25 December 2014, Volume 33 Issue 24
    

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  • Jun Chen;Ting Ye;Yixin Peng;
    . 2014, 33(24): 1-7.
    Abstract ( 350 ) Download PDF ( 487 )   Knowledge map   Save
    This is paper investigates acceleration response spectrum of long span floor under human walking loads. Three hundred and twenty experimental measurements of walking load curves have been applied to a long span floor to obtain the 10-second root-mean-square acceleration response spectrum, based on which a simplified mathematical model has been suggested for frequency range of 3-20Hz. The effect of several computational parameters including higher vibration modes, boundary condition, floor span, stride length and damping ratio on the spectrum has been studied and corresponding correction measure has been suggested. Detailed implementation procedure of the suggested response spectrum has been presented. The feasibility and applicability of the suggested spectrum has been validated by comparing the prediction results with field measurements of an existing long span floor.
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  • ZHANG Ming;FENG Kun;JIANG Zhi-nong
    . 2014, 33(24): 8-14.
    Abstract ( 492 ) Download PDF ( 422 )   Knowledge map   Save
    Because that the alarm mode of current online monitoring system is hard to warn early mechanical failure, an early warning methodology is proposed in this paper. Based on statistical analysis of mass data in online monitoring system, taking advantage of dynamic self learning threshold algorithm calculates warning threshold, and using ℓ1 trend filtering technology obtains filtered trend which has eliminated random errors. With dynamic self-learning threshold instead of general alarm threshold on monitoring system, early warning can be acquired by comparing the self-learning warning threshold and filtered trend. It can be shown form the project cases that early warning of mechanical failure can be achieved by the proposed method, which plays an important role in preventing occurrence of mechanical failure.
  • CHEN Hong-kai;;YANG Ming;TANG Hong-mei;HE Xiao-ying;WANG Zhi
    . 2014, 33(24): 15-18.
    Abstract ( 282 ) Download PDF ( )   Knowledge map   Save
    As one of emergency geological disasters, perilous rock will release abruptly energy at rupture. The energy pass into perilous rock blocks near the rupture position in excitation wave, and decreases stability of perilous rocks near the rupture position. By the de-noising processing in wavelet methods to excitation signals gathered in model test of falling perilous rock rupture in laboratory, this paper takes the signals during 10 ms duration from the 25 ms to 35 ms in model test as the essential data to analyze local and minutiae characteristics of excitation signals at perilous rock rupture. Under the experimental conditions, analysis results show that, local characteristics of excitation signals at perilous rock rupture has certain periodicity, i.e., 8 or 9 excitation peaks with 1.0~1.4 ms periodicity in horizontal direction, while 3 or 4 excitation peaks with 2.2~3.0 ms periodicity in vertical direction. The distance between measuring point and the rupture position significantly impacts the amplitude of excitation peaks, the closer the distance, the bigger the amplitude. Furthermore, the integrity of interface between two perilous rock blocks has a significant impact on frequency and amplitude of excitation peaks, for example, when the excitation signal pass into incomplete interface the peaks of excitation signal are lagged a little, about 10ms under the experiment. Specially, almost all local and minutiae characteristics of excitation signals at perilous rock rupture can be embodied by minutiae coefficient, and the main frequency of excitation signals appear in minutiae characteristics from d3 to d7. Achievements in the paper are valuable in implementation of similar model test of excitation effect at perilous rock rupture.
  • LI Chun-guang;CHEN Zhen-qing;;HAN Yang
    . 2014, 33(24): 19-25.
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    A long-span suspension bridge with streamlined box girder with cantilever walk slab is taken as an engineering example. Based on the series of section model wind tunnel tests, both the vortex induced vibration(VIV) performance of main girder and the mitigation aerodynamic measures are investigated. The influence of attack angles on VIV performance are investigated as well as the effect of guide vane. The aerodynamic measures whose control efficiencies are tested, including moving the maintenance rails,installing guide vanes with different forms.The research results indicate that VIV performance is sensitive to wind attack angles. The VIV performance gradually get worse with the increasing of wind attack angle, and the amplitude of VIV reduce nonlinearly with the increase of structure damp. The maintenance rails are the most sensitive element for the VIV performance of this type of beam section. The movement of maintenance rails towards central of undersurface can improve the VIV performance effectively. The use of the guide vane of maintenance rails can further mitigate the VIV amplitudes, and the wider the guide vane brings better mitigation efficiency. Furthermore, the guide vane attached to the corner of inclined web and bottom plate are not suitable to improve the VIV performance.
    measures
  • ZHANG Xiao-liang;NIE Jia-mei;CHEN Long
    . 2014, 33(24): 26-31.
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    Based on vibration state in transition from the mass to the inerter, a passive realization method of ideal skyhook damping was presented. According to such a method, a passive groundhook-damping suspension was designed. After the simscape model of the inerter was founded, the full-car simscape model was built by using the network approach of physical topology. By comparing the performances of conventional passive, ideal and passive groundhook-damping suspensions, the proposed realization method was verified. The results show that the proposed suspension can suppress wheel resonance, reduce RMS values of dynamic tire load by 30% or greater, and significantly improves ride safety. The results also indicate the performances of the ideal and passive groundhook-damping suspensions are basically the same.

