Advanced Materials Research Vols. 538-541

Abstract: The development of abrasive water jet cutting technology needs much higher reliability requirements of water cutting system. As one of the core parts in pressure generating system of water jet cutting, the High-pressure cylinder should have a stable fatigue life. The materials of the high-pressure cylinder are 34CrNi3MoA and AISl4340, and the stress of it under high pressure conditions was analyzed with the finite element analysis software ANSYS. For the existence of repeated plastic strain, the fatigue curves were gat by long-life theory. At last the fatigue of the high-pressure cylinder was simulated based on the stress. The results show that the stress is in distribution of 29MPa - 699MPa, and main of the body is under elastic strain. The whole fatigue condition can meet the requirements, but fatigue situation is worse in close to high pressure check export, the minimal life is 250000 cycle indexes.

Abstract: Geometrical calibration is one of the key technologies for multi-channel projection system. In consideration of the complexity and cost of existing correction methods which need camera to collect the feedback images, another algorithm was proposed to correct geometrical distortion. Firstly, the pixels of the uncorrected image were mapped to the cylindrical screen with equal-arc length method. Then the correction of the geometrical distortion was realized by transforming the pixels on the cylindrical screen to the 2D coordinate of pre-corrected image according to perspective projection. Combined with simplified edge blending method, this system completed the high-angle-of-attack flight simulation based on two-channel projection and could be a platform for high-angle-of-attack flight test and flight accident reconstruction.

Abstract: Turnout is one of the key components of high-speed railway, which directly affects the maximum lateral allowable speed. The formed milling cutters are usually used in the processing of turnout, and the milling force is an active factor in the milling process which affects the functions of the machine tool and the enactment of process parameters, then the processing quality of turnouts is affected. In the paper, the theoretical milling force model for formed milling cutter is built based on the theory of metal cutting, and the working profile of curved switch rail is chosen as processing object in the milling process experiments, the validity of the milling force model is verified, The study results will provide theoretical basis for tool machine design and process parameters selection, and ensuring the processing quality of turnout.

Abstract: The whole precision forging process of spur-gear with large module (module: 4) including warm forging, cold extrusion and cold sizing is analyzed. By using finite element method, cold sizing step of spur-gear basing on hollow-divided-flow method is simulated, the influenc of hollow diameter on the forging force and material flow is discussed in detail. Futher research shows that appropriate different tooth reduction is benefit to forming tooth profile without mechaning after forging. According to the research, to form such spur gear with module 4 and breadth 59mm studied in this paper, the hollow diameter should be 18mm and the tooth reduction should be 1.2mm. The necessary reference and basis to realize practical precision forging process of spur gear with large module is provided eventually.

Abstract: According to the expansion trend of plastic area, the locations and extension direction of five stress classification surfaces are determined in the danger position of nozzle-cylinder intersection. Through the orthogonal experimental design, the structure dimensions of 32 models of nozzle-cylinder intersection are determined. With the area where 0.2% plastic strain intensity occur being designated as the scope of the stress classification surface, extension length of these computation models can be obtained by FEA, and the empirical equations of extension length and structure dimensions are given by using the multivariate regression analysis method. Then all of the stress components are linearized and classified, based on a method of linearizing stresses on a curved surface( stress-on-a-surface method)suggested in this paper. At last, the limits of kinds of nominal stress intensities are taken as the stress criteria of the nozzle-cylinder intersection. The results show that, in the range of parameters for calculation, stress criteria vary with locations and their minimum is that the primary local membrane stress intensity SII is less than or equal to 1.5 times design stress intensity Sm and the primary membrane plus primary bening stress intensity SIII is not more than 1.5times Sm.

Abstract: In order to quickly assess the damaged long-span arch bridge in wartime, fuzzy comprehensive evaluation method (FCEM) is applied. Considering the main factors of strength, stiffness and stability, ignoring durability and applicability, the damage performance evaluation elements of long-span arch bridge subjected to blast loading are concluded. Combined with the specific long-span arch bridge subjected to blast loading, the damage condition is assessed with FCEM. For illustration, a highway arch bridge damaged in wartime is utilized to show the feasibility of FCEM. Because of the damaged features of uncertainty and fuzzy, FCEM can effectively assess the damaged conditions of a long-span arch bridge.

Abstract: The effects of processing parameters on deformation behavior of a new near β titanium alloy were investigated by using compression tests. The experiments were carried out in the Gleeble-3800 thermal and mechanical simulator in the temperature range of 770-970°C and strain rate range of 10^-3-10s^-1, and height direction reduction of 70%. The results show that the flow stress of Ti-7333 titanium alloy increases obviously with the strain and reaches a peak, then decreases to a steady value. The steady and peak stress significantly decreases with the increase of deformation temperature and decrease of strain rate. The flow stress model of Ti-7333 titanium alloy during high temperature deformation was established by using the regression method. The average relative difference between the calculated and experimental flow stress is 6.33%. The flow stress model can efficiently predict the deformation behavior of Ti-7333 titanium alloy during high temperature deformation.

Abstract: The simulation of computer numerically control (CNC) machining process is an important component of CAM, it can check errors and enhance the automation of machining process. In order to realize the material removal simulation of machining process through VC++ and OpenGL, this paper does the research on the Boolean operations based on the Constructive Solid Geometry (CSG) modeling technique. Firstly, this paper introduces the CSG technique, especially the creating complex object from simple primitives by the operations of Boolean algebra and the frame buffer. Then this paper achieves the solid modeling of cutter and stock through VC++ and OpenGL, and does the research on the theory of cutter’s swept volume generation. In terms of the theory, a cutter’s swept volume is created. Finally, the Boolean difference operation of a stock and the cutter’s swept volume is realized, and the code is also given.

Abstract: The substitution of carbazole with alkyl chains on the bay regions led to excellent semiconductor carbazole derivatives. In the present paper, we investigated the motion of HOMO and LUMO due to the substitution effects utilizing the density function theory (DFT). The computational results were in the good accordance with the experimental UV-vis spectra. Additionally, the Fukui function was employed to predict the chemical activites of various atoms of the derivatives, which exhibited distinct nucleophilic reaction regions.

Abstract: The front bumper inner plate was researched based on contrastive analysis of the crashworthiness considering using 22MnB5, a typical hot forming AHSS (Advanced High Strength Steel) and DP590, a kind of general high strength steel. In this paper, we contrasted energy absorption, section force, and maximum displacement of the two different front bumper systems in low-speed collision. The analysis shows the front bumper inner plate using hot forming AHSS can improve the crashworthiness of automobiles and make it more balanced and reasonable to transfer collision energy and force. As a result, the maximum displacement of the front bumper system decreases and other parts such as front side rails can be safer. Thus, using hot forming AHSS in designing a front bumper inner plate can improve the passive safety of automobiles.