Applied Mechanics and Materials Vols. 300-301

Abstract: Martensitic high-carbon high-strength SAE 52100 bearing steel has been widely used as the main alloys for rolling contact applications, and also at the components under bending and tension-compression. In order to enhance the material’s strength, refining the prior austenite grain size through repeated heating has been investigated. In this work, the microstructure of repeatedly quenched-tempered Ti, N-rich SAE 52100 steel was investigated. The material was melted by an electric furnace and formed by continuous casting and forging, and the crack origin on the fracture surface was investigated. It was found that repeated furnace quenching and tempering effectively refined the martenstic structure.

Abstract: The discrete element model and the model of single diamond grain grinding process of granite were constructed through numerical simulation and calibration of mechanical properties. Based on the models, the grinding processes of granite was dynamically simulated, and the effects of different rank angles, grinding speeds and cutting depths on the distribution of residual stresses as the depth of workpiece were also analyzed. The results show that the residual stress in the workpiece is relatively small after grinding when the tool rank angle lays in a small negative (-200 to 00). Otherwise, when the tool rank angle is too large or too small, there is a significant residual stress. The residual stresses in the workpiece increase with the increase of grinding speed and cutting depth. The residual stress nephogram was accomplished and the generated mechanism of residual stress was also analyzed. The results proved that the discrete element method (DEM) is an effective way to analyze the residual stress

Abstract: The Ansys simulate software is utilized to analyze pull-in voltages and stresses of the fixed end of micro- cantilever beam with different thicknesses respectively. Based on the analysis of the electrostatic force at the pull-in voltage, the stress of fixed end of micro-beam and the maximum deflection are obtained. The relationship between the stress of fixed end and thickness is established. The results show that the mutation thickness of the stress and the pull-in voltage are at and respectively , it is consistent with the intrinsic size of the polycrystalline copper micro-beam.

Abstract: The stirring assisted brazing of SiCp/A356 composites with a large size of diameter in air was investigated. A first stirring was applied in brazing of the composites at 470°C. Then, it was continuously heated up to 510°C. Then, a secondary stirring with a large size (2.4mm) diameter was introduced in process. It was found that a composite joint reinforced with SiC particles can be obtained by stirring at 510°C. The experiment result shows that micro-hardness of joint brazed by 2nd stirring is obviously higher than that of joint brazed without 2nd stirring. Moreover, micro-hardness of the upper part of joint is slightly higher than that of the bottom part.

Abstract: New smart materials have taken the lead position in modern design, photochromic materials with base of polymer gradually step into the range of new decorative materials in design of kindergarten, abundant color is the intuitional demonstration to attract children, however, if the color doesn’t change at all for a long term, children will be bored in both aesthetics and vision, such new photochromic materials bring a new breakthrough for design of kindergarten.

Abstract: This paper focuses on the effect the ratio of filler (Na10MB3A) on the tensile strength of polypropylene (PP). This filler has been added to PP in various ratios and mixed evenly before injecting. The tensile strength of PP increases gradually when the ratio of filler increases. Tensile strength reaches its maximum value with a certain ratio of filler, and thereafter the strength decreases as the ratio of fillers is increased. This research revealed that the tensile strength of PP can rise by approximately 13.5% with the addition of Na10MB3A at a ratio of 3%.

Abstract: Natural rubber (NR) was compounded with polyhydroxybutyrate-co-hydroxyvalerate (PHBV) to improve mechanical properties for making a composite to be used in packaging applications. Gamma radiation technique was used to improve adhesion properties between these materials. The results showed that gamma radiation could induce cross-linking between NR and PHBV. The SEM micrograph illustrated the radiated NR/PHBV blends with gamma dose 5 kGy, 10 kGy and 15 kGy presenting a good adhesion at the blend interface. The investigation by FTIR, showing the appearance of small peaks at 2950 and 2997 cm-1 related to CH3 asymmetric stretching, also confirmed the cross-linking after the exposure of the NR/PHBV blend to gamma radiation. Also, the tensile results supported cross-linking between NR and PHBV. The elongation at break of NR/PHBV blend decreased when increasing dosage of gamma ray from 0 kGy to 15 kGy.

Abstract: Titanium alloys ceramic membranes were prepared via micro-arc oxidation process in original electrolyte and in the electrolyte adding lanthanum nitrate respectively.The microscopic surface morphology,energy spectrum and phase composition were analysed.The biological activity was evaluated by soaking in simulated body fluid.The results indicate that lanthanum nitrate could improve the surface topography,make more calcium and phosphorus enter into the film and promote the generation of hydroxyapatite.

Abstract: The distribution, enrichment, accumulation, and potential ecological risk of Cadmium (Cd) in the surface sediments of northern Kaohsiung Harbor, Taiwan were investigated. Sediment samples from 12 locations of Kaohsiung Harbor were collected and characterized for Cd, aluminum, water content, organic matter, total nitrogen, total phosphorous, total grease, and grain size. Results showed that the Cd concentrations varied from 0.25–2.28 mg/kg with an average of 0.58±0.58 mg/kg. The spatial distribution of Cd reveals that the Cd concentration is relatively high in the river mouth region, and gradually diminishes toward the harbor entrance region. This indicates that upstream industrial and municipal wastewater discharges along the river bank are major sources of Cd pollution. Results from the enrichment factor and geo-accumulation index analyses imply that the sediments collected from the river mouth can be characterized between moderate and severe degree enrichment and between moderate and moderate to strong accumulation of Cd, respectively. Results of potential ecological risk index indicate that the sediment has higher to high ecological potential risk. Therefore, a strategy for effective controlling and managing river upstream pollution needs to be immediately implemented in order to improve the sediment quality and alleviate the ecological risk.

Abstract: As the fast development of industry, clean air quality environment are needed in more manufactory fields. Filter media is the key material for high efficiency filtration. In this paper, glass fiber filter and PTFE membrane filter are studied with filtration test. The results show that glass fiber filter has low porosity, lead to lower penetration and higher resistance than PTFE filter. Penetration of filters decrease with mass load increasing and face velocity decreasing. Resistance increase with mass loading and face velocity increasing.