25 June 2011, Volume 30 Issue 6
    

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  • JIANG Shao-Fei;LIN Jie
    . 2011, 30(6): 1-4.
    Abstract ( 1837 ) Download PDF ( 509 )   Knowledge map   Save
    In order to make full use of redundant, complementary and uncertain information and thus assess the structural health states from a structural health monitoring system, a new damage identification method by integrating with rough set and revised counter-propagation network (RCPN) was proposed in this paper. In this method, rough set is used to deal with data so as to reduce the uncertainties and the spatial dimensions of data firstly; then the current CPN model is revised so as to improve the capabilities of processing uncertainties and classification, and the RCPN model is used to identify damage. To validate the proposed method, single- and multi-damage patterns from one numerical frame were identified finally, and some important factors, such as measurement noise, neural network models and data processing technologies, were investigated with emphasis. The results show that the proposed method can not only reduce the spatial dimension of data, but also have preferable damage identification accuracy and robustness.
  • GUO xing-lin;GAO hai-yang
    . 2011, 30(6): 5-9.
    Abstract ( 1254 ) Download PDF ( 542 )   Knowledge map   Save
    A direct method based on orthogonality conditions for eigenvectors is improved for updating the mass and stiffness matrices of a structural model. Combined with the merit of element method and matrix method, the inner elements associative matrix is presented to make the updated mass and stiffness matrix physically meaningful as the bandwidth and inner elements connection. Dynamic characteristics of the structures can be effectively modified using measured first few eigenmodes. Examples of five-story building and plane frame structure are updated with measured first two and three natural frequency and eigenvectors respectively. It can be easily proved the validity and robustness of this method
  • XU Zhong-ming;YU Feng;WANG Xian-guo;SHI Fang-yuan;QIU Zhao-qiang
    . 2011, 30(6): 10-14.
    Abstract ( 1908 ) Download PDF ( )   Knowledge map   Save

    The structural dynamic characteristic of all-terrain vehicle (ATV) affects greatly its vibration performance and riding comfort, but a simple, common and effective finite-element modeling method for ATV frame with an elastically mounted engine is rare. Based on simulation and test for ATV body, a simple and common finite-element modeling method was proposed which simplified the engine as a meshed cuboid structure with same centroid, weight and rotary inertia to the engine and linked engine to MPCs fixed on the frame through SPRING elements. Considering nonlinear changes of elastic engine suspension stiffness in different operating conditions, the influences of the proposed modeling method on the structural dynamic characteristic of ATV body under different elastic engine suspension stiffness were studied. The results show that finite-element modeling method for ATV frame elastically connected with engine meets the engineering requirements. This simple and common modeling method is useful to know the structural dynamic characteristic of ATV frame elastically connected with engine in the phase of product design and retrofit which could applied in developing and design the ATV with an elastic engine suspension

  • chen shuai;yang zhi-chun;li bin
    . 2011, 30(6): 15-19.
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    Aimed to develop buffet fatigue spectrum, predict life and so on, the data process and analysis method is proposed for an identical flight condition using the probabilistic model to decrease data scattering. The dynamic time histories are split into several blocks by a suitable time range. The statistical characteristics of each block are investigated to express the response level in its corresponding root mean square, while the root mean squares in the blocks are used for representing the RMS variation. The Weibull distribution is chosen as the assumption of the response data in each block and its parameters are obtained though the method of maximum likelihood estimation. The method of distribution test is established to form a criterion for determining its accuracy. Then an empirical step function is introduced to represent RMS variation in the given flight condition. According to the given flow chart of application, it is available for us to carry out the work of aircraft design, strength certification and so on. The result of processing flight test data proves that this method is valid and available for the buffet issues
  • Su Wei-guo;Cai Xi-rong;Li Xiao-hua
    . 2011, 30(6): 20-25.
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    There is still not any specific experiment and theory to explain that impact roller vibration has effected on the buried optical fiber cables. And this has restricted applying impact compaction technology to the highway section with buried optical fiber cable. In order to solve this issue, based on practical project parameter, according to the relative hypothesis and simulating the multi-cycle loading mode of impact compaction construction, a 3-D finite element model was developed. The vibration effects on different optical fiber cable caused by impact compaction construction were analyzed with the Ansys software, and the results show that impact compaction construction has little effect on the optical fiber cable in 60cm buried depth. The impact of the construction on the cable was larger when the location of the cable gradually nears the direction of the pavement. The compressive stress of Z direction and the tensile stress of X direction came to the allowed values respectively when the cable buried up to 0.1 meter and 0.14 meter of the bottom of the subgrade, then the cable was destroyed
  • Deng Yu-lin;Peng Tian-bo;Li Jian-zhong
    . 2011, 30(6): 26-30.
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    For a long-span cable-stayed bridge, it is often required that the main tower be essentially elastic under strong earthquake. Therefore, a seismic isolation structural system is often adopted to reduce the seismic response, and the seismic displacement at the end of the deck may severely exceed the allowance which due to the occurrence of the pound between the main span and the approach span usually which can causes the collision of falling-beams and structures under strong earthquakes. In thi paper, based on the pounding phenomenon at expansion joints of long-span cable-stayed bridge under strong earthquake and employing a typical long-span cable-stayed bridges, the complex nonlinear model that considered the elasto-plastic behaviors of piers and pylon and the pound responses between the main span and the approach span was developed. With the time history analysis method of determining the nonlinear seismic responses,the pounding efects of adjacent girders at expansion joints on seismic responses of long-span cable-stayed bridge were studied. The results indicate that the pounding can amplify the seismic demand of piers of the approach span and also can amplify the displacement of beam of the approach span, the relative displacement between main span and approach span and the hinge seat width of beam of approach span obviously and it causes easily the collision of falling-beams and structures under strong earthquakes. But the pounding has minor effects on seismic demand of the main span
  • Ma Xin-na;Yang Shao-pu;Liu Xiao-xing;Ge Zhan-sheng
    . 2011, 30(6): 31-35.
