Advanced Materials Research Vols. 562-564

Abstract: Introduce a new type of non-adhesion braking mode - aerodynamic braking; Meanwhile we analyze the structure of the wind resistance brake mechanism. Based on commercial software Fluent, numeric simulation are applied to the flow field of high speed train with wind resistance brake mechanism in order to work out the pressure distribution law of wing plate and high speed train as well as wind resistance. Based on finite element theory, finite element model of wind resistance brake mechanism is built by ANSYS. Then we make static load analysis and modal analysis to the wind resistance brake mechanism. From the computation and analysis above we get some good conclusions.

Abstract: In order to resolver the question of transmission reverse gear noise, this paper construct virtual transmission model with MASTA soft and analyze NVH ,computed transmission system frequency and gear mesh frequency, finally, find system’ resonation point and corresponding engine speed, this result is accordant to test one, finally, paper draw a conclusion that the noise is caused by resonation at some engine speed.

Abstract: Intelligent driver based on C8051F500 and TLE7242-2G for electro-hydraulic proportional valve was designed in this paper. The driver has CAN interface, and can drive four channel electro-hydraulic proportional valves. The system scheme, power unit, MCU unit, drive unit and software were analyzed in detail. At last the system performance was simulated with MATLAB. The Intelligent driver is suit for modern engineering machine’s control system, which demands networking and distributed control.

Abstract: In this paper, a time-domain analysis method based on probability density estimation is presented for rotating machine fault detection. Generally, the vibration signals obtained from a rotating machine are time-variant since they are strongly related to the rotational speed that is not constant even in the macro steady state. Since the mostly used signal processing method, the Fourier analysis is only suitable for stationary signals, the development of the joint time-frequency analysis is demanded. Here, the probability density estimation method based on Parzen window is introduced. The probability density function of the vibration signal of the rotating machine is estimated by Parzen window, and a threshold value is predefined to decide the state of the rotating machine. By inspecting the change of the probability density of the vibration signal, the condition of the machine is monitored. Air gap eccentricity and ball cage broken bearing are considered in the experiment section, they are difficult to be detected in frequency domain while the rotating speed is not constant. The validity of the method is proved by the experiment.

Abstract: Reached the autonomous force system, indicate the concept of invariant manifold of autonomous system. If the autonomous force system exists the (n-1) dimensional invariant manifold,then the system invariant manifold’s generating function can be calculated, farther, we can construct the system’s conserved quantity by these generating functions. Last one illustrative example is given with the help of n-body.

Abstract: Since the mechanical properties of the skin and the core of corn stalk are different significantly. The basal fourth internode of the corn stalk was chosen to do the compression test. The Maximum Force, the Compressive Strength, and the Modulus of Elasticity of the stalk skin and the core were obtained respectively. Then, the modulus of elasticity parallel to the direction of stalk skin fiber was calculated based on the measured data. The fiber reinforcement effect of the corn stalk skin was analyzed, combined with the mechanics of composites. Furthermore, the finite element model of corn stalk, regarded as composites, was constructed by ANSYS to simulate the compression test. The results showed that the simulation of reinforcement effect was well consistent with the value calculated by the mechanics of composite.

Abstract: Through adopting the self-explored experimental system of ultrasonic vibration, this experiment studied the adsorption and desorption characteristics of methane in coal under the sound field varying in frequency and sound intensity. Results of the research showed that the methane absorption in coal reduces when being placed in the sound field, and the amount of absorption reduces as the sound intensity increases. The amount of methane desorbed in coal increases under the working of sound field, which indicates that the effect of sound field can promote methane desorption and diffusion. the adsorption 、desorption law of methane in coal are the same under the condition of sound field and no sound field, The absorption model can be described by the Eequation D-R、Langmuir Equation、Freundlich Equation and Equation BET. Plus, the Equation D-R、Langmuir Equation can better describe the law of methane absorption in coal. Desorption model can be expressed by empirical formula、diffusion model and percolation model, and the diffusion model can better describe the desorbing characteristics of methane. These results can provide theoretical principles to improve the rate of coal seam extraction under ultrasonic vibration.

Abstract: Under the background of China rapid development of high-speed train, this paper aims at prediction of the aerodynamic noise of train, which plays a key factor for controlling the train noise. In order to develop the prediction model of the aerodynamic noise of train, first the finite and boundary element theory are utilized to calculate the fluctuation pressure of the motion train; then Statistical Energy Analysis (SEA) model of the train noise is built and the SEA parameters are calculated. Based on the above models, the prediction method of aerodynamic noise of train is developed to calculate the train noise with train velocity.

Abstract: steel ropes are adopted to connect the locks in a space docking lock system. The dynamic transmitting characteristics of steel rope is analyzed and formulated, and then a dynamic model of space docking lock system including one active lock and five passive locks is established. The driving forces and movement synchronization of this lock system is revealed through simulation based on the dynamic model.

Abstract: Based on the actual pressure condition of throttle slice of telescopic shock absorber, the general solution of throttle-slice deformation curved surface’s differential equation on a non-uniform pressure, was given, and by mathematical transformation, the deformation analytic formula was established. With the practical example, the deformation of throttle slice on non-uniform pressure at any radius was computed, and was testified by ANSYS, the value computed is close to that simulated, and the relative deviation is only 0.0021%. The results shows that the method of deformation analysis computation of throttle slice on non-uniform pressure is reliable, which has important reference value for throttle slice thickness design and characteristic simulation modeling of shock absorber.