25 May 2011, Volume 30 Issue 5
    

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  • Chuan-Xiong Liu;Yu-Long Li;Zi-Yan Wu;Wei-Guo Guo;Yu-Zhuo Ge
    . 2011, 30(5): 1-5.
    Abstract ( 1515 ) Download PDF ( 1100 )   Knowledge map   Save
    Abstract:In order to investigate the dynamic compressive behavior of concrete, tests on concrete, the diameters of rough aggregates used in the concrete ranged form 15mm to 20mm, were performed under compressive impact loading using SHPB( )(Split Hopkinson Pressure Bar)apparatus, and the average strain-rate in these tests ranged from 30s-1 to 180s-1,the photograph related to the deformation or failure process for concrete specimens under dynamic compressure were obtained as well. Results show that once the stresses in specimen get up to a value nearby the peak stress, a macro-crack along the axes of concrete specimen can firstly be observed on its surface, but its failure are finally related to the developing and propagating of primary multi-macro-cracks along the axes of specimen. A modified ZWT concrete constitutive model was proposed, the results predicted from it are in agreement well with those of experiments.
  • HU Liang;GU Ming;LI Li
    . 2011, 30(5): 6-9.
    Abstract ( 874 ) Download PDF ( 525 )   Knowledge map   Save
    This paper assessed the errors of the simulation for a stationary Gaussian multi-variate wind process, which is carried out by using the original spectral representation method (OSRM) or the proper orthogonal decomposition-based spectral representation method (PSRM). To begin with, a set of formulas which describe the two types of SRM as well as the close-form stochastic errors produced by them are presented in a standard form. Accordingly, the errors produced by the simulation of a 64-point simplified wind field using the PSRM and OSRM are computed and then compared in terms of relative global spectral stochastic errors and relative stochastic errors of standard deviations. It can be concluded from the numerical example that the errors produced by the PSRM are not only less in total but also distributed to every point more uniformly than the PSRM; thus the PSRM should be preferred to. In addition, the influence of the number of frequency steps on the errors is discussed in detail. Some approaches for relieving the errors are also suggested.
  • WANG Yan;Wu Sheng-xing;Zhou Ji-kai;Chen Hou-qun;
    . 2011, 30(5): 10-17.
    Abstract ( 1072 ) Download PDF ( 652 )   Knowledge map   Save
    Abstract:Combining with the Flexural-Tensile tests of wet sieving and three-graded concrete in Xiaowan arch dam., feature parameters and waveforms of acoustic emission (AE) signals during the whole process of third-point flexural-tensile are acquired using full-digital acoustic emission system. The development of acoustic emission activities in each loading stages is analyzed, the statistical features of peak frequency and frequency centroid calculated from FFT power spectrum are compared, damage mechanisms are identified based on the acoustic emission parameters, and the extent of the localized failure zones of microcracks are also compared using commercial software of AEwin, the following characteristics are found in three-graded concrete comparing with wet sieving concrete: (1)Easier to induce damage, and lower b value is observed in each loading stages; (2) The peak frequency of hits also appear in the frequency band of 100-125kHz and 225-250kHz, and the distribution of frequency centroid tends to lower than wet sieving concrete; (3) The duration ranges of two specific mechanisms identified in three-graded concrete are covered by one duration range in wet sieving concrete; (4) it showed a wider localized zone of microcracking than wet sieving concrete.
  • Hu JiaShun;Sun WenYong;Zhou Jing
    . 2011, 30(5): 18-22.
    Abstract ( 1070 ) Download PDF ( 540 )   Knowledge map   Save
    Abstract: The local flexibility equations of the pipe with a circumferential part-through crack that subjected to axial force, shearing force and bending moment were derived by using of theories of linear fracture mechanics and stress energy release principle. An adaptive Simpson quadrature-revisted was used to perform the numerical integration to obtain the flexibility coefficients. A finite element model for cracked pipe was established to conduct the vibration analysis for cracked cantilever pipe. In addition, crack identifiation for a cracked cantilever pipe was investigated based on contour plots of frequency ratio as function of crack location and crack depth. The results show that the proposed crack model conquers the shortcoming that existing models usually apply for calculating special load or non-hollow structure, and the contour diagram can identify crack location and depth effectively.
  • Ledong Zhu;;Qing Zhu;Zhenshan Guo;
    . 2011, 30(5): 23-26.
    Abstract ( 962 ) Download PDF ( 369 )   Knowledge map   Save

    Abstract: Wind-induced static torsional angle has significant influence on the results of sectional model test. To accomplish accurate flutter analysis, wind-induced static torsional angle should be adjusted in sectional model test. An attack angle control facility was used to eliminate static wind induced additional attack angle. A comparison of test results before and after the attack angle adjustment based on the Xiang Shan Gang Bridge shows that static wind induced additional attack angle has influence on aerodynamic tortional damping ratio, aerodynamic derivatives related to torsional movement and critical wind speed. Before the adjustment, the wind induced additional attack angle on the sectional modal under critical wind speed was 0.32°at 3°initial attack angle. After the adjustment, the critical wind speed increased by 7%.

  • Yang Qiuwei;Sun Binxiang
    . 2011, 30(5): 27-31.
    Abstract ( 1141 ) Download PDF ( 1010 )   Knowledge map   Save

    Abstract: Structural damage identification based on an improved sensitivity technique of structural flexibility is studied in this paper. The drawback of the existing sensitivity methods is discussed firstly and then an improved technique is presented. The most significant contribution of this work is in the development of a simple accelerated formula used in the iteration process. With the introduction of the accelerated formula, the proposed method is able to quantify large damages without any high-order analysis on the flexibility or multi-iterations. The effectiveness of the proposed method is illustrated using simulated data with measurement noise on two numerical examples. The results show that the proposed procedure is economical in computation and is simple to implement. Regardless of whether the damage is small or large, the proposed method can identify both locations and extents of structural damages accurately only using the first iteration. It has been shown that the presented scheme may be useful for structural damage identification.