  • WANG Cheng LIU Hui XIANG Changle
    . 2014, 33(24): 32-38.
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    The influence of rotational speed fluctuation and the phase shift between forward and backward contact on mesh point position are analyzed, combined with boundary conditions of single tooth meshing, double tooth meshing, profile modification and analytical method of calculating mesh stiffness, the nonlinear mesh stiffness model is established which can achieve real-time feedback with nonlinear model of spur gears and produce more precise mathematical model of gear meshing process. A two-degree-of-freedom nonlinear model of spur gear pair with input torque fluctuation is established by taking the backlash and nonlinear mesh stiffness into consideration. Based on the nonlinear dynamic model, the influence of profile modification on dynamic behavior of spur gear pair is studied. The resluts show that the amount of profile modification significantly affect the dynamic characteristics of spur gear pair, and existing an optimal amount of profile modification to make the dynamic load factor reach to a minimum. When the amount of profile modification exceeds a certain critical value, single-side-impact or double-side-impact occur and gear dynamic loads significantly increase. Increasing the length of profile modification can reduce the minimum value of dynamic load factor under certain input torque. The maximum amount of profile modification should be the combined tooth deflection evaluated at the highest point of single tooth contact under the minimum input torque.

  • LI Rui-ping;ZHOU Ning;LV Qing-song ZHANG;ZHANG Wei-hua;MEI Gui-ming
    . 2014, 33(24): 39-44.
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    In order to study the influence of cross wind on pantograph-catenary dynamic behaviors, the stochastic wind field of pantograph-catenary system was established to obtain the wind speed time series on the pantograph and catenary based on the linear filtering method of AR model and the Davenport power spectrum. The aerodynamic model of pantograph/high-speed train was built and the computational fluid dynamics method was used to calculate the aerodynamic uplift forces of the pantograph for different cross wind speeds while the train running at a speed of 300 km/h, then the time series of aerodynamic uplift force was obtained under the average wind speed of 20m/s. The three dimensional pantograph-catenary coupled dynamic model was used to analyze the influence rule of the cross wind on pantograph-catenary dynamic systematically. The results show that the aerodynamic uplift force of the pantograph is increased while it is acted by cross wind and is directly proportional to the square of the cross wind speed. Moreover, the increase and fluctuation of the pantograph aerodynamic uplift force induced by the cross wind make the mean and standard deviation of the contact force increased. The contact status between the collector strip and the contact wire is changed due to the wind-induced vibration of the catenary which increases the fluctuation range of the contact force. Therefore, while the train running in the cross wind environment, not only the contact force is increased and will intensify the abrasion of the collector strip and the contact wire, but also the current collection quality is deteriorated because of the minimum value of the contact force decreased while the standard deviation increased.


  • YAN Jian;PENG You-duo;LONG Dong-ping;HE Yi;MA Jun;
    . 2014, 33(24): 45-53.
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    Based on Fluent 6.3 software, the Reynolds mean Navier-Stokes equations were selected to simulate 3D steady wind field of complex dish frame. Computational domain model which conform to unrestraint flow field and grid independent solutions was built by applying multi-angle wind modeling methods with inner domain subarea on cylindrical. And, 45 group results of total wind load, wind pressure distribution and flow around characteristic were acquired by simulation. Change regulations of wind load with different working condition were analyzed, and, the reasonableness of simulation results were verified by qualitative comparative analysis between load curve and parabolic radar antenna wind tunnel test. The ratio of condenser mirror load on total wind load of frame was explored by adopting dimensionless method. Condenser shape factor distribution and extremes of each subarea load were acquired under typical working conditions. And, load generating mechanism was revealed by further analysis of the flow around characteristics, which provide a load basis on wind-resistant design of the whole structure of dish photo-thermal solar energy.

