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2012 Vol. 31, No. 1 Published: 2012-01-10        论文 1 Theoretical study on a new dynamic multi-direction vibration absorber with ball ZHANG Xiao-long;DONG Ya-bin;ZHANG Xiao-zhong;LI Yu-tian DOI: A dynamic vibration absorber with ball is presented to control the special multi-direction forced vibra-tion. Based on the theoretical analysis and numerical calculation, the mechanism and the effects of parameters of vibration control of the absorber are clarified. According to fixed-points theory, the frequency and the damping of vibration control system are optimized. The results show that the special forced vibration at resonance point of machine or structure can be reduced effectively by using this simple ball type dynamic vibration absorber 2012 Vol. 31 (1): 1-4 [Abstract] ( 747 ) HTML (0 KB)  PDF (1391 KB)  ( 846 ) 5 Ultrasonic guided wave-based damage identification using split spectrum processing algorithm MIAO Xiao-ting;LI Fu-cai;MENG Guang DOI: A split spectrum processing (SSP) algorithm was proposed to estimate the time of flight (ToF) of the damage-scattered fundamental symmetrical (S0) mode by comparing the instantaneous phase variation degree (IPVD) of the captured wave signal from benchmark with that from a damage case, so as to realize the ultrasonic guided wave-based damage identification. Wave signals captured from an intact aluminum plate (benchmark) were firstly acquired in ideal environment (without noise). Then a notch was artificially introduced into the aluminum plate and wave signals captured from the notched aluminum plate (damage case) were acquired in different environments (without and with noise). Experimental results demonstrate that even though the captured wave signal from the damage case has a low signal-to-noise ratio (SNR), the IPVD of the captured wave signal extracted using the SSP algorithm was almost not influenced by the noise. As result, the proposed SSP algorithm was capable of estimating the ToF of the damage-scattered S0 mode with high precision, regardless of the very strong noise disturbance, leading to the successful identification of the notch in the aluminum plate using triangulation algorithm. 2012 Vol. 31 (1): 5-10,3 [Abstract] ( 876 ) HTML (0 KB)  PDF (2030 KB)  ( 303 ) 11 Study on optimal shock isolation design for vibration isolation system with a semi-active control dry friction damper Tang Si-mi;Zhu Shi-jian;Lou Jing-jun DOI: The math model of electromagnet is built, and the relationship between voltage and electromagnetic force is obtained. The dry friction force is controlled by adjusting the electromagnectic force that is applied to the interfaces, and a new semi-active control dry friction damper is designed based on this idea. According to the optimal shock isolation theory, a vibration and shock isolation system is designed, that is composed of semi-active control dry friction damper and a vibration isolator. Based on PID controlling, the performance of shock isolation can be improved greatly while assuming the performance of vibration isolation. The results of shock response and limiting performance analysis show: since the vibration isolation system is redesinged for shock isolation, the semi-active control shock isolator can get much more excellent performance than that of conventional one. 2012 Vol. 31 (1): 11-15 [Abstract] ( 1314 ) HTML (0 KB)  PDF (1385 KB)  ( 514 ) 16 A method for EMD boundary process based on intrinsic wave matching ZHONG You-ming;Zhao Qiang;ZHOU Jian-ting DOI: Hilbert-Huang Transform (HHT) is a new method for processing non-linear and non-stationary signals, which could be dated back to the end of the 20th century. Meanwhile, boundary process is one of its key technologies. This paper focus on introducing a method for EMD boundary process based on Intrinsic Wave Matching —— Intrinsic Wave Matching Prediction Method, especially on introducing the comparison between two representative EMD boundary process methods and Intrinsic Wave Matching Prediction Method in processing simulated signals and tested signals., which validates the advance of Intrinsic Wave Matching Prediction Method. Works of this paper deepen and perfect the existing correlative researches to great degree. 2012 Vol. 31 (1): 16-19 [Abstract] ( 1269 ) HTML (0 KB)  PDF (2125 KB)  ( 837 ) 20 Research of identification technology of dynamic load location ZHU De-chun;ZHANG Fang;JIANG Jin-hui DOI: Used a simply supported beam as the research object, proposed a dynamic load location identification method of "Law of the minimum coefficient of determination". Forecasted the virtual location of the load, two equivalent dynamic loads of virtual location were identified based on two groups of seclecting acceleration responses in the frequency domain. Ordered the difference of the two to be an optimal target variable, the virtual position that the target variable corresponding to is the real loading position. Simulation and experimental results show that the method is correct and feasible. 