  • ZHANG Ke;;ZHENG Hang;;WANG Yu;;TANG Zhiping
    . 2011, 30(5): 32-36.
    Abstract ( 1309 ) Download PDF ( 690 )   Knowledge map   Save
    Abstract: By using a composite structure of Titanium Nickel shape memory alloy(SMA) and rubber polymer, a repetitive-use shock resistance device for submarine platform was designed. The shock resistance characteristics of this device subjected to different pulse durations and amplitudes were simulated numerically with the ansys/ls-dyna finite software. The results show that the shock acceleration attenuation of this device is up to 95% or more, and it can protect the equipment of about 100kg effectively against the shock loading. Compare with the traditional linear spring, it has lower acceleration response and vibration amplitude. Most important, for the hysteretic characteristic from superelastic deformation of SMA, it can attenuate the vibration amplitude rapidly.
  • KONG Xianren;XU Dafu;YANG Zhengxian;WANG Benli
    . 2011, 30(5): 37-42.
    Abstract ( 988 ) Download PDF ( 666 )   Knowledge map   Save
    Abstract: The dynamic model of space tether deployment using Hamilton’s principle provides a way to study motion laws of drum releasing tether, tether vibration and end-mass moving during the tether deployment. Numerical simulation of tether free deployment is calculated using central differ-ence method, four-order Runge-Kutta method and predictor-corrector method and so on, the simula-tion results show that the model can accurately describe the complex nonlinear dynamic behavior of space tether system during deployment. Free deployment cannot meet the requirements of tether de-ployment stabilization, but the simulation data provide foundation for tether deployment control in further.
  • LI Zheng-liang;WEI Qi-ke;HUANG Han-jie;SUN Yi
    . 2011, 30(5): 43-48.
    Abstract ( 2207 ) Download PDF ( 971 )   Knowledge map   Save
    Abstract: Considerable changes of the amplitude and the spatial distribution of wind velocity take place under the interfering of hilly terrain. Wind load and response of super tall buildings at special location in hilly terrain is significantly different from that in flat terrain, therefore the current method of calculating wind-induced response of the super tall buildings in flat terrain may be unsafe under the condition of the hilly terrain. Previous researches were mainly focused on mean wind speed-up effect, and very few researches on the turbulent characteristic were referred to this subject. Besides, there is no comparison between the result of wind reduced response of super tall buildings in hilly terrain and that in flat terrain. In this paper, several kinds of 3D hill model, including bell, Gaussian and cosine shaped, are established by CFD software Fluent. Vertical profiles of mean velocity at crest are calculated under different hill slopes. According to the result of the numerical simulation, the great speed-up effect is found at the crest and the maximum speed-up ratio reach 1.7. The result of the numerical simulation is fitted by the inverse function very good. Compared to the experiment data, the simulation of the mean velocity is accurate, but the turbulence of the numerical simulation has a certain gap. Through a numerical example of the wind-induced response of a super-tall building, the effect of the hilly terrain can’t be ignored, and the displacement response of the super-tall building in hilly terrain increase 20% compared to in flat terrain.
  • WEI Hai-xia;CHEN Shi-hai;ZHANG An-kang
    . 2011, 30(5): 49-53.
    Abstract ( 1282 ) Download PDF ( 597 )   Knowledge map   Save
    Abstract: A three-dimensional solid model was built for an actual three-storey masonry building in blasting filed. Observation signals of blasting seismic waves at the bottom were loaded onto the foundation base of masonry model, and values of blasting vibration response of the other masonry storey calculated with dynamic finite element method were compared with observation results. One representative structure was separately selected among common masonry buildings of 2~4 storeys to build finite element model, and blasting seismic waves of different dominant frequency were loaded on its base nodes in vertical direction and cracking course of the model was simulated. Safety standards of blasting vibration of representative masonry buildings of 2~4 storeys under blasting seismic waves of different dominant-frequency bands were given, which were obtained by defining critical failure state of structural element. The results indicates that the safety standards of blasting vibration in existing Safety Regulations for Blasting , which were made on the base of engineering experience and macro-survey data , seem too gross and have no considering the difference of vibration characteristics between structural individuals for a same type of building. They can not be widely used because they can not guarantee the safety of all structures.
  • Huilin Shang
    . 2011, 30(5): 54-58.
    Abstract ( 1206 ) Download PDF ( 437 )   Knowledge map   Save
    Abstract: In order to apply delayed feedback controlling the erosion of safe basins in nonlinear systems, a softening Duffing oscillator is considered in the paper as an example, a linear delayed velocity feedback is induced to the system, and the effects of delayed velocity feedback on controlling the basin erosion are investigated. Firstly, the condition of fractal erosion of safe basin’s boundary of the delayed controlled system is obtained by the Melnikov method. Then considering time delay as a variable parameter and employing the 4th-order Runge-Kutta and the Monte-Carlo methods, the evolutions of boundaries and area of safe basins with the delay are presented. It is found that the delayed velocity feedback can greatly affect the safe basin, and the erosion of safe basin can be reduced by the increase of the delay effectively. It follows that the delayed velocity feedback can be used as a good approach to control the erosion of safe basins.
  • Zhang Yong
    . 2011, 30(5): 59-62.