  • WANG Wen-lian;ZHANG Jin-wen ZHAO Chen-yang ZHANG Zhi-jie;
    . 2014, 33(24): 54-57.
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    During the pressure signal measurement of explosion field, the interference signal of experiment field causes easily the false triggering resulting in the failed measurement. A measurement technology based on mass storage and less read is proposed for the distributed storage measurement system. Long signal acquisition is achieved by mass storage of measurement data, to avoid the failure due to false triggering. On the other hand, small valid data segment is extracted by signal identification, which improves the efficiency of data transmission and data processing. A measurement system based on mass storage and less read technology is designed and implemented for ground pressure of explosion field, and the measurement node is characterized by sampling rate of 1Msps, data storage of 128Gb, valid data segment of 512kW, and Wi-Fi wireless network coverage.

  • DANG Faning;LEI Guangyu;DING Weihua;LI Qian
    . 2014, 33(24): 58-63.
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    Concrete material under the dynamic load has different characteristics with itself under the static load. This paper study on the CT test,the plain concrete specimen under dynamic loading as the object of study. Analysis the concrete meso structure change effect on the dynamic mechanical properties such as strength, deformation and damage morphology under the sine wave dynamic pressure and dynamic tensile load. Through the research of CT difference image, the moving crack in concrete compressive loads is developed rapidly, short failure process, failure crack is much, damage area is large, etc; Through CT number density segmentation image research, the dynamic tensile loading concrete micro crack suddenly merged to form a main crack through the specimen, the specimen breaks suddenly. By research the CT number change law in the process of loading, the concrete density decrease after a first increases under the dynamic pressure load, specimens experienced compaction, expansion, crack coalescence until finally the failure process, and the specimen under the dynamic tensile load density continuously reduced until fracture, early without load compaction. Different stress state of concrete under dynamic pressure, dynamic, lead to the damage degree is different, the formation of the crack area is different, the total energy required is different also, eventually led to the determination of the strength of the different, different stress state is the root cause of the dynamic pressure, the difference of dynamic tensile strength.

  • ZHU Yuan-wu;ZHENG Rong-yue;LIU Gan-bin;WEI Wei;DENG Yue-bao
    . 2014, 33(24): 64-70.
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    An in-situ simulation explosion test is carried out at a site with Ningbo marine silt soft soil. The history and evolution laws of excess pore water pressure, shock pressure and temperature on the conditions of different explosive quantity and buried depth are obtained. The test results reveal the existence of coupling phenomena of seepage, stress and temperature. It is also shown that the peak of excess pore water pressure increases with the increase of explosive quantity and the dissipation of pore pressure is relatively quick in early minutes after the explosion and then it decreases. A dividing pressure which means a value from shock wave to elastic wave is determined and it found that the dividing pressure is related to the soils’ character,especially dependent on the air content. The explosion temperature has a certain conduction time and rise time in soft soil, and it rises more slowly than that in the air. Besides, relevant theories are used to compute the pressure and temperature.The calculated results are compared with the measured results. The conclusions of this paper provide a reference for the design of underground civil air defense engineering and ground compaction engineering in coastal soft soil area.


