Advanced Materials Research Vols. 472-475

Abstract: The significant die unfittingness and springback, occuring during the numerically controlled (NC) bending process of large diameter thin-walled CT20 titanium alloy tube, has an obvious influence on the shape and the geometrical precision of the bent tube, furthermore on the assembly precision and the sealing capability. The changing rules of die fittingness and springback of large diameter thin-walled CT20 titanium alloy tube under different bending parameters were investigated and the mechanism was analysed using finite element method (FEM) in this paper. The result shows that the springback of large diameter thin-walled CT20 titanium alloy tube is more significant than that of aluminum alloy and stainless steel tubes with the same specification. The die fittingness has a connection with the tangent compressive stress on the intrados of the tube before springback, the larger the tangent compressive stress, the worse is the die fittingness.The results may provide a significant guide to the control of bending radius and bending angle for large diameter thin-walled titanium alloy tube NC bending.

Abstract: Spring-back is one of the key factors affecting the forming quality of the NC bending of high-strength TA18 tubes (TA18-HS tubes). Since material parameters have a direct influence on stress and strain fields during the bending and after unloading, the springback of TA18-HS tubes after NC bending depends on material properties to a great degree. In order to study the effect of material parameters, the sensitivity of material parameters on spring-back of TA18-HS tubes is analyzed in this study, using the numerical simulation and the multi-parameters sensitivity analysis method. The results show the following: (1) The springback angle has a positive correlation with the strength coefficient and initial yield stress, and has a negative correlation with the elastic modulus and strain hardening exponent. Besides, with the increase of elastic modulus, the fluctuation of springback goes gently; with the increase of the strength coefficient and initial yield stress, the fluctuation of springback goes abruptly; but with the variation of the strain hardening exponent, the springback fluctuates slightly; (2) The elastic modulus is the most sensitive material parameter on spring-back, the strength coefficient and initial yield stress rank the second and third, respectively, and the strain hardening exponent is the last. The achievement of the study is valuable to eliminate the non-sensitivity parameters, simplify the optimization project, and improve the spring-back prediction capability.

Abstract: Based on the analysis of graphite processing characteristics, this work presents the research of the graphite electrode structural design for electric discharge machining, and also describes the option of graphite processing cutting tool materials and the angle of cutting parameters. The standard-processing technique of graphite electrode NC machining is discussed, and the special processing method of the kind of thin and narrow electrode machining is explored, The availability of research results is verified by the examine in practical machining

Abstract: Nowadays almost all the park toll management system in use is based on charging by operators, up and down the barrier gate manually or the motorman get through barrier gates by swiping card. This paper try to solve the problem by designed a intelligent park system based on image processing. The system capture video frames through camera, recognizing the vehicle license by pattern recognition, sending command throng CAN bus to control the barrier gate, what is more, the states of control system is shown on LCM.The system has realized automatic control of barrier gates without parking, which, of course, slows down the vehicle wear and tear, greatly improves the efficiency, reaching the goal of green, energy saving and environmental protecting.

Abstract: This paper introduced some indoor positioning techniques. On this basis, the indoor ultrasonic positioning system based on CDMA (Code Division Multiple Access)-TDOA (Time Difference of Arrival) is proposed, and its operating principle and the analysis of ultrasonic signals are described. The system based on the character of radio frequency and ultrasonic sensors encodes the ultrasonic signal using CDMA technology, so that the destination node can distinguish each beacon signal sent beacon ultrasound signal, and combines with the RF signal to achieve TDOA location algorithm, and ultimately performs three-dimensional positioning. Using the MATLAB/Simulink blocks, the three ultrasonic beacon signals are simulated and discussed. Finally, simulation results show that the three ultrasonic beacon signals can be received and identified in the destination node.

Abstract: The transition surface and the over-cutting phenomenon always appear in the screw surface form milling process which is based on the non instantaneous center envelope method. To solve this problem, an accurate calculation method of the cutter setting angle is proposed. The contact equation between cutter and workpiece is introduced. Spatial mathematical model is established according to the cutting tool profile calculation principle and the cutting mechanism. This method improves machining precision effectively, and can get the required screw surface. It also provides essential references for the design of form milling cutter.

Abstract: Carbon fiber reinforced plastics (CFRP) have been used widely in airplanes, spaceships, automobiles and sport equipment, etc. But the machining is very difficult due to the rigidity of its internal reinforced-phase. In order to settle the difficult machining problem of CFRP, ultrasonic vibration is introduced to common cutting. Through the experiment of common milling and ultrasonic milling of CFRP, the influences of different parameters on milling force are studied. The experimental results shows that the milling forces of ultrasonic milling are significantly lower than common milling using the same milling parameters. The processing vibration of ultrasonic milling is lesser and the process is more stable than the common milling.

Abstract: This present paper aims to investigate the effect of abrasive grinding on characteristics change of surface in fixed abrasives grinding. Different surface in experiment were generated in surface grinding through change of processing time while other experiment parameters remained, and those tests of surface strain and roughness of SUS304 strip were conducted. The magnitude of stress and roughness on sample after experiment increase with processing time, which is also fit for the change of the above index parameter between before and after experiment. Larger surface stress of sample, on which higher surface roughness is also seen, is found, and simultaneously, the dependable correlation between surface stress and roughness in grinding is appraently shown. Theose decsribed findings brings out direct help to researchers and practiitioners in industry engineering fields when searching for the soution of decreasing the surface stress and roughness and extending service life of product with high performance.

Abstract: First a new autopilot design model is presented for the interceptor missile with the blended aerodynamic lift and reaction jet. The reaction jet can improve the response speed, but the structure of control system becomes more complex. Therefore how to design control strategy properly is an urgent problem. Second, considering the discrete property of the lateral pulse jet thrusters and the continuous property of the aerodynamic fins, a kind of ADRC (active disturbance rejection control) autopilot system was designed for the aerodynamic lift/reaction jet missile. Finally, through a testing in the simulation of MATLAB, it is shown that, due to the sufficient utilization of the reaction jet, there is a significant improvement in the fast response and robust performance of the proposed controller. It is applicable to design the autopilot of aerodynamic lift and reaction jet blended missile.

Abstract: Some new technology and applications on passive millimeter wave (pmmW) sensors are reviewed. The development of passive millimeter wave imaging sensors, operating at W band, that are currently being manufactured for commercial markets using standard automated assembly processes. is described. The focus was to adapt the night vision passive thermal infrared imager performance models and apply them to pmmW imaging systems for prediction of field performance for the task of small watercraft and boat identification. A novel method of human presence detection using pmmW sensors is presented. The method focuses on detecting a standing human from a moving platform in a cluttered outdoor environment using pmmW radiometry. Finally the research and development in passive millimeter wave imaging and performance improvements is discussed. The future passive millimeter wave sensors are expected.