    Abstract ( 1020 ) Download PDF ( 411 )   Knowledge map   Save


    Abstract: Dynamics of the electrodynamic tethered system in circular inclined orbit is studied.The dynamic model of the system is described, the basic periodic solution is obtained using perturbation method and a new numerical method, The stability of periodic solutions is analysed based on the stability criterion in the numerical algorithm and the conclusions of system periodic motion instability was drawed. Finally, we compare two algorithms by simulation, the results show that periodic solutions obtained by the two algorithms are the same basically when perturbation is the smaller, but the periodic solutions obtained by the perturbation method occur distortion when large perturbation and is not good, at this time the numerical algorithm is normally adopted. Instability of periodic solutions is also confirmed by the simulation results.
  • Lu Shaobo;Li Yinong;Seungbok Choi
    . 2011, 30(5): 63-68.
    Abstract ( 1061 ) Download PDF ( 560 )   Knowledge map   Save

    Abstract: For purpose of improving the vibration absorption effect of magneto-rheological (MR) suspension sysytem, the bench test of response characteristic both in time and frequency domain have been done for the special magneto-rheological (MR) damper. Then a grey predictive-fuzzy controller(GPFC)is proposed by integrating the grey predictive theory and the traditional fuzzy control(TFC) algorithm and is applied to the control system of MR suspension . Inorder to verify the effectiveness of the proposed control strategy, the comparative study of simultion and bentch test among sky-hook control, TFC and GPFC has been presented. The results show that the response speed of MR damper is fast, the bend of frequency response is wide. Both the simulation and test results present that the performance of the GPFC is the best, the time response is superior to that of TFC, but slower than that of sky-hook control
  • GUO Tie-neng;LI Ling;CAI Li-gang;LIU Zhi-feng;ZHAO Yong-sheng;Yang Kun
    . 2011, 30(5): 69-72.
    Abstract ( 1215 ) Download PDF ( 832 )   Knowledge map   Save

    Abstract:In order to obtain a more accurate boundary condition of structure in dynamic analysis and optimization design, the parameter identification of joint as one of the key technologs. In combination with engineering practice, proposed the method of frequency response function (FRF) to identify the characteristic parameters of the joint. Whether it can obtain complete FRF is studied and propose the corresponding solution strategy in this paper. This method avoids the matrix inversion directly, and transforms contradictory equation to definite solution of equation with least-square principle, which ensures the stability of numerical calculation. Considering the damping information is inferior to stiffness information in identification process, in order to identify the damping more accurately, using the second identification method to identify damping parametres. This method has a certain practical value and the identification process is simple. Example analysis confirmed that this method has high identification accuracy.

  • YANG Qiong-;SHI Xiao-ming;TANG Guo-an
    . 2011, 30(5): 73-75.
    Abstract ( 1124 ) Download PDF ( 798 )   Knowledge map   Save
    Abstract: The expression of the unsteady aerodynamics in time domain or frequency domain is established based on Theodorsen theory. The expression with integration was converted into second order differential equation. The unsteady aerodynamics on the structure was regarded as the reinforcement of the mass matrix, stiffness matrix and damping matrix of the finite-element model of structure. The whole dynamic characteristics were reserved. The general finite-element software could be used to calculate the flutter boundary of the air-structure coupling model. The method is suitable for the aeroelastic problem with complex structure. The unsteady aerodynamics data getting from any numerical methods or experiments can be used to establish the unsteady aerodynamics model which makes the method applicable to different cases. The flutter boundary of high-aspect ratio wing is calculated.
  • LIAO Qing-bin;LI Shun-ming;WANG Xiao-dong;MA Shi-hu
    . 2011, 30(5): 76-82.
    Abstract ( 1151 ) Download PDF ( 372 )   Knowledge map   Save
    Abstract: The statistical characteristics of vibrational response to coupled dynamical system were analyzed in this paper. At first, the equation of energy balance on random dynamical system was gained based on statistical energy analysis (SEA). Then, the statistical estimated expression was proposed on vibrational response of coupled dynamical system. It mainly analyses the influence to the statistical estimation of all kinds of inputs forms and the confirming method of the loading parameters when analysis the statistical characteristics of vibrational response of complicated coupled dynamical system. Its show that the condition of independent- excitations was a special case of correlated-excitations, they could be expressed by uniform expression. Experimental sample was designed to validate the correctness of the method based on the estimated expression. The experimental results show that the proposed statistical analysis method was of more accuracy than the existent result, and it can reduce the relatively deviation of vibrational response effectively.
  • LI Miao;REN Wei-xin;
    . 2011, 30(5): 83-87.
    Abstract ( 2020 ) Download PDF ( 543 )   Knowledge map   Save
    eAbstract: Vibration-based SHM detects damage of structure through changes in vibration features, such as natural frequencies, mode shapes and modal flexibility. Modal parameters are not only affected by damage in structure, but also environmental and operational conditions. Compared to changes in the modal parameters induced by environmental and operational effect, those by local damage in structure could be much smaller. The subtle changes caused by delicate damage in structure may be masked because of such effect. To get real condition of structure, it is highly necessary to eliminate effect of environmental and operational condition on modal parameters. Modal flexibility was chosen as damage parameter for its sensitivity to damage. Via numerical model of simply supported beam, effect of local structure damage and temperature on modal flexibility was analyzed comparatively. After principal component analysis (PCA) being applied to modal flexibility under different conditions, statistical distribution patterns of structure were established on the residual errors of the PCA models. The structure novelty under environmental variations can be diagnosed by recognizing difference between the patterns using method of statistical pattern recognition. It’s demonstrated that false damage diagnosis may occur without considering effect of environmental variations; PCA-based novelty detection ffectively eliminate temperature influences on modal flexibility and provides indication of novelty for structure.
  • LUO Yin-miao
    . 2011, 30(5): 88-89,1.
