25 March 2009, Volume 28 Issue 3
    

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  • Piao Ming-wei Fang Ji Zhao Qian-xu Zhao Wen-zhong
    . 2009, 28(3): 1-5.
    Abstract ( 4389 )   Knowledge map   Save
    In order to analysis the influencing extent of structural vibration effects on fatigue life, a methodology of vibration fatigue analysis was presented based on rigid-flexible coupling simulation. With the Interface Transaction Technical Strategy (ITTS) for flex-body, the model of rigid-flexible coupling system is established, in which the flex-body can produce the elastic vibration characterized by the relevant modal vibrations under the dynamical constraint interactions. By the Component Modal Synthesis (CMS) approach of stress recovery, the following analyses are carried out to determine the fatigue quality and the influencing extent of vibration: the correlation between dynamical stress and modal vibration, and the stress range histograms by which the amplitude and number of cycle stress on critcal points are contrasted stastically among the multi-condition. For the vertical vibration problem of container flatcat, for instance, vertical acceleration on high side, it is sured that under the dynamical interaction of the wedge’s stick-slip friction, the flatcar produces the elastic vibration characterized by the 2nd vertical bending modal, which can be validated by both modal mass and attached mass models of flatcar. According to the modal correlation analysis and the statistical contrast of stress range histogram for the cycle stress on crotical points, the vertical and lateral constraint forces of container feets are one of the main causes of the large amplitude of cycle stress on critcal points, and the influencing extent of structural vibration on fatigue life is up to (20-25)%.
  • Yin Dong-mei;Qian Lin-fang
    . 2009, 28(3): 6-9.
    Abstract ( 1573 ) Download PDF ( )   Knowledge map   Save
    Foreign object damage(FOD) often occurs while engine blades are working.The damage due to different foreign object impacting is different.The energy balance model and the fundamental hydrodynamics were used to analyse the impact force for soft body and hard body impacting on the blades. Numerical simulations of soft body and hard body impacting on the blades were done in the LS-DYNA. Gelatine and sandstone were respectively used as soft body and hard body in the simulations.The results suggest that the amplitude value of the impact contact force for sandstone impacting is bigger than the one for gelatine impacting with the same initial impacting energy and the same impacting velocity and the same impacting angle.But its duration is shorter than the one for gelatine impacting. Sandstone and blade gain the most strain energy at the moment of impacting.Because of the gelatine’s rheology during the impacting, the local damage for blades due to gelatine impacting is smaller than the one due to sandstone impacting.
  • Chao Wang;Wei-xin Ren;Tian li Huang
    . 2009, 28(3): 10-13.
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    A method based on wavelet transform for identifying nonlinear structure system is presented. The method employs complex Morlet wavelet, and perform continuous wavelet transform on free respond signal of a nonlinear structure. According to maximum value of modulus of wavelet coefficient, the wavelet ridges and wavelet skeleton are extracted, which can be used to identified instantaneous frequency and amplitude of signal, then the skeleton curve of nonlinear structure is obtain. In additional, a method based on singular value decomposition (SVD) is proposed to proceed the obtained result for decrease the influence of noise. At last, the effectiveness and accuracy of the addressed method are validated via a numerical simulation of structure model with cubic nonlinear stiffness.
  • chen hai-long Yao Xiong-liang Qi Lei Zhang A-man
    . 2009, 28(3): 14-17.
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    Criterions for judging the dynamic stability of bulkheads in underwater explosion are presented, including the B-R criterion based on the charge weight, the B-R criterion based on the standoff distance and the B-R criterion based on the new impact factor. The dynamic stability of bulkheads of a certain warship is calculated with these criterions, and it is found out that the bubble pulsating loads can not be ignored in the stability analysis. The stability of the structure is separated into three stages. Besides, the collapsing loads and the collapsing modes in different attack angles are computed, and some laws are obtained which offers some valuable references to engineering.
  • Tao Xin-min;Sun Li-hua Du Bao-xiang;Xu Yong
    . 2009, 28(3): 18-22.
