25 April 2011, Volume 30 Issue 4
    

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  • LV Hong-ming;ZHANG Li-jun;YU Zhuo-ping
    . 2011, 30(4): 1-7.
    Abstract ( 1275 ) Download PDF ( 1524 )   Knowledge map   Save
    Abstract: Disc brake squeal is one of the most difficult quality issues concerned by automotive manufacturers and researchers. It is of critical importance to study the squeal generation mechanism, predict the brake squeal performance and propose the count measures in the product development phase for decreasing the noise pollution, satisfying customer requirements, accelerating new product development to improve the automobile competitiveness. The recent research advances are reviewed from the aspects of squeal generation mechanisms, analysis methods, influence factors and new technologies. Latest developments show that disc brake squeal is caused by complicated mechanisms and influenced by many factors. Utilizing modern design methods of complex eigenvalue analysis and transient dynamics analysis combined with on-road and bench tests is an important way to analyze the brake vibration characteristics and develop disc brakes with low squeal propensity. The existing problems and the further research needed to be carried out in the future are finally discussed.
  • ZHU Bo;ZHOU Ding;LIU Wei-qing
    . 2011, 30(4): 8-11.
    Abstract ( 1049 ) Download PDF ( 523 )   Knowledge map   Save
    Abstract: Using the finite element software ANSYS, a physical model is developed for the elasticity analysis of the sandwich plates reinforced by resinic columns. The SOLID82 elements are used to calculate buckling, free vibration and transient response. The effects of the material properties and the distributions of the resinic columns on the buckling loads and natural frequencies are studied. The displacement response of the plates under the transient shock is also discussed. The results show that the resinic columns have some contributions to the mechanical properties of the sandwich plates. The modulus influence of resinic columns on buckling and vibration of the composite plates is small. However, the distribution effect of the resinic columns on the mechanical properties of the composite plates is considerable.
  • HU Liang;GU Ming;LI Li
    . 2011, 30(4): 12-15.
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    Abstract:This paper derived the bias errors and the stochastic errors produced by wind field simulation using the proper orthogonal decomposition (POD)-based spectral representation method. An N-point Gaussian wind field is considered by taking its simulation formulas into account. The temporal first- and second-order statistics of the simulated wind process, i.e., mean values, correlation functions, power spectral densities and standard deviations, are derived to be stochastic variables or processes. Mean values and standard deviations of these derived random variables or processes thus lead to the bias errors and the stochastic errors of the temporal sample statistics, respectively. Finally, these close-form solutions of the errors are validated by a numerical example.
  • LIU Jian;QIU Jin-hao;CHANG Wei-jie;JI Hong-li;ZHU Kong-jun
    . 2011, 30(4): 16-20.
    Abstract ( 1047 ) Download PDF ( )   Knowledge map   Save
    Abstract:MPF (Metal-core Piezoelectric Ceramic Fiber) is a new type piezoelectric ceramic device. The configuration and its response to Lamb-wave fields excited by circular crested actuator are presented in this paper. According to calculating time delays of damage signals with Gabor wavelet transform, MPF sensing single-mode Lamb waves in one-dimensional structural damage localization is investigated. Results show that MPF can be used as the sensor for single mode Lamb wave. The performance of calculating of time delays of damage signals using Gabor wavelet transform is good; the damage localization accuracy is also high.
  • Hu JiaShun;Feng Xin;Zhou Jing
    . 2011, 30(4): 21-25.
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    Abstract: The local flexibility equations of the pipe with a crack that straight front and part-through-the-thickness 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. These conquer the shortcoming that existing methods usually apply for calculating special load or non-hollow structure. The model test results from Naniwadekar et al were used to validate the accuracy of the proposed local flexibilit. Moreover, a finite element model for cracked pipe was established to conduct the vibration analysis for cracked pipe-like structure. The vibration characteristics of a cantilever pipe and a simple support pipe were analyzed. The results show that crack location, crack severity all have influence on the natural frequencies of cracked pipe-like structure.
  • Wang Ai Lun;; Huang Fei;
    . 2011, 30(4): 26-28,9.
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    Abstract: Based on the solid modeling method, the finite element model of mistuned bladed disk with through crack was established, The effect of two cracked blades distribution on vibration characteristics of the mistuned bladed was revealed. Research results show that the distribution of two cracked blades can greatly influence the fundamental frequency of the mistuned bladed disk, as well as the degree of modal localization. When two cracked blades locate in the adjacent positions, the fundamental frequency of the mistuned bladed disk is the minimum, and the level of modal localization is the highest. Moreover, the phenomenon is particularly prominent under weak-coupling condition .While the centrifugal force (rotational speed) can weaken on vibratory localization of the mistuned bladed disk with two cracked blades .