    Abstract ( 1547 ) Download PDF ( 501 )   Knowledge map   Save
    Abstract: Modal iteration is a kind of classic technique in solving mode shapes,it is used in FEM software or other numerical area.The paper advanced experimental modal iterative method along with classic numerical modal itera-tion.Exciting force can be introduced by assumptive mode shape and steady response will be seized. It can get proto-type mode shapes.The idea of experimental modal iterative method is compeletely different from current resonance test to get mode shapes.It adjusts amplitude ad phase at same time and needs less test period.Mode shapes purity is re-lated with resonance frequency precision only. The complexity of exciting force adjusting is independent with shaker number. This technique can reduce resonance test work greatly.
  • Wang Jin-ming;Li Wei-ming;Peng ming-feng
    . 2011, 30(5): 90-95.
    Abstract ( 1269 ) Download PDF ( 383 )   Knowledge map   Save
    Abstract:In the model updating process, the experimentally measured frequenices and modal shapes should be used simultaneously when employing improved cross-model cross-mode (ICMCM) method. This paper takes the modal shapes of the finite element model as those of the experimental model and makes use of iteration to circumvent the drawback of lacking experimental modal shapes. Model updating of GARTEUR benchmark model using ICMCM mehtod based on the three international criteria and comparisons with those of others research institutes are shown. Results show the feasibility of the proposed improved method and the advantage of the GARTEUR updating results.
  • ZHENG Deqian;GU Ming;ZHANG Aishe;ZHANG Jianguo
    . 2011, 30(5): 96-100.
    Abstract ( 1003 ) Download PDF ( 421 )   Knowledge map   Save
    Abstract: Based on Fluent 6, the mean and fluctuating wind pressure coefficients of a high-rise building scaled model with aspect ratio of 1:1:6 were numerically simulated by adopting large eddy simulation (LES). The simulated results were first compared with those of wind tunnel tests. Then the effect of incoming flow turbulent intensity on the wind pressure distribution on the structure is investigated. The results show that: (1) For similar structures, the wind pressure on the windward face is directly affected by oncoming flow turbulence, while the lateral faces are nearly unaffected, but mainly affected by signature turbulence caused by the flow separation. For the reason that the leeward face is located in the wake of the flow, the influencing factors on wind pressure on the leeward face are relatively complex. (2) The statistic characteristics and the spectra of the wind pressure coefficients for LES results are elementarily in accordance with those of wind tunnel tests. LES technique could precisely predict the mean and fluctuating wind pressure distributions on structures.
  • Huang LiQuan; Wang WeiMin; Su YiRu; Gao JinJi
    . 2011, 30(5): 101-105.
    Abstract ( 1699 ) Download PDF ( 766 )   Knowledge map   Save
    Abstract: It is vital important for ensuring reliable and efficient rotating machinery operation to eliminate the vibration of rotor system online. Early in the rotor vibration control, a tentative control force is needed. The force might make the system vibration aggravate or reduce, which depends on the relationship between control force phase and excitation vibration force phase. So, depending on the analytic of the rotor system dynamics and electromagnetic force controllable characteristics, the regional division of the phase of control force was done. And the control model was built and some specific optimization strategy was proposed. The finite element analysis method was used to attain the system theory lagging angle under working speed. The phase value of control is determined and the phase is used as the initial value of optimal parameters, and ensuring the vibration amplitude is not more than the initial fault amplitude of rotor during control. Finally the test equipment was established and the experimental results show the algorithm is effective.
  • CUI Sheng-ai; ZHU Bing; BAI Feng-tao; LI Chao
    . 2011, 30(5): 106-110.
    Abstract ( 1407 ) Download PDF ( 913 )   Knowledge map   Save
    Abstract: Based on super-long crossing-channel cable-stayed bridge Scheme of over Qiongzhou strait, the refined numerical simulation model of whole vehicle and whole bridge system for coupled vibration analysis is set up. The dynamic analysis model of cable-stayed bridge Scheme of crossing-channel project over Qiongzhou strait is established by use of space bar-shell hybrid finite element method, and the natural vibration properties of the bridge are analyzed. The refined three-dimensional space vehicle model is set up by multi-system dynamics software SIMPACK, and the multiple non-linear properties are considered. The space vibration responses are calculated by co-simulation based on multi-body system dynamics and finite element method when only a train passes and when two trains pass the long span cable-stayed bridge with the opposite direction at different speeds in order to test if the bridge has the sufficient lateral or vertical rigidity and the operation stability is fine. The calculation results show: The operation safety can be guaranteed, and comfort index is “good”. The bridge has sufficient rigidity, and vibration is in good condition. The results provide a reference for design.
  • ZHU Junhua;YU Ling;
    . 2011, 30(5): 111-115.
    Abstract ( 1614 ) Download PDF ( 516 )   Knowledge map   Save
    Abstract: Based on measured Frequency Response Functions (FRFs), an easier and more efficient method for structural health monitoring is proposed by using Principle Component Analysis (PCA) in this paper. The FRFs of the healthy and damaged structure are used as initial data. The method uses a PCA transform technique to obtain the features of intact structure, also called the Principle Components (PCs), in which an orthogonal transformation matrix packed by the first few eigenvectors of covariance matrix can be found. Further, the orthogonal transformation matrix is applied to the FRFs of damage structures so as to find the features of the corresponding damage state of structures. Both structural damage detection and structural health monitoring can be achieved by comparing the two dimensional PCs distribution charts respectively corresponding to the damaged and to the healthy state of structures. Two numerical simulation examples show that the proposed method is correct, effective and feasible. Because it is based purely on the analysis of the vibration responses of structures, which makes it quite easy to perform and demonstrates its adaptability to structural health monitoring in field.
  • CHENG Xiao-xiang;FEI Qing-guo;HE Ding-ding;HAN Xiao-lin
    . 2011, 30(5): 116-122.
