Applied Mechanics and Materials Vols. 799-800

Abstract: Roll forming is a highly useful and important forming technique for sheet metal. As an economic profile product, roll forming products are widely used in transportation, engineering machinery, and civil construction because of their uniform sections, high strength, and low energy consumption^[1]. Roll forming is a rapid processing operation used for transforming flat sheets of material into useful profiled sections. However, a lot of components used in the automobile, railway cars, ship construction, and building industries have variable cross sections. Therefore, flexible roll forming was developed recently to produce variable cross section profiles.

Abstract: This research aims at analyzing and optimizing the hydroforming process parameters to achieve a sound bulged tube without failure. Theoretical constitutive model is formulated to build up a working diagram including process window, which is used to optimise the process parameters and predict the formability and the failure of the tube accurately. The model is validated using the published experimental and analytical results of previous research works for 37% bulging ration of low carbon steel (C1010). The model gave a very good agreement with the published data.

Abstract: The effect of annealing temperatures on surface morphologies, microstructure, and mechanical behaviors of CrAlSiN coatings with different Si content was investigated. EDX, XRD and SEM were employed to reveal the compositions and microstructure of CrAlSiN coatings. For Si content ≤8.6%, grain sizes reduced with temperature increasing to 400°C and then increased with further increase in temperature. For Si content ≥10.7%, grain sizes gradually reduced with annealing temperature increasing. When the annealing temperature arrived at 400°C, the hardness of CrAlSiN coatings with different Si content was much higher than as deposited. While the annealing further increased to 800°C, the hardness of CrAlSiN coatings with Si content ≤8.6% reduced, but the hardness of CrAlSiN coatings with Si content ≥10.7% continued to increase.

Abstract: Comparing to the preparation theory and automatic advantages of composite pultrusion process, a research on radius fillers’ automatic pulling equipment had been conducted. A certain width of prepregs were selected by radius fillers’ overall dimensions and performance requirements. Finally, qualified quality products were prepared continuously and stably by using the automatic pulling equipment. The equipment adopted measuring instruments, controller, actuators, operating panel and other automatic tools, forming a continuous and stable manufacturing process, meanwhile, achieved radius fillers’ automatic preparation and brought convenience to industrial application.

Abstract: In this paper, lapped C-face of single crystal SiC wafer was irradiated by femtosecond laser. Chemical mechanical polishing (CMP) was then carried out to polish the irradiated SiC C-face. The authors compared the results of femtosecond laser-assisted CMP process. A white-light interferometer was used to investigate the surface morphology of the processed SiC substrate before and after laser irradiation. It was found that the material removal rate (MRR) of the irradiated substrate is about 3 times higher than that of the substrate not treated by femtosecond laser. In addition, lower surface roughness was realized after femtosecond laser assisted CMP process.

Abstract: This research aims are to design, build and analyze the performance of concentrated solar energy onto a simple calorimeter, made of copper and stainless steel. A scrapped yard antenna dish with a diameter of 1.68 meters was lined with aluminum foil reflector sheet. The average dish aperture area of 2.21 m², the system uses water as a heat transfer fluid distributed from overhead tank. Absorbed energy was investigated at a water flow rate of 0.5 L/min were performed in the experiment and the maximum useful energy was determined. Parabolic dish concentrator displacement angle was adjusted in every 15 degrees per hour, with the used of electric controlled sun tracking system. The experimental tests carried out in Faculty of Industrial Technology, Vallaya Alongkorn Rajabhat University Pathum Thani, under Thailand climatic conditions (14.134°N, 100.611°E) during 2 selected days of the months April 2013. The performance of a paraboloidal concentrator was assessed using open-air experimental measurements including the incoming heat, the energy absorbed by the water, and the concentrator efficiency. The experimental results shown the maximum thermal efficiency was 89.73%. It was also found that copper calorimeter can simply attain during operation relatively high water temperature levels oncoming 97 °C. The concentrated solar flux at the focal point was 442,073.11W/m² for stainless steel calorimeter and 619,448.66 W/m² for copper calorimeter, respectively.

Abstract: Shortened single walled carbon nanotubes (SWNTs) were functionalized with chitosan (CS) oligomer to improve their water solubility and biocompatibility. The functional groups such as amino in CS benefit the further modification of other bio-functional molecules. Fluorescein isothiocyanate (FITC) were marked in CS decorated SWNTs through covalent bond for imaging and tracking SWNTs. Water soluble SWNTs wrapped by CS could also be suitable for drug delivery. Tea polyphenol (TP) and doxorubicin (DOX) drug molecules were loaded in the SWNTs system respectively through hydrogen bond and π-π interaction. The FITC labeled CS/SWNTs were co-incubated with cells and imaged under laser scanning confocal microscope (LSCM). With proper bio-functionalization, SWNTs could be easily internalized by cells via endocytosis.

Abstract: In this report, s-1-dodecyl-s’-(α,α’-dimethyl-α’’-dimethyl-α’’-aceticacid) trithiocarbonate (RAFT-COOH) was successfully synthesized by phase transfer catalyst reaction, which was then amidated with diaminopropyl terminated polydimethylsiloxane (NH₂-PDMS-NH₂) to synthesize PDMS-based macro-RAFT agent to control the synthesis of tri-block copolymer PDMA-b-PDMS-b-PDMA. The successful synthesis of small and macro chain transfer has been confirmed by techniques of FTIR. Moreover, the polymerization to synthesize tri-block copolymer proceeded with first-order kinetics, which showed the reaction system was a controlled/‘living’ polymerization. The triblock copolymers have also been characterized by FTIR, ¹HNMR, and GPC techniques, which confirmed the successful synthesis of triblock copolymer.

Abstract: Silica coated alumina abrasives, used for abrading the surface of Yttria stabilized tetragonal zirconia polycrystal ceramics, were produced in order to achieve successful bonding with resin luting cement. The source of the silica coating was from Silicon Nanoparticles (SiNPs) that were produced from spark erosion in high pressure flushing of deionized water. SEM images verified average size distribution of the SiNPs to be between 30-50nm. In contrast to the tribochemical methods that are used widely to produce such abrasives, a completely novel dry physical process was opted for this experiment. By optimization of the conditions, 2g of purified SiNPs was mixed with 20g of alumina μ-particles (approximated diameter of 100μm), in presence of 25ml ethanol, mixed thoroughly to form slurry. Heated up to 120°C for 20 minutes to evaporate the ethanol, the resultant powder mix was compacted and uploaded in furnace at temperature of 1100°C for 2hrs. This formed an oxide layer on the SiNPs which consequently formed bonding with the alumina particles. SEM/EDS results validate substantial amount of coating of silica on alumina. The paper hereby demonstrates a novel method of producing silica coated alumina abrasives, which is a dry and cleaner substitution method compared to tribochemical approach.

Abstract: The purpose of this study was to analyze the behavior of a lumbar spine disc prosthesis with different materials. The study was performed at L4-L5 lumbar motion segment using the finite element method (FEM). A healthy Finite Element (FE) model was used as a reference with which to compare the results of the FE simulations of the artificial discs. The healthy and the artificial FE models were subjected to a combination of 0.5 MPa Compression pre-load and 10Nm of Flexion moment. The artificial FE models were based on Maverick artificial disc, and the three materials proposed for study the artificial disk were Titanium, Ceramic and CrCoMo alloy. The most suitable material for developed the artificial disc was the CoCrMo alloy due to: The von Mises stresses on the bone with which this artificial disc was in contact were reduced as much as possible and also, were very similar to the von Mises stresses obtained in the bones from the healthy disc.