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    Nonlinear single degree of freedom magnetorheological damper system is study in the paper. The system can implement the semi-active on-off control strategy through the transformation of the MR damper voltage. In the based of analyzing the dynamic characteristics of the system, it gives the differential equation system. And the solution is obtained by the averaging method. According to singularity theory, the universal unfolding of system and transition set under a special circumstances are studied. Then the magnetorheological damper is applied in the lateral bogie dynamic system as the vibration controller. And the effects of system parameters on amplitude frequency curve and stability are analyzed in detail
  • Zeng Sheng;Ren Yi;Li Chang-pin
    . 2011, 30(6): 36-40.
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    In connection with the efficiency request of the unbalance measurement for the automatic rotor balancing machine, an 8th-order band-pass active filter is designed, which is compared experimentally with a 2nd-order low-pass active filter and a narrow band-pass tracing filter. The result demonstrates that the 2nd-order low-pass active filter has the characteristics of high measuring accuracy in the case of majority sampling loops, which may be used in the high accuracy requirement situation while the measurement efficiency is not so important. The repeatable accuracy of the narrow band-pass tracing filter is low, so it can only be used to the general balancing machine. In comparison, the 8th-order band-pass active filter hosts the high measuring accuracy, the high repeatability and the high efficiency, which can meet the measurement requirement of “Amplitude ±3mg, phase ±1ºand measurement time 5 seconds”
  • TENG Yun-long;SHI Yi-bing;ZHENG Zhi
    . 2011, 30(6): 41-43.
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    To augment the performance of detecting faulty satellite aiding of receiver clock bias (RCB), from the point of nonlinear time sequence, a combined model for predicting RCB based on grey system theory and Markov chain is proposed in this paper. The basic ideas and steps of the forecasting method are discussed respectively, and then this model is introduced into GPS receiver in order to detect faulty satellite. Test results are presented to demonstrate the feasibility and validity of the method in the end. The research work in this paper paves the way for detecting faulty satellite, and should be valuable in the project application for improving the positioning precision and reliability of GPS receivers
  • Liu Zhanfang;Zhang Kai;Yan Shijun;Feng Xiaowei
    . 2011, 30(6): 44-46.
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    Two dynamic frequencies and two complex modes are given out for a spring-mass vibration system with two degrees of freedom in a centrifugal field. The dynamic frequencies of the centrifugal vibration system are related to system rotation speed whereas to centrifugal softening and Coriolis force effects. Coriolis force leads to system vibration with complex modal vector and polarized circle motion of a mass. And owing to the motion coupling but not real physical damping, does not produce system attenuating vibration. Thus, the corresponding circle motion trajectory of mass is always kept for the single complex modes of rotating system
  • Su Wen-sheng;Wang Feng-tao;Zhu Hong;Zhang Zhixin;Li Hongkun;Guo Zhenggang
    . 2011, 30(6): 47-52.
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    A denoising method based on hidden Markov tree model in dual tree complex wavelet domain is proposed, and it is successfully applied in mechanical fault diagnosis. Noise is inevitably present in mechanical vibration signal, which makes the extraction of weak fault information be the difficulty and hotspot of fault diagnosis. Since dual tree complex wavelet transform has the approximate translation invariance while hidden Markov tree model can effectively describes the dependency between wavelet coefficients and the non-Gaussian nature of these coefficients, a method combining these advantages can achieve better denoising results than that of conventional soft or hard threshold denoising and hidden Markov tree model in wavelet domain. Applications of simulation signals verify that Gaussian white noise can be effectively inhibited, as well as abnormal impact can be removed by using this method. For actual rolling bearing signal, satisfied result also can be acquired
  • LIAO Yingying;LIU Jinxi ;LIU Yongqiang;YANG Shaopu
    . 2011, 30(6): 53-57.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Effects of semi-active control and time-delay on riding quality, running stability and safety of high-speed railway vehicle were analyzed. Firstly, 62 DOF nonlinear model was built using multi-body-dynamics technology, and then MR damper and semi-active controller was designed based on the modified cubic model of Bouc-Wen. Finally, the influences of semi-active control and time-delay on the dynamic performance of railway vehicle were investigated based on ADMAS+MATLAB co-simulation. The results show that semi-active control can effectively improve the riding quality and safety of vehicle, but in some extent reduce the running stability of vehicle. With the increasing of time-delay, the dynamic performance is not worsened gradually but presents wavelike change, and be poorest in the range of 100~200 ms and 400~500 ms. The control effects are different under semi-active control and improved semi-active control when consider time delay or not, which prove the necessity of time delay analysis
  • LU Yang GU Zhong-quan LING Ai-min
    . 2011, 30(6): 58-61.
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    Aimed at the optimization of sensors’ numbers and locations in helicopter active control of structural response (ACSR), a set of optimization selection method is brought out. This method can effectively reduce numbers of sensors and find their relevant optimization locations, and at the same time the effect of vibration reduction is almost no loss. So the control scale of hardware can be reduced distinctly. The optimization problem is resolved with the genetic algorithm. Taking the Z11 light helicopter as an example, the effectiveness of the method is validated. The results show that using this optimization method, the best collocation scheme of sensors in ACSR can be achieved, with fewest sensors and good effect of vibration reduction in whole observed locations
  • Yang qing;Chen Gui-ming;Xue Dong-lin
    . 2011, 30(6): 62-66.
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    Envelope Fitting is the most important step of Empirical Mode Decomposition, but the end swings exist in the course of getting envelops of the data because of the uncertain extrema near the ends of the data. On the basis of the existed algorithms, Improved Method for Empirical Mode Decomposition Based on SSDA was proposed. The method find the best correlative sequence in the inner data and adopt the optimum sequence to proofread Envelope near the ends of the data. The simulation and experiment results show the method is effective in restraining end effect, furthermore the method is simple and easy to realize
  • PENG L.X
    . 2011, 30(6): 67-73.