2012 Vol. 31 (1): 20-23,4 [Abstract] ( 1156 ) HTML (0 KB)  PDF (1234 KB)  ( 849 ) 24 Application research on separating noises from blasting vibration signal based on sgwt XIE Quan-min;LONG Yuan;LU Fan-dong;ZHONG Ming-shou;MAO Yi-min DOI: To improve the analysis efficiency and quality of the test signal, the second generation wavelet transform was introduced to separate noises from blasting induced vibration signal. By Daubechies and inter-polation subdivision wavelets based on lifting scheme, the wavelets decomposition-threshold denois-ing-reconstruction of blasting induced vibration signals were carried out and satisfactory results were achieved. Through the comparison of denoising quality and efficiency of four different lifting wavelets, the method to select the best one which is suitable for analyzing blasting induced vibration signals was got. The method pro-vides reference for the introduction of SGWT to the analysis of blasting induced vibration signals and can real-ize extracting rapidly of the blasting induced vibration characteristics. 2012 Vol. 31 (1): 24-28,4 [Abstract] ( 1175 ) HTML (0 KB)  PDF (2111 KB)  ( 486 ) 29 Experimental investigation of the worst case forced response localization of a mistuned bladed disk assemblies LIAO Hai-tao;WANG Shuai;WANG Jian-jun;LI Qi-han DOI: In order to validate the numerical methods and phenomena that have proposed by the previous theoretical study, the experimental demonstration are carried out. The numerical methods is first used to predict the worst-case mistuning patterns under different engine order excitations , the measurement of the validation blisk response to an engine order traveling wave excitation is then accomplished using the optical measurement systems. The results of the experimental data are used to verify the theoretical and numerical predictions about bladed disk dynamic behaviors. Good agreement between experimental measurements and finite element anal-ysis is obtained. The occurrence of mistuning jump- forced response localization phenomena is also validated. 2012 Vol. 31 (1): 29-34 [Abstract] ( 690 ) HTML (0 KB)  PDF (2956 KB)  ( 354 ) 35 Researched of vibration characteristic of launcher guider of MRLS in firing process He Jun-yi;Rui Xiao-ting;Wang Guo-ping;Zhan Zhi-huan DOI: To obtain the vibration characteristic of launcher guider muzzle of Multiple Launch Rocket System(MRLS) exactly in the firing process, The vibration characteristic of launcher guider muzzle of MRLS was researched. The dynamic model of MRLS and the simulation system was established by using transfer matrix method of multibody system and the theory of firing dynamics, The model were validated by the mode test results of the original vibration characteristic of MLRS; The time history of vibration signals at launch guider muzzle in the firing process was obtained by the simulation system, by using the technology of discrete Fourier transform(DFT), the frequency characteristic of displacement, velocity and acceleration at launch guider muzzle in the firing process was obtained. Basing on this, the Elliptic filter was designed, and by the comparison of the acceleration signal at the launcher guider muzzle with the filter and without, the context researched is useful and important was proved, and the important reference value for the movement signals of the launcher guider of MRLS measured and controlled in the firing process was offered. 2012 Vol. 31 (1): 35-38,1 [Abstract] ( 637 ) HTML (0 KB)  PDF (1423 KB)  ( 864 ) 39 Research on complicated finite element model updating based on bayesian method Han Fang;Zhong Dong-wang;Wang Jun DOI: It is proved that the Bayes criterion function method based on maximum entropy principle is in accordance with the regularization method solving ill-posed problems from the probabilistic perspective, and a new method based on information fusion and Bayes for model modification is established. Samples are designed by test and second-order response surface is adopted as the fast operation model which can be easily modified and perfected by fully use of prior information(design code information, the finite element calculation information and test information).This method can be generalized to large and complicated nonlinear structures for its computational efficiency and solution convergence.The underground powerhouse of pumped-storage power station is employed to verify the effectiveness of the method. 2012 Vol. 31 (1): 39-43 [Abstract] ( 1081 ) HTML (0 KB)  PDF (941 KB)  ( 533 ) 44 Study on reducing vibration characteristics of b-g platform damper using micro-slip model HE Shang-Wen; REN Xing-Min; QIN Wei-Yang;DENG Wang-Qun DOI: Elastic shear layer is introduced into friction surface to simulate dry friction contact. Considering that dry friction surface may pass through three phases as fully viscosity, partial slip, and gross slip during the vibration, an improved micro-slip model is presented. By employing this model, hysteresis curve of friction-to-displacement is obtained, the results agree well with practical data. The friction distribution on friction surface is analyzed under various external forces, and the real condition of micro-slip model is revealed. Further more, by using method of equivalent linearization associated with first order harmonic balance method (HBM), influences of multiple parameters on the equivalent stiffness and damping, and characteristics of reducing vibration of the dry friction damper are studied. Conclusions drawn from the analyses of the simulations above will be helpful for design of B-G platform damper. 