Applied Mechanics and Materials Vol. 187

Abstract: In this research, dynamic behaviour of a cracked cantilever beam has been analysed using finite element and experimental analysis. Deviations in mode shapes and natural frequencies have been noticed due to the presence of crack in the beam. The variation in the dynamic response is due to change in local flexibility because of the presence of crack in the beam. Finite element and experimental analyses have been carried out to find out the vibration indices of the cracked cantilever beam for validating the robustness of the theoretical model used for crack detection. The numerical results obtained through FEA are in good agreement with experimental results.

Abstract: This paper describes the characteristics of supersonic non-Newtonian liquid jets injected in ambient air. The main focus is to visualize three types of time-independent non-Newtonian liquid jet and to describe their behaviors. Moreover, comparisons between their dynamic behaviors with Newtonian liquid jet are reported. The supersonic liquid jets are generated by impact driven method in a horizontal single-stage power gun. Jets have been visualized by the high speed digital video camera and shadowgraph method. Effects of different liquid types on the jet penetration distance, average jet velocity and other characteristics have been examined. From shadowgraph images, the unique dynamic behaviors of each non-Newtonian liquid jets are observed and found obviously different from that of the Newtonian liquid jet. The maximum average jet velocity of 1,802.18 m/s (Mach no. 5.30) has been obtained. The jet penetration distance and average velocity are significantly varied when the liquid types are different.

Abstract: In this paper, a new solution is presented for one-dimensional steady-state mechanical and thermal stresses in a FG rotating hollow disk and cylinder. The material properties for FG are expressed as nonlinear exponential functions through the radius and Poisson’s ratio is taken to be constant. The temperature distribution is derived from first law of thermodynamics by solving energy equation, with a general thermal and mechanical boundary conditions on the inside and outside surfaces. Heat conduction and Navier equations are solved analytically by choosing elliptic cylinder coordinates system and the results are shown for displacement and stress components along the radial direction.

Abstract: Underwater explosion is a complex discussion because it has two phase environment including shock waves, bubble effects, cavitation, high strain rate, geometric and material non linearity. Results of underwater explosion tests on the circular steel plates have been discussd. Test results compared with numerical analysis results which it is done by LS-DYNA code. LS-DYNA is the software which is used to analyze large dynamic deflections by use of explicit method. We found that this code has good accuracy to predict the maximum deflections. Strain rate effects included in the program by use of Cowper-Symonds relation.

Abstract: Welding-titanium and titanium alloys must be performed with special precautions because these materials are very reactive to contamination from atmosphere gases. One of the important technological considerations in welding titanium and its alloys is protection of the molten weld pool and HAZ from atmospheric gases such as nitrogen, oxygen, carbon dioxide and moisture and contamination. Absorption of the atmospheric gases affects the mechanical and metallurgical properties and may cause embrittlement, lake of fatigue strength and hydrogen cracking of titanium welds. In this paper, the effect of welding atmosphere moisture on hydrogen absorption and distribution in Ti-6Al-4V, pure titanium and TI-15V-3CR-3SN-3AL TIG welds has been studied. The experimental results indicated that hydrogen distribution which was symmetrical with respect to the weld axis had maximum and minimum points. It was also observed that heat treating the joints after welding resulted in reduction of the magnitude of the maximum and minimum points as well as redistributed the hydrogen in the welds in such a way that the distance of the maximum and minimum points got farther from the weld axis. This distribution is affected by type of titanium alloy and degree of annealing .in this investigation we used vacuum welding chamber with TIG welding apparatus and a special metal sampling and composition detecting systems for joining the samples and detecting the amount of hydrogen in the weld metal .the aim of this investigation was to increase the level of our knowledge about harmful effect of diffusion the hydrogen in the different titanium alloys. Introduction

Abstract: Motor driving system is a key technology for electric vehicle (EV), and brake energy feedback technology which benefits to prolong driving rang is typical feature of electric vehicle driving system. Hardware logic realization of permanent magnet synchronous motor (PMSM) driving control algorithm for EV in some sense contributes to the integration of EV controller. This paper mainly researches on vector control and energy feedback algorithm for PMSM, constructs digital high performance algorithm test platform for low power PMSM, and completes driving control of PMSM based on this platform

Abstract: Based on the analysis of starting process of wet dual clutch transmission, dynamic rules for piston pressure and relative angular velocity of wet clutch were determined, According to the unsteady heat exchanging theory and the heat exchanging process of clutch engagement, a two dimensional heat conduction model of wet clutch was developed with reasonable initial conditions and boundary conditions. Matlab/PDE toolbox was used to solve the established model. The temperature distribution of friction pairs along the axial and radial direction were revealed in the Simulation results. Testing program had been designed, and real vehicle test was done to the temperature field on friction interface of wet dual clutch transmission in starting process. The test result indicated that the temperature field model and its solution were reliability, and it was instructive to optimize the design of wet clutch and its engaging control in starting process.

Abstract: Cooling technique is one of the most important parts to improve the development of turbo generator. Turbo generator with evaporative cooling stator and water cooling rotor possesses many excellent qualities for mid unit. In this system the stator bars and core are immerged in evaporative coolant, which could be cooled fully. The rotor bars are cooled by water inner cooling mode. In this paper, we describe the Taylor Vortices in the Wedge-shaped air gap of Evaporation cooling Turbo Generator and present the research on gas-flow and heat-transfer with different features in the turbo generator. The CFD method is used to analyze this system, which has different features, including gap size, rotating speed, Apex angle. And the heat-transfer calculation proves the axial direction gas-flow can do well to the rotator heat-emitting.

Abstract: In order to realize omni-vision system of intelligent car for auto wandering in real-time processing, an image processing system with 6 vision channels based on FPGA&DSP is designed. In the system, two ZBT SRAM chips are used as the input and output cache for high data transferring. A FPGA chip is responsible for the core logic controlling and video synchronous. Digital videos are sent so processing module by camlink bus. Data are exchanged by EMIF and McBSP between FPGA and DSPs. EDMA is used for data transferring between SRAM in FPGA and ZBT SRAM. The QDMA is used for 2D data transferring to 1D into DSP cache. Tasks are assigned to chips by μC/OS on master DSP. All this together, real-time data sampling and processing for multi-channel vision was realized.

Abstract: In this paper, a new chaotic system is discussed. Some basic dynamical properties are studied , and we also deal with the finite-time chaos control and synchronization of the new chaotic system. Based on the finite-time stability theory, the control law are proposed to drive chaos to equilibria within finite time, and the control law and the parameter update law are proposed to realize finite-time synchronization of the new chaotic system under unknown parameters. The controller is simple and robust to noise. Numerical simulations are given to show the effectiveness of the proposed controllers.