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    In order to study the free vibration behavior of ribbed plates, a meshless method based on the moving-least square approximation is proposed. A ribbed plate is considered as a composite structure of a plate and ribs and the ribs are simulated as beams. The potential energy functional of the plate and the ribs are superposed by applying the displacement compatible conditions between them. The governing equation of the entire ribbed plate is then established from the potential energy functional of the entire structure. The meshless feature of the proposed method allows the ribs to be placed anywhere on the plate, and that remeshing is avoided when the stiffener positions change. A large amount of analysis burden is expected to be reduced if the proposed method is extended to the optimization design of ribbed plates. Some selected numerical examples are employed to compare the solutions from the proposed method with those given by ANSYS and exiting literatures, which can prove the validity of the proposed method
  • QU Xiu-xiu;CHEN Guo;QIAO Bao-dong
    . 2011, 30(6): 74-77.
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    An unbalance-rubbing-looseness coupling faults dynamic model for rotor is established. In the model, bearings were reduced to a linear spring, and the rotor shaft was considered as equisection Euler free beam model. While, the differential equations of the system were established, using modal truncation method. Then the vibration response of this rotor system was obtained by a fast- numerical intergral method. Clearly, the system response must be a mixture of multiple fault signals. In this paper blind source separation was used to achieve the separation of rotor fault signal. And ZT-3 multi-function rotor test device was experimentally. Simulation and experimental results show the correctness of the dynamic model in this paper, and the effectiveness of blind source separation approach in implementing the coupling fault isolation
  • An Mujin;Li Shunming;Miao Xiaodong;Liu Xiaowei;Du Jianjian;Fan Cuilian
    . 2011, 30(6): 78-82.
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    A subsystem-input/single-output system model is p.roposed,after that, the correlation between inputs is analyzed which in two subsystem-inputs/single-output system, and the input relationship after average process is given. On this basis, the correlation between inputs is derived which in multi correlated subsystem-inputs /single-output system and the model after average process is proposed. To address the source identification of inputs in multi correlated subsystem-inputs system, the value changes of correlated input matrix and the impact of the output in various relevant cases of input of subsystem-inputs are analyzed, and according to coherence analysis, the method to know the contribution of inputs to the output is obtained. Finally, the results of vibration test data are given, which is measured in a vertical plane of an automobile front and rear axes; the usefulness of the theoretical analysis is verified. Theoretical analysis and experiment are valuable reference for the same engineering problems
  • Qin Hu;Aihong Han
    . 2011, 30(6): 83-85.
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    In Hamiltonian space, the dispersion effect of the longitudinal wave in elastic bar
    is investigated by multi-symplectic method. The multi-symplectic formulations and several local
    conservation laws (including the multi-symplectic conservation law, the local energy conservation
    law and the local momentum conservation law) of the longitudinal wave equation that describes
    the dispersion effect in elastic bar are presented firstly. Then the multi-symplectic midpoint
    scheme is constructed to solve the multi-symplectic partial differential equations that are derived
    from the longitudinal wave equation. The numerical experiments are also reported finally, the
    results of which show that the multi-symplectic scheme can simulate the dispersion effect of the
    longitudinal wave in elastic bar well. In addition, the multi-symplectic scheme can satisfy the local
    conservation laws exactly, which implies that the multi-symplectic method is an efficient
    algorithm with excellent long-time numerical behaviors
  • GAO Guang-yun;;Li Ning;;HE jun-feng;GAO Meng
    . 2011, 30(6): 86-92.
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    Based on Biot’s wave propagation equations and boundary conditions, the Galerkin method is used to derive the u-w format finite element equation in the frequency domain by Fourier transform. The track and the attached sleepers are simplified as Euler beams resting on saturated half-space, the wave-number transform in the load moving direction is applied to reduce the three-dimensional (3D) dynamic problem to a two-dimensional (2D) problem. The displacement in frequency-wave number domain is obtained by solving the equations, and the 3D time-space domain displacement of the track and the ground is obtained from the fast Fournier transform. The model of 2.5D FEM is verified by calculation example. The paper has presented a track-ground interaction model. The dynamic response is given to evaluate the ground vibration induced by a moving train on the saturated ground. The effect of the soil parameters (such as permeability coefficient, porosity, soil skeleton density and shear wave velocity) on the attenuation of ground vibration are investigated in detail. The results show that acceleration amplitude and frequency decay quickly with the distance increasing from the track. It is also found that the permeability coefficient of soil, porosity, and shear wave velocity and soil skeleton density have great influence on the ground vibrations
  • Wu Guiying;Zhou Wen;Li Xin
    . 2011, 30(6): 93-96.
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    The anomalous response of spherical shell subjected to blast loading is studied in this paper. The spherical shell midpoint displacement-time curve and the final deformation pattern are got by numerical analyses. The effect of strain rate has been taken into account for the numerical analyses in this research., the parameters with the effect of the rise of arch and thickness to the anomalous response is analyzed. The results show that only explosives in particular distance from spherical shell, there exists anomalous response. When the explosive charge is constant, the region for anomalous response distance will decreased with rise of arch increase. The anomalous response will not appear when rises- span ratio over a certain value
  • ZHAO Jun;;ZHANG WEI-wei;MA Hong-wei
    . 2011, 30(6): 97-103.
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    The objective is to show the potential of the crack detection method based on Multi-resolution Analysis of Wavelet, which is depending on the response at a single point on a beam-like structure subject to concentrated moving loads. When moving along the structure ,the moving loads cause small distortions in the dynamic response of the beam-like structure at the crack locations .In general, these small distortions are difficult to detect visually. An ANSYS model of a cracked beam is established. The moving load is transient analyzed by shifting the point of the concentrated force. The response at mid-span of the beam-like structure is calculated and Wavelet Multi-resolution transformed. The crack on the beam-like structure can be found by position of peak of Wavelet Multi-Resolution Analysis, also the velocity and acceleration of the moving load. Furthermore, By the Principle of superposition, the solution obtained for a single moving load will be expanded to deal with a series of identical , equi-distant moving loads and opposite direction moving loads, by which the key parameter dominating the dynamic response of the beam-like structure can be identified. Finally, The effects of several cracks location and the best wavelet selection are discussed in detail. The proposed method is applicable for low velocity-movements while high velocity-movements are not recommended
  • XIONG Xue-yu;GAO Feng;LI Yang
    . 2011, 30(6): 104-108.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The formula of natural frequency about double broken line externally prestressed concrete beam is derived by Ayaho Miyamoto and improved and extended by Xue-Yu Xiong, etc., but the formula only applies to simple beam. taken the two-cross single (double) broken line externally prestressed concrete beam for example in this paper, the transverse vibration of externally prestressed concrete beam is researched by the method of overall analysis and Laplace transform. And the frequency equation and analytical expression of mode shape function are induced. The inducing process can be used in the natural frequency calculations of continuous beam. The error of measured results between calculation results is -2.8%. Its results agree well, which is helpful to guide the actual project
  • QIAO Lei;Tan Feng;YANG Qingshan
    . 2011, 30(6): 109-113.