2012 Vol. 31 (1): 44-48 [Abstract] ( 1332 ) HTML (0 KB)  PDF (1478 KB)  ( 420 ) 49 Transient wave response analysis of bridge under vertical earthquakes XU Ran;YIN Xiao-chun DOI: Under the strong ground motion excited by vertical earthquakes, structural damage may occur in bridges. Based on the model of a single-pier and two-span continuous bridge under vertical earthquakes, the transient wave effect approach is presented to solve the transient responses of the bridge . The numerical results show that the propagations of stress wave including reflection, reaction and wave impacts throughout the pier and the girders can be depicted. By the comparison of the seismic responses of bridge with different vertical-to-horizontal peak acceleration ratio, it is shown that the responses characteristics change obviously with increasing of vertical-to-horizontal peak acceleration ratio. Four main variations of response characteristics might take place as the ratio increase. Firstly, the fluctuating of contact force between the superstructure and the pier increases and the larger contact force may damage bridge bearing. Secondly, the smaller contact force and even the zero contact force may largely increase the possibility of the sliding between the superstructure and pier. Thirdly, the tensile stress that even exceeds the tensile strength of concrete takes place in the pier originally in whole compressed stress state when the ratio is small, and the alternating tensile-compression stress make the pier bottom in a dangerous stress state. Finally, the maximum dynamic deflection of the middle of the superstructure exceed to the deflection of the ending, implying that the superstructure may jump up. 2012 Vol. 31 (1): 49-55 [Abstract] ( 628 ) HTML (0 KB)  PDF (1616 KB)  ( 428 ) 56 Study on the superposition effect of shock waves in the formation of the grouped multiple explosive formed projectile ZHANG Yang-yi;LONG Yuan;JI Chong;MA Hai-yang;ZHOU Xiang;HE Yang-yang DOI: To investigate the forming mechanism of Multiple Explosive Formed Projectile（MEFP）and find the key factors effecting forming aerodynamic projectile, LS-DYNA was used to simulate the forming process of the grouped MEFP on the condition of simultaneous and asynchronous detonation. Also the superposition effect of shock waves was theoretical analyzed. The study indicates: the superposition of the shock waves which are reflected by parietal cliff of the charge and top of the liner is the reason of the center projectile tend to break with a bigger velocity and the around projectile has an asymmetrical shape; Choosing a low density filled material with a good energy absorption characteristic can minimize intensity of the reflect waves and superposition effect; When the detonating delay is bigger than 5µs, the liner of center charge would be “over collapsed” which is against the formation of the projectile. The conclusions can supply a theoretic basis for choosing a property filled material、confirming the space between the charges and adjusting precision of the multi-point detonating equipment. 2012 Vol. 31 (1): 56-60 [Abstract] ( 1153 ) HTML (0 KB)  PDF (1839 KB)  ( 574 ) 61 Experimental research on the shock test of fiber bragg grating strain sensors in SHPB YANG Ji-xiang;YU Shang-jiang;CHEN Xian DOI: FBG strain sensors packaged by the carbon fibre reinforced polymer is developed which can be used to measure dynamical strain in the concrete under the impact of high-speed collision or the Explosion and Shock. In the split Hopkinson pressure bar the high-speed impact tests were conducted with the Fiber Bragg Grating and the FBG strain sensos, the results indicated that: the transient response rise time of the FBG sensors is less than 20μs, with good dynamical response characteristics, it can be used to measure the dynamical strain in the concrete structures under high dynamic strain test under the impact of high-speed collision. 2012 Vol. 31 (1): 61-63,8 [Abstract] ( 1159 ) HTML (0 KB)  PDF (1321 KB)  ( 281 ) 64 Experimental analysis and dynamic model of a gun magneto-rheological damper LI Zhao-chun; WANG Jiong DOI: As the gun magneto-rheological damper works in the conditions of high impulsive loading, its dynamic characteristic and mechanical model are different from the common MR damper. A MR damper used for recoil system is designed according to a type of gun. The dynamic tests under 5 kind of current are carried out which verifies the feasibility of the MR damper to control the recoil motion. The experimental analysis results show that the output force of the MR damper is not only related with the applied current and recoil velocity but also with the inertia force, gas pressure in the cylinder, and the complexity of MR effect when subjected to impact loading. An improved polynomial model, which is of simple form, easy to solve the inverse model and suitable for real time control, is presented in this paper. After parameter identification, the polynomial model can well describe the relationship of recoil velocity and output force during recoil motion. 