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    The new scheme for bearing fault diagnosis based on wavelet variance spectrum entropy is proposed by combining wavelet analysis with entropy theory. The signal variance spectrum entropy in wavelet domain is used as fault diagnosis characteristics. The detection and diagnosis scheme of bearing vibration faults are proposed and the selection method for wavelet base based on discrimination ability factor is also presented. The results show that the wavelet variance spectrum entropy is particularly well adapted to describe bearings fault characteristics and fault diagnosis. The comparison with the method based on wavelet energy spectrum entropy is experimented which demonstrates that the proposed scheme outperforms efficiently other methods in terms of detection time and detection rate.
  • Peng Xian Zhang Pu Liu Zijian
    . 2009, 28(3): 23-26.
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    In this paper the dynamic equations of the gun-projectile system and the corresponding two kinds of solving methods which are perturbation method and numerical method are established, respectively. After that the effects of the ultimate velocity of the projectile, the elevation of the gun, the acceleration of the barbette and the rotation velocity of the gun to the deflection at the end of the gun are studied. The numerical results of the two methods tally extremely well with each other ,which indicate that the theory established in this paper is reliable. Further research indicates that the main factors which influence the deflection at the end of the gun are the ultimate velocity of the projectile, the elevation of the gun, the transverse acceleration of the barbette and the rotation velocity of the gun and then a formulation of the deflection at the end of the gun about the forenamed factors under the barbette motion is put forward.
  • Guo Xinglin Mao Yuming Zhao Yan Zhu Liwen Pan Zhongwen
    . 2009, 28(3): 27-30.
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    In many practical situations, it is difficult, if not impossible, to perform direct measurements or calculations of the external multi-force acting on vibrating structures. This paper presents a multi-force identification method which can commendably reconstruct the spatially distributed multi-force making use of limited measurement points. This method constitutes a discrete dynamic moving average model in state space and further adopts 2N algorithm precisely seeking for Markov parameter matrix in identification model. A regularization technique based on truncated singular value decomposition method is introduced to seek for a stability and approximate solution for the inverse process in whole time domain. Numerical simulation shows that this method is valid and effective.
  • DU Jian-guo;LIN Gao;XIE Qing-liang
    . 2009, 28(3): 31-34.
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    Based on the Scaled Boundary Finite Element Method (SBFEM), an equation for calculating hydrodynamic pressure on dams was derived, which can consider the effects of compressibility of water and reservoir bottom absorption. A new semi-analytical method for calculating hydrodynamic pressure was proposed. Numerical examples of two-dimensional gravity dam have been provided. It is shown that this approach is superior to conventional methods in computational efforts and accuracy.
  • CAO Chong-feng YANG Shi-xi YANG Jiang-xin
    . 2009, 28(3): 35-39.
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    In order to catch typical fault characteristics of steam turbine generator set rotor under nonlinear and nonstable instance, a new instantaneous energy (IE) distribution characteristics extraction method based on Hilbert-Huang transformation (HHT), which is used to recognize different operating state (such as normal state or oil film turbulence of rotor system. Analyzed physical relationship in theory between instantaneous energy and structural state variation of system, by the use of HHT, obtained instantaneous energy distribution feature of unstable vibration signal, and eliminated noise according to relative contribution quantization -based method, discussed the typical character of instantaneous energy using correlative coefficient, presented a new fault diagnosis method for steam turbine generator set rotor based on instantaneous energy distribution feature, and the results of experiment proves that this kind of method is effective.
  • WU Hui-Min WANG Yu; TANG Zhi-ping
    . 2009, 28(3): 40-45.
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    The response of the TiNi alloy clipped beam under drop hammer impact was investigated by employing experimental and numerical methods. The purpose of this study is to explore the effect of phase transformation on the dynamic behavior of structures. The result shows that under the drop hammer impact the response of the clipped beam is the elastic flexural wave propagation in the beam during early period and then lead to structural response. The structural response of the TiNi alloy clipped beam will be different compared to the ideal elastic-plastic material as the phase transformations arise and the phase transformation hinges generate. The recoverable character of the phase transformation leads the beam recover to its original shape as the unloading fulfill.
  • Hao Xiuhong Xu Lizhong
    . 2009, 28(3): 46-50.
