Advanced Materials Research Vols. 712-715

Abstract: As to the optimization of double chamber hydro-pneumatic suspension,we researched the influence of excitation signal on the the damping characteristics. First of all, the double chamber hydro-pneumatic suspension nonlinear mathematical model and simulation model were set up to get the damping characteristic curves of different sources.And the influence of different factors was obtained according to the orthogonal test method. The results of the study show that the hydro-pneumatic suspension have nonlinear variable damping characteristics,the excitation signal with higher frequency and larger amplitude have superior damping effect;and the speed of the excitation signal have the biggest influence on its performance.The order of the influence of frequency (f), amplitude (A) and velocity (ν) to suspension performance is: ν>f>A.

Abstract: The method of compression and reconstruction for wind turbine vibration signal based on Discrete Cosine Transform is presented. Two group wind turbine vibration signals are compressed and reconstructed by DCT. The compression ratio and the compression reconstruction accuracy are investigated. The relationship between compression ratio, NSRMSE and the number of the reserved data is clarified. The result facilitates the application of compression and reconstruction for wind turbine vibration signal based on DCT.

Abstract: For a building under multi-dimensional seismic excitations, a new random vibration analysis based on equivalent excitation method is presented, in which, a new equation of motion of the building is used to depict its dynamics and kinematics features. Since most of the earth shocks are non-stationary random processes, the input power spectral density of the seismic excitations are modulated by a time varying function, and their equivalent excitations are constructed by using continuous wavelet transform, where the continuous wavelet coefficients are calculated by using scales and the evolutionary power spectral density, while the equivalent excitations are constructed by inverse continuous wavelet transform. The random vibration analysis is carried out following the procedures of the equivalent excitation method. A simulation example is given to investigate some affection of the multi-dimensional seismic inputs, especially the rotational one.

Abstract: This paper presents an investigation of the vibration control performance of a nonlinear damper system under multi-axis excitations, focusing on its optimum strategy. The nonlinear damper system is composed of a particle damper and a primary structure. Cross-correlation functions and auto-correlation functions are shown to be suitable means to interpret the physics involved in the behavior of such a nonlinear system. Using different types of random excitations, the optimum operating regions are all determined, within which particles move in a plug flow pattern and correlation functions decay much faster than that under the inefficient operating conditions.

Abstract: This paper studies the influence of system parameters to the vibration control effects of a nonlinear damper system under multi-axis excitations. The nonlinear damper system is composed of a particle damper and a primary structure. Based on numerical simulations, it is shown that: increasing the mass ratio can improve the dampers effectiveness, but only up to a certain level; applying particles with a high value of the coefficient of restitution can result in a broader range of acceptable response levels; a lightly-damped primary system can achieve a considerable reduction in its response with a small weight penalty; and that a cylindrically-shaped container provides a higher level of effectiveness than a rectangularly-shaped one.

Abstract: For the short-range defensive weapons, extracting the acoustic characteristic of attacking aircraft at low altitude is an effective way to detect and recognize the target. The signal characteristics of radiated noise of the typical vehicle propulsion system are analyzed, and thus the signal models for propulsion system noise and for passive acoustic early-warning system are given. Finally, the analysis result of the measured aircraft noise validates the feasibility of the signal model.

Abstract: In order to ensure the strength, stiffness and stability of the overall structure of three-ring roller coaster in the seism, the response spectrum method is used for anti-seismic analysis of the overall structure of three-ring roller coaster, the dynamic response under seism and anti-seismic characteristics is calculated, the safety of three-ring roller coaster under seism is verified, and practical method for anti-seismic analysis of roller coaster is explored.

Abstract: In this paper I make use of the gridding function of ANSYS establish spiral bevel gear mesh model firstly.Then I transform the date of the meshing model and input then into the ANSYS. After assembly and structural expansion, I use the model to do the contact stress analysis of the spiral bevel gear.Through this,I obtain the distribution and changes of its contact stress.

Abstract: In this paper, a kind of advanced gear body form is proposed, which has the structure characteristics of no weight reducing whole, thin spoke platesthick rim and large fillet. The optimization effect is confirmated by comparative analyzing the structure before and after optimization on strengthstiffnessweight and frequency adjustment performance of gear. The results show that the kind of optimization gear body is suitable for application in aviation, for which has the features of high strengthgood stiffness and light weight and which is easy to adjust gear frequency.

Abstract: Involute straight bevel gear pair often appears the phenomenons of meshing interference, impact and "end contact" in the course of meshing. Usually, symmetrical crowning is adopted to improve above phenomenons, however, due to the influence of complicated tooth loads and other complicated factors, the symmetrical crowned gear may not reach a good modification effect. In this paper, we adopt target variable curvature crowning according to the specific conditions of bevel gears in order to obtain good modification effect, nevertheless, because of the complexity of the variable curvature crowning, the conventional method of using space spherical involute stretch and sweep standard gear model to remove tooth surface materials has been unable to meet the accurate requirements of the variable curvature crowned model, at the same time, this method can not realize parametric modeling of modification bevel gear. Therefore, this paper puts forward an easy to realize parametric modeling method of accurate variable curvature crowning for involute straight bevel gear based on ANSYS/LS-DYNA, Imageware, Matlab and Solidworks. This method can realize the accurate modeling for variable curvature crowned involute straight bevel gear and ensure the accuracy of modification gears and follow-up finite element simulation, meanwhile, it provides theoretical basis for parametric modeling of variable curvature crowned involute straight bevel gear. Finally, the superiority of variable curvature crowning is tested through numerical simulation under specific conditions.