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    Based on the Newmark method of dynamic analysis and the full Newton-Raphson Iteration method in nonlinear analysis, the nonlinear dynamic response analysis of membrane structure was then carried out by applying self-made program. Principal stress-strain criterion was used in determining the wrinkling areas. And the modified constitutive relationship method was adopted to consider the physical nonlinear caused by local wrinkle. The fluctuation and the nonlinear characteristic of vibration pattern in membrane structure are summarized through cases study. The dynamic response of membrane structure with Saddle shape is analyzed under the wind loading. Then the influence of membrane wrinkling on the dynamic response of membrane structure is discussed
  • Men Jinjie;Shi Qingxuan
    . 2011, 30(6): 114-119.
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    Considering the dynamical characteristic of structure under different earthquake hazard level, inelastic demand curves, namely, inter-story shear versus inter-story displacement curve are established by using mode spectrum method. And then taking into account the capacity curves of structures, a new method named inter-story capacity spectrum is put forward for the performance based seismic evaluation of vertically irregular frame structures. An example is presented to explain how to make use of the method and to demonstrate the applicability and utility of the proposed method. It is concluded that the new method can availably identify the soft story of the structure, estimate the displacement of stories under different earthquake hazard action and comparing to the result of capacity spectrum method, it is superior to capacity spectrum method
  • LIU Jun-zhong;XU Jin-yu;;LV Xiao-cong;ZHANG Lei;WANG Ze-dong
    . 2011, 30(6): 120-126.
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    In order to investigate rock’s dynamic compression mechanical capabilities, the amphibolites were subjected to impact with different confining pressure (0~6MPa) and strain rate (50~170s-1) by using the split Hopkinson pressure bar (SHPB) of 100mm diameter with confining pressure device and a thin red copper circular plate as pulse shaper, and the validity of SHPB experiment was analyzed. Experimental results show that the dynamic compressive strength and specific energy absorption of amphibolites are strain-rate dependent, the strain-rate effect can be expressed by linear approximations, the failure strain of rock increase with the strain-rate, and the relationship between dynamic strength increase factor and logarithm of strain-rate is approximately linear. The strengthening effect and toughening effect gets more prominent with the increase of confining pressure at same range of strain rate. Under confining pressure and dynamic loads, rock takes compress-shearing damage as the principal failure mode. In SHPB of the amphibolites are tested, the proportion is about 69.5 that loads time at nearly constant strain rate, which can fulfill the requests of stress equilibrium and load at nearly constant strain rate comparatively well. Demonstrate that the SHPB tests are effective and the results of amphibolites are reliable
  • CHENG Kang;SHEN Wei;CHEN Zhuang-ming;WU Jin-gui
    . 2011, 30(6): 127-129.
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    In this paper,the calculation formula of blasting vibration velocity was analyzed and generalized. Based on similarity theory, the formula to estimate the blasting vibration velocity had been derived. In the same terrain, geological conditions and explosives,the ground vibration velocity depends on Maximum amount of primary explosive(Q),distance from Explosion source to measuring point(R) and blasting action index(n). The calculation formula which was put forward by previous USSR scholar is useless unless standard throw blasting and concentrated cartridge. Finally, according to equivalence principle ,linear charge was assumed to be numerous equivalent concentrated charge,the equation of deep-hole blasting was derived,and it was successful in practical engineering applications
  • Zhang De-man;Li Shun-ming
    . 2011, 30(6): 130-133.
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    Traditional design method of micro-perforated panel structure is analyzed, some problems are discovered in the method, include some approximate formulas are not exact and some parameters can not be ascertained. These problems lead directly can’t design or got false parameters of micro-perforated panel structure. Complex formula in the design method was expanded to approximate formulas with Taylor formula, the approximate formulas was amended and it’s precision was improved. Calculate correlative expressions, discovers that the half-absorption band is in direct proportion to cavity depth of micro-perforated panel structure, Base on this relationship, ascertain the cavity depth by spatial restrict firstly, then compute other parameters, engineering-oriented design method of micro-perforated panel structure was proposed. For the noise of a fan, engineering-oriented design method of micro-perforated panel structure was used, got an absorption coefficient curve which can meet the requirements of design. Engineering application shows that engineering-oriented design method of micro-perforated panel structure is more convenient and more exac
  • LI Li;HU Zi-dong;NIE Sui-fei;Long Xiao-hong;
    . 2011, 30(6): 134-138.
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    Isolated bridge with LRB have large response under near-fault earthquake, the isolated bridge may perform poorly because of excessively large deformation of LRB, so it is necessary to study the optimum yield strength of LRB. For this purpose, non-linear time history analyses with different mechanical properties and bearing parameters of isolated bridge were performed. According to the result of LRB bridge’s response, the system response function with acceleration of beck, displacement of pier top, displacement of LRB and dimension of lead diameter is derivated. It is found that there is an optimal yield force of LRB which makes the bridge’s response to be relatively small, and the optimum yield strength of LRB is related with pier frequency
  • YAN Wu-zhu;LIU Jun;WEN Shi-feng;YUE Zhu-feng
    . 2011, 30(6): 139-142.