2012 Vol. 31 (1): 64-67 [Abstract] ( 1135 ) HTML (0 KB)  PDF (1202 KB)  ( 427 ) 68 Testing and analysis on vibration of Plastic concrete impermeable wall caused by dynamic compaction ＬＵＦａｎｄｏｎｇ;ＦＡＮＧＸｉａｎｇ;ＤＯＮＧＷｅｎ;ＤＩＮＧＫａｉ;ＬＩＤｏｎg DOI: A plan based on vibration test of plastic concrete impermeable wall caused by dynamic compaction is presented. Experimental data shows: acceleration control index 0.1g is more stringent than speed control index 5cm/s; safety protection ranges of five different damping energy levels are given. Based on time-frequency analysis of HHT method, dominant frequencies of monitor points of plastic concrete impermeable wall under different damping energy levels are lower than 20Hz; Rayleigh wave plays a dominant role on vibration of plastic concrete impermeable wall which is buried five meters deep under the land surface, performed as the top of the wall vibrated firstly and the largest data appeared at the top; stress distributes uniformly along the wall in the vertical direction; due to the influence of layered foundation to Rayleigh wave, when dominant frequency descends ,wave velocity and wave length are increased, so do maximum instantaneous energy and energy at dominant frequency. 2012 Vol. 31 (1): 68-71,1 [Abstract] ( 654 ) HTML (0 KB)  PDF (1583 KB)  ( 758 ) 72 The characteristics of acoustic wave propagation along the non-periodic ideal drill strings ZHANG Mei-ling;YAN Xiang-hong;LIU Wen-li;SU Yuan-da;CHEN Xue-lian;LU Bin DOI: The non-periodic structure’s dispersion equation and the sound attenuation equation have been given based on the one-dimensional model of sound propagation. The relationship between the geometry parameters of drill strings with the dispersion characteristic as well as the attenuation characteristic is investigated numerically for a non-periodic drill string system, and the FEM software- ANSYS were used to confirm the theory results. The results shows that the dispersion characteristic of a non-periodic drill string system is identical with the result from of 'and' operation of dispersion characteristic of multiple periodic structure systems．The non-periodic structure’ passband is narrow while the stopband is wide, If the sound wave frequency were in the stopband, the acoustic attenuation would be larger than it in passband. 2012 Vol. 31 (1): 72-75 [Abstract] ( 1001 ) HTML (0 KB)  PDF (1293 KB)  ( 325 ) 76 Experimental study on seismic behavior of new steel truss coupling beams Deng Zhi-heng;Lin Qian;Hu Qiang;Pan Zhi-ming;Xu Dong-xiao DOI: Based on the pseudo-static test of 8 small span-depth ratio steel truss coupling beams, the composite coupling beams' failure characteristics, shear-bearing capacity, deformation capacity, hysteretic curve, Skeleton, ductility, energy dissipation, rigidity decline and reasonable truss style are analyzed. The test results show that: The steel beams with cross abdominal trusses have bigger shear-bearing capacity and better ductility and energy dissipation capability than those beams without cross abdominal trusses. A better bearing capacity can be obtained when span-depth ratio is smaller and stiffness is bigger .The two design methods of the beams’ ends, pre-buried steel plates and buried steel chord members in concrete, are available and easier to construct than reinforced coupling beams . The steel truss coupling beams have fairly good mechanisms and seismic behavior. 2012 Vol. 31 (1): 76-81 [Abstract] ( 1069 ) HTML (0 KB)  PDF (2715 KB)  ( 881 ) 82 System parameter sensitivity analysis under multi-source random excitation Tang Fan;Wang Xi-ping;Zhu Wen-hai;Zhou Shen-jie DOI: Parameter sensitivity expression excited by random excitation were presented with the theory of decoupled in state space, Kronecker algebra, matrix differential and pseudo-excitation method. According to the parameter sensitivity caculation result and requirment of actual engineering, the ride comfort of ligth-duty truck model was optimized with MATLAB. Meanwhile the optimization included linear and nonlinear constraint condition. 2012 Vol. 31 (1): 82-85 [Abstract] ( 686 ) HTML (0 KB)  PDF (899 KB)  ( 409 ) 86 Parameter optimization study for unseating prevention device of rc simple-supported girder bridge based on nonlinear static and dynamic analysis methods JIANG Hui;Li Yu;Xiong Zhi-yang;YANG Qing-Sshan;ZHU Xi;ＮＩＹｏｎｇ-ｊｕｎ DOI: Unseating prevention device is an effective measure to forefend beams from falling from RC girder bridges, so it is necessary to study thoroughly the reasonable range of the stiffness of this rubber-tie bar device. Based on capacity spectra method of FEMA440, a typical railway RC simple-supported girder bridge was taken to discuss the stiffness distribution for different site soils and fortification intensities under the seismic demand of current design spectra and Wenchuan Earthquake. It indicates that the site soil has no obvious influence on the stiffness value of unseating prevention device, and the rational stiffness ratio is between 0.05~0.15 times of the linear stiffness of the adjacent beams for 8 degree of high-level fortification intensity, in which condition the relative displacement between the piers and beams as well as the overall structural response can be effectively