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    Electromechanical integrating toroidal drive is a new-style generalized composite transmission, in which drive, power and control are integrated. Nonlinear electromagnetic meshing force can lead to obvious internal resonance during operation and cause drive system to run unusually. In this paper, for the nonlinear electromagnetic mesh forces between planets, worm and stator, strongly nonlinear dynamic differential equations of toroidal drive are presented. Based on two different situations of internal resonance and non-internal resonance, the first order approximate analytic solutions of time responses are obtained by multiscale method. Time responses of vibration amplitudes and displacements of the drive system are obtained. Meanwhile, changes of time responses of the different components for the drive system under the two situations of the internal resonance and non-internal resonance are investigated. The results show that the internal resonance makes energy alternately transfer between different components. It leads to increase of amplitudes and affects dynamic performance of drive system, so it should be removed during design.
  • YUAN Sheng-fa CHU Fu-lei
    . 2009, 28(3): 51-54.
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    If the classifiers of support vector machines with binary tree architecture are arrayed randomly in the binary tree, their performance is not the best. A sequenced method in consideration of the sample range is proposed to rationally array the classifiers of support vector machines with binary tree architecture. A sample distribution radius and a sample distribution distance are introduced to estimate the sample range of all classes in the high-dimension characteristic space. The classes with bigger sample range are classified earlier in the higher nodal point of the binary tree architecture, and are given wider classificatory areas in the characteristic space. The experiment of multi-class faults diagnosis of the rotor shows that the method distinctly improves the fault recognition accuracy, the diagnosis speed and the generalization, and it is more suitable for practical application of multi-class fault diagnosis.
  • LI Wu;YAO Wen-juan;Huang Xin-sheng;LI Xiao-qing
    . 2009, 28(3): 55-58.
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    Six hypotheses were drawn based on machine middle ear model, and mechanical model was constructed. Functional relationship of displacement and sound pressure was got by variational principles and Bessel function. Then analytic solution was obtained, and moreover ear ossicle displacement was obtained. Comparing the results with the test , the results show the correctness of equation. The equation of this paper can be applied on estimating the acoustic characteristics of ossicular well and avoiding disturbance of condition and technical level of personnel. Furthermore this method is easy and this equation can be used to optimize the material and shape of ossicle.
  • CHEN Guo
    . 2009, 28(3): 59-62.
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    In neural network intelligent (NN) diagnosis, the knowledge which is acquired by NN, is very difficult to be explained and understood, therefore, the further application of NN intelligent diagnosis is limited. In this paper, the rules extraction method from neural network based on the functional point of view is studied, and the key algorithms are introduced, such as the discretization of continuous attributes, the generation of train samples of neural network (NN), the training of NN, the generation of the instance samples from the trained NN, and rule extraction. The new method is compared with the other methods, and its correction is verified. Finally, the fault experimentation samples are obtained by a multi-function rotor experimental rig, the rules extraction method is used to extract the diagnosis knowledge rules from fault samples, and the results show the correctness and rationality of the new method.
  • Luo Songnan;Wang Lizhe;Deng Qingtian;Peng Liang
    . 2009, 28(3): 63-67.
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    The effects of shear deformation and piezoelectric-elastic coupling are considered. The beam is divided into different regions in order to describe the different sizes and positions of the delamination easily. The governing equations for the flexural wave propagation in the beam are derived based on Timoshenko beam theory. According to the potential distributing simplification for the long wave propagation, the harmonic response of the cantilever beams without the additional potential is gained. The dispersion relations and the closed solution of the displacements and the potentials are obtained. The influence of delamination parameters on displacements and potentials is discussed.
  • HU Shi-feng;ZHU Shi-jian;LOU Jing-Jun;XIE Xiang-Rong
    . 2009, 28(3): 68-72.
