Papers by Keyword: Mechanical Property

Abstract: Al0.5CoCrFeNi high-entropy alloy (HEAp) reinforced AA2218 metal matrix composites (MMCs) by stir casting and successive rolling. Mechanical characteristics of the AA2218 HEAp MMCs are analysed. The stir-casted AA2218 HEAp MMCs' ultimate tensile strength rose by 74.3 percent when HEAp was added at a weight percentage of 4 wt percent. When the MMCs were made by rolling, they had greater mechanical qualities than those made by RTR. Higher rolling deformation and lower HEAp mass fraction led to greater mechanical characteristics discrepancies between the AA2218 HEAp MMCs formed by CR and RTR. In the AA2218 HEAp MMCs after RTR, there were voids that were not present in the CR MMCs. Micro holes and the mechanical properties of metal matrix composites were also discussed in detail.

Abstract: Ni/Al energetic structural materials were prepared by vacuum hot-pressing method and then treated by secondary treatment of cold rolling or cold isostatic pressing. The effects of secondary treatment on the surface morphology, the phase composition, density, exothermic properties and tensile properties of Ni/Al energetic structural materials were investigated. The results showed that the density, the reaction energy density and the sensitivity of energetic materials improved significantly by the secondary treatment of cold rolling or cold isostatic pressing. It was also found that, after cold rolling and cold isostatic pressing, the energy density increased from 780 J/g to 1089 J/g and 993 J/g, respectively, and the initial reaction temperature was advanced by 46 °C and 14°C simultaneously. This is related to the increased in the contact area between Al particles and Ni particles. Meanwhile, the tensile strength increased from 166.7 MPa to 254.8 MPa and 211.3 MPa, respectively.

Abstract: Ti-6Al-4V is one of the popular choices for biomedical implants due to multiple advantages, such as corrosion resistance, high strength-to-weight ratio, biocompatibility, lightweight, durability, and osseointegration properties. However, Young’s modulus (E) of Ti-6Al-4V is much higher than the E of natural human bone, which may lead to stress shielding. Therefore, it is critical that we need to fabricate the implant with specific mechanical properties that can match the patient’s existing bone. With the advent of 3D printing, we now can design porous structures with the most suitable E through adjusting porosity to suit individual needs. Porous structures with various porosities were manufactured by selective laser melting (SLM). Mechanical testing was performed to show that the E of the printed samples was related to the porosities only. Based on the simulated and actual results, there are still many areas that can be improved to enhance the quality of the printed structures. Indirect cytotoxicity tests were performed to verify the biocompatibility of the porous structures.

Abstract: This research focused on the effect of initiator and accelerator amounts on mechanical properties of unsaturated polyester resin (UPR). Methyl ethyl ketone peroxide (MEKP) and cobalt octoate (CoO) were used as an initiator and an accelerator, respectively. The amount of each chemical was varied from 1, 1.5 to 2 phr. In each batch, UPR, MEKP and CoO were mixed, casted and allowed for curing at room temperature for 24 hours. Mechanical properties of the cured samples were then studied. The results indicated that the effects of MEKP and CoO amounts on flexural properties and impact resistance were greater than those on hardness. It was found that UPR samples prepared by using the same ratio of MEKP and CoO exhibited overall mechanical properties better that those prepared with different MEKP and CoO ratios. When all mechanical properties were considered, the results suggested that the best overall mechanical properties were achieved when MEKP 1.5 phr and CoO 1.5 phr were employed.

Abstract: Grain characteristics are one of the most important factors in determining alloy properties. Thermal deformation and solution treatment experiments were used to investigate the evolution of grain features and mechanical properties of Al-9.39 Zn-1.92 Mg-1.98 Cu alloy. The results reveal that when the deformation temperature rises, the recrystallized grain size, recrystallization fraction, and sub-grain size for the alloy's final microstructure gradually increase. The recrystallized grain size and fraction increase as the solution temperature rises, although the sub-grain size of the final microstructure of the corresponding alloy changes slightly. Fitting is used to deriving the function of recrystallization size, recrystallization fraction, and sub-grain size as a function of deformation temperature. The tensile properties of the alloy at T6 state are the best after deformation at 400°C and solution treatment at 470°C. The brittle fracture mode is shown in recrystallized grains, whereas the toughness fracture mode is shown in sub-grains.