  • HAO Yu XU Deyuan YANG Qiongliang LIU Jinfan LIU Zhengyong TANG Guoan
    . 2014, 33(24): 71-76.
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    For the problem of structure-propulsion coupled longitudinal vibration of a liquid-propulsion launch vehicle, dynamic model of each component of the propulsion system is established in time domain. Governing equation of the coupled system is deduced in the form of second-order linear differential equation. With this method, all eigenvalues of the coupled system can be obtained quickly, and their sensitivities with respect to physical parameters of the accumulator and pump can be calculated easily, providing technique method for optimization of liquid rockets.
  • Chen Jiang-pan;Cheng Wei;Xia Ming-yi
    . 2014, 33(24): 77-81.
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    In order to measure the micro-vibration of SADA (Solar Array Drive Assembly) in low and ultra-low frequency zone caused by electromechanical coupling, a six-component testing platform based on the strain-resistance effect is invented, whose response characteristic in low frequency zone is outstanding and installation interface is flexible. The working principle and dynamic calibration method of this platform is shown in detail. In order to assess the performance of this testing platform, linearity examination, natural frequency testing and dynamic testing error examination are done. The results show that: linearity error of the eight force sensors is within ±3.4% under the action of external force within 100N; there is no natural frequency within 100Hz, so that the micro-vibration signal would not be modulated; in frequency domain (0-100Hz), dynamic testing error of the six-component is within ±9.6%; in frequency domain (0-100Hz), testing resolutions of the three forces and three moments can reach 0.0lN and 0.001N.m respectively.
  • WU Jing ZHANG Wei-wei MA Hong-wei
    . 2014, 33(24): 82-87.
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    A sensitive damage detection method is proposed in this paper, which is based on analyzing ultrasonic guided waves signal using Lyapunov exponents of Duffing equation. The feasibility of the method is verified by indetifying Guided wave signal in a steel pipe. Firstly, the Duffing Inspection System and the inspection principle are explained. The determination of system parameters is described in detail. Secondly, the propagation of guided wave in 3m-in-length steel pipe is measured experimentally, and the measured signals are analyzed by the Duffing Inspection System. The experimental results show that the Lyapunov exponents of Duffing Inspection System can effectively identify small defect echo and has strong immunity to the noise simultaneously. In addition, a damage index is defined by the ratio of the Lyapunov Exponent when inputting measured guided wave signal with noise to the one when only inputting measured noised signal. It can help us evaluate the damage level of defect. This method is significant for improving the sensitivity of small defects detection using ultrasonic guided wave.

  • HUANG Jia;YI Jin;Zhang Sheng;Chen Biao-song;Zhang Hong-wu
    . 2014, 33(24): 88-94.
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    The tension-shear chain model and 2D finite element model of nacre—a kind of stacking composite material—are built up, and its band gap is computed based on a multi-level substructure scheme. The results show that the nacre-like material is a kind of Bragg phononic crystal holding a relatively wide first band gap in low frequency domain and several flat bands in high frequency domain. So this kind of material can lead to the vibration reduction in a wide frequency range. Moreover, these materials are more efficient to realize the goal of vibration reduction in low frequencies, because it doesn’t have the Fano-like interference phenomena, which will happen in the locally resonant phononic crystals for the mechanism of their band gaps. Furthermore, the transmission characteristics are computed to verify the result of band gap. The further research demonstrates that band gap characteristics are mainly influenced by density of the mineral (“Brick”) component and elastic modulus of the protein (“Mortar”) component and the first band gap of nacre-like material subjects to the coupling influence of the two material parameters. An appropriate match of the two material parameters can contribute to a larger relative band gap. And the band gap is adjustable as well, which makes the nacre-like material a novel idea for the design of new vibration reduction structure.