    Abstract ( 1152 ) Download PDF ( 494 )   Knowledge map   Save
    Abstract: To conquor the deficiency of poor computational efficiency and slow convergence of traditional sensitivity analysis-based finite element model updating methodology which is widely applied, response surface methodology has been introduced into a 500KV large transmission tower's dynamic FE model updating. Based on study group’s former findings, elastic stiffness of the tower's three directional foot bearings is selected as updating parameter. Key steps in updating process, including one factor test, sample on FE platform, building and analyzing response surface, parameter optimization, are presented in succession, response surface-based dynamic FE model updating being completed. The updated tower model accurately recurred the structure’s primary and secondary natural frequencies, and its effect approximates that of sensitivity analysis-based methodology, proving its application value. Based on the towered work, analysis of parameter selection is also presented for reference.
  • Wu Chen;ZHOU Ruizhong
    . 2011, 30(5): 123-126.
    Abstract ( 1848 ) Download PDF ( 488 )   Knowledge map   Save
    Abstract: The transient response of a structure is usually ignored in traditional dynamics. Based on the theory of harmonic earthquake response and wavelet packets analysis, the transient vibration of MDOF systems subjected to real earthquake ground motion is derived. Response spectra and transient vibration rules of equivalent SDOF system are got. It is concluded that the maximum displacement of a long period structure could occur in transient vibration and the value could be greater than sympathetic vibration. By comparing the transient response of a long period building with that of a short period building, it is shown that short period structure is mainly controlled by steady state vibration and the effects of transient vibration on a long period structure is prominent. Therefore, transient displacement as well as sympathetic displacement must be considered in the earthquake-resistant design of long period structures.
  • Tang Jinyuan; Chen Haifeng
    . 2011, 30(5): 127-130,.
    Abstract ( 1019 ) Download PDF ( 426 )   Knowledge map   Save
    Keywords: sustainable pre-loading; spring; bond graph; dynamic simulation; 20-sim
  • Wang Fu-tong;Tao Xia-xin;Cui Gao-hang;Zheng Xin;Liang De-yong;
    . 2011, 30(5): 131-135.
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    Abstract:Ground vibrations induced by urban rail traffic are a major environmental concern in urban areas. In order to study the vertical vibration characteristics and its propagation behavior, an in situ test was carried out near the Line 13 of the Beijing Urban Railway between the Huilongguan Station and the Huoying Station. The responses of the free field ground were analyzed from three aspects as acceleration time histories, power spectra and vibration levels. Results show that the PGA of ground surface displays a pronounced attenuation with the increase of distance from track, while the vibration duration is somewhat prolonged. The dominant frequency ranges from 10Hz to 80Hz, whose lower band is primary for the points near track and upper band is primary for the ones further from track. The weighing VLz monotonic decay with distance, whereas at some frequency points close to natural frequencies of ground, the banded VLzs are amplified notably at certain distances. There is no significant change in the weighing VLz whether coaches are full or not. Comparing with InterCity railways, the urban rail traffic produces a more moderate ground vibration.

  • YANG Fei ;YANG Zhi-chun
    . 2011, 30(5): 136-139.
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    Abstract:The flutter calculation method to convensional aircraft tail wing can not be applied directly to T-tail flutter analysis due to its features in structural and aerodynamic configurations, and the effects of in-plane motion and steady aerodynamics of horizontal plane should be considered in T-tail flutter calculation. From the view point of engineering analysis for T-tail flutter, some key issues of T-tail flutter calculation are discussed in this paper, the characteristics of T-tail flutter problem and the key parameters that effect T-tail flutter properties are described. Especilly foure methods to revise the aerodynamics of T-tail in its flutter calculation are intruduced and finally some specific problems in T-tail flutter analysis that worthy of further study are emphasized
  • Liu wenguang; Chen guoping
    . 2011, 30(5): 140-144.
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    Abstract: An analytical method about vibration fatigue of cracked beam was proposed based on timing analysis and Paris equation. Coupling relationship between vibration and fatigue crack growth was considered by using timing analysis methods. Crack part was replaced by linear spring and damping loss factor was introduced by complex elastic modulus during vibration analysis. So that crack growth together with excitation frequency and damping were considered in the vibration analysis. Results indicate that crack length, excitation frequency and damping have important effects on the fatigue life of structural crack propagation. In the resonance region, the rate of crack growth is obvious and the speed is decreasing with damping increases. The structure far away from resonance region with crack propagation and the crack propagation speed increases with excitation frequency near to natural frequency. The prediction precision of fatigue life can be further improved through using this new analytical method.
  • Huang Xiu-chang;Xu Shi-yin;Zhang Zhi-yi;Hua Hong-Xing
    . 2011, 30(5): 145-151.
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    Abstract: A general method for the design sensitivity analysis of forces on and power transmission to the base in a typical floating raft system is presented using the FRF-based substructuring formulation. The proposed method gives an expression of design sensitivity in terms of the partial derivatives of the physical parameters of upper and lower isolators as well as the transfer functions of the substructures. An optimization scheme involving the derived sensitivity formula is applied to obtain the optimal physical parameters of isolators of the floating raft system to minimize the mean-square forces transmitted to the base and the time-averaged power transmission to the base, respectively. The simulation results have demonstrated that the proposed method is efficient and accurate, and that the minimization of force transmissibility does not necessarily provide a minimum power transmission.
  • Ma Renle;Ma Yueqiang;Liu Huiqun
    . 2011, 30(5): 152-155.