  • PEI Jianghong; TANG Chuanlin; HU Dong
    . 2011, 30(4): 29-32.
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    Abstract:As the exploration on self-excited pulsed water jet nozzle of double chambers, based on the theory of fluid network, the mathematical model of the self-excited oscillation pulsed water jet device was established, theory analyses the frequency characteristic of self-excited pulsed water jet nozzle on double chambers. The result shows that structural parameters greatly affect natural frequency of the device. And also, there has the optimized range among structural parameters which is different from the range of singlet chamber nozzle. lastly, self-excited pulsed water jet nozzle of double chambers can improved the surge pressure higher than singlet chamber nozzle in the same condition. The result is useful to the design of pulsed jet nozzle.
  • WU Li-gang;DUAN Xiao-cheng;HUANG Xing;XU-Chi
    . 2011, 30(4): 33-37.
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    Abstract: A kind of semi-active engine mount (SEM) with switchable stiffness decoupler is designed and manufactured, and the dynamic characteristics are measured with MTS 831 servo-controlled hydraulic test rig. The linear Lumped Parameter (LP) model for SEM is proposed. The methods for the calculation of dynamic stiffness and loss angle with high amplitude in low frequency domain are presented using the linear LP model. The dynamic properties of SEM are estimated with LP model, and the predicted results have a good agreement with the experimental data, which validate the proposed LP model. Some applications of SEM for solving NVH (Noise, Vibration and Harshness) problems in powertrain mounting system are illustrated. The presented modeling method and conclusions are contributed to research and development of SEM and hydraulic engine mount (HEM).
  • Li Yan;Wang Weimin;Huang Liquan;Gao Jinji
    . 2011, 30(4): 38-41.
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    Abstract:Automatic balance of rotor is the key technology of the long running of equipments, and normal injection balance device will lose balance ability after some working cycles without dripping the liquid in the chamber, and the vibration will increase with the fist liquid injection. To improve the disadvantage of normal injection balance device, the continuously dripping liquid-injection automatic balance device were developed. The balance device can change the mass distribution of rotor with injecting liquid to right chamber, and it’s balance capability can’t be reduced by dripping. If this balance device applied in equipments which the vibration phase varying, it has two advantages to normal injection balance head, that are fast response to varying vibration and the balance ability not lost. Construct a vibration self-recovery system using the device. The system can analyze the vibration signal on real time and output the unbalance mass and it’s phase, make sure the balance device’s installation position, to balance the unbalance directly by inject liquid, so the rotor vibration will fall in a short time. The balance device was installed on a high gravity machine which is a typical vertical cantilever rotor machine. The experiment results show that the continuously dripping liquid-injection balance device can decrease the vibration effectively, and response to the phase shift in a short time, satisfy the safe long ruing of equipment.
  • WEI Kexiang; MENG Guang;ZHANG Wenming
    . 2011, 30(4): 42-46,9.
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    Abstract: The motion equations of a rotating electrorheological (ER) sandwich beam subjected to base excitation are derived. The vibration stability of the ER sandwich beam under constant angular velocity and harmonic base excitation is studied. The multiple scale method is used to determine the first order approximate analytic solutions and the necessary conditions for the existence of parametric unstable of the beam. The time responses and phase domains of the rotating ER sandwich beam for various excited parameters, electric fields, and rotating speed are presented to demonstrate the parametric dynamic stability of the beam under rotation and based joint excitation. Numerical results show that the critical value of excitation parameter of the rotating ER sandwich beam under base excitation can be adjusted when it subjected to an electric field, and the ER material layer can be used to improve the dynamic stability of the beam.
  • Yu Miao Xia Yongqiang Wang Siqi Zhu Lixi
    . 2011, 30(4): 47-50.
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    Abstract: Magnetorheological elastomer(MRE) is a new kind of Magnetorheological material, which are mainly composed of polymer rubber and micron-sized magnetizable iron particles. The isolator based on MR elastomer has the features of no sealing equipments, good stability and rapid response etc, so it has wide potential applications in the small amplitude vibration systems. In this paper, the isolator’s magnetic circuit design was studied and analyzed by the ANSYS FEM. The analysis can be utilized as a reference for designing and predicting the performances of MRE isolator.
  • LI Hao;MEI Zhi-yuan;ZHU Xi
    . 2011, 30(4): 51-54.