  • TAN Ping WANG Bin JIN Jian-min ZHOU Fu-lin
    . 2014, 33(24): 95-100.
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    This paper presents a new type of isolator—Fiber-Reinforced-Plastic Plate Isolation Bearing(FRPB), taking lightweight and low-cost Fiber-Reinforced-Plastics as reinforced layer. A 3-D solid finite element modal of UFRPB and BFRPB is established by ABAQUS. The size and distribution of horizontal stress、Vertical stress、shear stress of UFRPB and BFRPB is comparatively discussed under the action of pressure and shear. This paper introduces the horizontal bearing mechanism of UFRPB and BFRPB, reveals the effect of warpage on stress state in the inner rubber layer of UFRPB, and provides a reference for design and research of the lateral bearing capacity and horizontal stiffness of UFRPB.
  • Chen Hongyong Chen Haibo Zhang Peiqiang
    . 2014, 33(24): 101-105.
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    The error becomes larger when using Galerkin method to calculate the lower order natural frequencies of axially moving beam with axial load. By introducing the effect of axial load, the test functions are modified and the vibration characteristics of axially moving Timoshenko beam of clamped-clamped and clamped - free boundary conditions are investigated. Simulation results show that: The effect of axial load can not be ignored when calculating lower order natural frequencies of axial moving beam with compressive load. The proposed modified approach based on Galerkin method improves the numerical results greatly when the axial compressive load is large, and it also has a good applicability for different boundary conditions. The effect of axial compressive load and axially moving situation cause the state of instability of beam more easily.
  • Wang Junwen;Zhuang Weiguang;Li Jianzhong
    . 2014, 33(24): 106-111.
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    Based on performance-based design philosophy, a displacement-based seismic design procedure for rocking bridge piers with post tensioning tendons is developed. In this design procedure, the level of piers damage is determined on the basis of earthquake fortification level, target displacement of piers is estimated considering the effect of deformation of the interface region where piers connect to footings; with inelastic response spectrum, the displacement demand under the earthquake is calculated. Energy dissipation bars or additional external dissipation devices in the piers-to-foundation critical interface region are used to dissipate earthquake energy by yielding, unbonded post-tensioning tendons are used to provide the shear resistance through friction developed at the pier-to-footings interface by the post-tensioning force, the initial tension of tendons is designed in details to maintain stress in tendons in the elastic range, and negligible residual displacements of piers are expected. The reliability of this design procedure is assessed by comparison with existing design procedures. The results of studies show that, compared with existing design procedures, the proposed design procedure gives results that is more consistent with the results of nonlinear time-history analysis.
  • PEI Xing-zhu;WANG Pei
    . 2014, 33(24): 112-122.
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    For the large vertical displacement between the frame and rocking wall, energy consumption components should be added to protect the main structure. Based on this, additional damping frame-rocking wall is proposed and structural single type of damper amount also could be calculated through the equivalent linearization theory, by defining the objective function, the best damper layout of structure with viscous damper and metal damper which can make the minimum value of the function could be determined, and conclusions are as follows: (1) for the shear-bending structure, the viscous damper can be arranged along the total height of structure when acceleration is considered and the metal damper arranged at two thirds the lower part while the viscous damper arranged at one third the upper when displacement, acceleration and storey drift are considered; (2) for the shearing structure, the metal damper arranged at half the lower part while the viscous damper arranged at half the upper when storey drift is considered, in addition, the metal damper arranged at one third the lower part while the viscous damper arranged at two thirds the upper when displacement, acceleration and storey drift are all considered.

  • Li Shouke;Li Shouyin;Chen Zhengqing;Sun Hongxing
    . 2014, 33(24): 123-128.
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    Based on the Non-Gaussian Simulation of multivariate stochastic processes method, one prediction method for wind pressure extreme value is proposed. The wind pressures time histories of several taps on opening roof are simulated by Multivariate Non-Gaussian Simulation method based on wind tunnel test data. It is shown that the power spectra density, coherence, deviation, skewness, kurtosis of simulated non-gaussian time histories are very close to the destination. Then the peak factors of wind pressures on opening roof are predicted from Multivariate Non-Gaussian Simulation time histories for several times by typical extreme value theory, and the results are compared with that of several general methods. It is shown that Davenport method overestimated the positive peak factor by 60% whose skewness is negative, and underestimated the negative peak factor by 43%; Sadek-Simiu method overestimated the peak factor by 50% which have high kurtosis; the proposed method can predict the peak factor effectively, and the overall error is smallest.