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    Abstract: Based on the theory of random vibration and system identification, the ambient vibration tests of the three wind turbine towers in wind-power station of the Inner Mongolia Wulanyiligeng were carried out. The method of coupling overall modeling of blade, hub, nacelle and tower was put forward, and the numerical stimulation and tests results show that the wind turbine towers can effectively avoid resonance, and meet the standard design requirements of Germanischer Lloyd. The vibrational forms of wind turbine tower mainly are lateral bending vibration, forth-and-back bending vibration and torsional vibration; the translational damping ratio in the first phrase is about 1.75%, and the torsional damping ratio in the first phrase about 0.6%. The overall modeling shows excellent consistency with the tests results, which can benefit the wind-induced dynamic response analysis and the vibration control research on the wind turbine tower system.

  • Zhong Chongming;Wan Quan;Jiang Weikang
    . 2011, 30(5): 156-160.
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    Abstract:The FEM method is used to study the vibration response of one reciprocating compressor due to the mechanical excitations caused by the crank-connecting rod-piston system. It is shown that the crank-connecting rod-piston mechanism system is the main excitation source for low-frequency vibration of the reciprocating compressor, and the gas force is the main reason for the horizontally torsional vibration of the pump body. Some tests are implemented to validate the feasibility of the FEM method in the dynamic response analysis of the reciprocating compressor. The normal velocity distribution on the compressor shell due to the mechanical excitations can be obtained by FEM method, on the basis of which the prediction of the mechanical noise becomes possible for the reciprocating compressor.
  • Li Weil;Ma Ji-sheng;Sun He-yang;Cheng Li;Qiao Liang
    . 2011, 30(5): 161-163.
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    Based on the elastic-plastic contact finite element theory, inertial bayonet-chamber process of the projectile was analyzed, and its finite element model was built. Inertial bayonet-chamber process at 1~4 m/s was computed, the elastic-plastic deformation and dynamic response was obtained and the influence of the friction coefficient to the computed results of inertial bayonet-chamber process was analyzed.
  • Wang Yu;Ji Chen;Du Jianye;Zhu Changsheng
    . 2011, 30(5): 164-168.
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    Abstract:The types of shock impulse of ship shaft system are introduced. A shock dynamic model of ship shaft system is built up with the finite element method, and a software (SHAFTFE) for the ship shaft system dynamics and shock response simulation is developed on MATLAB. Dynamic characteristics of a ship power shaft system including propulsion shaft, propulsion electric motor and vibration isolator of electric motor, are analyzed by the SHAFTFE in the condition of different shock forces and parameters, and effects of the structure design parameters of the ship shaft system on the shock response are dealt with. It shows that the ship power shaft system will have a large motion on the action of base shock, so we must pay more attention on the shock character of the ship power shaft system during the design in order to increase the reliability and survival performance of whole ship.

  • Hu JiaShun Sun WenYong Liu Duo Zhou Jing
    . 2011, 30(5): 169-173,.
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    Abstract: The crack model based on local flexibility has received attractive attention in engineering. However, the study on the local flexibility of pipe with a crack that has an arbitrary angle is scarce. The local flexibility equations of the pipe with a part-through crack that subjected to axial force, shearing force and bending moment were deduced from theories of linear fracture mechanics taking into the effect of the angle of crack on the local flexibility of pipe account. An adaptive Simpson method was used to obtain the flexibility coefficients of cracked pipe and the results of Naniwadekar’s experiment was used to validate the proposed approach. The results demonstrate that the proposed approach to local flexibility is accurate, which is suitable for vibration analysis of pipe-like structure with an arbitrary angle crack.
  • WEI Demin;; WEN Xingyu
    . 2011, 30(5): 174-178.
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    Abstract: A hybrid algorithm is proposed for the dynamic topology optimization of truss structures. In optimization analyses the dynamic displacement responses of nodes are constrainted and the minimal weight of the truss structure is as the objective function. A particle which has the best fitness from the swarm is chosen as the special particle, and it moves by means of iteration expressions in the optimality criteria methods. The other particles comply to the evolution rules of PSO algorithm, and their displacement constraints are approximately calculated by using the dynamic sensitivity of the special particle. The optimization results of a computational example show that the hybrid PSO algorithm is suitable for the topology optimization of truss structures under the harmonic load and impulsive load. The optimization efficiency of hybrid PSO algorithm is higher than PSO algorithm, and the optimization precision of hybrid PSO algorithm is better than the optimality criteria method.
  • YOU Wei-qian;CUI Xu-li;CHEN Huai-hai;HE Xu-dong
    . 2011, 30(5): 179-183,.
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    Abstract:A new approach is presented for dual-shaker random vibration test using Η-infinity-based optimal decoupling method with two degrees-of-freedom controller without taking the cross-spectra into account. A cantilever beam is used to verify the proposed control approach. A two - inputs two - outputs control model is set up based on the beam. The results demonstrated that, in the frequency range from 20 Hz to 2000 Hz, the controller can make the error between the output PSD (power spectrum density) and the reference PSD less than ±1dB, which is perfect for the dual-shaker random vibration control test. Finally, a test is performed and the test results show that the proposed method can meet the engineering demand.
  • Rongwu XU Lin HE
    . 2011, 30(5): 184-187.
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    Abstract: The J-divergence has been brought forward as an improvement of directive divergence. By introducing a
    new kind of evaluation index called Normalized Key-points Height(NKH), a simulation and a cabinet model test has been
    proposed to evaluate the effectivness of five different distance concepts including Euclidean distance on four kinds of acoustic
    faults. The result shows that the J-divergence is the best choice for acoustic fault detection.
  • CAO Hui;CHEN Xinghua;HUA Jianmin;HU Zhimao
    . 2011, 30(5): 188-191.
