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With the extensive use of composite materials in aviation industry, the research of factors which affect their basic performances in production and usage has become very important. In this paper, a finite element analysis model is built by the commercial software MSC.Nastran / Patran to research the effect of fiber lay-up direction misalignment on the natural frequency of composite laminates. The results show that, in the same boundary conditions, stacking sequence has a significant impact on the natural frequencies and vibration modes of composite laminates, and in the lay-up process, the natural frequency change of laminates caused by 0° fiber lay-up direction misalignment is much larger than the natural frequency change of laminates due to 90° fiber lay-up direction misalignment. In the process control and certification of composite laminate plates lay-up, special attention should be taken to the inspection of 0° direction fibers.

Ha Tai high speed rail is a high-speed railway in cold region of China. The design criteria is very strict. There is many frozen soil over cold region. The research how to reduce the amount of subgrade frost heaving over Ha Tai high speed rail is of great significance.We use a frost heave model to simulate the subgrade frost heaving in the paper.We research how the fine power content and water content influence the frost heave amount of graded crushed stone by contrast test.The result shows that the fine power content and the water content have great influence on the frost heave amount of graded crushed stone .The frost heave ratio increases with the fine powder content and the water content.

The Fast-Tool-Servo (FTS) is widely used for micro-structure manufacturing especially for micro optical lens. The working principle of FTS presented by Qiang Liu et.al is that, a voice coil motor and a piezoelectric（PZT） actuator are used as the driving elements, and two flexure hinges are developed as the guide mechanisms. However, vertical displacement jump happens when the flexure hinges are driven by a voice coil motor or a piezoelectric actuator. In this paper, a new amplified structure is presented, allowing the horizontal motion while reducing the vertical displacement jump. The working principle is that, the piezoelectric actuator is applied to a beam which has two flexure hinges, one is linked to the frame, and the other is linked to a tool holder which is situated through two parallel membranes. When the piezoelectric actuator deforms, the beam will rotate around the frame, while the displacement is amplified at the other end, causing the tool holder’s motion and the membranes are forced to bend, while the vertical motion is restrained by the membranes. As a result, the presented membrane based flexure structure is able to amplify the motion of the piezoelectric actuator. In addition, the vibration frequency of the membrane is easy to be adjusted by the preloaded force. It is important to know when the FTS is working at different frequency. The performance of the presented structure is analyzed by structural dynamics coupled with piezoelectric, and the parameters of the structure are optimized to remain linear relation between the tool holder and the piezoelectric actuator, while the vertical displacement jump is much smaller than the structure presented in reference.

In this paper, the structural cell design optimization of 15kV 4H-SiC p-channel IGBT is performed. The effects of the parameters of JFET region on the blocking voltage and the forward characteristics are analyzed by numerical simulations. The results indicate that the JFET width and JFET region concentration have an important effect on the performance of IGBTs. Based on the simulation structure in this paper, the optimum JFET width is 10μm, and the optimum JFET concentration is 7×10¹⁵cm⁻³. Meanwhile, they should be carefully designed to achieve the best trade-off between the blocking voltage and the forward voltage drop.

High-strength aluminum alloy with large-scale and thin-walled complex castings have broad application prospects in aerospace, weapons, electronics, defense and military industries. However, due to the uneven thickness of the plate, the casting defects are inevitable by the ordinary casting method, and it is impossible to accurately control the shape and performance of the casting in the casting process. Previous studies have found that the semi-solid rheological extrusion casting technology with short process and near-end type can help solve this technical problem. Therefore, this paper studies the semi-solid rheological extrusion casting process of thin-walled complex casting of ZL114A aluminum alloy. The combination of numerical simulation and experimental research is used to simulate and optimize the filling and solidification process of thin-walled specimens. Based on this, a semi-solid rheological extrusion casting test was conducted. The result showed that, (1) The optimized model can well reflect the filling and solidification process under different rheological extrusion casting parameters, and obtain defect-free castings through process optimization. (2) The thin-walled parts of the thin plate casting produced by semi-solid rheology extrusion have excellent mechanical property and ductility.

Mismatch is one of the main defects of tailor welded blanks(TWB), and leveling technology is a new method which can solve this problem. The structures, force analysis and flange morphology of the leveling mechanism are studied in this paper, and a three-dimensional prototype is designed. The results have practical significance for improving welding quality of TWB.

Geotechnical centrifuges are globally used to investigate the structures which of behaviors are strongly dependent on the physical properties of soil. A new 1.4 m diameter 450 g-Tonne drum centrifuge GT450/1.4, manufactured by Broadbent & G-max company, has been installed at Dalian University of Technology in 2009. Control and data acquisition systems are provided in modular form, allowing a flexible choice of sampling and recording modes. The details including the development of the facility, the additional accessories required and a centrifugal test of submarine landslide are described.

Food waste is rich in nutrients. It can be disposed safely by biotechnology, which can make a contribution to environment, and avoid wasting resources. The bio-reactive food waste disposal processor basing on aerobic composting technology is designed in the research. The miniaturization and practical of it can be realized by studying its integrated form and structural components.

Coal is a continuous unconventional gas reservoir and coal bed methane has the potential to make an important contribution to the future energy demands. The second member coal seam of Shaxi Formation in the Mengjin coalfield is one of the most important methane bearing and exploration formations. Based on industrial analysis, elemental analysis and methane content test of thirty-five coal samples from the Mengjin coalfield, together with other geological data of the past five-year exploration, the factors that controlling the coal bed methane reservoir are identified in the Mengjin coalfield. The thick-bedded No. 2 coal seam, about 6 meters, of the Shaxi formation are continuous distributed in the Mengjin coalfield. The burial depth is from 400 to 800 meters, this is suitable for coal bed methane exploit. There is a trend which an increase in the degree of coalification is correlated with rise content of methane in No. 2 coal. Coal rank has a significant effect on the content of coal bed methane. The relationships between methane content and basin hydrodynamics are also described and discussed in this paper. The deep stagnant zone contains the largest coal bed methane accumulation. Future geological exploration for coal bed methane in Mengjin coalfield should be guided by the essential factors identified in this study. The application of them could benefit to solving the discrepancy between the amount of reserves and the question of their exploitability.

Bolt joint has an important influence on the dynamic characteristic of guide rail. Linear rolling guide is chosen as the research object in this paper. Firstly, the dynamic model of the linear rolling guide joint surface is established and its natural frequency is figured out. Then we use ANSYS to make finite element analysis of guide on whether the bolt joint is considered or not. Finally, the validity of finite element model is verified through modal test. By comparing the results of the two kinds of finite element analysis with the theoretical result, we can conclude that the finite element model considering the bolts joint is closer to the theoretical result. So the bolt joint has a great influence on the dynamic characteristics of linear rolling guide. This paper provides the theoretical guide for the research on the bolt joint.