Advanced Materials Research Vols. 403-408

Abstract: In microbending experiments of metal foils an increase of non-dimensional bending moment with decreasing foil thickness has been observed, which indicates the obvious presence of size effects. It is attributed to plastic strain gradient. So a constitutive model taking into account plastic strain gradient together with conventional plastic strain hardening is proposed to analyze the non-dimensional bending moment in microbending process. It is confirmed that the predictions by using the proposed hardening model agree well with the experimental data, while those determined by using conventional elastoplastic model cannot capture such size effects. A semi-empirical expression is reasonable to determine the material intrinsic length as a function of shear modulus, initial yield strength, length of Burger’s vector, grain size, and macro geometrical characteristic scale of the specimen.

Abstract: A 50,000g three-axis accelerometer using a single proof mass is presented. The sensitive structure is made of a single proof mass and eight cantilever beams. Twelve piezoresistors are placed on the cantilevers symmetrically, which can be used to detect 3-dimensional acceleration. The symmetric placement of the piezoresistors brings the reasonable sensitivity and simultaneously decreases the cross-axis sensitivity significantly. Simulation results show that the sensitivity in X-, Y- and Z-axis are 0.806uV/g, 0.806uV/g and 3.71uV/g respectively with 5V supply and the cross-axis sensitivities are all less than 2.4%, which ensures the high performance of the three-axis accelerometer.

Abstract: Using robot manipulators for high accuracy applications require precise value of the kinematics parameters. Since measurement of kinematics parameters are usually corrupted with errors and their accurate measurements are usually expensive, automatic calibration of robot link parameters makes the determination of kinematic parameters much simpler. In this paper a simple and easy to use algorithm is introduced for correction and calibration of robot kinematics parameters. Actually, at several end-effecter positions, the corresponding joint variables are measured simultaneously. This information is then used in three different algorithms; the Least Square (LS), the Particle Swarm Optimization (PSO) and the Genetic algorithms (GA) for automatic calibration and correction of the kinematics parameters. This process was also tested experimentally using a three degree of freedom manipulator which was actually built as a coordinate measuring machine (CMM). The experimental Results show that the intelligent algorithms provide better results for both parameter identification and calibration of the link parameters.

Abstract: In the paper, the feasibility of the Mg-Sr master alloys production by the metallothermic reduction of SrO into magnesium melt was investigated. The results preliminarily indicated that it was feasible to produce the Mg-Sr master alloys by the metallothermic reduction of SrO into magnesium melt. The mechanism about the production of the Mg-Sr master alloys by the metallothermic reduction of SrO into magnesium melt was possibly related to the following reaction: SrO_(s) +Mg_(l) =[Sr]+MgO_(s) . In the further study, the effects of the technological factors such as holding time and holding temperature on the Sr content of the Mg-Sr master alloys produced by the metallothermic reduction of SrO into magnesium melt needed to be considered.

Abstract: In order to increase the solubility of ursolic acid, the inclusion complexes of ursolic acid with γ-cyclodextrin were prepared by grinding, ultrasonic and stirring methods. The characterizations of the inclusion complexes were proved by x-ray powder diffraction, fourier transform infrared spectroscopy, differential scanning calorimetry and scanning electron microscopy. The results confirmed the interactions of ursolic acid with γ-cyclodextrin, indicating the formation of the inclusion complexes. In addition, grinding method is a better way of preparing inclusion complex of ursolic acid with γ-cyclodextrin.

Abstract: Polyurethane (PU) pervaporation (PV) membranes are promising for the recovery of phenol from water. The PU membranes with and without cyclodextrin (CD) were prepared. The CD-containing membranes had the special structures with CD chemically crosslinked in PU backbones. The structures of these membranes were characterized by means of FT-IR. Furthermore, the PV performances were investigated for separating phenol/water mixtures at different temperatures. The results showed that the CD-containing PU membrane had better permeability and selectivity than those without CD. For 2 wt% phenol in feed mixture at 65 °C, the PU membrane containing CD had a flux of 3.96 kg µm m-2 h-1 and separation factor of 52.79.

Abstract: Elastic tube bundles are universally used in heat transfer enhancement via the flow-induced vibration in heat exchangers, and the study of the tube vibration characteristic is essential. The natural vibration of multiple conical spiral tube bundles was discussed in this paper based on numerical simulation. The substructures of ten conical spiral tubes, the inlet and the outlet branch were set up individually. Then the mass matrix and the stiffness matrix of these substructures were calculated. The general matrices were obtained and the vibration equation of the overall structure was founded. The results show that the natural frequencies of the multiple conical spiral tube bundles are smaller than the traditional planar elastic tube bundles and each natural vibration mode has a frequency band, which contains several natural frequencies.

Abstract: In this article, a PID control modle of working accuracy is constructed to control the processing process，regarding the closed loop manufacture system as a black box and the processing error as system deviation. A slender shaft with a surface is turned,the control points of the error compensation can be abtained by a probe.Based on the CAM technology，an automatic programming system is developmented to control the processing process.Through a set of comparative experiments,the detaction and the analysis of datas confirmed the validity of the PID control modle,validated the accuracy of the slender shaft can be improved by the PID control modle.

Abstract: In order to find optimal cutting parameters of carbon steel C45, the optimizing experiment of the cutting parameters in High-Speed Machining based on Taguchi method is presented in this paper. High-Speed milling experiments were designed with high-speed machining tool and surface roughness tester as the equipment. The cutting speed, the feed per tooth and the cutting depth were selected as the cutting parameters while the surface roughness was taken as the criterion. The mean surface roughness and SNR of every factor at different levels was obtained. The effects of these parameters on the surface roughness have been researched by means of the analysis of variance, and then the optimal cutting parameters were found.

Abstract: The principles of ECDM and micro-milling were described in the article. The ECDM technology and micro-milling technology were combined, and a milling platform was designed, through the analysis of the affecting factors in the processing, the Pyrex glass was machined by using the electrochemical discharge micro-milling machining and the experiment results were discussed. The results showed that the electrochemical discharge milling machining had a good prospect for the micro machining of the non-conductive materials.