Advanced Materials Research Vols. 488-489

Abstract: Natural rubber (NR) based composites with various amount of kaolinite were performed via the latex compounding method. The aim of this work was to investigate the effect of clay modification and clay contents on tensile properties of the NR composites. The kaolinite clay was modified by an ion exchange reaction with octadecylammonium ion. FTIR spectrum of modified kaolinite revealed the evidence of octadecylamine signals. The modified kaolinite investigated using SEM represents the platelet shape and the size distribution of organoclay particles is consistency. The tensile moduli and strengths of unmodified clay composites tend to decrease whereas those of modified clay composites are improved and increased with the modified kaolinite contents. Swelling resistance in non-polar solvent of the NR/ODA-kaolinite composites is greater than that of NR and NR/kaolinite composites. The morphological study by the SEM suggested that the modification of kaolinite clay helped improve the dispersion of clay in rubber phase. These results reflected that the dispersion of silicate layers was the key parameters in enhancing the physical properties of the composites.

Abstract: This paper proposes a fuzzy control scheme to achieve the high-precision and high-speed continuous transportation of ultra-thin flexible substrates with variable-section. A tension control model is presented based on the torque balance of pinches. In the model, the flexible substrate is regarded as a parallel spring-damp system, challenged by the dynamics associated with low-tension operation, besides the time-variation resulted by the variable-section. A fuzzy control algorithm is designed for the tension controller. Finally, the analysis in dynamic performance of the whole system is done using MATLAB toolbox. The simulation results show that the fuzzy control algorithm presented is effective to the tension even in transient state.

Abstract: The applications of composite materials based on Carbon Fiber Reinforced Plastic (CFRP) have been increasing considerably in aerospace industries, because of their good physical and mechanical characteristics. It is necessary to develop new manufacturing process and production techniques to ensure good surface quality of the components. As a result of this manufacturing scenario, it is necessary to study the machining process. This study reports practical experiments in turning, to study the performance of Poly Crystalline Diamond (PCD) inserts of 1500 grade. The results show that diamond tools are suitable for use in finish turning. The tests were carried out with PCD insert at various cutting speeds on a medium duty lathe of spindle power 2KW. In the optimization method, turning was done by grade (PCD 1500) for 30 seconds duration for each trial at different cutting conditions by using design of experiments. Parameters such as power consumed by main spindle, surface roughness were measured. Graphs were drawn to analyze the performance of1500 grade on various parameters.

Abstract: Natural fiber composite has already proved its worth in various mechanical applications. Natural fibres with attractive properties such as low density, environment-friendliness and less processing work are widely available and provide an alternative to the conventional fibres. In this paper, the fibre reshira has been tried for the first time for cryogenic applications. Initially, the fibre is given chemical treatment with sodium hydroxide solution to enhance the adhesion between the fibre and the resin. The treated fibre is reinforced with epoxy resin and its properties such as storage modulus, loss modulus and Glass Transition Temperature are evaluated both at room temperature and under cryogenic conditions and these are compared to see which condition produces better mechanical performance.

Abstract: Using polycrystalline cubic boron nitride compact (cBN) tools, which have different cBN contents and cBN particle sizes, the influences of both the cBN content and the cBN particle size on tool wear in turning of hardened steel at various cutting speeds was experimentally investigated. Three types of cBN tools (a cBN content of 45-55% and 75%, and a cBN particle size of 0.5 μm and 5 μm, respectively) were tested. Furthermore, three kinds of chamfered and honed cutting edges were also used. The main results obtained are as follows: (1) In the case of the cBN tools with the same cBN particle size of 5.0 μm, the tool life of the cBN tool with a cBN content of 75% was longer than that of the cBN tool with a cBN content of 45% at low cutting speed. However, at high cutting speed, the tool life of the cBN tool with a cBN content of 75% was shorter. (2) The tool life of the cBN tool with both a cBN content of 55% and a cBN particle size of 0.5 μm was the longest. (3) The tool wear of cBN tools decreased with a decrease in chamfer width.

Abstract: A new modified strategy is proposed based on the analysis of convergence of particle swarm optimization (PSO). Each particle is manipulated by its convergence center, and then randomly perturbed around it. Some mutation operators are used to retain diversity of population and avoid being plunged to local optimum. Moreover, theoretical analysis has been made to prove that it can more easily converge to the global optimum. Experiment results show that it is superior to basic particle swarm optimization in quality and efficiency.

Abstract: Aluminum honeycomb core sandwich panels are now commercially available and are widely used as light weight materials in aircraft, naval and other applications because of their high strength to weight ratio, high bending stiffness, fire retardant resistance, insulation properties and sound attenuation properties. In all these applications extensive joining is encountered in fabricating the panels to complex shapes. This paper has investigated various edging and configuration details to secure butt joints with adequate soundness through adhesive joining methods. The compression strength of the joints has been assessed experimentally. The configuration of each butt joint is discussed and best combinations of edging and configuration are recommended for successful fabrication of complex assembles with aluminum honey core sandwich panels.

Abstract: Thin films of elements (Cd,Te,Ag) were layered as a stack (Te/Cd/Te/Ag/Cd) for doping process with different Ag and Cd thickness by SEL method. The XRD results were depicted the presence of Cubic phase CdTe with (111) orientation along with Ag2Te, CdAgTe, AgTe phases. The peaks related to Ag atom at higher concentration evinced the presence of non-reacted Ag atoms on the surface with higher Ag concentration. The observed results showed the growth of CdTe crystals in (111) orientation with high Ag concentration. The AFM results of the annealed stack were clearly indicated the influence of Ag concentration in grain growth as well as surface roughness. Photo-resistivity studies of the annealed stacks also revealed the effect of Ag concentration in reducing the resistance with difference light sources. The observed results suggested that the SEL method could be used for effective doping of transition metals to achieve desired properties.

Abstract: The glass fiber drawing from the silica preform in a draw furnace is one of the important processes in a mass manufacturing system of optical fiber. When a preform of cylindrical shape is fed and heated in draw furnace and very thin glass fiber is pulled from the softened preform by applying a proper amount of draw tension, the preform experiences a drastic diameter change or neck-down shape. In this paper, neck-down shape formation and glass fiber drawing in heated preform is numerically modeled into one-dimensional formulation of momentum balance in order to examine the effects of the silica preform temperature such as the maximum temperature of preform and the cooling rate of glass fiber at high fiber drawing speed. The results show the typical shape of preform neck-down and the draw tension which is comparable to the industry value of approximately 100 g. Also, it is found that the axial location of glass fiber re-solidification sensitively depends on the cooling rate, while the draw tension is insensitive to the cooling rate of glass fiber.

Abstract: The friction stir welded superplastic forming of AA6061-T6 sheet has been numerically analyzed based on the experimental and finite element software. A selected range of tool rotating speeds of 500, 1000 and 2000 rpm was used for friction stir welding. At constant temperature of 550^O C and constant pressure of 0.4 Mpa, superplastic forming experiments was performed using free forming die for the friction stir welded sheets. A detailed 3D element type study has been performed in the finite element analysis. The proposed finite element model has been validated in comparison with experimental data. The results are found to have reasonably good agreement between simulations and experiment. The effect of constant pressure, coefficient of friction, strainrate and strain-rate sensitivity has been studied using the proposed finite element model.