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    In order to compensate the inherent hysteresis nonlinearity and improve the precision of giant magnetostrictive actuator(GMA), a real-time hysteretic compensation control strategy was proposed, combining a cerebellar model articulation controller(CMAC) feedforward controller and a proportional integral derivative(PID) feedback controller,and the precision position tracking control of the GMA was realized. As CMAC neural network could not be used to approximate the multi-valued mapping of inverse hysteresis directly, an inverse hysteretic operator was proposed to transform the multi-valued mapping into a one-to-one mapping which enabled neural networks to approximate the behavior of inverse hysteresis. Simulation results showed that the proposed control strategy can adapt itself to the changes of the hysteretic characteristics of the GMA under different input reference signals,and that on-line inverse hysteresis model of the GMA can be obtained,and thus the hysteretic impact was eliminated and the high precision control of the GMA was achieved.
  • CHEN Zhang-wei;YUHui-jun
    . 2009, 28(3): 73-77.
    Abstract ( )   Knowledge map   Save
    Main achievements of vibration control technology since 1940s were summarized, including vibration
    control algorithms, vibration testing devices, ets. Severalpromising research fields, such as, controlof realvibration en-
    vironment reproduction, control ofmult-i axe andmult-i freedom vibration, were presented accordingly.
  • RESEARCH ON DYNAMICS OF
    . 2009, 28(3): 78-82.
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    Meshing force model of misaligned spline coupling is derived, dynamic equation of rotor system considering the influence of misaligned spline coupling was established based on finite element analysis. The influence rules of meshing force on rotor-spline coupling system are simulated with numerical integral method. Theory analysis and simulation results show: meshing force of spline coupling is related to structure parameters of coupling, transfer torque, static misalignment, dynamic vibration displacement, and so on; stiffness of coupling which is not a constant, relates to dynamic vibration displacement and depends on static misalignment. Dynamic behavior of rotor-spline coupling system reveals that 1X -rotating speed is the main response of system when there is no misalignment while 1X -rotating speed appears with some misalignment; moreover, when misalignment increase, shaft orbit deviates origin and magnitudes of all frequency come larger, the vibration of system gets complex. This research results can provide important criterions for trouble shooting of rotor systems connected by spline coupling.
  • WU Zhen-yu;YUAN Hui-qun
    . 2009, 28(3): 83-86.
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    For the blindness of man made choice of the parameter of support vector machine , a ant colony optimization was applied to select parameters of SVM ; and a novel algorithm, ant colony optimization support vector machine was put forward. According to the measured data of the vibration signal of the engine valve, the engine valve faults diagnosis model based on the ACO-SVM was established, and was compared with the models based on GA-SVM and BPNN. Results show that the engine valve faults diagnosis model based on the ACO-SVM outperforms the models based on other two algorithms in learning efficiency and diagnosis accuracy, and is available for the faults diagnosis of engine .
  • Zhang Wenbin;Zhou Xiaojun;Lin Yong
    . 2009, 28(3): 87-89,9.
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    Singular non-stable signal will occur when the rotating machinery gets some faults. Hence, it is important to detect the singularities for the condition monitoring and the fault pre-diagnosis of the machinery. Based on the partial decomposition in frequency domain, using the harmonic wavelet package method to analyze the simulated signal and diagnosis the practical rub faults of rotor, it expressed the ability of harmonic wavelet analysis on arbitrary detail of frequency section. It is shown that harmonic wavelet package method has many advantages over other wavelets. The satisfied results are received over the analysis of the practical signal. This provides a new method for fault signal analysis of rotating machinery.
  • Teng Jun;Lu Zhixiong;Yan Anzhi;Xiao Yiqing;Li Chengtao
    . 2009, 28(3): 90-97.
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    It is effective for the Tuned Mass Damper(TMD) to reduce the vibration response of high buildings under the wind excitation, but the displacement of the TMD sub-structure is too much bigger. So it is necessary for us to design the parameter for limiting position of TMD in the applications. Firstly, the dynamical characteristic of analysis model, which is the Guangzhou new TV tower that will be the first highest tower among the world, is introduced. The system equilibrium equations of the two limiting cases, which include on-off damper limiting position and OE(off-equilibrium)- damper limiting position control strategies, are deduced. Under the fluctuating wind excitations the simulation analysis is done. And the results show that the limiting position distance is the key point to decide the OE and On-Off damper control method, which is more effective to control different objective. When the position distance is about 36% of the classical TMD displacement response, the TMD’s displacement response with limiting position can be reduced about 45% with only 4% control effect loss. And it is more effective for the OE-damper limiting postion strategy to control the main structure acceleration peak response. So it is significant to choose right limiting distance and damping parameter to design the limit position system according to the different object demand.
