Jinyang Xu; Ming Chen; J. Paulo Davim; Mohamed El Mansori
Abstract
Multilayer stacks constituted by carbon fiber reinforced polymers (CFRPs) and titanium (Ti) alloys are advanced structural materials being extensively used in the modern aerospace industry in view of their superior properties and functionality. Prior to the final industrial applications, CFRP/Ti stacks ...
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Multilayer stacks constituted by carbon fiber reinforced polymers (CFRPs) and titanium (Ti) alloys are advanced structural materials being extensively used in the modern aerospace industry in view of their superior properties and functionality. Prior to the final industrial applications, CFRP/Ti stacks have to be machined into desired shapes with qualified surface quality. However, these multilayer materials possess rather poor machinability due to the disparate natures of constituted phases. The present review aims to report on the recent advancements and achievements in the machining of CFRP/Ti stacks by emphasizing the key challenges and difficulties faced by the manufacturing community to achieve the high-quality drilling of the stack materials. A careful discussion on the machinability aspects of the aerospace-grade stacks in terms of chip separation mechanisms, cutting forces, machining temperatures and surface quality attributes was made following a detailed literature survey. The work summarizes the current research progress in the subject area of composite/titanium machining and highlights the future research directions. It will help both academic scholars and industrial engineers specializing in the fields of machining multilayer composite-metallic stacks.
Yasuhiro Hayakawa; Yuuta Kimata
Abstract
With the aging of society, accidental falls among the elderly are increasing. The main factor is the deterioration of balance due to the decrease in physical ability. Another key factor with elderly people is that the position of the body's center of gravity tends to sway from side to side while walking. ...
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With the aging of society, accidental falls among the elderly are increasing. The main factor is the deterioration of balance due to the decrease in physical ability. Another key factor with elderly people is that the position of the body's center of gravity tends to sway from side to side while walking. To find a way to cope with falls in the elderly, we have developed a new gait training system that handles the central gap of gravity position with soles. Here, a new element consisting of silicone rubber and foam rubber is used for the insole of the shoe. By using this element, it is possible to measure the foot pressure distribution and adjust the change in element stiffness. Further, the measured data of the insole can be displayed on the terminal device. Also, this data can be stored on the server. Moreover, by operating the terminal device, the insole element is pressurized and the stiffness of the element can be adjusted. Further, the developed system enables real-time measurement of changes in foot pressure distribution during walking. In this paper, we show that the difference in walking patterns can be clarified.
Igor Shishkovsky; Stanislav Volchkov; Vladimir Scherbakov; Larisa Volova
Abstract
Superparamagnetic oxide nanoparticles attract increasing attention in biomedical applications for tagging, imaging, separation and/or purification of cancer cells in living tissue. At the present study the selective laser sintering/melting (SLS/M) process using the Nd +3 YAG laser was carried out to ...
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Superparamagnetic oxide nanoparticles attract increasing attention in biomedical applications for tagging, imaging, separation and/or purification of cancer cells in living tissue. At the present study the selective laser sintering/melting (SLS/M) process using the Nd +3 YAG laser was carried out to fabricate and characterize polymer composites based on nano-oxides of FexOy type or of high-temperature superconductivity (HTS) of SrFe12O19 with bioresorbable polycaprolactone (PCL) powders and manufacture porous tissue engineering scaffolds. Practicability of the method for synthesis of functional-gradient three dimensional (3D) parts with magnetic nano-oxide particles and structural ordering were shown and appropriated laser regimes were assigned. The stem cellular morphometry, proliferative and adhesive activity to the 3D magnetic nanocomposites were compared. The medical tests show that all the 3D printed composites have biocompatible features. Medical potential of the SLS/M-fabricated superparamagnetic nano oxides for application as cell targeting systems and tissue engineering scaffolds is being discussed.
Kumar Digvijay Satapathy; Kalim Deshmukh; M. Basheer Ahamed; Kishor Kumar Sadasivuni; Deepalekshmi Ponnamma; S. K. Khadheer Pasha; Mariam Al-Ali AlMaadeed; Jamil Ahmad
Abstract
Herein, we report the synthesis of poly (vinylidene fluoride) (PVDF) based novel nanocomposites reinforced with graphene nanoplatelets (GNP) and vanadium pentoxide (V2O5) as nanofillers. The PVDF/V2O5/GNP nanocomposite films were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray ...
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Herein, we report the synthesis of poly (vinylidene fluoride) (PVDF) based novel nanocomposites reinforced with graphene nanoplatelets (GNP) and vanadium pentoxide (V2O5) as nanofillers. The PVDF/V2O5/GNP nanocomposite films were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), polarized optical microscopy (POM) and scanning electron microscopy (SEM). The electrical properties of nanocomposites were investigated to ascertain the synergistic effect of fillers on the quality factor (Q-factor) of nanocomposites. The FTIR and XRD results infer good interaction between PVDF and V2O5 and the good dispersion of nanofillers in the PVDF matrix. The TGA results revealed that the thermal stability of PVDF/V2O5/GNP nanocomposite has improved at higher loading of nanofillers due to the good interaction between the nanofillers and the polymer matrix. The electrical analysis of nanocomposite films demonstrates high Q-factor value (1099.04) at 4.7 wt % V2O5 and 0.3 wt % GNP loading. With further increase in GNP loading to 1 wt %, the Q-factor becomes lower (356.52) which could be due to the enhanced conductivity of the samples. The significant enhancement in the value of Q-factor shows that the nanocomposites can be used as a potential candidate for high-Q capacitor applications.
