mastic in pavement engineering.

Microstructural and mechanical properties evaluation of Calcium and zinc-modified WE43-based nanocomposites through stir casting for biodegradable applications

Magnesium-based alloys and composites have potential as biodegradable materials due to their moderate biodegradability, biocompatibility, and usefulness, but their mechanical strength limits their clinical use. The study synthesised a WE43-based alloy with calcium (Ca) and zinc (Zn), then reinforced it with nano reinforcements (hydroxyapatite, beta-tricalcium phosphate, graphene, and bioglass) through stir casting to create four nanocomposites. The microstructural and mechanical properties were examined to assess Ca and Zn's influence and determine the most effective reinforcement. The result showed that Ca and Zn-modified alloys and all nanocomposite materials have two additional phases, LPSO and Ca2Mg6Zn3, compared to the monolithic WE43 alloy. With the addition of Ca and Zn, S-2 saw significant increases in ultimate tensile strength (UTS), tensile yield strength (TYS), and uniform elongation (U.El), reaching ∼246 MPa, ∼144 MPa, and ∼8 %, respectively, while maintaining an elastic modulus of ∼19 GPa. This resulted in improvements of ∼29 %, ∼25 %, and ∼9 % compared to the as-cast WE43. Graphene-reinforced S-4 demonstrated superior mechanical properties with a UTS of 294 MPa, TYS of 194 MPa, U.El of ∼8 %, and an elastic modulus of 24 GPa, representing increases of ∼52 %, ∼69 %, and 6.05 %, respectively, compared to as-cast WE43. Additionally, S-4 exhibited impressive compressive properties, with an ultimate compressive strength (UCS) of 370 MPa, a compressive yield strength (CYS) of ∼185 MPa, and an U.El of ∼26 %. The bioglass-reinforced nanocomposites had a maximum hardness of 74.8 HV, whereas the as-cast WE43 had a maximum toughness of ∼4 J. These enhancements in mechanical properties are attributed to strengthening processes, including thermal mismatch, orowan, and grain refinement mechanisms. Graphene reinforcement shows promise for biodegradable applications.

Study on poly(butylene adipate‐co‐terephthalate)/thermoplastic starch/poly((R)‐3‐hydroxybutyrate‐co‐(R)‐3‐hydroxyhexanoate) biodegradable films with enhanced gas barrier properties

AbstractBioplastic films with excellent barrier properties were successfully prepared from poly(butylene adipate‐co‐terephthalate) (PBAT), thermoplastic starch (TPS), and poly((R)‐3‐hydroxybutyrate‐co‐(R)‐3‐hydroxyhexanoate) (PHBHHx). The rheological, mechanical, barrier, dynamic mechanical properties, and microstructure of the PBAT/TPS/PHBHHx films were studied. The transition of the continuous phase in the blend significantly affects the properties of the films. The increase in PHBHHx content results in its transition from a dispersed phase to a continuous phase. This phase transition, along with the consequent increase in the crystallinity of PHBHHx, greatly enhances the barrier properties of the film. The percentage crystalline degree of PHBHHx increased from 10.9% to 25.1% with increasing PHBHHx content from 0% to 50%. The film containing 50% PHBHHx showed a significant decrease in both water vapor permeability (WVP) and oxygen permeability (OP) by 75.1% and 69.6%, respectively. It found that the film containing 50% PHBHHx exhibited a decrease of elongation at break from 505% to less than 10% but an unusual increase of tensile strength after a 72‐hour aging test, which is different from PBAT and PBAT/TPS films. However, this indicates that the extensibility of PHBHHx is more susceptible to the effects of aging test, leading to the rearrangement of polymer chains from disordered to ordered morphology.

Utilizing photodeposition to fabricate micro-nano structured microcapsules for enhancing mechanical and high-temperature tribological performance of fabric composites

Fabric composite materials face significant challenges in maintaining excellent tribological properties at high temperatures. This study employed photodeposition to deposit gold (Au) and copper (Cu) nanoparticles on the surface of titanium dioxide-coated jojoba oil microcapsules (TiO2 @jojoba), yielding micro-nanostructured Au-TiO2 @jojoba and Cu-TiO2 @jojoba microcapsules. Subsequently, microcapsules participated in the in-situ polymerization of polyimide (PI), serving as crosslinking points in PEEK/PTFE fabric-reinforced composites. PEEK/PTFE-Au composites containing Au-TiO2 @jojoba microcapsules exhibited outstanding tribological and mechanical properties. Compared to microcapsule-free samples, PEEK/PTFE-Au composites showed a 30.26 % reduction in friction coefficient at 250 °C and a 24.28 % increase in tensile strength. In addition, mechanistic studies indicated that TiO2 underwent a friction chemical reaction converting to TiNF during friction accompanying by friction-induced phase transitions. The release of jojoba oil during friction and the occurrence of friction chemical reactions were the main friction reduction mechanisms of PEEK/PTFE-Au composites at high temperatures.

