25 July 2009, Volume 28 Issue 7
    

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  • JIANG Ji Song YE Ji Hong
    . 2009, 28(7): 1-7.
    Abstract ( 1550 ) Download PDF ( 915 )   Knowledge map   Save
    Abstract: The classical genetic algorithm (GA) itself has the limitation of weakness local search ability,converging prematurely and reducing convergence speed in the anaphase. The theory of adaptive strategy and niche technique of pre-selection mechanism are introduced into the GA. Niche technique is used to avoid the problem of converging to the part-optimum. Adaptive strategy is presented for the adaptive controlling of the crossover probability and mutation probability. The new type of algorithm is adaptive niche genetic algorithm (ANGA),for the purpose of maintaining the population diversity and improving the reliability of holistic convergence. This algorithm is verified by three typical examples. Besides, a numerical case of 70m single-layer reticulated dome is given to demonstrate good operation steadiness and strong holistic searching capability,however the consuming time using proposed algorithm is longer than that using ANSYS optimistic built-in module. The algorithm can be applied to section optimization of large and medium reticulated dome with several optimum variables,and can ensure the quality of results.
  • Hu Feng;Wu Bo;Hu You-min;Shi Tie-lin
    . 2009, 28(7): 8-11,2.
    Abstract ( 1551 ) Download PDF ( 917 )   Knowledge map   Save
    This paper proposes a novel approach for structure modal parameter identification. The approach changes the identification problem to an optimal one. The global optimal solutions for the required parameters, including frequency, damping ratio, amplitude and phase of the structure can be obtained by taking the advantage of the Partical Swarm Optimization. The results of numerical simulation studies showed that the accuracy of this method is comparatively higher, and the adjacent modal coupling has no effect on its accuracy. The FIR lowpass has effect on the phase’s identification.
  • Liu Lili Wen Hao Jin Dongping Hu Haiyan
    . 2009, 28(7): 12-16.
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    Abstract: The paper presents the optimal retrieval control for a three-dimensional tethered satellite system subject to different level of impacts from space debris. Tether elasticity and complex constraints are taken into consideration in the controller design firstly, which features full exploitation of the second-order differential inclusion concept and the Legendre pseudo-spectral algorithm. The optimal tension and state profiles are solved with respect to the initial impact velocities. The various effects of impacts from space debris on the tethered satellite system are analyzed.
  • Guo Bi;Jin Chen
    . 2009, 28(7): 17-21.
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    Abstract: Gear vibration signals are cyclostationary. Character cyclic frequencies of its spectral correlation density (SCD) function are harmonic clusters, whose basic frequencies traverse modulation frequencies and meshing frequencies of the system. Therefore, the information of the SCD for harmonic cyclic frequency clusters
    is concentrated as accumulation energy factor (AEF) for gear precise condition monitoring in this paper, which named as meshing vibration monitoring factor and modulation monitoring factor separately. AEF can be employed to monitor certain vibration phenomena in gear transmission system, which is favorable for fault location determination. AEF extracts information from whole analysis frequency band, and it is superior at early weak fault identification. Experimental results in this paper verified the sensitivity and the practicability of AEF.
  • LIU Wen;LIN Teng-jiao;LI Run-fang;WANG Jia-xu
    . 2009, 28(7): 22-27.
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    Abstract: By the finite element method of multi-body contact problem, the time-variable stiffness at different rotational position of a new type gear reducer with small tooth number difference was obtained, and the dynamic contact finite element method was used to analyze the meshing impact, and then the internal excitation which composed of the excitations of time-variable stiffness, gear error and meshing impact were calculated. A dynamic finite element model of reducer was established and used to analyze the dynamic response of time-domain and frequency-domain as well as one-third octave acceleration grade structural borne noise of gear reducer under dynamic excitation. At last an experiment of vibration analysis of reducer was conducted using the analysis instrument of vibration test. The computational results obtained are in a good agreement with the data of experimental tests.
  • YUAN Hui-qun;ZHU Xiang-zhe ;LI Dong;WEN Bang-chun
    . 2009, 28(7): 33-37.