  • WAN Xiao-zhi;MA Hong-hao;SHEN Zhao-wu;LIN Mou-jin
    . 2014, 33(24): 129-132.
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    In order to improve comprehensive properties of the traditional aluminized explosive, a new non-ideal composite explosive is obtained by that aluminum fiber instead of aluminum powder in traditional aluminized explosive. The pressure-time curves of aluminum fiber explosive, traditional aluminized explosive and RDX are measured by underwater explosion experiments and the peak pressure, impulse, specific shock wave energy, specific bubble energy, specific explosion energy of three types of explosives are obtained by analyzing the curves. The results show that the peak pressure, impulse, specific shock wave energy of aluminum fiber explosive is lower than traditional aluminized explosive’s because the reaction rate of aluminum fiber is slower than aluminum particle’s in the beginning and the duration of the pressure-time curves of explosive is short. The specific bubble energy of aluminum fiber explosive is slightly greater than traditional aluminized explosive’s because the specific surface area of aluminum fiber is less than aluminum particle’s lead to the Al of aluminum fiber being more, and the duration of the pulsation period of explosive is longer lead to the reaction of aluminum fiber being sufficient, so that the total energy of aluminum fiber explosive is closely equal to traditional aluminized explosive’s.
  • ZHANG Yun-hua;;LI Shan;LIU Guan-yu;CHEN Ji;LI Hong-bing
    . 2014, 33(24): 133-137.
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    The dropping process of a infrared lens and its package are analysised based on Explicit dynamic analysis theory in the paper,the maximum stress of infrared lens,large lens and small lens are extracted in each moment and then the curve was generated in MATLAB,the stress of large lens was higher than small lens at the initial moment and at the end of the stage the result is opposite,so it set off thinking of the thickness design of barrel; The cushioning packaging of this infrared lens such as rigid polyurethane foam,partial cushion packaging is better than comprehensive cushion packaging in the protection of product. And compared with bare machine drops, it is obvious that the Z acceleration response of the lager and small lens center node when the partial cushion packaging drops is much lower than it. Finally, the partial cushion packaging was put into corrugated box for the drop test, and then through it. This simulation-based design approach provided an effective means for the structure design of the infrared product and selection of cushioning packaging method.
  • LUAN Qiang-li CHEN Zhang-wei HE Hui-nong
    . 2014, 33(24): 138-143.
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    Systematically researched the control strategy of the 3-stage electro-hydraulic servo valve controlled hydraulic shaker, and designed an integrated controller used for the large-flow hydraulic shaker. The controller could simultaneously achieve the servo control and vibration control functions of the hydraulic shaker. In the process of servo control, a dual-PID servo-control strategy was presented for the 3-stage electro-hydraulic servo valve and the servo cylinder. In the process of vibration control, aiming at the good low-frequency characteristics of the hydraulic shaker, a waveform replication method based on the closed-loop iterative control was designed. Through the waveform replication tests with different time histories and different bandwidths on the hydraulic shaker controlled by the integrated controller, it indicates that the controller has a strong waveform control ability to achieve high-precision waveform replication on the hydraulic shaker.
    Key words: the hydraulic shaker; the 3-stage electro-hydraulic servo valve; seismic waveform replication; road spectrum simulation
  • WANG Yu-kui;LI Hong-ru;YE Peng
    . 2014, 33(24): 144-149.
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    Aiming at the existing problem of discrete cosine transform (DCT) threshold de-noising method, an adaptive de-noising method named cosine neighboring coefficients (CNC) is put forward, and the results which are gotten by performing CNC de-noising to simulation signal demonstrated that the proposed method has more excellent performance. A novel method for the preprocessing of hydraulic pump vibration signal is proposed based on the combination of fast pre-whitening (FastPW) and cosine neighboring coefficients (CNC) de-noising method. Firstly, the pre-whitening (PW) signal which only includes shocking components and noise is gained by performing FastPW to the original signal, and the harmonic component of the original signal is removed. And then the de-noising processing is preformed to PW signal with CNC de-noising method. The analysis results of the practical signal testified that the proposed method can remove the harmonic component and noise preferably and reserve the fault component in the signal more excellently.
  • LIU Chang-zhao QIN Da-tong LIAO Ying-hua
    . 2014, 33(24): 150-157.
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    a dynamic model for parallel-axis helical gears is proposed including friction between the contact teeth which can be used in dynamic analysis of variable speed process. In this model, the position of the action line and sliding velocity are determined by the angular displacement of the driving gear, and the translational displacements and angular displacements are chosen as generalized coordinates, so the model can be used in analysis of the process of variable speed of gear transmission system, furthermore the friction is calculated by variable friction coefficient. The acceleration process of an example is numerically simulated with the model proposed in this paper and the dynamics responses are compared with that from the model utilizing constant friction coefficient and without friction. Some conclusion can be obtained from the comparison: friction decreases the critical speed of meshing aparting of helical gear transmission and has effects of damping and excitation, which affects the dynamic responses of helical gears. Moreover, the variable friction coefficient has different effects on the dynamic responses of helical gears than the constant friction coefficient.


