Papers by Keyword: Elastic Recovery

Abstract: Now a days, extensive research has been attracted by the α + β based Ti alloys in biomedical applications due to their low elastic modulus and high strength properties. In order to explore the performance of Ti6AlxMo based alloys, Ti6Al with different amount of Mo-based samples were fabricated by powder metallurgy technique. The mechanical properties of the samples such as elastic energy, total energy and elastic recovery were studied through nanoindentation tests. Designed alloys exhibit elastic recovery values in the range of 25.4% - 33.7% which is higher than commonly used biomaterial such as CP Ti therefore it has good impact resistance properties. Ti6Al15Mo alloy with dominant β phase microstructure shows a high elastic energy as well as elastic recovery values which makes it more advantageous than CP Ti for load bearing implant applications.

Abstract: NbN/TiN, TiNb-N_X and CH-TiNb-N₁₂ coatings are deposited by RF magnetron sputtering to determine the tribological properties and corrosion resistance. ‘x’ is the flux rate for nitrogen and ‘CH’ signifies the addition of acetylene. In terms of the corrosion resistance, all the coatings have a similar corrosion potential and NbN/TiN multilayer coatings exhibit the lowest corrosion current. The NbN/TiN multilayer has a low pitting potential so severe pitting corrosion is observed on the surface. CH-TiNb-N₁₂ coating is most resistant to corrosion and exhibits no pitting before the test ends. In contact with counter-bodies with a Si₃N₄ ball or an AISI 52100 ball, a CH-TiNb-N₁₂ coating acts as a solid lubricant so the wear mechanism shows the least abrasion. The CH-TiNb-N₁₂ coating has the lowest wear rate and coefficient of friction for sliding against Si₃N₄ and AISI 52100 balls. The wear rate is respectively 3.2 and 6.8 times less than that for SKH51 substrate when sliding against Si₃N₄ and AISI 52100 balls. The results for this study show that a TiNb-N₁₂-CH coating has the best tribological properties and corrosion resistance.

Abstract: CN-Nb, CN-Ti and CN-Zr that are respectively doped with Nb, Ti and Zr metal in a CN coating are deposited on SKH51 substrate using DC unbalanced magnetron sputtering (DC-UBM). The coatings’ chemical characterization, morphology, mechanical, tribological and corrosion properties are determined. The XRD analysis shows when a low content of metal is added, the coatings exhibit DLC structures. Result from the incorporation of metals, coatings performed denser texture. Simultaneously, the surface became smoother and denser while surface roughness varied from 0.036 to about 0.020 mm. Various properties are improved over CN coating, CN-Ti has a 64% greater hardness at 21.9 Gpa and adhesion 26% better, with a critical load of 87 N. The elastic recovery ranges from 68% (CN) to 100% (CN-Nb and CN-Zr), the wear rate varies from 0.51 10^-6mm³/Nm (CN) to 0.1 10^-6mm³/Nm (CN-Zr) and the wear depth is reduced by about 73%. An increase in the elastic recovery gives a decreased wear rate. In addition, the corrosion resistance is increased because there is a decrease in the corrosion current density and the CN-Zr coating performed about 35 times better than a CN coating.

Abstract: Microstructures and mechanical properties of melt spinning spandex were studied in this article.Cross section and longitudinal surface were observed and analyzed by JSM-5610LV scanning electron microscopy. Q2000 DSC differential scanning calorimeter was used to test the glass transition temperature and melting temperature which indicated glass transition temperature is about 44°C and melting temperature is about 200°C. We employed JSM-5610LV scanning electron microscopy to observe adhesion of melt spinning spandex with nylon filament after different time and temperature processing. It concluded that after 150°C90s、160°C60s、160°C90s、170°C30s heat treatment, the adhesive of melt spinning spandex with nylon is good. At the same time,tensile strength and elastic properties of melt spinning spandex which was processed under different time and temperature were tested, tensile strength and elastic recovery of melt spinning spandex after160°C 90s heat treatment is the best.

Abstract: In order to test the elastic recovery, 25 samples of seamless-knitted women's gymnastics clothing were weaved. They were designed by two factors: fabric weaves and ratios of coolmax / nylon. Empirical results show that the ratios of coolmax / nylon have little effect on elastic recovery at certain elongation and the main influence factor is fabric weaves. 2+1 mock rib fabric performs best on elastic recovery, while mesh fabric performs worst.