repressed. However, the fortification intensity has remarkable influence on the stiffness. When PGA is less than 0.2g, it is not essential to install unseating prevention device, and when PGA is 0.4g and 0.6g, the reasonable stiffness ratio may be 0.1 and 0.2 respectively. The rationality and reliability of above conclusion was validated by nonlinear time history analysis, which can provide reference for the seismic design of RC bridges and the revision of related seismic design codes 2012 Vol. 31 (1): 86-91,9 [Abstract] ( 1006 ) HTML (0 KB)  PDF (2250 KB)  ( 299 ) 92 Cause analysis on vertically and horizontally beams of bodies floor cracking and rupture of dump truck by the ore impact ZHU Long-long;Liu Da-wei;Wang Feng;Cheng Xiao-dong DOI: This article aims to the issues of the vertically and horizontally beams of bodies floor cracking and rupture of heavy dump truck by the ore impact. The FEA model of dump truck was established by taking plate as basic element by using the so-called HyperMesh software, the FEA model of ore was established according to the loading characteristics, the explicit dynamic finite element method was applied by using ANSYS / LS-DYNA as solver and the impact response of different quality ore falling from different heights to the bodies floor of dump truck was solved. The results of our analysis indicate that: the vertically and horizontally beams of bodies floor abnormal cracking and rupture is that the impact stress value of floor joints on vertical and horizontal beams is greater than the minimum tensile strength of the material, and this is consistent with the actual situation of cracking and rupture. When the thickness of bodies floor is 16mm and the quality of falling ore is heavier than 0.3t, the maximum stress value of cracking and rupture is greater than the yield strength (345 MPa) or minimum tensile strength (470 MPa) of the material. To avoid the phenomenon of vertically and horizontally beams of bodies floor abnormal cracking and rupture, we should limit the quality and falling height of the ore under the condition of the determined thickness of bodies floor. 2012 Vol. 31 (1): 92-96 [Abstract] ( 1207 ) HTML (0 KB)  PDF (1856 KB)  ( 418 ) 97 A optimal separation hyper-sphere classification model with double proportion control parameters WU Ding-hai;Zhang Pei-lin;Wang Huai-guang;Wang Zheng-jun;Wang Guo-de DOI: After analysis the disadvantage of unsupervised training of support vector data description(SVDD) and combine the advantage of optimal separation hyper-plane and SVDD, the supervision with the information of negative class and the hyper-sphere classification model with optimal Separation are proposed with one minimum hyper-sphere including positive class and one maximum hyper-sphere excluding negative class, and then the decision hyper-sphere can Separate the two hyper-spheres with max distance which improves the model’s description accuracy and generalization performance. To removal the interference of bad point, a method of double proportion control parameter is proposed which can realize soft separation. Experimental results on Banana and UCI data sets show that the proposed model has better classification performance than SVDD. 2012 Vol. 31 (1): 97-100 [Abstract] ( 626 ) HTML (0 KB)  PDF (1137 KB)  ( 266 ) 101 Semi-active Fuzzy Control for Cylindrical Turning Chatter ＺＨＡＮＧ Ｙｏｎｇ-ｌｉａｎｇ;ＬＩＨａｏ-ｌｉｎ;ＬＩＵＪｕｎ;ＹＵＪｕｎ-ｙｉ DOI: Smart material is increasingly being used for vibration control systems due to its fast response, easy control and little energy consumption. In this paper, A damping device based on smart materials——electrorheological fluid (ERF) was developed to suppress the chatter in turning slender shaft. The theoretical analysis shows that the control voltage corresponding to the best damping effect is not the same under different cutting conditions. Thus, a fuzzy control system with ERF for turning chatter was developed, and semi-active fuzzy control experiments were carried on. The experimental results show that under different cutting conditions the fuzzy control systems can adjust the control voltage adaptively so that the acceleration response were reduced and the chatter was inhibited. 2012 Vol. 31 (1): 101-105 [Abstract] ( 1043 ) HTML (0 KB)  PDF (2107 KB)  ( 436 ) 106 Mechanical impact faults extraction method based on nonlinear manifold learning for continuous wavelet coefficients LI Mao-lin;LIANG Lin;WANG Sun-an;ZHUANG Jian DOI: To acquire the impact component aroused by mechanical fault, a novel feature extraction method based on nonlinear manifold learning for continuous wavelet coefficients is put forward. Firstly, the wavelet entropy method is adopted to optimize the Morlet wavelet shape factor in order to match with the impact components to obtain the optimal continuous wavelet coefficients. Secondly, the nonlinear manifold learning algorithm named local tangent space alignment is used to the reduction analysis of the optimal wavelet coefficients matrix, and according to the principle of the maximum kurtosis index, the low-dimensional embedded vectors which introduced to reflect the impact of the failure are extracted from the global coordinates feature matrix. Finally, the simulation and industrial applications show that this approach, compared with the singular value decomposition, is effective to extract not only the weak periodic impacts with the greater kurtosis in time waveform, but also the fault feature frequency in frequency spectrum. 