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    Abstract: Great thermal bending of aeroengine, especially high pressure (HP) rotor, is come into being frequently in course of cooling after parking. When the rotor system starts up again, it brings relative big thermal vibrations which threaten the safe operation of aeroengine. In this paper, the thermal vibration characteristics of HP rotor system of certain aeroengine were studied by means of the coupling theory of flow-thermal-structure-dynamics. The effect of temperature in different parking times on dynamics characteristics for HP rotor was discussed. At same time the calculated results were compared with experiment. The results show that during 65~90min, the maximal vibration velocity of HP rotor exceed critical safe vibration velocity, 80mm/s. So when the rotor starts up after parking, it should be avoid the times of 65~90min to minish thermal vibration velocity. Or after cooling running, the rotor start up again. The calculated results offer theoretical direction of design and fault diagnosis of HP for avoiding thermal vibration.
  • Dong Xing-jian;Meng Guang
    . 2009, 28(7): 38-40.
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    Abstract Based on the residual dynamic flexibility, a new definition of the inertia relief attachment mode is proposed. The approximated representations of residual mass and residual stiffness are deduced by partly ignoring the dynamic effects of the truncated modes. The free interface component mode synthesis method is used to set up the dynamic model of the full structure by coupling experimental model of component A and finite element model of component B. Finally, numerical examples have demonstrated the validity and efficiency of proposed method. Furthermore, the results indicate that the influence of the residual mass and residual stiffness on the accuracy of final results can be neglected.
  • YUAN Li-yun; XIANG Yu; HUANG Yu-ying NI Qiao
    . 2009, 28(7): 41-49.
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    Abstract: Based on the general linear elastic theory of thin shells and the potential flow theory, considering the energy dissipation of passive constrained layer damping (PCLD) due to shear deformation of the viscoelastic core and the fluid-solid coupled interaction, a first order integrated differential matrix equation of the circular cylindrical shell with PCLD treatment was derived firstly. Each element in the state vector of the equation has clearly physical means, so it can be conveniently applied to solve dynamic problems of circular cylindrical shell with different boundary conditions. Secondly, by writing the fluid dynamic pressure as analytical form with undefined coefficients, and applying the fluid-solid interaction condition, the homogenous extended capacity precision integration method and the superposition principle, a semi-analytical and semi-numerical method with high efficient and precision is established. Comparing to the analytical solutions of the axissymmetrical free vibration of cylindrical shell (no water filled) fully treated with PCLD under the freely supported, the results obtained by this method is effective. Finally, the dynamic responses of the fluid-filled cylindrical shells with partially treated PCLD under harmonic ground motion are represented, and the damping effects of different thicknesses, lengths, and locations of PCLD and the complex shear modulus of the viscoelastic core are studied.
  • He Jian-jun;Jiang Jie-sheng
    . 2009, 28(7): 50-54.
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    Abstract: The paper presents an approximate method for reanalysis of topological modification of non-classical damping structure with added degrees of freedom (DOF). The method,which is based on reduced model of original and topological structures, is followed by introducing dynamic condensation and singular value decomposition of complex matrix, and then combining the Rayleigh quotient inverse iteration method to obtain the final results. The results of numerical examples show that the suggested method can provide good approximation solutions with high precision, and it is very effective and feasible.
  • SHAO Min-qiang;CHEN Wei-dong;CHEN Qiang
    . 2009, 28(7): 55-60.
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    A porgram of active vibration control with unknown excitations was studied here.According to the knowledge of Kalman filtering kand linear quadratic Gaussian(LQG) methd,the control algorithm based on random walk and input estimation was proposed.First,the excitations were described as discrete recursive forms by using random walk model and they were introduced into state functions of the control system as auxiliary state variables.And then,the Kalman filtering principle was used to estimate the unknown excitation combining the auxiliary the auxiliary state functions.So,the system tarber functions could be created according to the estimation values of the estimation values of the unknown excitations,state variables and the known measured outputs.Finally,using the LQG algorithm to get the optimal values of current control inputs.Good control effects were proved by numeric simulation with sdof and 2 dof models.The results were better than those based on the conventional LQG method .

  • YANG Fei;YANG Zhi-chun;WANG Wei
    . 2009, 28(7): 65-68.
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    Abstract: A novel scheme for panel flutter suppression is proposed by the authors of this article. In this scheme the panel is designed as a sandwich panel incorporated with distributed micro beam-type dynamic absorbers acting as its core layer. To improve this scheme, the frequency design method for the dynamic absorber is investigated in the present study. Based on the mode-coupling mechanism of panel flutter, the frequency design of dynamic absorber is performed according to the single-frequency design scheme and double-frequency design scheme respectively. Numerical simulation results show that when all the micro dynamic absorbers are designed with single-frequency design scheme, a maximum flutter speed for the sandwich panel can be achieved at the optimal absorber frequency, which is different from the flutter frequency or the natural mode frequencies of the original sandwich panel; and when the micro dynamic absorbers are designed with double-frequency design scheme, a maximum flutter speed of the sandwich panel which is much bigger than that obtained by single-frequency design scheme can be achieved.