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    Abstract: Sound absorption structure of sandwich composite had been extensively applied because it was designable. In this paper, in order to solving this problem that the density of sound absorption core material of previous sandwich composite structure was larger, a kind of sound absorption structure of light sandwich composite was designed. The surface material of this structure is GFRP, and the core material is polymer sound absorption material synthesized from a variety of hollow glass microsphere, epoxy resin and polyurethane- modified epoxy resin. The thickness of surface GERP material was study and determined. The underwater acoustical properties of specimen were measured in the sound pulse tube. The synthetic formula of core material was determined based the test results of pulse tube specimen. The sample was prepared for anechoic tank test. The sound reflection coefficient and sound absorption coefficient of this sample was measured in the anechoic tank. Then, the sound absorption mechanism of sound absorption structure of sandwich composite was analyzed. The research results showed that polymer sound absorption material synthesized from a variety of hollow glass microsphere, epoxy resin and polyurethane-modified epoxy resin has a low density(relative density 0.8±0.05). Sound absorption structure of sandwich composite has an excellent underwater sound absorption property using this core material. This light sandwich structure must be more conducive to engineering applications because of its low density and excellent sound stealth properties.
  • GAO Yang;YANG Zhi-chun
    . 2011, 30(4): 55-59.
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    Abstract: This paper presents a comparison of thermal flutter characteristics between flat and curved composite panels. Three layup types are introduced to form laminated panels modeled by Finite Element Method (FEM). The nonlinear static analysis is firstly implemented to evaluate thermal effect on structural stiffness and high supersonic flutter analysis is then performed on the panel with updated rigidity. The second order piston theory is employed to represent high supersonic aerodynamics and the flutter speed is predicted by PK method. It is found that the flutter speed of heated panels decrease linearly with elevated temperature increasing. This decreasing tendency moves faster for quasi-isotropic laminates compared with orthotropic laminates in the case of curved panels, whereas the flat panel case is on the contrary. The results show that flutter modes of curved panels are strongly depending on the layup type; however, flutter modes keep consistent for flat panels.
  • Xiao Shi-;Liu Xin-en;Du Qiang
    . 2011, 30(4): 60-63.
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    Abstract: Effectual identification of the structural bolted state is the base to inure the structural reliability and safety. Generally, the traditional identification methods based on modal parameter are not so ideal. At present work, plural and real indication parameters, which present relatively modal connection stiffness, are constructed in the modal space to indicate the structural bolted state. The efficiency of the indication parameters are tested by modal experiments of the bolted beam with different bolted moments. The results show that the indication parameters are more sensitive to the structural bolted state than the nature frequencies.
  • Chen Sheng-bing; Han Xiao-yun; Wang Gang; Wen Ji-hong
    . 2011, 30(4): 64-67.
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    Abstract:The electromagnetic oscillations of piezoelectric shunting circuits can induce locally resonant gap in a phononic rod. The formation mechanisms of locally resonant gap are analyzed. The band gaps of the rod are calculated by transfer matrix method. Furthermore, the influences of inductance, capacitance and resistive in the shunting circuits to the locally resonant gap are summarized. The electromagnetic oscillations of piezoelectric shunting circuits make the equivalent elastic modulus of piezoelectric patch become to negative and reduce elastic modulus of the rod with piezoelectric patch. When the real part of elastic modulus equal to zero, vibration induces sound wave can’t propagate in the rod, so that locally resonant gap produced. The location of locally resonant gap can be actively tuned by changing the parameters of inductance and capacitance in the shunting circuits, which put forward a new way to actively control the band gaps of phononic crystals.
  • Li Chun-xiang;Li Jin-hua;GU Xinhua
    . 2011, 30(4): 68-80.
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    Abstract: In order to comprehensively and comparatively investigate the wind-induced lateral-torsional responses of structures whose mass centers at different floors are not located on a single vertical axis, a dynamic analytic framework of non-coaxial eccentric structures under wind loading is presented in this paper. First, the dynamic equations of a N-storey non-coaxial eccentric building, with 3N-degree-of- freedom, is set up via expanding dynamic equations of a two-storey non-coaxial eccentric structure with 6-degree-of-freedom. Then, based on the power spectra of the aerodynamics wind forces in along-wind, across-wind, and torsional directions established by resorting to the high frequency force balance (HFFB) technique and the multiple point synchronous scanning (MPSS) technique, and simultaneously considering the structural mode coupling and the statistical correlation between across-wind and torsional loading, the wind-induced lateral-torsional coupled responses of structures with non-coaxial mass eccentricity were analyzed in the frequency domain. According to the present framework, the effects of non-coaxial mass eccentricity on the wind-induced lateral-torsional coupled responses of a rectangular steel structure with 120m in height, which is reduced as a three-dimensional analytical model with 15-degree-of-freedom, were analyzed through setting different locations of mass eccentricity.