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    Three-dimensional FE model of the shot peening process was developed in the present study to investigate the effects of mechanical properties of the target and the impact velocity on energy transformation coefficient K as well as residual stress distribution. The FE results show that the target with a higher ratio of E/y and a lower strain hardening rate exhibits a high efficiency of shot peening. The increase of yield stress of the target can induce an increase of maximum residual compression stress, while a decreased depth of the residual stress filed can be observed. Both of the increases of strain hardening rate and impact velocity can induce increases of maximum residual compression stress as well as depth of residual compression stress field, meanwhile, it could also cause the surface residual compression stress to decrease. The result of the present study provides a theoretical foundation for the selection of target material in view of energy transformation
  • Cai Fengchun;Zang Fenggang;Ye Xianhui;Huang Qian
    . 2011, 30(6): 143-146.
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    Based on absolute nodal coordinate formulation(ANCF), a new pipe finite element conveying fluid is presented. An extended version of Lagrange’s equations which are written for the system containing non-material volumes by Irschik, are used to obtain the equations of the pipe finite element conveying fluid. The pipe is modeled as Bernoulli Euler beam theory and the fully nonlinear Green stain tensor and second Piola Kirchhoff stress tensor are used. The influences of the lateral contraction resulted from axial elongation of the pipe on the fluid velocity are taken into account and the assumption that the cantilevered pipe is inextensible is not assumed. Consequently, the proposed equations are better than the existed equation in which order-of-magnitude consideration have been performed during derivation. The numerical results of the pipes with different boundary conditions are depicted and compared with the existed works. The proposed methods provided accurate results
  • LI Xiao-ni;XIANG Yu;HUANG Yu-ying;YUAN Li-yun;LU Jing;
    . 2011, 30(6): 147-152.
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    The commonly used model for dynamics analysis of the shell with active constrained layer damping (ACLD) is a simply coupled electro-mechanical model (SCEM). In this model the electric field is assumed to be negligible in the in-plane directions of piezoelectric layer and to be constant throughout the thickness in the normal direction. The reason for ineffectiveness of SCEM is firstly analyzed theoretically. A fully coupled electro-mechanical model(FCEM) is further developed. Then a first-order differential matrix equation for FCFM of thin ACLD circular cylindrical shell is derived. A high precision and high efficiency transfer matrix method based on the extended homogeneous capacity precision integration approach is employed to solve the matrix equation. Compared with the classical 3D method, the proposed method can greatly simplify computation, and be applied to analyze the vibration control problems of thin circular cylindrical shell partially treated with ACLD under arbitrary boundary conditions as well. Numerical results are given to compare with two kinds of models(SCEM and FCEM) at a wider frequency range. Both models agree exactly in the low-frequency range, whereas differ significantly in the high-frequency range. This confirms sufficiently SCME is only applicable to low-frequency vibration problems while FCEM can be used at a wider frequency range
  • Zhang Xiaoguang;Hu Yuda;Ren Xingli
    . 2011, 30(6): 153-157.
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    In this paper, a ceramic/metal functionally graded rectangular plate was considered. Based on the Stress-strain relationship and nonlinear geometric equations of inhomogeneous materials, the nonlinear partial differential equations of functionally graded plate subjected to transverse harmonic excitation force were derived by using principle of virtual work. For the clamped rectangular plate, by assuming the displacement functions,the Duffing nonlinear vibration equation was obtained by using Galerkin method. Using the modified multiscale method, the amplitude-frequency response equation of the Steady-state movement was obtained. Based on Lyapunov stable theory, the stability analysis of the resonance solution was obtained. By some examples, the amplitude-detuning parameter curves and phase trajectories in moving phase plane were plotted under different situations. The effects of different parameters were discussed
  • LI Bin;ZHANG Gui-tian;LI Feng;HUANG Jin-ping
    . 2011, 30(6): 158-161.
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    Based on the operating characteristics of the liquid rocket engine turbopump, two novel modal balancing methods have been presented by utilizing the run-up unbalance response data. In method I, the first two modal unbalance is expressed with the corresponding modal unbalance angle and the equivalent modal unbalance magnitudes respectively. And in each of the first two resonant regions, the modal unbalance angle can be identified by using the accelerating response data. After that, according to the modal knowledge, a pair of appropriate trial weights are determined and placed on the rotor, and the correction masses are calculated by using the linear relationship between the modal trial weights and the corresponding modal response increment. In method II, the modal ratio among measurement points(MRMP coefficient) is firstly introduced. Then, through 4 run-up processes, the three-circle balancing method is used to correct the first and second modal unbalances respectively. The proposed methods are validated by two model experiments
  • Guohua Liu;Zhigen Wu
    . 2011, 30(6): 162-171.
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    A general summary and review of state-of-the-art of vibration-based RC structural damage detection is firstly presented. Various disadvantages of damage detection methods are abstracted, such as low sensitivity, inability of non-linear analysis, limitation of application scope, incomplete validation methods and unreasonable numerical-simulation. Then, the thought of dissipative structure and information entropy theory are introduced into the study of concrete damage detection based on the analysis of feasibility on the theory and technology and through establishing the information entropy index, the disorder extent of system’s damage is presented. Furthermore, it is showing a great potential in following areas: optimal arrangement of sensor location and identification of damage location and extent, as well as treatment of damage. Therefore, information entropy theory is probably a promising method for partly improving damage identification technology, as well as supporting scientific evidence and technical support in construction and operation of Structural Health Monitoring system
  • WANG Jian-Jun;HAN Zhi-Jun;LU Guo-Yun;ZHANG Shan-Yuan
    . 2011, 30(6): 172-175.