  • SHI Xiu-zhi;XUE Jian-guang;CHEN Shou-ru
    . 2009, 28(7): 73-76.
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    Abstract The characteristic variables of blasting vibration have great effects on its damage degree. The prediction of characteristic variables caused by blasting vibration is helpful to study blasting vibration effect. For the first time, the prediction of the PPV and first dominant frequency band and its duration are achieved on the basis of rough set and Fuzzy-Neural Network (FNN) theory. The purpose of this study is to explore a method which can avoid the limitation of the prediction by only one index and to improve the prediction precision. Firstly, the drawback of prediction of the PPV based on Sadov’s vibration formula was analyzed. Secondly, Rough Set and Fuzzy-Neural Network (RSFNN) theory were introduced briefly. Thirdly, Rough set-based FNN prediction model for the characteristic variables of blasting vibration is established based on the analysis of factors affecting blasting vibration characteristic variables. Finally, the model was trained by data come form Tonglvshan Copper Mine and was tested by 15 groups of data. The results show that rough set and FNN prediction model reflects the nonlinear relationship between factors and characteristic variables and can be used to predict the characteristic variables of blasting vibration. It is also found that the precision of prediction single index a time is higher than that of prediction three indexes at the same time.
  • XU Fuyou;ZHANG Zhe;LI Tianfei;SHI Lei
    . 2009, 28(7): 77-80.
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    Abstract: The aero-stability performance of Houlongxi Bridge in Taiwan is investigated via wind tunnel tests. The conditions for vortex induced vibration of concrete and steel deck sections, as well as the lock-in wind velocity regions and vibration amplitudes are obtained. The similarity and discrepancy between the wind-axis and body-axis for natural field and wind tunnel are expounded and discriminated. Then the aerostatic force coefficients are measured. The non-linear aerostatic response analysis is conducted finally. The research results reveal that the real bridge will not diverge when the velocity attains13.5m/s. In smooth flows, vertical bending and torsional vortex vibration occur for two models with +3° attack angle. For torsional vortex vibration,the wind velocity is quite high and lock-in region is wide. In flows with turbulence intensity of 10%, when attack angle varies form -3° to +3°, no apparent vortex can be observed The deck added attack angle incurred by static wind loads is very tiny. The wind load non-linearity plays negligible role on deck torsional and lateral displacement. Owing to the vertical lift wind loads will cause the obvious change of main cable rigidity, the vertical displacement is more relevant with the wind load non-linearity.
  • Li Xue-bing;Hou Chuan-lun;Zhang shu-guang;Zhang Ji-ye;Zhang Wei-hua
    . 2009, 28(7): 81-84.
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    Considering the effects of the aerodynamics, vehicle dynamic responses of high-speed train in passing events are studied in this paper. For obtaining the aerodynamic load, a simplified geometry model of high-speed train (CRH-2) is built, and a 50-degree-of-freedom dynamic system is represented for modeling each of three cars which constitute the train, the three-dimensional compressible Reynolds-averaged Navier-Stokes equation, combined with the k-e two equations turbulence model, was solved by using finite volume method, and the motion of the train is carried out by using sliding meshes. The response of the train consider aerodynamic load or not are calculated by Multi-Body Simulation. The safety and riding quality of the train in passing events considering aerodynamics or not are discussed. It is found that, the aerodynamic force changes rapidly in the process of passing events, the aerodynamics has obvious effect on the vehicle system dynamics, which cause the train drastic vibration, the most serious deterioration of safety and riding quality can be found at the leading and tail car.
  • YAO Xiong-liang;ZHANG Lin-gen;CHENG Min-liang;LAN Jing-lei;PANG Fu-zhen
    . 2009, 28(7): 85-89.
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    Abstract: in order to decrease the cost though predicting the noise before building to improve the ship. This paper introduces the prediction of the noise of the ship’s superstructure cabins based on SVM method. This paper establishes two nonlinear regression models of the noise of the superstructure cabins of large container ship, which is based on Support Vector Machine, using RBF kernel function and ERBF kernel function, taking the actual measurement noise of one container ship’s superstructure cabins as the training sample. The two models are applied to predict the noise of the parent ship and another container ship’s superstructure cabins. Compare to the result and choose the better model, then predict the noise of 174000DWT bulk carrier’s superstructure cabins. The result shows that, it is feasible to predict the noise of the ship’s superstructure cabins,and the effect is good.