Strength Indicators of Fiber Reinforced Concrete with Carbon Nanomaterials

Concrete composites with low defects, dense and homogeneous, with a high degree of adhesion between the cement matrix and aggregates, as well as a high ratio between static tensile and compressive strengths and plasticity have the best crack resistance characteristics. This ratio increases in the case of the use of fiber-reinforced concrete. Modern research in nanotechnology focuses on the management of matter at the nanoscale level, which makes it possible to create materials with new properties. Due to the high aspect ratio, flexibility, high strength and rigidity, carbon nanotubes (CNTs) exhibit reinforcing properties. Due to their nanoscale features, CNTs interact with a complex network of calcium-silicate-hydrate binder (C – S – H), contribute to a decrease in porosity and compaction of the cement stone structure, increase the shear forces of matrix adhesion in the contact zone. Thus, there are all prerequisites to assert that fiber concrete with a cement matrix modified with carbon nanotubes will have the required high strength characteristics and crack resistance due to multilevel dispersed reinforcement and the efficient operation of fiber in a nanomodified concrete matrix. This article presents the results of testing samples made of cement stone, concrete and fiber concrete with carbon nanotubes. The presence of carbon nanotubes in cement stone contributes to an increase in compressive strength by 11 %, tensile strength during bending by 20 %. The test results of samples made of reinforced fiber concrete modified with nanocarbon materials have shown an increase in tensile strength during bending up to 109 %, tensile strength during splitting up to 82 %, axial tensile strength up to 78 %.

Research on the deformation law of ultra-thin fiber metal laminates under the synergistic effect of nano-reinforcement and scale effect

At present, titanium alloy/carbon fiber reinforced polymer (TA1/CFRP) laminates, representing the latest fourth generation of fiber metal laminates (FMLs), are predominantly applied in the field of aerospace. The miniaturization of traditional FMLs in thickness or plane size to the micron level for the study of structural properties of ultra-thin laminates will further expand the application of FMLs in the field of micro-devices. Given that carbon nanotubes have a strengthening mechanism in polymers. However, most existing studies have focused on the effect of carbon nanotubes on the properties of macro-scale FMLs, while the enhancement mechanism of the interfacial and mechanical properties of ultra-thin micro-scale FMLs has not been studied, leaving the mechanism still unclear. Based on this, this paper explores the interfacial deformation mode, damage fracture and performance enhancement mechanism of the ultra-thin TA1/CFRP laminates by comparing the parameters of tensile strength and elongation under quasi-static conditions and different process parameters of multi-walled carbon nanotubes content, test temperature, geometry size and grain size. Meanwhile, the correlation law between high-speed tension and quasi-static tension is determined, a 29.3 % increase in tensile strength as the strain rate rises from 0.001 s−1 to 100 s−1, yielding the basic deformation law of ultra-thin FMLs.

Performance Assessment of A Developed Rolling Mill

Rolling of metals has found applications in automotive, construction, agriculture, railroads, housing, metal furniture making, home appliances, electronic cabinetry, pipes and tubing etc. These have as well contributed to human and environmental sustainability. Nevertheless, the applications of metal rolling processes and machines have not been adequately harnessed in our locality due to unavailability of the rolling machine in small scale industries, laboratories and workshops in institutions of learning in the region. Annealing heat treatment was carried out on a mild steel round bar of 50 mm diameter and length of 200 samples. The samples were charged into an SXL muffle furnace with an annealing temperature of 950oC. The mechanical properties and the microstructure of the rolled mild carbon steel were evaluated. The results of the performance evaluation of the machine through assessment of the metallurgical characteristics of the rolled products from the machine and assessment of mechanical properties such as tensile strength and hardness of the rolled products from the machine showed an increase in the tensile strength from 250.85 MPa to 258.85 MPa, an increase in the ultimate tensile strength from 535.88 MPa to 540.05 MPa, an increase in the hardness from 140 HV to 145 HV, and a decrease in the percentage ductility of the mild carbon steel from 56% to 51%. Also, the optical micrograph of the rolled samples shows a coarse microstructure of grain refinement from slipping and pilling of dislocations.