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    Chaotic behavior of viscoelastic cylindrical shell under axial pressure and transverse periodic excitation was investigated on the basis of Donnell-Kármán theory of thin shell with large deflection and Kelvin–Voigt constitutive relation.The governing equations for the deflection and stress function are derived,and the governing equations of viscoelastic cylindrical shell are changed into the square-order and cubic nonlinear differential dynamic system by Galerkin method.The critical conditions of horseshoe-type chaos are obtained by using Melnikov function.The influences of axial pressures and viscous damper coefficients on chaotic motion of system are analysed by numerical calculation.The motion behaviors of system are described through the bifurcation diagrams, the time-history curve, phase portrait and Poincaré map.The results are given as follows.When the relation between axial pressure and material parameters of cylindrical shell is given,the system can occur horseshoe-type chaos.The chaotic motive region will decrease with increase of axial pressure and the ratio of viscous damper coefficients to external damper coefficients.The system of viscoelastic cylindrical shell under axial pressure and transverse periodic excitation may occur steady motion and chaotic motion
  • JIANG Wan-lu;NIU Hui-feng;LIU Si-yuan
    . 2011, 30(6): 176-180.
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    A composite fault diagnosis approach is proposed, combining the real-valued negative selection algorithm and the support vector machine, after researching the shortcoming about the conventional classification algorithm in the fault diagnosis. In the new method, the RNS algorithm is used to generate the detector (non-self) as the unknown fault samples, which are used as input to SVM algorithm for training purpose. The difficult problem, lacking the training samples, is solved using the new method on the conventional classification algorithm. When the axial piston pump have fault because vibration signal generated from slipper/swashplate impact is modulated by high frequency resonance signal, the modulation signal has to be demodulated using the wavelet cluster envelope demodulation method. Where after, the envelope signal is decomposed using wavelet packet and signal eigenvectors are extracted. At last, the loose slipper and the wearing valve plate fault samples of axial piston pump are tested using the composite approach. The classification right rate of this method reaches to 90%, so the composite approach is valid for the fault diagnosis.
  • Feng Zhihong;;Huo rui;
    . 2011, 30(6): 181-184.
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    Based on the closed-up control strategy of acceleration time-delay feedback, a dynamics model of a piezoelectric-coupling flexible cantilever beam is set up. We obtain the stability condition and analysis method for the system by condcuting the modal analysis and free vibration trivial solutions analysis. We also consider the condition of piezoelectric coupling and time delay, then present a specific example to proof the previous stability condition and analysis. The example shows that ignoring time-delay unreasonably can cause the system respond divergently, while a reasonable amount of time-delay can also be used to improve the efficiency of vibration control
  • LIU Jun-long;DAI Jing-hui;ZHANG Chun-wei;LI Lu-yu;OU Jin-ping;HAO Lei
    . 2011, 30(6): 185-191.
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    Time delay is a more general phenomenon in the structure vibration control. Time delay may not only degrade the performance of the control system but also induce instability to the system. In the view of this practical problem, the objectives of the present study are divided into three parts. The first part presents the stability analysis of a SDOF system with time delayed feedback. The purpose is to find a analytic solution for the maximum allowable time delay. This value can be used as a criterion for deciding the need of time delay compensation as significant degradation in the control performance occurs only when the time delay in the system is close to this value. The second part presents a technique for compensation of time delay-active increasing time delay compensation when actual time delays larger than the maximum allowable time delay. At last, the experimental study of based on displacement feedback active increasing time delays compensation is conducted. The numerical simulation and experimental results demonstrated that the presented time delay compensation control algorithm is effective in reducing the maximum response of the systems and the system stability can be guaranteed
  • YU Tian-lai;;SHAN Si-di;LEI Junqing;ZHANG Li-yuan
    . 2011, 30(6): 192-195.
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    Adopting the explicit dynamical analysis software package LS-DYNA, the calculation model of collision effect between river ice and pier is studied. The simplified constitutive relation of river ice is proposed, and the finite element analysis model of contact-impact effect of ricer ice on pier is established. Effects of contact type and arithmetic, mesh density of ice sheet, mesh density of pier in contact area are discussed, and the calculation results on impact force are compared with the measured ones. The conclusions can be drawn as follow: It is feasible that solid164 element is adopted for floating ice elements and the pier elements in contact area. Linear elastic material model as well as failure criteria of the maximum flexural-tensile stress can be apt for river ice impact analysis. The automatic surface to surface contact type and the symmetrical penalty function algorithms are appropriate for the calculation model of impact force of river ice. The collision force will be largely influenced by element size of ice drifting located at a distance near the contact area and the mesh density of the pier in contact area have more influence on the collision force, so it is important to rationally choose the element size. A new method for the collision force analysis between river ice and pier has been provided and it is very important in theory and practice to improve calculation method of collision force between river ice and pier
  • Tian He;Yizhou Lin;PuGang Gao;Yongjun Shen
    . 2011, 30(6): 196-201.
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    As a new kind of self-adaptation time-frequency analysis approach, Local mean decomposition (LMD) is began to study in the field of fault diagnosis. In this paper, the simulation signal is used to illustrate the effectiveness of the proposed method for processing multi-component modulated signal which expresses the characteristics of fault signals of gear. Then, the LMD method was applied to diagnose gear faults including wear, fracture and spalling by extracting the fault characteristics from the test signals. The analysis results demonstrate that LMD can diagnose gear faults and improve the accuracy of gear fault diagnosis, compared with the traditional demodulation approach
  • Wang YU;Fan HongHai;Zhang Li Ping;Yang Hang;Feng GuangQing
    . 2011, 30(6): 202-207.
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    The current study of tubing string used in high pressure gas well did not take into account the influence of transient flow induced vibration, but tubing string and conveying fluid actually interact through mutual boundary, and this paper considered the influence of flow induced vibrations on those gas-filled tubing system. The fluid and structure coupled numerical model was presented, the model was decoupled by the method of characteristics. The response of liquid pressure, pipe stress and pipe motion distance to transient excitation of gas unsteady flow were predicted, based on data of one specific high pressure gas well. The results show that: Alternating dynamic stress, reciprocating motion caused by fluid-structure interaction would aggravate completion string’s condition by fatigue damage and wear damage
  • Xia Qi-qiang;Chen Zhi-jian;Li Ke-ji
    . 2011, 30(6): 208-212.