  • Yu Guo;Yilin Chi
    . 2009, 28(7): 90-94.
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    Abstract:Vold-Kalman-filtering order tracking (VKF_OT) is famous for its decoupling ability for crossing or close orders. However, the conventional decoupling approach for VKF_OT has two deficiencies in applications. First, it is a time consuming scheme. Second, it becomes invalid when the instantaneous frequencies of coupled order disturbances are unknown. A new approach for the decoupling of crossing orders for VKF_OT is proposed in this paper. It utilizes the independent component analysis (ICA) approach to separate the mixed observed data into the order components corresponding independent component and order-coupled disturbance independent components (ICs). Subsequently, VKF_OT is only applied to the separated order components corresponding independent component. The deficiencies such as the intensive computation and the instantaneous frequency of disturbance signals formation for the conventional decoupling method are avoided. Following the brief instruction on VKF_OT and ICA, the scheme of the proposed approach is presented. Simulations and tests are also introduced to evaluate the validity of the present approach.
  • The Wavelet Analysis and Feature Extraction for Sound
    Guo Chao.) Yao Hong-yu. ) Shu ping. ) Chen Guo. )
    . 2009, 28(7): 95-98.
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    Abstract: For the aircraft cockpit background sound analysis in civil aviation accident investigation, the wavelet packet analysis method is used to carry out the time-frequency analysis of the different types of switches’ sounds, and extract the bands normalization energy characteristics which can be applied to identify various types of switches sounds. Finally, the typical switches sounds for the B737 aircraft are acted as the research objects, and a number of samples coming from various types of switches sounds are collected from experiments. The sounds samples are analyzed and the energy features are extracted and the results are statistically verified which are fully show the validity of this method.
  • Li Jin-ping; Chen Jian-jun; Huang Bai; Zhu Zeng-qing
    . 2009, 28(7): 99-104.
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    Abstract: A new maximum entropy stochastic finite element method was proposed on the basis of the dimension-reduction method. In this method, the multi-dimensional random response functions were decomposed into the combination of one-dimensional response functions by the univariate dimension-reduction method, so the multi-dimensional integration which was employed to calculate statistical moments of response of stochastic structures was transformed into one-dimensional integration, and the one-dimensional integration was calculated by the Gauss-Hermite integration. After getting the statistical moments of response of structures, the explicit expression of probability density function of response of structures was obtained using the Maximum Entropy Principle(MEP). The proposed method doesn’t involve the calculation of partial derivatives of response and is fit for nonlinear stochastic problems. The examples illustrate that the proposed method has good accuracy and computational efficiency.
  • CHEN Wei-Shan HAO Ming ZHAO Xue-Tao CHEN Si SHI Sheng-Jun
    . 2009, 28(7): 105-110.
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    Abstract: Presently, the research and application of the multi-DOF USM in the world is in the investigating stage, many structure multi-DOF USM have come forth. A multi-DOF USM based on single longitudinal-bending transducer vibrator was proposed and studied. The transducer brings multi-DOF driving trajectories only with single tip. The tip drives spherical spinner. model analysis was carry out on cross orthogonal transducer, with the FEM method, the longitudinal and bending resonance frequencies are degenerated; An analytical model of the multi-DOF driving foot trajectories has been developed; analyzed the driving foot trajectories with typical driving mode by simulation; Relationship of rotary speed with voltage and torque with rotary speed around coordinate axis was measured, corresponding efficiency was figured out. The experimentation is conformity with trajectories of analysis.
  • Gong Zhiguo;ZHU Lei;Xie Qiang
    . 2009, 28(7): 111-114.
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    Abstract: A self-organizing sequential Monte Carlo filter for nonlinear state-space model is proposed. An expanded state-space model is defined by augmenting the state vector with the unknown parameters of the original state-space model. The self-organizing state-space model can also be applied to the self-tuning of the noises dispersion. A local likelihood is introduced and used to select the optimal parameter from a finite number of possible values. Examples of hysteretic system identification are shown to verify the effectiveness of the proposed method.
  • LI Shun-bo;DONG Zhao-xing;QI Yan-jun;JIAO Jin-feng;
    . 2009, 28(7): 115-117.