  • Yang Hong Zou Lihua Huang Libin John Butterworth
    . 2009, 28(3): 98-101.
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    Abstract: This paper use the elastic half-space hypothesis. The vibration control equations of structural motion are derived when considering soil-structure dynamic interaction (SSI) and the soil-structure interaction’s effects on structural vibration control are analyzed. The effects of every parameter of soil and structures on structural vibration control are researched. The results show that: soil-structure interaction have some effects on the vibration control; the properties of foundation soil 、story stiffness and buried depth have significant effects on structural vibration control to some extent.
    Key words: Vibration control; Soil-Structure Interaction; Seismic Response
  • WANG Wei LI Gui-xian SONG Yu-ling
    . 2009, 28(3): 102-105.
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    Hyper chaotic behavior of whole vehicle model is found in this research. According to idiographic 14 dimension nonlinear dynamic system, the method of global bifurcation, frequency chart and poincare maps are used simultaneously in the study. Strange hyper chaotic attractor of each dimension are obtained. Lyapunov exponents chart calculated result imply the hyper chaotic characteristic and unstable range of nonlinear system. Numerical value study indicate that in the special range of bifurcation parameter, system exist chaos, hyper chaos, and so on. From bifurcation diagram, the system exist converse motion that from period to chaotic vibration. The method of analysis is important instructional significant to vehicle dynamic design and dynamic control under the condition of different surface of road.
  • PANG Huan-dong;CHEN Shi-hai
    . 2009, 28(3): 105-107.
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    Seismic wave produces and propagates around after blasting. In the course of the propagation, for the change of underground strata, the amplitude and frequency of the seismic wave may vary a lot. And these variations change with time and space, and have great effect on the ground architecture. According to the practical requirement, by analytic and numerical method, some different zones have been mapped out, and the general variation rule in blasting seismic wave has been worked out.
  • WANG Ying-Feng;Ta Na;RAO Zhu-Shi
    . 2009, 28(3): 108-111.
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    According to the operating principle of piezoelectric vibrant soundbridge, the paper build the dynamic model which couple the piezoelectric transducer and round window in inner ear, and deduced the electron-mechanical transfer function of the model. Through simulating experiments in Matlab, the parameters influenced the system such as piezoelectric deformation constant, support mass, support stiffness were discussed and optimized. The results assigned the theoretical basis in the development of a new piezoelectric vibrant soundbridge.
  • XING Juan ZHANG Tao HAO Song
    . 2009, 28(3): 112-115.
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    It is well known that the vortex flowmeter based on piezoelectric effect widely used in flow measuring applications is sensitive to the vibration of the pipeline where it locates, which brings detection errors. In order to study the pipeline vibration influence on the measuring accuracy of the vortex flowmeter, a number of experiments under the gas flow rate in the rang from 35m3/h to 145 m3/h have been carried out on the application-specific pipe vibrating facility, where the vibration parameters can be configured ( vibrating acceleration:0.05g, 0.1g, 0.2g, 0.5g, 1g; vibrating frequency: 40Hz, 100 Hz, 200 Hz; vibrating direction: vertical and horizontal ). The pipeline vibration influence and the anti-vibration performance of the vortex flowmeter are evaluated in terms of its meter coefficient. The results show that with an increase in vibrating acceleration, there is an increase in the meter coefficient error; with an increase either in vibrating frequency or flow rate at the same vibrating acceleration, there is a decrease in the meter coefficient error; and smaller influence on the measuring accuracy is caused by the horizontal-oriented pipeline vibration compared with the vertical-oriented one.
  • QI Dun-jie;LI Ning;HUANG Shu-ke;HUANG Yun
    . 2009, 28(3): 116-118.