2012 Vol. 31 (1): 106-111, [Abstract] ( 721 ) HTML (0 KB)  PDF (2209 KB)  ( 839 ) 112 Dynamic characteristic analysis of open-loop system for the intelligent beams with interval parameters WANG Min-juan;CHEN Jian-jun;WEI Yong-xiang;ZHANG Chao;MA Hong-bo DOI: Structures with piezoelectricity intelligent beam are taken as research objects in this paper. According to the method of interval analysis, the interval model of mass matrix and stiffness matrices with the interval variables for structural physical parameters and geometric dimensions is built. From the Rayleigh quotient of dynamic characteristic of structural vibration, and based on the interval algorithms, the computation expression of structural natural frequency of open-loop system is obtained. Via an example, the effects of the uncertainty of the structural interval parameters on the structural natural frequency were inspected, and the model constructed and the method presented in this paper are verified, by which it is verified that the interval coefficient method is of importance value in engineering in dealing with the dynamic characteristic of open-loop system of the intelligent beam. 2012 Vol. 31 (1): 112-115, [Abstract] ( 1174 ) HTML (0 KB)  PDF (1648 KB)  ( 312 ) 116 The influence of conductor structure and loads on the galloping of transmission line ZHOU Kun-tao;HAO Shu-ying;LIU Jun;ZHANG Qi-chang DOI: For profoundly understanding the influence of conductor structure forms and aerodynamic torsion loads on the dynamic characteristics, the galloping law and amplitude of iced transmission line, a computer program based on nonlinear finite element analysis was developed by applying ANSYS parametric design language, time history curve was obtained. Result indicates that: the galloping amplitude of the bundle conductors is obviously greater than a single conductor, Time needed to come into being steady state of galloping decrease noticeably as more conductors are added ,in the same weather conditions, consequently single conductor and less numbers of conductors in bundle should be adopted as far as possible; aerodynamic torsion loads have slight influence on galloping law and amplitude for in-plane and out-of-plane galloping, but have a greater effect on the amplitude of angle of torsion, therefore the effect of the aerodynamic torsion loads on the breaking of iced transmission lines and towers can be ignored. 2012 Vol. 31 (1): 116-120 [Abstract] ( 712 ) HTML (0 KB)  PDF (2594 KB)  ( 587 ) 121 Structural damage identification based on anslysis of modal strain energy and wavelet transformation YAN Ping;LI Hu-sheng;GE Ji-ping;YE Qian-yuan DOI: Single method for structural multiple different degree damage identification is not sensitive to small defects. The paper presents an approach of structural damage identification based on modal strain energy and wavelet transformation characteristics to denote local signal in time domain or frequency domain and process any details of the signal or function. The structural damage index is given out with the change and distribution of wavelet transform coefficients based on elemental modal strain energy. Through the numerical simulation of a simply supported beam and a cable-stayed bridge model experiment study, the method compared with elemental modal strain energy method can effectively determine the structure multiple different degree damage location and estimate damage degree. The method research laid the foundation for the practical application of engineering 2012 Vol. 31 (1): 121-126 [Abstract] ( 1345 ) HTML (0 KB)  PDF (2001 KB)  ( 869 ) 127 Pump cavitation state estimation based on the complexity and symbolic space Song Xiang-rong;Li Jian-kang DOI: In order to construct the symbolic space to descript the dynamic characteristics of structure, vibration response sequences of several points are measured. First, these sequences are converted to symbolic series by using the multi-segmented coarse-grained method. With the Lempel-Ziv complexity analysis, the symbolic space is constructed. A centrifugal pump is studied as an example. Its cavitation state is estimated in the symbolic space. It provides a novel method of state estimation to the complex structures difficult to exact modeling or the structures working in complexity environment. 2012 Vol. 31 (1): 127-130 [Abstract] ( 1236 ) HTML (0 KB)  PDF (1388 KB)  ( 311 ) 131 Design and FEM analysis of assembled biconical energy dissipator(BED) Zhou Yun;Huang Hui-min;Zhu Yong DOI: The author figures out a new type of assembled Biconical Energy Dissipator, called BED for short. Carrying on the FEM analysis for 18 pieces of BEDCs(Biconical Energy Dissipated Cell) and 3 pieces of BEDs, the author gains the characteristics of the BEDs, including the hysteresis performances, stress distribution forms and practical assemblies. The analysis results turn out that if the height of the BEDC is determined, the initial stiffness and the yielding displacement of the BEDC are determined by the height of the bigger cone; the yielding displacement can be set less than 1mm; the energy dissipation index can reach 2.6; the hysteresis performances of different patterns of the assembled BEDs depend on the adopted BEDCs and the stiffnesses of the top and bottom connecting plates, in case of the connecting plates have enough stiffness, the relative hysteresis performances parameters of the BED can be gained by superposition of the relevant parameters of the adopted BEDCs, such as the initial stiffness, the yielding displacement and the coefficient of energy dissipation. 