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    Abstract: The attenuation law of shock wave in water, soil and concrete were numerically simulated by applying ANSYS/LS-DYNA. The results showed that: The magnitude of wave impedance has greater effects of the shock wave initial peak; the shock wave in soil lasted the longest and decay slower. The relationship between the shock wave speed and intensity is approved, the greater intensity, the higher velocity. The media compressibility has greater effects of the energy. The energy in soil is maximal, which in water is minimum.
  • Tang Jinyuan Chen Weitao Chen Siyu Zhou Wei
    . 2009, 28(7): 118-121.
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    Abstract:A new adaptive thresholding function used to denoise signals is studied. The construction of the new thresholding function is illustrated in detail, and the advantages and handicaps of the new method comparing with the hard and soft thresholding function is given. The measurement system based on visual instrument LabVIEW and Matlab used to acquire and analysis the vibration signals of gear case is built. The experimental results shows that the denoising method using the new adaptive thresholding function is valid, which can obtain the main characteristic of original signals and has superior features over conventional methods, possess certain practical value.
  • Zhang Jian-tao;Zhu Hua;Zhao Chun-sheng
    . 2009, 28(7): 122-125.
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    Abstract: This paper presents the optimum design of a bar-like ultrasonic motor (USM) stator using finite element (FE) parametric optimum method. Firstly, the parameterized FE model of the stator is created on the basis of its initial configuration. Then, the modal frequency sensitivities of the stator to the structure parameters are investigated by modal analysis. The structure parameters which have an important effect on the working mode frequency are chosen as design variables. The important judgment parameter of the motor output properties is selected as the objective functions. Zero-order optimization method is chosen as the basic tool of structural updating of the stator. A structural optimization scheme is applied to optimum design of the stator. Finally, a prototype USM is fabricated using optimum design results. The experimental results show that working mode of the prototype and the amplitude of driving points on the stator meet the design requirements. Moreover, the test results are consistent with the optimized results. The optimization method mentioned in the paper can shorten the USM design cycle and allow one to explore a new way in the optimization of the USM.
  • Xinna Ma; Shaopu Yang Shuling Di
    . 2009, 28(7): 126-130.
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    Abstract:According to analyzing the vibration characteristic of high-speed locomotive and the Bouc-Wen model of magnetorheological damper, a vibration control method based on magnetorheological damper was put forward, and a seventeen-degree-of-freedom lateral semi-active control model of high-speed locomotive with magnetorheological damper was established. Taking into account of the nonlinear of model, a fuzzy control rule and a self-adapt control strategy to modify the input parameter of magnetorheological damper in time according to control effect was put forward. The simulation of model was studied by using MatLab. The simulation results showed that compared with the passive control and simply fuzzy control, the self-adapt fuzzy semi-active control strategy with magnetorheological damper could attenuate the vibration of the locomotive effectively and improve the ride comfort and stationarity obviously, especially in the domain of 5~8HZ which are sensitive to the human body.
  • MU Wenpin
    . 2009, 28(7): 131-134.
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    Abstract: An extended precise integration method for computing the non-stationary response of linear MDOF structure subjected to evolutionary random excitation is proposed. Random loads are first transformed into deterministic loads using Pseudo-excitation algorithm before precise and efficient recursive relations with unified form are constructed by using the precise computing method of Duhamel integration. The avoidance of inverse matrix computing makes the presented method independent to the nature of system matrix or its dynamic matrices, enhancing the numerical stability and expanding its applied scopes. The presented method enjoys the same high numerical precision as HPD-M and a higher efficiency than the expanding precise integration method. Examples are given to show advantages of this method.
  • NAN Guo-fang;REN Xing-min;HE Shang-wen;YANG Yong-feng
    . 2009, 28(7): 135-138.
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    Abstract: The blade with tips can be equivalent to the model of mass with springs in this paper. It is achieved for the blade with tips to be damping by means of the multiple motions of impact and friction between the blades with tips, so in the paper, the friction between blades with tips can be equivalent to the spring and damping model with symmetry gap. Sgn contact model is used, thus the paper gets the dynamical equation of the system, and solves the equation by Runge-Kutta numerical method. The paper mainly discusses how the parameters such as gap of tips, stiffness ratio, contact angle, friction coefficient make impact on damping effect. The result shows that the parameters make an important impact on vibration energy, selecting parameter is subjected to span of rotate speed. The multiple motions of impact and friction between the blades with tips is hard piecewise linear vibration which is actually nonlinear, so the paper also makes certain research on the nonlinear characteristic of the system by means of Poincaré graph and frequency spectrum etc.