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    Abstract: It is essential for the new emerging combined structure of railway-bridge and building to alleviate the vibration induced by the high speed train. A kind of polymer was mixed with concrete to improve its damping. A series of experiments including vibration test, static loading and fatigue loading were carried out on small species, simple beams and reduced scale models of a real long span box girder, to compare the compression strength, static modulus and damping, as well as the static and fatigue performance of ordinary concrete and polymer concrete. The results show that the damping ratio increases with the increasing ratio of polymer and cement, while the compression strength and static modulus decrease a little. The static performance of the polymer concrete beams is better than that of the ordinary concrete beam, and the fatigue behavior of the former is the same as that of the latter. The workability of the polymer concrete including slump and slump flow is good.
  • Xu yu-xin; Wang Shu-shan; Bo Xue-fei; Liang Yong
    . 2011, 30(5): 192-195.
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    Abstract: Research the extreme on specific mass tungsten alloy fragment penetrated and perforated low-carbon steel. For armor-piercing of tungsten alloy spherical fragment against semi-infinite and finite thickness steel on higher projectiles penetration speed, firstly, ultimate penetration depth of the spherical fragment on the diameter in common use was obtained by numerical simulation, at the same time, the relation between ultimate pierced thickness and diameter of the spherical fragment was obtained; Base on these, armor-piercing experiments on different diameter fragments against Q235 steel plate was done, the outcomes on experiments and numerical simulation had better consistency, based on the experiment phenomena and numerical simulation, damage format on the spherical fragment was analyzed under different impact speed. The research results were important value for application.
  • Wu Shengxing; Wang Yan; Li Jia; Shen Dejian
    . 2011, 30(5): 196-204.
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    Abstract: The setting of hardware parameters, filtering parameters for acoustic emission (AE) acquiring system, and the AE parameters as well as their correlations are studied systematically by experiments, 11 groups of pensile lead break tests and 13 concrete specimens loaded in uniaxial tension are carried out. Feature parameters and waveforms of AE signals acquired by 3 kinds of sensors during the processes of tests are stored using parameter-waveform system. The test data are analyzed using both parameter combined with waveform analysis method and the post-extracting technique for waveforms. The results show that: there are reasonable values for the gain value of preamplifier, threshold, the sampling rate, sampling length and band pass filter; amplitude, count, duration, AE signal energy, absolute energy and signal strength are suitable for evaluating the phased damage feature of concrete under uniaxial tension loading; the significant correlations among amplitude, count, duration, rise time and signal strength are found. The study results of this paper can provide reference for the study of concrete failure process using AE technology.
  • Cui Ying;Liu Zhansheng;Ye Jianhuai
    . 2011, 30(5): 205-207.
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    Abstract: A nonlinear dynamic model of rotor - seal - bearing system with ultra-large-scale dimension for an actual steam turbine is proposed, in which the non-linear seal-excited force, the elastic support force of tilting-pad bearing, the damping force, imbalance force and gravity of rotor are considered. The unbalance response of the rotor is numerically calculated by the Newmark method. The typical characteristic of self-excited vibration and threshold speed of instability induced by the seal-force were revealed. The effects of system parameters on dynamic response and instability were also investigated. The results show that appropriately increases of rotor damping, seal’s radius clearance and axial velocity of seal fluid can improve the stability of the system by increasing the threshold speed of instability. The results can be used for improving the stability of rotor-seal-bearing system in the designing and operating of large steam turbine.
  • QI Hui YANG Jie Li Hongliang Yang Zailin
    . 2011, 30(5): 208-212.
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    Abstract: Green’s function and complex function methods are used here to investigate the problem of the scattering of SH-wave by a cylindrical inclusion in right-angle plane with an arbitrary beeline crack. Firstly, Green’s function was constructed which was an essential solution of displacement field for an elastic right-angle plane possessing a cylindrical inclusion while bearing out-of-plane harmonic line source load at any point. Secondly, crack was made out with crack-division technique, and expressions of displacement and stress are written while crack and cylindrical inclusion are both in existent. Finally, some examples and results for dynamic stress concentration factor of the cylindrical elastic inclusion are given, and the influence of crack to dynamic stress concentration factor at the edge of cylindrical elastic inclusion is discussed.
  • REN Xin-jian; LI Guang-xin ZHANG Sheng-min
    . 2011, 30(5): 213-217.
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    Abstract: An explosion-proof pot is a common protection equipment in poblic safety fields,of which index on antidetonation property and mobility is critical for safety protection.At present an explosion-proof pot made in China is heavy and massive,whose performance is bad.In order to generate a portable pot with new style and high antidetonation property, sandwich pot models with aluminium foam were manufactured,and experiments were accomplished to verify their antidetonation property compared with domestic traditional explosion-proof pot.Fading characteristic of stress wave in sandwich structures were analyzed.Core factors which influenced the ability of explosion-proof pot were discussed.Tests indicate that antidetonation property of pots with new style is more excellent than traditional pots.
  • JIN Guang-wen;Zhang Lin-ke;MIAO Xu-hong;Jia Di;Wang Xue-ren
    . 2011, 30(5): 218-220.
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    Abastract: Proceeding from timely reconstructing velocity field and evaluating noise for outer shell of submarine, vibration transmissibility between double shells of submerged cylindrical double-shell structure has studied by underwater vibration test. An finite element model of ribbed cylindrical double-shell was established in the paper. Analyzed the vibration response of shells, and founded the law of transmissibility for cylindrical double-shell in different forms, there are fluid-structure coupling, exciting-forces and connection dimension between double shells. The results of test and calculation provided some theoretical basis for velocity field reconstruct of outer shell and noise source identification of the submarine.
  • Hu Lingling;Chen Yili
    . 2011, 30(5): 226-229.