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    Acceleration sensors and strain sensorswere used to study damping properties ofaFe-16Cr-2. 5Mo alloy cantileverbeam and a 18-8 stainless steel cantileverbeam in frequency range of20Hz~ 400Hz under identical experimental conditions. The results indicated that the acceleration and strain of the Fe16Cr-2. 5Mo alloy beam (annealed at 1100e) decaymore significantly comparedwith those of the 18-8 stainless steelone. The results also showed that the acceleration peaks and strain peaks of the Fe-16Cr-2. 5Mo alloy beam are obviously lower than those of the 18-8 stainless steel one.
  • DONG Jian-hua;ZHU Yan-peng
    . 2009, 28(3): 119-124.
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    Under the situation of considering the soil nailing effects on stability of soil side-slope,according to the damage model of the slip surface, the limit equilibrium theory and pseudo static approach,the seismic stability model and search model of the most dangerous slip surface are set up. The function relationship between stability coefficient and the center of circular slip surface is derived. Errors should be induced in calculating horizontal seismic inertial force and anti-sliding moment according to vertical slice. The seismic stability analysis method of slope protected by soil sailing is improved by using horizontal and vertical slice method. Calculation of the stability of slip surface is carried out by using the genetic algorithms. It can avoid getting in local minimum in optimal design. Using object-oriented programming language VC++, a computing program is implemented to make the optimization course reality. Finally,the method is applied to a case record. The results show the proposal method is credible.
  • xie qingliang zhou jing du jianguo han peng fei li lisha
    . 2009, 28(3): 125-130.
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    Based on the Scaled Boundary Finite Element Method (SBFEM), an equation for calculating hydrodynamic pressure on dams was derived, which can consider the effects of compressibility of water and reservoir bottom absorption. A new semi-analytical method for calculating hydrodynamic pressure was proposed. Numerical examples of two-dimensional gravity dam have been provided. It is shown that this approach is superior to conventional methods in computational efforts and accuracy.
  • HU Jialiang;ZHOU Li;YAN Gang
    . 2009, 28(3): 131-135.
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    Recently, semi-active control using megnetorheological (MR) dampers that combines the advantages of both active control and passive control has received considerable attention. However, how to design the corresponding control system is still a challenge task. This study proposes a genetic algorithms-based strategy for designing the fuzzy controller for the multi-input-multi-output (MIMO) structure-MR dampers system. This strategy determines the command voltages of MR dampers from the acceleration responses of the structure. Genetic algorithms are employed to adaptively design and optimize the fuzzy rule bases. The experimental studies have demonstrated the effectiveness and efficiency of the fuzzy control systems based on the proposed design strategy in reducing the responses of a vibrating structure.
  • TIAN Yong-sheng;LI Shou-ying;CHEN Zheng-qing
    . 2009, 28(3): 136-140.
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    Summary: Taking the stadium of Mongol Wuhai Olympic center as project background, by adopting wind tunnel test with synchronously measured pressure on the rigidity model, we have studied the interference effects between two coverings with different altitude, including total wind suction, the distribution of average and fluctuating wind pressure coefficients, and the wind pressure power spectrum of main test points, etc. The results manifest that the interference of the higher canopy roof to the lower is significant on some angles, and it mainly affect as ‘cover effect’; The interference of lower canopy roof to the higher is the same, but not as obviously as the effect that the interference of the higher canopy roof to the lower .
  • Li Yanqiang Du Yanliang
    . 2009, 28(3): 141-143.
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    Based on a more perfect finite element model of stay cable, the relative sensitivity of calculational frequencies for long stay cable and short stay cable were analyzed respectively, according to the different design variable of cable such as tension force, tensile rigidity, flexural rigidity , density and the most sensitivity design variable was established. On the basis, according to the optimization theory, the dynamic finite element model updating of a stay-cable of Dongting Lake Bridge based on the most sensitive design variable was processed. The final updated FE model was able to produce natural frequencies closer to the test ones. The updated FE model was useful for the reference model to tension force assessment.
  • REN Yichun Zhang Jiefeng YI Weijian
    . 2009, 28(3): 144-148.