V. Saikiran; N. Manikanthababu; N. Srinivasa Rao; S. V. S. Nageswara Rao; A. P. Pathak
Abstract
Trilayered HfO2/Ge/HfO2 thin films were grown on Si substrate by RF magnetron sputtering with HfO2 and Ge targets. The subsequent rapid thermal annealing (RTA) of these films at 700 & 800°C results in formation of Ge nanocrystals (NCs) in HfO2 matrix. X-ray diffraction (XRD) and micro-Raman spectroscopy ...
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Trilayered HfO2/Ge/HfO2 thin films were grown on Si substrate by RF magnetron sputtering with HfO2 and Ge targets. The subsequent rapid thermal annealing (RTA) of these films at 700 & 800°C results in formation of Ge nanocrystals (NCs) in HfO2 matrix. X-ray diffraction (XRD) and micro-Raman spectroscopy measurements were performed to confirm the formation of Ge NCs in the annealed samples. XRD results indicate that the as-deposited samples show amorphous behaviour, whereas the annealed samples clearly confirm the crystallinity of the films. The average size of the Ge NCs was found to increase with an increase in annealing temperature. Raman scattering studies confirm that the annealed samples exhibit a shift in peak position corresponding to Ge-Ge optical phonon vibrations, which clearly indicates the formation of Ge NCs. Conversely, as-deposited samples were also irradiated with swift heavy ions of 150 MeV Au and 80 MeV Ni at a fluence of 3×10 13 ions/cm 2 to synthesize Ge NCs. The structural properties of pristine and irradiated samples have been studied by using X-ray diffraction, Raman spectroscopy to substantiate the growth of Ge NCs upon irradiation. The results obtained by RTA are compared with the irradiated ones.
Ashutosh Tiwari
Abstract
The design of innovative materials is one of measure for driving industry to place the sustainable basis of new technology in order to enhance the wealth and well-being of society. The last half century has realized a vital development in the area of high-tech materials ranging from various elements ...
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The design of innovative materials is one of measure for driving industry to place the sustainable basis of new technology in order to enhance the wealth and well-being of society. The last half century has realized a vital development in the area of high-tech materials ranging from various elements and composites, emerged through synthetic chemistry and often drawing motivation from the nature. The idea of an intelligent material imagines added values in terms of functionality built into the materials structure desirable to response the defined conditions. The previous two decades has emerged to understand the extraordinary behavior and properties of engineered nanostructured materials.
Anatoly A. Popovich; Nikolay G. Razumov
Abstract
In this work, we investigated the effect of the treatment duration on the phase formation and dissolution of alloying elements in the process of mechanical alloying (MA) of iron with austenite forming elements in the nitrogen-containing atmosphere. The influence of MA parameters on the phase composition ...
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In this work, we investigated the effect of the treatment duration on the phase formation and dissolution of alloying elements in the process of mechanical alloying (MA) of iron with austenite forming elements in the nitrogen-containing atmosphere. The influence of MA parameters on the phase composition of the alloy showed the first of the alloying elements dissolved in the lattice of iron are nickel, then chrome and manganese. According to experimental data, the dissolution proceeds through the formation of a layered composite. Also the features of the nanocrystalline structure of powder materials Fe-18Cr-8Ni-12Mn-N, synthesized by mechanical alloying are presented. The nanocrystalline structure of these alloys consists of two structural components: grain-crystallites and grain boundary regions. Such type of structure corresponds to the Gleiter model. Dimensions of nanocrystals are in range from 6 to 20 nm.
Hakan Yilmazer; Mitsuo Niinomi; Ken Cho; Masaaki Nakai; Junko Hieda; Shigeo Sato; Yoshikazu Todaka
Abstract
A novel β-type titanium alloy Ti–29Nb–13Ta–4.6Zr (TNTZ) has been developed and extensively researched to achieve highly desirable mechanical properties such as a high strength while maintaining a low Young’s modulus that is close to that of bone, as an alternative candidate ...
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A novel β-type titanium alloy Ti–29Nb–13Ta–4.6Zr (TNTZ) has been developed and extensively researched to achieve highly desirable mechanical properties such as a high strength while maintaining a low Young’s modulus that is close to that of bone, as an alternative candidate for conventional titanium metallic biomaterials such as Ti-6Al-4V ELI. Therefore, strengthening by grain refinement and increasing dislocation density is expected to provide TNTZ high mechanical strength while keeping a low Young’s modulus because they keep the original β phase. In this case, severe plastic deformation, such as high-pressure torsion (HPT) processing, is a potential treatment for obtaining these properties. Furthermore, HPT processing is effective for producing ultrafine-grained TNTZ having high dislocation density in single β structure. The obtained promising results, which are a tensile strength of around 1100 MPa and a Young's modulus of around 60 GPa, motivated that the above mentioned mechanical properties can be achieved by microstructural refinement through HPT processing However, the mechanism of microstructural refinement is unclear for TNTZ during HPT processing. Therefore, the aim of this study is to investigate microstructural changes of TNTZ through HPT processing by X-ray diffraction analysis and transmission electron microscopy. The microstructures of TNTZ subjected to cold rolling (TNTZCR) and HPT processing (TNTZHPT) comprised single β grains; however, the intense β {110} peak reveals that the preferred orientation is β <110> for TNTZHPT. While the microstructure of TNTZCR shows a comparatively high dislocation density (2.3 x 1016 m -2 ), HPT processing leads to a drastic accumulation of dislocations (5.3 x 1016 m -2 in dislocation density). Dislocations in the microstructures of TNTZHPT are well arranged for the cell wall and/or subgrain boundaries, with a stronger dipole character than random distribution. The dislocation density, arrangement parameter and crystallite diameter (around 11 nm) of TNTZHPT saturate from the center to the peripheral region of a coin shaped specimen at N = 20. Therefore, such a microstructural saturation in a specific strain inducing, N = 20, suggests a threshold for further investigation of β-type titanium alloys.
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