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    Abstract: The deformation patterns, the carrying capacity, and the energy absorption of honeycombs filled with regular-arranged and stagger-arranged triangular cells under in-plane impact are studied by numerical simulation. The results show that the deformation bound of honeycombs is more and more close to the impact end with increase of impact velocity or decrease of cell wall thickness. The honeycomb filled with regular-arranged cells is crushed row by row to densification, while four kinds of deformation pattern are summed up for the honeycomb filled with stagger-arranged cells. Most of the absorbed energy of honeycomb is translated into internal energy, while kinetic energy has a less proportion. With increase of impact velocity, both of the two kinds of honeycomb are better in both carrying capacity and energy absorption. The proportion of internal energy decreases with increase of impact velocity, while the proportion of kinetic energy increases. The honeycombs filled with regular-arranged cells show better carrying capacity and better energy absorption than the honeycombs filled with stagger-arranged cells, which is attributed to different internal energy absorbed by them, and the difference will gradually diminish after the core region forms in the honeycomb filled with stagger-arranged cells.
  • Zhihui Han;Xuanyi Zhou;Ming Gu;Anan Zhang;Weiyu Zhang;Wei Fang
    . 2011, 30(5): 230-235.
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    Abstract: Based on the wind pressure data from the wind tunnel test, the wind-induced responses of the sun-valley structure of Expo Axis are calculated both in the frequency domain and in the time domain. Then the characteristics of the wind-induced responses are analyzed. The RSM values, the peak values and the power spectral density of some typical displacements and axial force obtained through two different methods above are compared. The results indicate that the RSM values computed in frequency domain are smaller than those in time domain ; the comparison of power spectral density curves shows similar energy distributions; the most unfavorable condition is 225°wind direction.
  • PAN Bo ;SUN Jing ;LOU Li-fen
    . 2011, 30(5): 236-240.
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    Abstract: A correct dynamic model of the generator is the foundation of the analysis on the stability and dynamic characteristics of the system. The current pulse of the consumer is the major source of torsional vibration of drive mechnism in the generator. Considering such current pulse,the dynamic model was established by the lumped pa-rameter method and simulated in MATLAB. And the comparative analysis of the simulation results was carried out. It shows that if the diameter of the shaft is properly increased, the peak torque of torsional vibration on the elastic shaft can be effectively alleviated and the frequency margin is increased. The validity of the dynamic model and the simula-tion results was verified by the dynamic experiments.
  • Wang Jian-qiang;Ding Yong-gang;Li Da-wang
    . 2011, 30(5): 241-244.
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    Abstract: The analysis on energy response of base-isolated structures with friction pendulum system is carried out, the influence of multi-axial ground motions, seismic intensity and bearing friction coefficient about the energy response is studied. When the bilateral horizontal ground motions are considered, the total input energy of the structure and the energy dissipation ratio of base-isolation system will increase, the potential energy dissipation ratio of the superstructure will decrease. When the vertical ground excitation is considered, the total input energy of the structure and the potential energy dissipation ratio of the superstructure will increase, the energy dissipation ratio of base-isolation system will decrease. As the seismic intensity increasing, the total input energy and the energy dissipation ratio of base-isolation system will increase, the potential energy dissipation ratio of the superstructure will decrease. As the friction coefficient of the FPS increasing, the total input energy and the potential energy dissipation ratio of the superstructure will increase, and the energy dissipation ratio of base-isolation system will decrease.
  • ZHANG Jun-bing ZHU Hong-ping WANG Dan-sheng GE Dong-dong
    . 2011, 30(5): 245-251.
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    Abstract: An extended spectral element method (SEM) is established to get the dynamic responses of space truss subjected to seismic load. The seismic load is equivalent to concentrated node forces by integrating the shape function in SEM base on the principle of virtual work. Both internal viscoelastic damping and external viscous damping of truss bar are considered by just simply modifying the wave number. Laplace transform instead of fast Fourier transform (FFT) is utilized in SEM to avoid the periodicity of FFT. To evaluate the accuracy of Laplace-based SEM, the dynamic responses of a space truss under seismic load is analyzed as a numerical example. The numerical results obtained from FEM are compared with those from SEM. It has been found that the SEM provides good dynamic results under seismic load. The equivalent seismic node forces are convenient to get by programming calculation. The SEM has been proved to be an efficient method to analyze the dynamic of structures accurately while the number of elements can greatly decrease.
  • LU Yan-Jun;YU Yang-Bing;ZHANG Yong-Fang;WANG Dong;YU Lie
    . 2011, 30(5): 257-262.
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    Abstract: Based on the Reynolds equation with Reynolds boundary conditions, the Castelli method was employed to solve the Reynolds equation for oil lubrication upon bearings. By doing so, a profile of nonlinear oil film force of single pad journal bearings is established. According to the structure of combination journal bearings, nonlinear oil film force of combination journal bearing is obtained by retrieval, interpolation, and assembly techniques. As for symmetrical flexible Jeffcott rotor system supported by combination journal bearings, the nonlinear motions of the center of the rotor are calculated by self-adaptive Runge-Kutta method and Poincaré mapping during different rotational speed tests under different pivot ratio. Numerical results show that the performance of system becomes slightly better when the pivot ratio changes from 0.5 to 0.6, and reveal periodic, period-doubling, quasi-periodic motion, etc. nonlinear behaviors.
  • WANG Dong-heng;SHI Xiu-dong
    . 2011, 30(5): 263-266.
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    Abstract:The dynamic model of the metal plate spring vibration isolator system was built up. The friction curve was calculated using finite element method. Through the analysis of dynamic equation, the responses of the system under different harmonic exciting forces, as well as the impact of acceleration response were studied .The results indicate: When electronic cabinet loaded on the isolator, the system maximum acceleration reduces by 72%. The metal plate spring vibration isolator has good vibration damping and impact resistance performance. This study will provide a theoretical basis of optimal designing for the dry friction absorber.