Abstract: The dimensional change of tooth profile by heat treatment of helical gear was investigated by experimental and numerical approaches. Especially, the three-dimensional elasto-plastic finite element (FE) simulation was adopted to analyze the elastic deformation during load, unloading, ejecting of workpiece. Quenching simulation was also carried out to investigate the change of tooth profile on the forged gear. In experiments, the amount of elastic deformation of the forged gear was quantitatively determined by comparing the tooth profiles on the forged gear and die. The dimensional change of the forged gear tooth after quenching was also evaluated from the comparision of the cold forged and quenched gear teeth. From experimental works, it was found that the amounts of dimensional changes after forging and quenching of helical gear are 10 and 10 μm, respectively.

Abstract: The elastic recovery property of a novel poly(ester-imide-ether) (PEIE) was prepared from the 1, 4-butanediol (BD), poly(tetramethylene glycol) (PTMG1000) and imide dicarboxylic acid based on 1, 2, 4-benzenetricarboxylic (TMA) and aminobenzoic acid (PABA) was studied. The elastic recovery of the PEIE was studied in the fiber form. The influences of the draw ratio, temperature and heat treatment on elastic recovery were investigated. The results show that the novel PEIE possesses the excellent elastic recovery at low temperature and the quickly-changed temperature is lower than that of traditional poly(ester-ether)s. Meanwhile, the heat treatment process can improve the elastic recovery of the PEIE because this process improves the crystallization of the hard segments.

Abstract: A new poly(ester-imide-ether) (PEIE) was prepared by melt polymerization from 1,4-butanediol(BD), polytetrahydrofuran diol (PTMG) and a novel imide dicarboxylic acid monomer which was synthesized from 3,3',4,4'-biphenyltetracarboxylic di-anhydride(BPDA) and glycine acid(GLY). The structure, thermal behaviour and elastic recovery of polymer were characterized by FT-IR. thermogravimetric analysis (TGA), differential scanning calorimetry thermograms (DSC) and laboratory stretching machine. The results showed this polymer has excellent thermal stability, 5 % weight loss temperature was at 354°C. Meanwhile, the DSC curve showed that glass-transition temperature and crystallization temperature of the polymer were at -30 °C and 160 °C, respectively. The excellent elastic recovery was still displayed at low temperature.

Abstract: In the tension leveling process, calculation of the strip elongation by the traditional method only considers the extension rate after the tension response, while ignoring elastic bending recovered, so the calculation of elongation is large enough to affect the process control accuracy. This paper considers not only the residual strain after elastic bend recovery, but also the affection of the residual deformation under plain cross-section assumption. The calculation of the elongation is less 4-10% than that of the traditional one. It shows that parameters of the tension leveling process set by the new method will be calculated accurately.

Abstract: Micro-milling with a cutting tool is a manufacturing technique that allows production of parts ranging from several millimeters to several micrometers. The technique is based on a downscaling of macroscopic milling process. Micro-milling is one of the most effective process to produce complex three-dimensional micro-parts, including sharp edges and with a good surface quality. Reducing the dimensions of the cutter and the cutting conditions requires taking into account physical phenomena that can be neglected in macro-milling. These phenomena include a size effect (nonlinear rising of specific cutting force when chip thickness decreases), the minimum chip thickness (under a given dimension, no chip can be machined) and the heterogeneity of the material (the size of the grains composing the material is significant as compared to the dimension of the chip). The aim of this paper is to introduce some phenomena, appearing in micromilling, in the mechanistic dynamic simulation software ‘dystamill’ developed for macro-milling. The software is able to simulate the cutting forces, the dynamic behavior of the tool and the workpiece and the kinematic surface finish in 2D1/2 milling operation (slotting, face milling, shoulder milling,…). It can be used to predict chatter-free cutting condition for example. The mechanistic model of the cutting forces is deduced from the local FEM simulation of orthogonal cutting. This FEM model uses the commercial software ABAQUS and is able to simulate chip formation and cutting forces in an orthogonal cutting test. This model is able to reproduce physical phenomena in macro cutting conditions (including segmented chip) as well as specific phenomena in micro cutting conditions (minimum chip thickness and size effect). The minimum chip thickness is also taken into account by the global model. The results of simulation for the machining of titanium alloy Ti6Al4V under macro and micro milling condition with the mechanistic model are presented discussed. This approach connects together local machining simulation and global models.