  • GUO Wen-hua;LIU Hai-tao
    . 2009, 28(7): 139-142.
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    Abstract: This paper presents an approach for dynamic analysis of coupled monorail train-bridge system in time domain. The bridge is represented by the conventional finite elements while the monorail train is idealized as a combination of a number of rigid bodies connected by a series of springs and dampers which can easily take into consideration the effect of lateral and vertical surface roughness at driving, steering, and stabilizing wheels. The governing equation of motion for the monorail train-bridge is formed on the basis of the bridge dynamic equation and assembled by the adoption of fully computerized approach. Direct integration method is used to solve the equation. A case study of a 3×30 m double-line continuous track beam is analysed. Effects of driving speed and different conditions on the coupled system as well as impact coefficient are discussed. The results demonstrate that the proposed framework can efficiently predict the dynamic response of coupled monorail train and bridge system and the train can safely and comfortably go through the double-line continuous track beam in the design speed.
  • XU Fuyou;TAN Yanbin;ZHANG Zhe;CHEN Guofang
    . 2009, 28(7): 143-146.
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    Abstract: The wind response performance of Huanghe Park landscape footbridge in Suqian city is investigated via full bride aeroelastic model test in smooth and turbulent flows with 3 types attack angles. The wind velocity factor for height modification is compared between the theoretical values and those offered in specification, and the discrepancy reasons are analyzed. The research results reveal that the much rougher ground surface, the lower height, and the obvious difference for modification factor. The factor values agree well if it is higher than 40m. For Huanghe Park landscape footbridge, with 3 kinds of attack angles, no obvious vortex vibration can be observed, and the aerodynamic stability satisfies the requirements. The buffeting displacement standard deviation may be higher than the mean value, even for higher wind velocity. The displacement peak factors and their ratios in smooth and turbulent flows varies in the interval of [2.5,4] and [0.8, 1.2]. No explicit relations exist between peak factors and wind flows, wind velocities, wind attack angles. The investigations can offer valuable reference for rational determination of peak value in wind vibration theoretical analysis.
  • CAI Hao-gang;DING Gui-fu;Yang Zhuo-qing; ZHOU Zhen-wei;WANG Hong
    . 2009, 28(7): 147-152.
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    Abstract: A novel shock switch based on the micro-electro-mechanical system (MEMS) for vibration monitoring was designed and fabricated by non-silicon surface micromaching technology, which consists of three main parts: the proof mass as the movable electrode, the cross beam as the stationary electrode and the movable contact point to prolong the contact time. The ANSYS model was built, by which the modal analysis was carried out showing that the new design reduces the sensitivity to off-axis accelerations compared with the previous design, and the physical parameters was extracted from geometric structure to apply in the Simulink model. Based on the dynamic simulation, the contact-enhancing mechanism was confirmed and compared with the traditional design. The fabricated micro shock switch was tested by dropping hammer experiment. Test results indicate that the threshold acceleration was about 145g and a stable contact time of over 50μs was observed under half-sine wave acceleration with 1ms duration, in agreement with the simulation. The contact effect was improved significantly as expected and the models were able to describe the device behavior correctly.
  • Bao Ri-dong;Jin Zhi-hao;Wen Bang-chun
    . 2009, 28(7): 153-157.
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    Abstract The nonlinear dynamical characteristics of vertical fluid conveying pipe under the condition of commonly elastic supports at both ends and the excitation of pulsating fluid and harmonic motion of the base were studied by using the nonlinear analysis methods to find out systematical parameter conditions and the forerunner of chaos. Numerical results show that the system goes through the transitions from periodic motion and chaotic motion alternately with the increase of mean flowrate and mass ratio. Doubling bifurcation is the route leading to chaotic motion, and the inverse doubling bifurcation is its converse way to leave chaotic motion. The parameter conditions of chaotic motion and periodic motion are closely related with fluid flowrate and supporting elastic coefficients of piping system. The parametric range of chaotic motion becomes short with the increase of elastic supporting and restraining coefficients. That shows that the coefficients are good for controlling the chaotic motion.
  • ZhANG Xiao-dan;YAO Qian-feng;LIU Pei
    . 2009, 28(7): 158-161,.