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    Aiming at ship vibration brought about by wet-deck bottom slamming when it is sailing on waves ,a study on dynamic response of SWATH under slamming load has been done. Slamming load that varied with space and time is obtained by applying relative motion between ship and waves, then the numerical calculation of dynamic response is performed. The distribution law of deformation and stress is analyzed for discussing the characteristic of load impacting on the structure. Compared with the static slamming response, an effective strength design criterion of wet-deck is discussed, which can be used as reference in the structure design of SWATH
  • SUN Fangjin;YIN Zhixiang;GU Ming
    . 2011, 30(6): 213-217.
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    Implementation and application of strongly coupled program in fluid-structure interaction analysis in wind-induced vibration of membrane structures are studied. Based on simultaneous strongly coupled equations, program implementation process of calculating fluid-structure interaction in wind-induced vibration of membrane structures using Fortran, and the numerical methods needed in the program are both presented. Corresponding implementation process is given when important procedures in the calculation program are analyzed. Finally, the program is applied in the calculation of fluid-structure interaction in wind-induced vibration of a typical membrane structure. Wind pressure coefficients are computed when considering and not considering interaction effects under different wind azimuths, respectively. The results compare well with those obtained from the existing wind tunnel test. Meanwhile, wind-induced responses and flow distribution around the membrane structure are computed as well. It is shown that the presented strongly coupled method and its program are valid and accurate in computing fluid-structure interaction analysis in wind-induced vibration of membrane structures
  • LOU Jingjun;TANG Simi;ZHU Shijian;ZHAO Cunsheng
    . 2011, 30(6): 218-222.
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    The essentially nonlinear absorber is improved considering engineering implementation. The dynamical model of an essentially nonlinear absorber with weak linear stiffness coupled with a linear oscillator is studied, which is under periodic excitation. The differential equations of amplitude-frequency of the system is obtained based on harmonic balance method. The relationship of linear stiffness, generalized excitation and performance of absorption over broad range frequency is studied. The results show that the weak linear stiffness is in favor of amplitude attenuation over broad frequence range. The maximum and minimum of generalized excitation that contains the information about force and nonlinear stiffness is obtained, which is significant for engineering application. Comparing the performance of improved essentially absorber with that of linear absorber under muti-frequency excitation, the result shows the excellent performance over broad range frequence
  • ZHAO Hui-min;MEI Jian-min;XIAO Yun-kui;Qiao Long;Chen Xiang-long
    . 2011, 30(6): 223-228.
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    The unstable vibration signal of diesel engine crankshaft bearing is analyzed by the method of bispectrum, according to the symmetry of bispectrum the area below the diagonal in the first quadrant is ploted as many identical regions in which the bispectrum average breadth value is calculated as the feature of the analytic object, and the Variable Precision Rough Set Theory (VPRST) is used to extract the feature parameters that correlate with the fault parts tightly. The analytic results show that the noise embeded in the unstable vibration signal of crankshaft bearing can be eliminated by bispectrum, the key factors relevant to the analytic object can be mined by VPRST, and the fault feature can be extracted automatically by bispectrum combined with VPRST
  • WANG Wenlong;Hu Qun’ai;LIU Huawei;Zhang Wei
    . 2011, 30(6): 229-233.
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    Using the mathematical model of longitudinal vibration of drill string, the authors analyzed the characteristics of the axial stress amplitude distribution curve and the maximum axial stress amplitude-frequency curve in the drill string and the impact of drilling fluid viscosity, bit displacement, shock absorber’s installation position on the maximum axial stress amplitude in the drill pipe. Analysis shows that: the axial stress amplitude along the drill string appears in waveforms and the point of the maximum axial stress amplitude is at the bottom of drill string or in drill pipe; the rotary speed-dependent curve of the maximum axial stress amplitude in drill pipe appears at least one pit, and the speed between the margins of the pits should be chose when drilling a well; the variation trend of the maximum axial stress amplitude in drill pipe with rotary speed does not quite fit in with that of the axial stress amplitude at the bottom of drill string with rotary speed, and the former but not the latter should be the target for resonance judging and rotary speed optimizing; the maximum axial stress amplitude in drill pipe varies roughly directly with the bit displacement; the higher viscosity of drilling fluid is, the smaller the maximum axial stress amplitude in drill pipe is; a shock absorber can change the natural frequency of a drill string, and the shock absorber should be fixed close to the bit when drilling with low rotary speed and kept a certain distance with the bit when drilling with high rotary speed to protect the drilling tools more effectively; optimizing make-up of a drill string and rotary speed can prevent drilling tool failure effectively
  • Zhou Jianxing;Liu Geng;Ma Shangjun
    . 2011, 30(6): 234-238.
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    The dynamic response of the gear box is researched in consideration of the time-varying mesh stiffness and gear errors. The dynamic response model is set up and solved by using mode superposition method. Then the time history of node displacement of the gear box is obtained, and the effect of the excitation of frequency doubling of mesh frequency on dynamic response of the gear box is researched. Structural-acoustic coupling noise response analysis is done. The improving plan of the gear box is propound based on contribution of the gear box panels to noise radiation. The study provides useful theoretical guideline to the design of the gear box
  • LV Xiao-hong ZHU Xi-feng
    . 2011, 30(6): 239-242.
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    An impact-progressive mechanical system is considered.the type of periodic-impact motion is analyzed and the condition for judgement of progressive motion of system is put forward.the dynamic behavior and The influence of system parameters on progression rate are investigated by numerical simulations. The results indicated that grazing bifurcation point is the dividing line between two very different motion of the system, a grazing contact instability of motion occurs, one impact in the motion period vanishes and the motion transits into motion, or falls into long periodic or chaotic motion immediately;the maximum impact velocity and the largest progression of the system are found to occur for period-1 single-impact motion with the peak-impact velocity
  • WANG Jin-li;LI Yu-long;HU Hai-tao;XUE Pu;LIU Xiao-dong;ZENG Ning;LIU Yuan-yong
    . 2011, 30(6): 243-247.