2012 Vol. 31 (1): 131-139 [Abstract] ( 975 ) HTML (0 KB)  PDF (5076 KB)  ( 284 ) 140 A simulation research on a new combination denoise algorithm for narrow-band signal Li Yong-jun;Ma Li-yuan;Wang Tian-hui;Duan Yong-gang DOI: A spectral-line enhancement algorithm based on linear combination is applied to denoise the narrow vibration signal. Aim at the disadvantage of traditional adaptive spectral-line enhancement algorithm, a new LMS algorithm with output feedback is brought out in this paper., which comprise the historic information output by filter and the output by the linear combination to form the new output. So a new algorithm is set up. The effect of the combination filter is researched with Matlab simulation. The simulation and actual signal is applied in the simulation. From the results of simulation, it can be concluded that the new algorithm is better than the original algorithm in time domain waveforms, and the performance of the noise reduction is verify. 2012 Vol. 31 (1): 140-143 [Abstract] ( 1169 ) HTML (0 KB)  PDF (1930 KB)  ( 1095 ) 144 Dynamic properties analysis of hydraulic rubber isolator under the excitation with different amplitude Pan Xiao-yong;Xie Xin-xing;Shang-guan Wenbin; DOI: The dynamic properties of a typical hydrobush are tested. It’s shown that the amplitude dependency and frequency dependency of the hydrobush dynamic properties are correlative. Hyperelastic-viscoelastic-plastic (VEP) Finite Element model of a hydrobush, containing hyperelastic-viscoelastic (VE) model and elastic-plastic (EP) model, is constructed based on an approach named mesh-superimposition. The dynamic properties of main rubber element (MRE) of the hydrobush is calculated by VE model and VEP model respectively, the simulation results of the two models have been compared, the results show that using VEP model can help to express exactly the contribution of MRE to the hydrobush dynamic properties. The Fluid-Structure Interactive (FSI) model of a hydrobush is described in details. Furthermore, the VE model and VEP model are applied respectively in the analysis for the dynamic properties of a hydrobush using FSI method. The simulation results of the two models have been compared, the results show that VEP model is better than VE model to reflect the actual correlation characteristic of the amplitude dependency and frequency dependency of the dynamic properties for a hydrobush, these methods would give effective guidance to early development and design of hydraulic rubber isolator. 2012 Vol. 31 (1): 144-149 [Abstract] ( 763 ) HTML (0 KB)  PDF (2873 KB)  ( 803 ) 150 Targeted energy transfer in coupled nonlinear oscillators I: complete energy exchange in conservative system Zhang Y C;Kong X R;Zhang H L DOI: Targeted energy transfer in a system of two-degree-of-freedom coupled nonlinear oscillators is investigated. Based on the slow-flow dynamics of the original system, the relation between complete energy change and the initial conditions is derived in the first part of the research. Numerical simulation shows that the initial energy required for complete energy exchange between the two oscillators can be calculated precisely using the formula derived; and the initial energy required for optimal targeted energy transfer also can be approximately estimated under the assumption of small damping. 2012 Vol. 31 (1): 150-155 [Abstract] ( 734 ) HTML (0 KB)  PDF (1312 KB)  ( 483 ) 156 Study of big charge blasting damping and monitoring under intracity complicated environment JIANG Yao-gang;SHEN Zhao-wu;YANG Chang-de DOI: With the background of one garden building foundation and underground garage excavation blasting, several of vibration damping technologies were adopted to actualize large blasting excavation in city, blasting vibration was real-timely monitored by instrument, and vibration data was analyzed. Finding that the vibration peak of the monitor points around blasting zone was too small (less than 1cm/s) to cause damage for surrounding structure. The vibration peak, main frequency and duration time in fore-and-aft monitoring points was more than one in transverse, the frequency spectrum energy distribution in fore-and-aft monitoring points was more centralized than one in transverse, The vertical signal frequency spectrum energy of the monitoring points were centralized between 7.8125 and 62.5Hz. with the increase of height when the blasting vibration propagate between floors in high buildings, the vertical blasting vibration peak and signal response energy increased, and the frequency spectrum energy distribution was more centralized, the vibration peak on the top floor was about two times than one on the bottom，the signal energy on the top floor is about three times than that on the bottom of buildings. 