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    Abstract: It’s important to identify structural modal parameters, especially the mode shapes in time and accurately for accurate damage identification and health monitoring of structures. Normally, lots of time domain modal identification methods are generally achieved by curve fitting or calculating eigenvalues process. Mode shape matrix is obtained by calculating various modal residues. These methods depend on the identifying modal frequency and modal damping ratio. In this paper, a novel method based on FastICA for mode shapes identification is proposed. This method uses the independence between the modal responses to create the object function, and obtains the optimal solutions of the mode shape matrix by optimizing the object function. It extracts the mode shapes directly from the free responses or the pulse responses of structures. An numerical application of three DOF(degrees of freedom) is performed and shows the efficiency of this method, which gives a high identification accuracy and a good robust to the measuring noises.

  • ZHOU Tian-yue WANG Cun-tang GU Jian CHEN Jun-qiang
    . 2009, 28(7): 162-165.
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    Abstract The working mode of constant-pressure radial piston pump includes mode of constant flow and constant pressure. The dynamic model was established and analysis was made on displacement vibration in frequency domain to the two modes. Measurement mechanism was designed to test the vibration of stator of JB32H-type radial piston pump. It is concluded from analysis and test results that the displacement of stator vibrates periodically on the two modes. The frequency band is narrower on the mode of constant pressure than that on the mode of constant flow because of action of constant pressure control system. The amplitude on the mode of constant flow is smaller than the one on the mode of constant pressure in the range of the frequency band of the mode of constant pressure. The conclusions will be helpful to the noise and vibration control of piston pump.
  • Chunxiang Li Wenti Hu Zebing Dai Xiang Bian
    . 2009, 28(7): 166-168.
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    Abstract The main objective of the present paper is to investigate the wind-induced dynamic fatigue of main-shaft in the vertical-axis wind turbines (VAWT) under the rotation with resorting to the ANSYS code. Firstly, the dynamic responses in three critical positions of main-shaft in the current vertical-axis are analyzed in the case of including the rotation and wind loads into consideration. Based on the investigations on the dynamic responses, the wind-induced dynamic fatigue of main-shaft in the current VAWT under the rotation is then studied, so as to determine the fatigue life usage coefficient and evaluate the working requirements of the main-shaft in the current VAWT.
  • WANG Lei;WANG San-min;NIU Zhi-yong
    . 2009, 28(7): 169-174.
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    Abstract It's the foudation of error control that nonlinear dynamical analysing for rigid-flexible coupling manipulator.The system of astronautics manipulator is equivalent to a RRRP system including an infegrated mass. The one order similar modal function of extendible manipulator is set up by use of finite element method. It’s dynamic model is set up by use of Lagrange’s Equation and the assumed mode method. With help of Longgekuta numerical method, the dynamical characteristic of the rigid-flexible coupling RRRP system are found. The numerical results indicate that the change of the structure parameters will influence the lateral vibration of the manipulator. Based on the above results, its optional design and error control can be realized.
  • Zhang Kai;Liu Hongbing;Wang Weifeng;Liu Wei
    . 2009, 28(7): 175-178.
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    Abstract: Based on the modal pushover analysis (MPA) and constant-strength ductility demand spectrum method, the basic solving process of the vertical irregular structure is put forward. Using the modal pushover analysis, the influence of high modes can be taken into account. Using the constant-strength ductility demand spectrum method, the ductility and displacement demand of the equivalent single degree of freedom is obtained, then translate them into the displacement demand of multi degree of freedom system. Using these methods to analyze the examples of typical irregular vertical structures, the results demonstrate that these methods can be used in the calculation of the vertical irregular structure.
  • Li Wei;Ma Ji-sheng;Li Zhiqiang;Fan Zhaojun
    . 2009, 28(7): 179-182.
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    Abstract: Based on virtual prototyping technology, emergency braking dynamic model of a certain tracked vehicle was established by means of ADAMS/ATV software. By travel test and emergency braking test of the tracked vehicle, VV&A of the emergency braking dynamic model was carried out and its credence was proved. Using it as a simulation base, emergency braking dynamic simulation analysis of the tracked vehicle was carried out. The emergency braking dynamic responses at mean velocity of 3-6 gear were analyzed and braking characteristic curve was obtained by emergency braking simulation test.
  • ZHAO Qun;ZHANG Yi-min;ZHAO Jin-fang
    . 2009, 28(7): 183-186.
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    Abstract: This paper based on the theory of powerflow and the generalized probabilistic perturbation method, the path powerflow transfer ratio are solved, and the new concept and effective approach of path powerflow transfer probability for vibration transfer path systems in frequency range are presented. The powerflow transfer probability among vibration paths are described correctly and expressly in frequency range as uncertain factors are considered. The sensitivity of the system to uncertain factors is studied. It is supposed to study the sensitivity of the system to these parameters, to estimate the effect of the change of parameters, to improve design performance.