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    The effect of load frequency on the vibration fatigue behavior of cantilever beam was studied. First, three kinds of sine loads with different frequencies were loaded on three groups of cantilever beams. The initial stress on each specimen is the same. The variations of stress vs cycle for each specimen were measured. Then, base on the stress history from experiment, the fatigue damage of cantilever beam was calculated, and the effect of different load frequencies on vibration fatigue behavior of the same cantilever beam had been investigated. Finally, the calculation results was compared with the results of the frequency decrease that measured by experiment. The results show: the load frequencies have a large effect on vibration fatigue life, the calculation results was agreed well with the experiment results
  • Zhu Nanhai;Ye Jihong
    . 2011, 30(6): 248-255.
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    Structures must be robust so that they will be steadily kept to work under the influence of internal uncertainty factors and external environmental disturbance. At present, there is no accepted theory or measure of robustness. Vulnerability is the opposite of robustness, thus, a measure of vulnerability can help to gain an insight into the lack of robustness. This concept has been developed into a theory of structural vulnerability by Blockley. The purpose of this theory is to identify the weakness of the structure by analyzing the influence of different damages to the structural form. The structure is divided into different level structural clusters according to the connectivity of structural nodes and the structural hierarchical model is formed to find the weak elements of the structure. Thus, the weakness of the structure is identified. In this paper, the vulnerability theory is used to analyze the failure scenarios of single layer-latticed domes. A computer program has been written to perform vulnerability analysis and the accuracy of this analysis has been verified with an example that exists in the literature. Numerical analysis is carried out for the failure scenarios analysis of a 24-member space frame dome. It is shown that the failure scenarios of long-span single layer-latticed dome can be obtained by the structural vulnerability analysis. The failure scenario of the 24-member space frame dome subjected to earthquake motion is compared with the result of vulnerability analysis indicating an effective way to know the weakness of the structure based on the theory. The damage demand and the vulnerability index are two variables in the evaluation index of failure scenarios and they are the measures of the effort required to damage a member and the “disproportionateness” of the consequences to the damage respectively
  • Chen Xin;Li Ai-qun;;Zuo Xiao-bao;Ding You-liang;
    . 2011, 30(6): 256-260.
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    With regard to the application of shape memory alloy (SMA) in the isolation field, investigation of isolation devices based on the unique performance of the SMA is one of the key points. In order to study the SMA isolation effects, a super-elastic SMA isolator was designed using the SMA’s super-elastic effect in this paper. Its theoretical calculation model was deduced from its structural construction and working principle. A finite element model was further established, the results of which was to be compared with the results of the theoretical model. Then the main parameters of the isolator such as the length of the SMA rods, radius of the SMA rods, the angles between SMA rods and horizontal direction were disscussed, and its effects on SMA isolators’ mechanical properties were numerically analyzed. Results indicated that the SMA isolator shows a nonlinear hysteresis behavior, and its properties can be improved in some degree by adjusting parameters reasonably
  • LU Guan;LIANG Da-kai;ZENG Jie;HU Xing-liu
    . 2011, 30(6): 261-264.
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    Damages which can not be detected from surface of composite material smart structure are often brought by low velocity impacts(LVI). By using this characteristic that the center wave-lengths of Bragg grating sensors in optic fiber composite material structure under LVIs are determined by stress, Bragg grating sensors were adopted for detecting the positions of LVIs which might cause damage on the structure in constant temperature. By analyzing the frequency spectrums of LVI signals captured by optic fiber grating demodulator, the frequency spectrum peak value threshold for distinguishing energy classes can be figured out after calculating frequency spectrum peak values of all energy classes. The experiment has proved that Bragg grating sensors can be used for monitoring impacts and detecting the grade energy of LVIs on composite material structure
  • LIU Wei;LIU Yongshou;JIANG zhifeng;YUE Zhufeng
    . 2011, 30(6): 265-268.
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    The pressure pulsations inner the hydraulic power pipelines were treaded as a stationary random process approximately. Based on frequency-responses results, the mean square deviation of terminal pressure pulsations was calculated under the white noise excitation of pumping source. The first-passage failure criterion and fatigue damage accumulation failure criterion were adopted to analyze the dynamic pressure reliability respectively, and the influence of amplitude pulsations of pumping source for the reliability of pipelines was obtained. The results indicated that the traditional estimation method of below 10% of rated pressure did not meet the security specification of the hydraulic power unit. The paper proposed the evaluation method for random pressure pulsation based on reliability, which provides a new approach for the dynamics assessment and design of hydraulic pipelines
  • LIU Fang;MENG Guang;WANG Wen
    . 2011, 30(6): 269-271.
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    Non-contact laser holography exciting approach was adopted to conduct experimental modal analysis of the test vehicle (printed circuit board assembly) and understand its dynamic characteristics. Then its first-order natural frequency was used as the center frequency, and three different acceleration power spectral density (PSD) amplitudes of narrow-band random vibration fatigue tests were respectively carried out. Subsequently failed BGA solder joints were cross-sectioned and metallurgical analysis was done to investigate the failure mechanisms of BGA lead-free solder joints under random vibration loading. The results show that the failure mechanisms of BGA lead-free solder joint vary as the PSD amplitude increases. Solder joint failure locations are changed from the solder bump body of the PCB side to the solder ball neck, finally to the Ni / intermetallic compound (IMC) interface of the package side. The corresponding failure modes are also converted from fatigue fracture to brittle fracture
  • ZHAO Da-hai;;LI Hong-nan
    . 2011, 30(6): 272-272.
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    Based on the performance experiment of piezoelectric friction damper, a series of shake table tests were carried out using a piezoelectric friction damper under various earthquakes. The simulation model of the structure with piezoelectric friction damper was established by using MATLAB/Simulink software platform and software/hardware resources of dSPACE (digital Signal Processing and Control Engineering). The shake table experiments were implemented by using rapid control prototype technology. The seismic efficiencies of the designed piezoelectric friction damper and proposed velocity-input fuzzy control strategy were both evaluated. Experimental results indicate that the designed piezoelectric friction damper can adjust its damping force according to structure responses by proposed control method in real-time and effectively suppress the structural responses under earthquake excitations