Advanced Materials Research Vols. 463-464

Abstract: Zn films were prepared on Si (111) substrates by radio frequency magnetron sputtering system, which were subsequently annealed at different temperature in O2 ambient. Their microstructure, morphology, composition and optical properties, particularly as a function of annealing temperature, were studied by XRD, SEM, FTIR, XPS and PL characterizations. All the results show that the crystal quality of ZnO film can be improved by increasing annealing temperature, and the optimum annealing temperature is 800°C in our experiment. The XRD and SEM results show that the ZnO films have a hexagonal structure with cell constants of nm and nm under the optimum experimental conditions. The FTIR and XPS results further confirm hexagonal structure of ZnO. The PL result shows that best UV and green light emission are found in the samples annealed at 800°C.

Abstract: Based on unified strength theory, the unified stresses solution for sheet forming is presented according to mechanical analysis developed, and accurate enough for much material due to the contributions of both intermediate principal shear stress and varying tension-compression-ratio included. Notably, by denoting a notation of h, the expressions presented to estimate stresses of billet for sheet forming can be apply to both drawing and extrusion. In addition, when material has identical strength in tension and compression, i.e., the tension-compression-ratio of the material is equal to unit, the stresses solution based on unified strength theory become that based on unified yield criterion. Accordingly, it can be proved that the stresses solution based on Mises criterion is just a special case of that based on unified yield criterion.

Abstract: Article in the first quantitative analysis of milling process of material removal on the work piece model effects, using matrix perturbation theory gives the work piece modal approximation, fast algorithms. Major sources of uncertain factors analysis of milling process, based on the interval algebra, derivation of the work piece (or tool) interval characteristics of matrix, the use of interval finite element method for calculating the tool dynamic response of upper and lower bounds. Modal experimental results and theoretical predictions dovetailed.

Abstract: At present, the main methods used to predict welding residual stresses are the three dimensional thermo-elastic-plastic FEA method and the inherent method.Many learners had simulated the residual stresses of FSW used the thermo -elastic-plastic FEA method which was proved to be time consuming and not very effective. The inherent strain method neglects the whole welding process, and predicts distortion using an elastic finite element analysis by applying the inherent strains on the structure. In this paper,the inherent strains are firstly obtained for an flat butt-joint of aluminum alloy through experiments and three dimensional thermo-elastic-plastic FEA. Computational and experimental results showed that the inherent strain method could predict welding distortion with acceptable accuracy and greatly reduced running time when comparing to the thermo-elastic-plastic FEA method.

Abstract: To achieve high quality and productivity during continuous contouring, it is important to know how the two axes work together to move the machine in a circular or rectangular path. For this reason, we have analyzed circular and linear motion trajectories and the frequency response of the system during milling process. In the same time, is required to analyses simultaneously both mechanical and control subsystems. Based on these problems, the main objectives of this work have been defined to find a way to improve dimensional accuracy.

Abstract: This paper focuses upon the research and development of a method for modeling human teeth. By the use of virtual reality and haptics technology an application was created, that allows dentists to prepare their next procedures or students to learn dental skills by visualizing a three-dimensional virtual human tooth and feeling real tactile sensations while touching or deforming the surface of the tooth.

Abstract: The engine piston is the critical component of the automobile, which always show high nonlinear behaviours under the thermal and mechanical cycling load. By contracting known metal material’s common constitutive theory、analyzing its composition method of continuous function and considering the special requirements of engine piston runs in the high temperature environment, the thesis could find a practical constitutive model which is applicable for aluminum alloy material used on engine piston. Through ways of analyzing and contracting, the constitutive model proposed by Sehitoglu proved to be applicable.

Abstract: One of the most important requirements of part manufacturing is the surface quality. This is so because the most important part is meeting the specific requirements of customers. The surface roughness is a leading indicator of the quality of the machined surface Parts. In the present work in an experimental study to achieve by application of Taguchi method to investigate the effect of three parameters, which known as cutting speeds of (45, 90, and 135 m/min), feed rate of (0.1, 0.2, and 0.3 mm/rev), and cut depth of (0.05, 0.1, and 0.15 mm) on performance measure of surface roughness (Ra). Thus to determine the optimal levels and to analyze the cutting parameter’s effect on the surface finish values by employing different method of Orthogonal array, S/N ratio, analysis of variance (ANOVA). During our work two models for prediction have been used. The first one is known as the method of regression analysis, and the second is the method of Adaptive - Neural Network (ANN) relying on practical results. The achieved results show that the estimation and prediction ability of neural networks is better than the regression analysis. Experimental results confirmed with optimal levels of the machining parameters which are clarified by using Taguchi optimization method. Also, the indicated results of the Taguchi’s method show its ability to improve the process.

Abstract: Large amounts of silicon dusts, including band saw dusts, grinding dusts and wire saw dusts were generated in photovoltaic industry. Recovery of pure silicon from the dusts is of great value to industry, and understanding their oxidation behaviors is essential for such recovery. The present paper reports our investigations into the oxidation status of the as-generated dusts and their oxidation kinetics in further exposure. Hand-ground multi-crystalline silicon fine powders from broken wafers were used as reference. And the oxidation behaviors of the reference silicon powders were also discussed. The results show that severe oxidation on the surface of the band saw and grinding dusts occurs due to the existence of the aqueous medium. With the storage time prolonged, the oxidation increases rapidly in the aqueous medium in the ambient temperature initially, and then it drives to stabilize. While no obvious oxidation appears in the wire saw dusts due to the protection of PEG (polyethylene glycol). With the PEG concentration in the liquid medium increased, the oxidation degrees of the multi-crystalline silicon fine powders are decreased. Based on above knowledge, an efficient suppression of oxidation of band saw and grinding dusts was proposed lastly.

Abstract: The most significant process parameters affecting dimensional shrinkage in transverse and longitudinal directions of molded parts in Plastic Injection Molding (PIM) process are injection velocity, mold temperature, melt temperature and packing pressure. In the present work, ANN model was developed for forward and reverse mapping prediction. In forward mapping PIM process parameters are expressed as the input parameters to predict dimensional shrinkage, whereas in reverse mapping, attempts were made to predict an appropriate set of process parameters required for arriving at the required dimensional shrinkage. The trained network with one thousand input-output data randomly generated from regression equations reported by earlier researchers resulted in minimum mean squared error. The performance of developed model was compared with experimental values for ten different test cases. The results show that ANN model with both forward and reverse mapping is capable of prediction with an error level of less than ten percent.