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    The identification of time-variant modal parameters by modified Littlewood-Paley (L-P) wavelet transformation is studied. The responses of structure subjected to dynamic load are transformed by modified L-P wavelet. The bands with significant energy content are the bands where the natural frequencies are located. The changes of the natural frequencies with time are determined by the wavelet coefficients graph. The mode shape is estimated by the ratio of the wavelet coefficients of two considered degrees of freedom at an instant time, corresponding to the band of freqency in which the natural frequency lies. The damage of shear frame structure is detected and the time when the damage occurs is estimated by the change of the frequency identified by modified L-P wavelet. The damage location is detected by the change of the slope of mode shape from the undamaged structure to the damaged one. By this method stucture damage is detected without excitation information, even when there is noise in recorded responses.
  • Zhao Yan-ju Wang tai-yong Xu Yue Leng Yong-gang Zhang Pan
    . 2009, 28(3): 149-151.
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    The empirical mode decomposition (EMD) of weak signals submerged in a heavy noise was conducted and a method of stochastic resonance (SR) used for noisy EMD was presented. This method used SR as the pretreatment of EMD to remove noise and detect weak signals. The experiment result prove that this method, Compared with that using EMD directly, not only improve SNR, enhance weak signals, but also improve the decomposition performance and reduce the decomposition layers of signals.
  • ZHANG Yu-xin;LI Guo-qiang;ZHAO Shi-feng
    . 2009, 28(3): 152-157.
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    Based on mechanical properties of a beam string structures ( BSS), the vibration model of the side cable
    at lower chord of the BSS was proposed first.The implicit free vibration solution of the cable was obtained by analyzing the
    vibration model here in. The solution reflected the recurrent relationship among cable tension, natural frequencies, flexural
    rigidity and boundary conditions. Based on the solution, nonlinear numerical computation was conducted to study how
    flexural rigidity and boundary conditions influenced the free vibration properties of the cable by introducing a set of dimensionless
    parameters, which represented flexural rigidity and boundary conditions, respectively. Some instructive conclusions
    were obtained here in. Furthermore, the preliminary identification model was proposed according to the above analysis.
  • ZHANG Yu-xin;LIGuo-qiang;ZHAO Shi-feng
    . 2009, 28(3): 158-160.
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    Based on the frequency equation of the lower-chord cable of a beam string structure, the numerical sta-
    bility for cable tension estimationwas investigated using a numerical iterative solutionmethod. The results illustrates that
    the solution precision could be guaranteed when using the proposed numerical iterative solution method. In order to im-
    prove and simplify the solution, the relationship between frequency and cable tensionwas studied by conducting numerical
    iterative computation. Furthermore, the formatof the existing formula for cable tension identificationwas investigated, and
    one setof practical formula for cable tension identification were proposed by employing numerical fittingmethod. Error
    sensitivity and identification precision of themethodwere discussed in the end.
  • ZHENG Rong-yue HUANG Yan LIN Wen-feng
    . 2009, 28(3): 161-163.
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    A box orthotropic rectangular plate structure is a structure made by four plates. To solve the free vibration problem of this structure, it may be analyzed by the method of general analytical solution. This solution can be used to solve the plate with arbitrary boundaries. For each plate there are boundary conditions at the top and the bottom. While at the edge connected between two plates there are continuous conditions. From equations caused by all of the conditions of four plates, it can be used to solve the natural frequencies and vibration modes. For solve all of the frequencies it may be make use of symmetric and antisymmetric conditions in deformation. For example, a rectangular and a square plate structure has been calculated and discussed.
  • . 2009, 28(3): 164-167.
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    This paper studies the forced vibration behavior of magnetostrictive actuator eradiation plate excited by a variable force due to displacement excitation produced by magnetostrictive bar inside the magnetostrictive actuator through a single elastic ring between concentric point of the plate and the end of the bar. Meanwhile, the influence of elastic coefficient of the ring on amplitude of plate vibration is discussed also. The calculating model and the analytic method discussed in the paper are useful to determine the structure and the dimension of eradiation plate as well as to optimize the working parameter matched in the system.
  • YANG Ping;CHEN Zi-xia;TAN Guang-bin
    . 2009, 28(3): 168-170.
