Advanced Materials Research Vols. 189-193

Abstract: Layered double hydroxides (LDHs), consist of cationic brucite-like layers and exchangeable interlayer anions. In this thesis LDHs consist of brucite-like layers of zinc hydroxide, with the exchanging propertity of interlayer anions in hydrotalcites, used Mg/Zn/Al-LDH as precursor to prepare the theophylline intercalation assembly hydrotalcites to obtain supramolecular complex for the first time by co-precipitation under a nitrogen atmosphere, determined the reaction conditions and influential factors of the synthesis of theophylline-pillared hydrotalcites, and tested its sustained-release performance in different media. The product has been characterized by powder X-ray diffraction (XRD), FT-IR spectroscopy, uv-vis spectrophotometer and thermogravimetry-Differential thermal analysis (TG-DTA) . Results demonstrated that : Through co-precipitation intercalation methods, with molar ratio of Mg/Zn/Al/ theophylline being 3:1:1:2, co-precipitation medium pH9, crystallization temperature 80 °C and crystallization time 12h can obtain the clear chemical composition and good crystallization of inorganic - organic hybrid-type drugs hydrotalcites. In addition, according to Pharmacopoeia measured the release rate of theophylline-LDH in the different media including distilled water,0.9%saline,simulated intestinal fluid (pH7.4 phosphate buffer) by UV spectrophotometry, Theophylline pillared hydrotalcite has a certain release in the media above all. And calculated the release of intercalation theophylline, lay the foundation for the further clinical application.

Abstract: Thin film based passive optical components assembled with a stainless steel tube via soldering is investigated under a packaging procedure. Finite element analysis is utilized to simulate the packaging procedure in the present study. Mismatch of the coefficient of thermal expansion among various components could induce residual stress over the assembly structure. Coupled thermal-elastoplastic analysis is adopted to predict the plastic deformation of the structure under the solidification process of solder joints. This post-solder-deformation could deteriorate the associated coupling efficiency due to the mis-alignment of the optical fibers. Temperature-dependent mechanical properties of the solder joint are employed in the simulations. Both two-dimensional plane strain and three-dimensional solid models are implemented into the analysis for comparisons. In order to improve the fiber alignment, and thus the coupling efficiency, a three-point bending device is externally loaded on the structure. Unloading procedure is subsequently performed to evaluate the ultimate deformed shape of the structure. Measurements of the insertion loss will be conducted using a power meter in the near future, while a correlation between the coupling efficiency and the fiber alignment can then be expected.

Abstract: Cast, sub-rapidly solidified and rapidly solidified Al-5Fe alloy and Al-5Fe-3Y alloy were respectively prepared by vacuum melting, suction casting and melt spinning. The effect of increasing cooling rate and adding rare earth Y alloy on microstructures and phase composition were investigated. The results showed that the acicular Al₃Fe phase transferred to spherical phase and dispersed secondary precipitations were also found when 3.0 wt% Y was added in the Al-5Fe alloy. Meanwhile, the microstructures were apparently refined by the increasing of cooling rate. The metastable phase A₁₆Fe and intermetallic compound A1₁₀Fe₂Y phase have been observed in Al-5Fe alloy and Al-5Fe-3Y alloy, respectively.

Abstract: The varying target component virtual disassembly simulation technology is presented to support the disassembly analysis and feedback in product design for disassembly by a 3D visualization way. The disassembly weighted hybrid graph (DWHG) is constructed to describe the constraints and disassembly priority relationships among constituting components of product. In addition, a hierarchical recursive construction method is proposed to enable the rapid construction of DWHG for complex products. Based on the DWHG, varying target component disassembly sequences are generated by a recursive reasoning method. To facilitate the virtual disassembly simulation, the component disassembly path is translated into the discrete critical path points and the critical path point recognition technology is proposed to obtain them. The disassembly simulation of components could be controlled through the transform of pose matrix. Finally, a case study proves the validity and feasibility of the proposed method.

Abstract: In this paper the metallic glass particles reinforced aluminium matrix composites without obvious defects were obtained successfully by explosive compaction of mixed powders. The mass fraction of the amorphous phase is 10%, 15% and 20% respectively in the specimens. The scaning electric microscope micrographs of the composites show that the metallic glass particles are uniformly distributed in the matrix. The x-ray diffraction and differential thermal analysis of the composite specimens show that the amorphous phase is maintained in the composites without crystallization during the compaction. Finally the influences of macro-temperature rise and micro-heat transfer on the crystallization were analyzed.

Abstract: In order to further investigate the influence of mold temperature in rapid heat cycle molding on shrinkage of plastic past, a self-developed vehicle-used blue-tooth front shell high-gloss mold and an auxiliary device for controlling the mold temperature were employed in experiments. And the effect of the other parameters on shrinkage of part with fixed or changed mold temperature conditions was also studied. Results reveal that the shrinkage of RHCM part is reduced obviously compared with a conventional one, decreasing as quasi-linear with mold temperature increased gradually. At same mold temperature conditions, packing pressure, followed by packing time, is the most significant parameter on shrinkage of part, while cooling time has almost no impact on it. Melt temperature and injection pressure effecting on shrinkage of part exists a critical value, near the thermal deformation temperature of plastic. When mold temperature is set below this temperature, injection pressure has more significant than melt temperature, but it is the opposite. With being elevated gradually of mold temperature, shrinkage of part shows a slight decrease trend under same melt temperature and injecting pressure. While it fluctuates as a “V” shape with a narrow range under same packing pressure, packing time and cooling time presumed conditions, and reaches the minimum near the thermal deformation temperature of plastic.

Abstract: Because of its low stiffness and intensity structural features, thin-walled parts affected by milling force, easily produce deformation and vibration among processing. In this paper, by optimizing milling parameters, it can be realized to control the size of the dynamic milling force and the milling state. Then it reaches the purpose to decrease workpiece deformation, and makes processing conditions maintain a stable. It not only reduces deformation caused by the vibration, but also makes thin-walled parts errors meet the tolerance requirements.

Abstract: Based on the cutting and polishing comparison experiments, the machinability and polishing performance of 1CrMn2MoVTiB non-quenched and tempered plastic mould steel were studied. The cutting comparison experiment showed that the plastic mould steel that had developed recently was better than P20 both in surface roughness and cutter wear; and the polishing experiment indicated that the surface roughness of the two plastic mould steels reached uniformity under the conditions that TriDent polishing fabrics and W0.5 polishing compound were adopted.

Abstract: For forging die fracture behaviors during the actual forging process of compactor grinding tooth, the fully forging process has been simulated based on FEM. Die stress changes and distributions were analyzed in details through two related simulation processes. The maximum load acting on the die which type is ideal rigid body predicted firstly. Then, the die stress can be obtained by the elastic-plastic analysis when the die bears maximum load. Results show that Local stress concentration beyond ultimate strength of material causes the fracture of lower die.

Abstract: Blanker holder force (BHF) is one of the important parameters in sheet metal forming process, which is loaded by blanker holder in order to avoid wrinkling. With the development of technology, segmented blanker holder is applied to complicated product forming in order to improve the parts quality. On the basis of analyzing the character of rectangle box forming, the blank holder was divided eight portions, including 2 long straight segments, 2 short straight segments and 4 corners, which each part can separately move. Then the forming simulation of the low carbon steel rectangular box with segmented constant BHF was conducted using orthogonal experiment and considering test conditions. After the results were analyzed according to the thinnest level of the parts, the influence of the segmented blank holder on rectangular box forming was obtained. It indicates that the segmented blank holder has the ability of the local control to sheet metal forming, and can effectively adjust material flow and the strain distribution.