2012 Vol. 31 (1): 156-161 [Abstract] ( 1219 ) HTML (0 KB)  PDF (1585 KB)  ( 979 ) 162 A modified frequency spectrum correction method based on the phase difference correction method HU Wen-biao;XIA Li;XIANG Dong-yang;WU Zheng-guo DOI: Amplitude correction can not void dependence of the spectrum functions of window functions, when the phase difference correction method is employed to correct frequency spectrums. However certain window functions are very complex actually and the analytic expression of their spectrum function can’t be obtained. This paper proposed a novel amplitude correction method. After frequency correcting value is calculated based on the phase difference correction method, a new numerical sequence can be obtained by multiply the primary sequence and a plural sequence which is produced by the frequency correcting value. Then signal frequency of the new plural sequence aims at a certain spectral line, and frequency spectral analysis doesn’t produce the leak of the frequency spectrum. So the amplitude correction doesn’t depend on the spectral functions of window functions. Computer simulation results and the application example demonstrate that we can achieve the ideal correction precision even if in the dense distribution frequency spectrum by using the method which this paper proposed and choosing the appropriate window function. 2012 Vol. 31 (1): 162-166 [Abstract] ( 998 ) HTML (0 KB)  PDF (831 KB)  ( 744 ) 167 Evolution of micro-cracks in composite laminates and the effect to elastic moduli under low velocity impact Zhang Si-jin;Wen Gui-lin DOI: The evolution of micro-cracks in a lamina of composite laminates is studied by using double-linear characteristic model of damage. With the representation of crack-effect coefficients for elastic moduli, a set of ordinary differential equations about crack-effect coefficients are derived. Furthermore, the relations of dissipated power with crack-effect coefficients are also presented during the cracking process. Together with the dynamic governing equations of a composite laminate, these ordinary differential equations can be solved when initial conditions are known, yielding the crack-effect coefficients. Hence the micro-cracks’ expanding in every point of a lamina and its effect to elastic moduli can be obtained. Subsequently, the distribution regions of micro-crack after impact are predicted by examining whether any of crack-effect coefficients is changed at all points in the lamina. The result shows that the elastic moduli start to decay in the point where the stress reaches its yield strength, and the decaying amplitude increases as the initial impact speed of iron ball being raised. With all boundaries being clamped, the distribution regions of micro-crack appear initially both near the impact point and near the center of boundaries of composite laminates. Moreover, they expand as the initial impact velocity being raised 2012 Vol. 31 (1): 167-172 [Abstract] ( 1135 ) HTML (0 KB)  PDF (1563 KB)  ( 255 ) 173 Total reflection through effect of elastic wave in 1D phononic crystal LIU Qi-neng DOI: For studying total reflection through effect of elastic wave in 1D phononic crystal , the transition matrix method is adopted and the transmissivity of elastic is studied when incident angle greater than full reflection angle. Two transmission peaks are found in the transmission wave, it is total reflection through effect . Response curves of the through effect versus incident angle is obtained and response curves of the through effect versus medium thickness is obtained and response curves of the through effect versus cycle number is obtained. Total reflection through effect of elastic wave in 1D phononic crystal is explained with the theory of quantum and the theory of evanescent wave. 2012 Vol. 31 (1): 173-176 [Abstract] ( 1175 ) HTML (0 KB)  PDF (1590 KB)  ( 738 ) 177 Analysis of dynamic behavior of externally prestressed beam by energy method Fang De-ping;Wang Quan-feng DOI: The assumption in the analytical method is not adopted, that is, the prestress increment of external tendon is proportional to the mid-span vibration displacement of the beam. The energy method to analyze the dynamic behavior of externally prestressed beam is presented. Due to not adopting the assumption in the analytical method, the natural vibration frequencies are more accurate, and conform well to the numerical results. The calculation results show: the effect of external tendon on 1st frequency is underestimated, and the effect on 2nd frequency is overestimated by the analytical method; the influence of externally prestressed tendon on 1st frequency is significant, the influence on higher frequencies is slight and can be neglected; with increasing the area and the eccentricity of external tendon, the frequency of the beam increases. Theoretically, the external prestress can reduce the 1st frequency of beam, but internal prestress has no influence on the frequency of beam. 2012 Vol. 31 (1): 177-180 [Abstract] ( 637 ) HTML (0 KB)  PDF (907 KB)  ( 353 )

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