Abstract: Three polyethylene glycol propargyl ethers (PGPEs), namely 4,7,10-trioxatrideca-1,12-diyne (TOTDY), 4,7,10,13-tetraoxahexadeca-1,15-diyne (TOHDY) and 4,7,10,13,16-pentaoxanonadeca-1,18-diyne (TONDY) were designed and successfully synthesized as curing agents for glycidyl azide polymer (GAP). Their structures were characterized by FT-IR, 1H NMR, 13C NMR and elemental analysis, and their glass transition temperatures (Tg) were measured by DSC. The films of GAP cured by the title compounds were prepared via 1,3 dipolar cycloaddition, and then the influences of PGPEs on the Tg, decomposition temperature (Td) and mechanical properties of the films were studied accordingly. The results showed that the Tg of GAP cured by TOTDY and TOHDY were-38.1 oC and-38.2 oC, respectively. The Td of GAP cured by PGPEs was in the range of 235.5 oC - 241.0 oC. The results of tensile tests showed that the maximum stress of GAP films cured with PGPEs were in the range of 0.11 MPa to 0.52 MPa at elongation from 29% to 48%. These results indicated that PGPEs would have potential application in GAP based high energy solid propellant formulations.

Abstract: In general, the lower prosthesis consists of socket, leg, ankle, and foot. The socket is the crucial part for connecting the remaining part of the limb and the prosthesis, as it is essential to distribute the load to the amputation patient to provide comfort and add to the proper appearance of the amputation patient. A research that was included methods of manufacturing it, choosing the composite materials necessary for the design, higher durability, lighter weight, and less cost. Previous research used polymer composites reinforced with fibers as glass fibers, carbon fiber, and Kevlar. Other researchers have studied natural fibers' use as reinforcement fiber by mixing resin materials or adding nanomaterials to modify the mechanical properties and reduce costs. After calculating performing the required mechanical tests such as tensile, fatigue, and impact testing, the required properties of the composite material are found, where the prosthesis socket is manufactured below the knee with the application of different loads of the socket. A review of socket models used in developing countries was performed with regard to design, modeling, and finite element analysis (FEA). This review aims to study the material's behavior and mechanical properties by using natural fibers for manufacturing prosthetic sockets. The review discusses the socket manufacture methods proposed to develop the socket industry based on natural fibers to reduce the hot and humid environment using Kenaf and other natural fibers.

Abstract: In this research work, bioactive Ti15Mg alloy was prepared by powder metallurgy route to investigate its biocompatibility and mechanical properties. Many tests were performed including X-ray diffraction; optical microscope analysis, scanning electron microscope analysis, ultrasonic wave test, corrosion behavior test, Static immersion test, and the wet sliding wear test. The XRD result shows that the prepared alloy sample consist of (α-Ti phase) and Mg. The microstructure of the prepared alloy sample consisted of a biodegradable Mg or pore and alpha titanium. The effect of the Mg content on degradability was tested based on simulated body fluid of Ringer solutions using electrochemical corrosion. The findings indicate that an elastic modulus of 47GPa exhibits the alloy. There were low corrosion rates of the alloy. The Ti matrix remained integrity after 14 days of immersion in the Ringer solutions, and the magnesium phase dissolved in the solution, causing a layer to form on the alloy. The wear behavior of the prepared ally at wet sliding conditions was evaluated using pin on disc method. The in vitro analysis showed good biocompatibility with Ti15Mg alloy. The prepared alloy demonstrates good biocompatibility and bioactivity.

Abstract: In this paper, the influence of liquid alkali-free accelerator and advanced composite cementitious materials on the mechanical properties, durability and workability of shotcrete was studied. The important role of the two materials in the performance improvement of shotcrete was clarified. The technical measures proposed were verified by field test. The results show that: In terms of workability, the composite use of alkali-free accelerator and functional admixture can achieve fast setting and high early strength of shotcrete, thus effectively reducing the rebound rate; In terms of mechanical properties, functional admixture can effectively improve the early mechanical properties of shotcrete, while alkali-free accelerator can ensure the long-term development of mechanical properties; In terms of durability, the use of functional admixtures can effectively improve the compactness of shotcrete, and the test results of 56d electric flux are lower than 1000C.

Abstract: In this paper, the influence of some ingredient concentrations such as SBR ratio, DCP/S, CBS/DPG accelerator, EPDM-g-AM and cord surface on mechanical, thermal aging properties and adhesion between rubber compounds and cord have been investigated. The results showed that with suitable ingredients loading such as EPDM/SBR is 85/15 phr, DCP/S is 2.0/1.5 phr and EPDM-g-AM content is 2.0 phr with respect to rubber, the vulcanizates had good mechanical properties, thermal stability and adhesion level to the zinc/copper galvanized cord. The highest tensile strength, elongation at break and pull out strength reached 18.1 MPa, 432% and 60.3 N/mm respectively, and the highest retention after thermal aging at 150°C for 168 hours was about 0.76.