Applied Mechanics and Materials Vols. 66-68

Abstract: Aiming at the installation angle measuring requirement of cylinder rod located at some kind of laser target for inertial confinement fusion, a non-contact five-coordinate measuring machine is exploited and built. According to the projection characteristic of spatial line, the mathematical model of spatial angle between the cylinder rod and support rod is established. Combining with image processing technique, the angle measurement issue between spatial lines can be dexterously transformed into the plane image processing problem. Based on this projection method, the direction vector of cylinder rod centerline can be obtained by testing the cylinder rod from two perpendicular directions with CCD camera. LOG operator is applied to detect the edge of image, which is able to reach single-pixel positioning precision. Furthermore, the application of sub-pixel detecting method based on least squares linear regression can further improve the positioning precision of image edge. The experiments illustrate the measuring accuracy of angle can reach 0.1 degree with the projection method.

Abstract: B₄C-Al and B₄C-TiB₂-Al composites were fabricated by infiltrating aluminum into porous B₄C and B₄C-TiB₂ preforms in vacuum. The effect of TiB₂ addition on the microstucture and mechanical properties of the B₄C-Al composites were investigated. The flexural strength and the fracture toughness of composite improved greatly as the result of TiB₂ addition. The TiB₂ addition inhibited the reaction between B₄C and Al. The infiltrated aluminum addition was the leading reason for the fracture toughness improvement of the composites. Inter/transgranular fracture mode with many tear ridges and dimples was showing in the fracture surface of the B₄C-TiB₂-Al composite. The relationships between the microstructures and the mechanical properties of the B₄C-TiB₂-Al composites were discussed.

Abstract: The chief aim of the present study is to find the effect of the nose motion upon the main body of the deflectable nose missile. The dynamic model including the motions of the nose and main body is built. The dynamic simulation and analysis show the interferential moment of the nose and main body can cause disadvantageous “body flutter”. The coupling motions can be decreased through lightening the weight of the nose. The coupling motion can be decreased greatly when the point of hinge、mass center the nose are set on one place. The roll increases the motion coupling of the three channels of the missile.

Abstract: Using the wind tunnel experimental data, the main aerodynamic coefficients are select, computed and analyzed for vehicles with deflectable nose and canard controls during different trim conditions. By analyzing the difference between aerodynamic coefficient of the two vehicle, the deflectable nose control offers increased control effectiveness 、maneuverability and stability ,reduces the aerodynamic drag. The performance of vehicle is enhanced with the deflectable nose control.

Abstract: This paper presents a predictive control strategy for seismic protection of a benchmark cable-stayed bridge with consideration of multiple-support excitations. In this active control strategy, a multi-step predictive model is built to estimate the seismic dynamics of cable-stayed bridge and the effects of some complicated factors such as time-varying, model mismatching, disturbances and uncertainty of controlled system, are taken into account by the prediction error feedback in the multi-step predictive model. The prediction error is that the actual system output is compared to the model prediction at each time step. Numerical simulation is carried out for analyzing the seismic responses of the controlled cable-stayed bridge and the results show that the developed predictive control strategy can reduce the seismic response of benchmark cable-stayed bridge efficiently.

Abstract: In the computer aided process design, the choice of processing methods is one important part. In order to improve quality and short the design process, the intelligence of computer aided process planning system is a research direction. This paper use the theory of data reduction, based on success stories, then the rule base derived. According to the method designed in this paper, tested through the use of Finishing the hole (black metal) test samples, finishing the hole (non-ferrous metals) test samples, the super finishing hole test samples, the hole semi-finished test samples, Achieve the purpose of processing methods Automatic select.

Abstract: The motor imagery to be widely used in BCI systems, the traditional focus on EEG analysis in feature extraction and classification, this paper of EEG from the left and right imaginary frequency domain, time domain and brain mapping analysis on the EEG, to analyze the characteristics of EEG signals about imagination.

Abstract: The current CAPP system has complicated operation, not high degree of intelligence, can not meet the needs of many varieties of small batch production. This paper combines the method of parts surface elements describing and method of parts coding. Formed by the 20-bit code to establish a hybrid coding system, used rough set to extract the parts feature, used the information system method to reduce the rule of processing, and from match the feature and the expert knowledge base, Automatic selection processing methods to generate process routes; use database technology to build parts diagrams and other databases, semi-automatic process documentation.

Abstract: By using digital micro-hardness testing, mechanical testing, optical microscopy(OM), scanning electron microscopy(SEM), transimission electron microscopy(TEM), microstructure and mechanical properties of Mg-9Gd-3Y-xZn (x=0,1,2,3 wt.%) alloys during extrusion and following aging at 210 °C were investigated. The results showed that Zn can refined grains of the alloy. In T5 condition the average grains of the alloy without Zn addition were about 20.08 μm; the average grains of the alloys with 1 wt.% Zn addition and 3 wt.% Zn addition were about 15.26 μm and 10.17 μm, respectively. For the alloy with 1 wt.% Zn addition in peak-aged state, the values of tensile strength and yield strength reached 418MPa and 329 MPa, as well as ductility rate reached 5.6 %, respectively, exhibiting superior mechanical properties .

Abstract: The high-speed processing performance test table has been built, the automatic return circuit test has also been designed to ensure convenience. The high-speed processing performance measurement test system has been established, the corresponding test results have been obtained. Finally, effective measures have been obtained through the rational analysis of the test results to improve the precision CNC(computer numerical control) machining.