  • Huang Wei;Zhang Chenghua;Yao Qianfeng;Wei Xiao;Jing Gang;Hou Lina;MuLin
    . 2009, 28(7): 187-191.
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    Abstract: The multi-ribbed slab structure uses various materials and components nesting each other, which makes the entities calculation model extremely complicated, therefore, it is necessary to present the simplified calculation model of the structure.. Based on previous study and the calculation theory of modern high-rise structure , the simplified numerical model and analytical model of multi-ribbed slab structure in elastic stage are presented. According to the previous results of shaking table test on a 1/10 scaled model, the rigid frame-composite elastic plate model is employed to perform the time-history analysis, therefore, the validity of the model is verified. In addition, the comparative analysis of simplified numerical model and analytical model in practical engineering is carried out to verify the rationality of analytical model. Theoretical researches and experimental analysis show that it is not only supported by theory but also useful for practice to adopt the rigid frame-composite elastic plate model as the numerical model in elastic stage, and it is more reasonable to take the frame-composite wall model as the simplified analytical model in elastic stage ,which provides a more simplified and practical hand-calculation method for practical engineering.
  • Pan Jin;Wu Chengliang;Tong Qiang; Gao Fengli
    . 2009, 28(7): 192-195.
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    Abstract: According to the overseas research conclusion, an E shape steel damper that mild steel is used instead of high-strength steel was designed。The restore force model of E shape steel damper is studied through tests and numerical analysis. The results of test and simulation analysis show that the damper has very well hysteresis loop curve between force and displacement under cycle loading under considering the ideal elastic-plastic model. The analysis in this paper show that such design method can be applied to high-strength steel and reduce productive costs obviously.
  • CHEN Xueqian;DU Qiang;FENG Jiaquan
    . 2009, 28(7): 196-198.
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    Abstract: Bolt joints are widely used in many structures, they represent some nonlinearity subjected to different environment exciting generally. In order to study on their nonlinear characteristic, a bolt-joints system is designed, and the sin-sweep vibration tests are done on the system subjected to different base exciting. The resonant frequencies and the relative damping coefficients of the bolt-joints system are obtained by analyzing the test data, they show obvious nonlinear characteristic with the vibration level changing. In theory study, the system is simplified to be a single freedom degree mass-spring-damper model with nonlinear spring and nonlinear damper. The coefficients of the nonlinear equation are identified by the test data. Last, the main resonant frequencies and the relative damping coefficients of the system are obtained by the nonlinear equation. The theory results are coincident with the test results better, as shows that the nonlinear equation in the paper depicts the vibration characteristics of the bolt-joints better.
  • OUYANG Ke-jian;CHEN Zheng-qing;HAN Yan;LI Hong-li
    . 2009, 28(7): 199-202.
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    Abstract: Vortex induced vibrations(VIV) and the controlling measure of Central-slotted Box Section for Suspension Bridges have been studyed by wind tunnel experiments in this paper, The conversion relationships between the resonant amplitudes of the sectional model and the prototype bridge are considered, and the correction coefficients of mode shape are also presented. Both of the two controlling VIV methods designed in this paper may control the VIV successful. The second method is able to control the VIV effectively which have been presented in this paper on condition that do not alter the the section shape,and the second method also correspond to actual engineering practice needs. The research has alsio shown that it is effective to restrain the amplituds of VIV by increasing the damping ratio.
  • CHU Zhi-gang;XU Shao-hua;LU Xi Yang Liang
    . 2009, 28(7): 203-207.
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    Abstract: The traditional measurement of the transmission loss of muffler was done in single terminal boundary conditions, the sound fields at the upstream side and downstream side of the muffler were considered to be two independent acoustic systems. Then the transmission loss of muffle was determined by calculating the incidence power of upstream side and the transmitted power of downstream side respectively. But it failed to take into account the full coupling effect on the sound field of upstream side for the reflected wave from the terminal of the downstream side of the muffler, limiting the measurement accuracy of the sound transmission loss. Consequently, in order to take into account the coupling fully, the new measurement method of transmission loss, which based on transfer function, 4 microphone locations, and dual terminal boundary conditions, was put forward. Furthermore, transfer function correction algorithm which can improve the accuracy of transfer function measurements also was derived. In the end, the experiment for transmission loss of a typical expansion muffler using hardware platform of B&K acoustical material testing system was done, and the results were consistent with the theory.