  • HU Jun-ping;HU Qian
    . 2014, 33(24): 158-163.
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    Due to the fact that the high pressure oil could mix together with low pressure oil under using underlapped oil distributing valves which were widely used in domestic hydraulic impactor, a study on the dynamic performance of hydraulic impactor with using overlapped oil distributing valve and the optimal neutral position type of the valve was explored. According to the operating principle of hydraulic impactor and transform principle of seam flow state, a nonlinear dynamic mathematical model was established, and combining with Stateflow to manage the state transfer of spool movement, the dynamic simulation model of hydraulic impactor was obtained. During the simulation, the impact on dynamic chamber pressure at different neutral open value was focused analyzed. To verify the theory of simulation computation, an experiment was carried out. And the result of experiment corresponded to simulation computation. All these researches laid a certain theoretical foundation to the design on optimal neutral position type of the oil distributing valve in hydraulic impact mechanism.
  • GAO Ming-wang ZHANG Xian-min
    . 2014, 33(24): 164-168.
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    An experiment for residual vibration suspension of parallel robot was done based on input shaping control. Firstly, the kinematics of the planar parallel mechanism was analyzed and the dynamic of the manipulator was constructed. Then, a dynamic formula including these PD controllers was made up. Lastly, zero vibration (ZV), zero vibration and derivative (ZVD) for one mode shaper and zero vibration-zero vibration and derivative (ZV-ZVD) for two-mode input shapers were designed. An experiment system was set up. The experimental results show that input shapers offer significant reduction in the residual oscillation and the ZV-ZVD shaper is more effective for suspending residual oscillation.
  • ZHAO Chun-xiang;QI Hui;YANG Zai-lin;WANG Lei-lei
    . 2014, 33(24): 169-172.
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    The dynamic stress of interface cracks originating at an hole in half-space to SH-wave was studied using the methods of ‘image’ and ‘partitioning -conjunction’. Firstly, the problem was transformed from half space to whole space and the scattering waves which satisfy the boundary condition were constructed by the method of ‘image’. Secondly, with the help of ‘partitioning-conjunction’ method and ‘crack-division’ technique, the solving domain was divided into two parts along the interface, the two sub-domains satisfying the continuous ‘conjunction’ conditions of displacement and stress on interface were conjoined, and a group of integral equations were built to solve this problem. Finally, the dynamic stress intensity factor of the interface cracks tip was analyzed by numerical method. Numerical results demonstrate that the purpose of reducing crack tip’s dynamic stress can be achieved by properly avoiding the combination of the most adversely effective factors, such as incident wave number, incident angle, and the crack length, etc.
  • Yang Guigeng;Zhu Minbo;Lian Peiyuan;Gao Feng;Zong Yali
    . 2014, 33(24): 173-178.
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    The coupling-vibration of spacecraft with large ring-shaped deployable antenna induced by temperature variations during the spacecraft entering and leaving the Earth’s shadow was numercially analysized. The transient temperature field of large deployable antenna was solved using the finite element method, and a rigid-flexible coupling dynamic model was established for the coupling-vibration analysis. The results show that temperature gradient of the antenna itself is mainly between the light side and the backlight side, and with which the thermal response characteristic time of antenna can be estimated. Obvious thermally induced coupling-vibration of antenna structure and the satellite attitude can be observed. The method present in this paper can reasonably be used to predict the thermally induced coupling-dynamic of deployable satellite antenna system.