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    In order to obtain the influence of chip position and fix methods to dynamic property of Plastic Ball Grid Array (PBGA) under vibration environment. In this paper, a group of specified PBGA assembly chips which contain different structure and material parameters are designed and produced. ANSYS is used to build up the finite element model. In modeling process, simplified PBGA structure accompanied with numbers of solder joints are utilized to decrease the calculation. From simulation, 1st frequency and deformation can be achieved under different fixed ways. Experimental modal analysis method is combined with the dynamic test under different consolidations. Finally, take Side Four-points fixed way as an example to compare the correspondence and difference between the simulation and test. Results show the ways like make the chips on four-point board; increase the constraints; make chips near the constrains can well improve the dynamic property.
  • CHU Zhi-gang;DENG Zhao-xiang;WANG Liang;WANGWei-dong
    . 2009, 28(3): 171-173.
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    Aiming at an idle abnormal noise of a middle-duty truck, several approaches, such as, spectral analysismethod, acoustics interaction filter, selective sound intersitymethod for surface source identification and physical separation ofnoise source base on expunctionmethodwere used to identifynoise source and rereal its spread and radiationmechanism. Analysis showed that the frequency range of the idle abnormal noise is from 274Hz to 330Hz; the air intake and the air cleaner shell of the intake system are the surface noise sources; while the intake noise of the air compressor is the essentialnoise source; the edle abnormalnoise can be eliminated bymodifying the intake system of the air compressor.
  • LIU Jun;GAO Jian-li;MU Gui-zhi;XIE Wen-lei
    . 2009, 28(3): 174-177.
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    The self-developed hammering method experiment modal analysis system is introduced, which including software modules of the digital signal sampling and analyzing system(VTCL_DSP) and experiment modal analysis system(VTCL_MDT) self-developed and hardware modules of the NI-USB9215A signal collector, a three-dimensional acceleration sensor and computer etc. In this system, fixed acquisition time-length and varied-time-based technology is adopted for getting the signals of the three-vector response accelerations and impact force during the trigger process. The advantages of the method are discussed. This paper also introduces two application examples: a modal analysis for power-train of a SUV and a modal analysis for Body-in-White of a sports-car. The results have high accuracy and high stability. The system will push forward the technology of model test and analysis.
  • LIU Jintang;YANG Xiaodong;Wen Bangchun
    . 2009, 28(3): 178-181.
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    The governing equation of an axially moving plate on simple supports is derived. The differential quadrature method is employed to analyze the natural frequencies and critical speed of the plate under in-plane loading. The contribution of the axially moving speed, plate stiffness and length-width ratio is discussed. It is concluded that the increasing axial speed leads to decreasing of natural frequencies while the stiffness causes higher values of natural frequencies. When the length-width ratio is small enough, the axially moving plate can be studied by beam model.
  • yan xiaoqiang liu lina shi can cao xi
    . 2009, 28(3): 182-185.
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    Actually on the manufacturing of CSP mill, main drive system will produce strong torsional vibration and lateral vibration. The two vibrations are coupled and take on complicated nonlinear dynamic characteristics. Therefore it is of great theoretic and applied importance to carry through researches on dynamic coupling characteristics of mill main drive system to make sure efficient and reposeful production of the mill. Using differential equations for coupling of lateral and torsional vibration which were predefined, interactional factors between lateral and torsional vibration are theoretically analyzed and experimentally proved. This indicates that coupling phenomenon of lateral and torsional vibration really exits while exceptional vibration of CSP mill is taking place.
  • LUO Zhigao WANG Xiang LI Ju FAN Binin GUO Xiaodong
    . 2009, 28(3): 186-189.
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    According to the characteristics of the acoustic emission signal which was induced by punching die when it fail, and though which to determine the characteristic parameters of failure signal; extracting the energy eigenvector of signal failure die by wavelet packet analysis technology, and Take the comparison between the energy in different frequency bands energy and total energy as the characteristic parameters. then though genetic algorithm to optimal the characteristic parameters. the principle of probabilistic consistency and the fuzzy mathematics possible theory were taken as the foundation to obtain the membership grade function of characteristic parameter .Last, the method was used to identify the state of punching die. Experiment shows that the method can reliably discriminate the conditions of the punching die and it has strong practicability.