  • LIU Yan-bin;HAN Xiu-ying;MA Jia-jia;YIN Chen-xu
    . 2014, 33(24): 179-186.
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    In order to realize simple, reliable, low power consumption and high efficient broad-frequency micro-vibration isolation, a new vibration isolation system was set up by using the pneumatic artificial muscle (PAM) and the negative stiffness element, and active and passive control for the vibration isolation system were discussed. Firstly, the dynamics model of the vibration isolation system were built, the quasi-zero stiffness characteristics was analyzed, and the vibration transmissibility, response and nonlinear phenomena were analyzed by using the approximate analytical method and numerical method. And then, the low-frequency active control strategy for the vibration isolation system was developed by using backstepping control method and adaptive control technology and sliding mode control technology, and the vibration isolation performance under the active control was analyzed by using numerical method. The results show that the vibration isolation system widens the frequency band of low-frequency vibration isolation, the vibration isolation frequency can be lowered to 0.033Hz for the harmonic excitation whose amplitude is less than 5mm, and low power consumption and high precision vibration isolation can be realized by using the active control method, for this reason, simple, reliable, low power consumption and high efficient broad-frequency micro-vibration isolation can be realized by combining the passive control with the active control.
  • Fei Xiang Jiang Weikang Zhu Zhiyong Yang Wenhua
    . 2014, 33(24): 187-191.
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    To exclude the interference of the bench vibration on the fuel tank sloshing noise experiment, a signal processing method was proposed. By using a multi-input/single-output system method, the independent sound sources and the typical vibration test points were identified by singular value analysis. The coherence of typical vibration and noise signals was calculated by using coherence analysis methods. The fuel tank sloshing noise was separated from combined signals of stand and tank. To quickly correct the noise results of the fuel tank sloshing bench evaluation test, a method was proposed to get the sound pressure level correction curve. This signal processing method can effectively eliminate the interference from the bench vibration during the test.
  • LiuGuangxiao;MengLingya;LiuCuiwei;QianHaocheng;LiYuxing
    . 2014, 33(24): 192-199.
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    In the natural gas pipeline leak detection field, acoustic leak detection technology has the advantage of high sensitivity, strong real-time and high accuracy of leakage location. Acoustic method is limited by wave filtering technology and has not been used widely. To solve the problem, the main filtering methods in time and frequency domain was summarized, the typical methods of Wavelet and Wiener filtering was chosen, the principle of the two methods was listed, the actual filtering effect was studied. Filtering methods cannot attain satisfying effect under some situations, the reason is explained and the shortcoming of filtering methods was analyzed. A rapidly developing method-the blind source separation technology was introduced, the theory of signal separation was discussed. By separating structured signals, the blind source separation technology was proved to have better applicability and filtering effect. The separating results of experimental leaky acoustic wave indicates this technology has practical application value.
  • WANG Jian qiang;;YU Long;ZHANG Yu;LIU Liu
    . 2014, 33(24): 200-204.
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    It will make damage detection based on lamb wave more effectively to obtain accurate damage-scattered signal. Meanwhile, one of the key obstacles in the process of extracting damage-scattered signal is the fact that damage-scattered signal is often overlapped with many other reflected signals from structural features such as the boundary. To solve overlap, the baseline subtraction approach which is sensitive to external factors such as structure and environment is adopted in many existing methods to obtain damage-scattered signal. Due to the signal after incident wave in the damage signal captured by sensor is not an arbitrary signal, but rather a superposition of several reflected waves, so as long as the superposition of reflected waves which is most similar to the target signal is got, the target signal is considered to be interpreted successfully, and consequently, damage-reflected signal is got. Therefore, an approach is proposed based on the maximum likelihood for damage signal decomposition. Damage-reflected signals and boundary-reflected signals are simulated on the basis of analysis of lamb wave propagation characteristics, and then the various parameters of the synthesis of the above signals are optimized through genetic algorithm based on similarity index in order to make the similarity between the synthetic signal and the target signal reach the maximum. Finally, damage is localized through Time of Flight (ToF). The experimental results on an aluminum plate indicate that damage- reflected signal can be accurately extracted from the aliasing signal by means of the proposed method.


  • CUI Guangyao;ZHAO Rui-hua;LIU Weidong;WANG Mingnian;LIN Guojin
    . 2014, 33(24): 205-210.
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    In order to change weaker seismic behavior of tunnel structure of fault rupture zone under large earthquakes,the monolayer reinforcement aseismic technology of second liner collapse control is proposed, cooperate with the traditional double reinforcement aseismatic technology,the aseismic design of tunnel portal section of dynamics is proceeded. According to the regulations of highway and railway tunnel current seismic code, the principles of tunnel portal section second liner collapse control of aseismic reinforcement is established, and finite difference numerical simulation technology is used to study the collapse prevention aseismic reinforcement scope of application, the results show that monolayer reinforcement aseismic technology is used for the tunnel portal shallow buried section, the tunnel portal effect transition section need not take the aseismic fortification measures at 7 degree earthquake intensity; the double-layer reinforcement aseismatic technology is used for the tunnel portal shallow buried section, and take the monolayer reinforcement aseismatic technology on the tunnel portal effect transition section at 8 degree earthquake intensity; the double-layer reinforcement aseismatic technology is used for the tunnel portal shallow buried section and the tunnel portal effect transition section at 9 degree earthquake intensity. These results are significant to the development of dynamic portal section aseismatic technology.
  • HE Shan;YANG Zhi jian;DING Kang;WU Qing jie
    . 2014, 33(24): 211-214.
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    For the convenience of matching the optimal parameters of dynamic vibration absorber, the main system need to be simplified to single degree of freedom system by estimated its equivalent mass of mounting point. As the traditional mass response method have the shortcomings of complex operation and low accuracy, this paper use orthogonal polynomials to estimate the equivalent mass. Then contrast the results of orthogonal polynomial method and mass response method by the simulation combined with experiment. Results show that the orthogonal polynomial method identification precision is high and the experimental results is close to the simulation results. In addition, through experiment proved using the method of orthogonal polynomial matching with dynamic vibration absorber has a better effect, which coincidence with the optimal conditions of fixed point theory.