  • Zhang Jingchuan; Zeng Zhoumo; Cao Qingsong; Feng Hao; Jin Shijiu
    . 2011, 30(4): 81-85.
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    Abstract: Aiming at the limitation of conventional cross-correlation algorithm for time delay estimation, a cross-correlation algorithm for time delay estimation based on Independent Component Analysis (ICA) for location of petroleum pipeline abnormal vibration events was proposed, which was used in the distributed optical fiber petroleum pipeline safety detection system for the safety of pipeline. During the pipeline detection, the environment is very complicated, the correlated Gaussian noises impacts the accuracy of time delay estimation. ICA has good effect on removing the Gaussian interference and can protect the available signals effectively. This method used the de-noised signals by ICA to make cross-correlation analysis for time delay estimation. This method can suppress the correlated Gaussian noises effectively. Finally, compared with the results of the conventional cross-correlation algorithm, the simulation results and the signals obtained from the experiment field prove that the method can decrease the average error and mean square deviation of location results and improve location accuracy and consistency.
  • . 2011, 30(4): 86-90.
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    Abstract: Compared with the conventional multiple scattering theories for vibration isolation of Aviles, an improved expansion method of wave functions using more complete Fourier-Bessel function series has been adopted in this article. With the help of boundary conditions of continuous displacements, and Graf’s addition theorem which is in a more generalized perspective, the analytical solutions for multiple scattering by an arbitrary configuration of parallel rigid cylinders, which are located in homogeneous unbounded soil, have been gained under the incidence of SV waves. Then, all the cylinders have been rearranged in two parallel lines, which makes the problem turn into the vibration isolation using rigid multiple-row piles. The effect of this vibration isolation system and other properties of the system were researched with the variation of h, the distance between two rows.
  • LI Chuan-zeng;;Wang Shu-shan;Rong Zhu
    . 2011, 30(4): 91-94.
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    Abstract: Experiment of EFP impact 603 armor targets with a high speed, showing the macro-phenomenon as follows: curling petal-shaped damage of target entrance, valgus petal-shaped damage with tensile fracture characteristics of target exit, entrance diameter is larger than exit diameter and so on. In order to study the mechanism of high speed impact effects, using ANSYS/LS-DYNA to simulate the whole impacting process, which reappears the physical process from EFP formation, punching, quasi-steady penetration, empennage penetration to pass through. Simulation results are in good agreement with experimental phenomena. The reasons why these macro-phenomenons happened are analyzed in principle. Research results not only understand the mechanism of EFP impact armor targets, but also provide theoretical reference to improve armor protection capability and optimize design methods of EFP, which is very important and valuable in engineering.
  • XU Lueqin;LI Jianzhong;WU Taojing
    . 2011, 30(4): 95-99,1.
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    Abstract: Taking the pounding effects between the girder and the retainer into account, a comparative study is conducted on the distribution of transverse seismic force among the piers using linear and nonlinear time history analysis methods. The results show that, by utilizing rubber bearings, it is effective to distribute the transverse seismic force uniformly to the piers. But in the mean time, the possibility of pounding between the girder and the retainer comes into reality. It is found that pounding effects will not only amplify the dynamic response of bridge, but also make the distribution of transverse seismic force uneven among the piers. Based on the results of parametric analysis, some constructive conclusions on variation laws of the transverse seismic force distribution under different pounding conditions are made.
  • NING Jing-feng;HE Xi-ping;LI Na
    . 2011, 30(4): 100-102.
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    Abstract: Using finite element method(FEM), piezoelectric ceramic sandwiched transducers of unchanged excitative area and different frequencies incentives a thin circular plate that produces a first-order flexural vibration, which is studied. The results show that as the excitation frequency increases, fundamental frequency of the circular flexural vibration has also increased, while also increasing the radius of pitch circle, the amplitude of lateral displacement increases firstly and then decreases. It was clarified experimentally that the results are consistent with the FEM basically, which are significant for the designers and applications.
  • PANG Fu-zhen;YAO Xiong-liang
    . 2011, 30(4): 103-108.
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    Abstract: In order to improve stealthy capacity of a submersible structure, acoustic Tiles are usually covered on hull surfaces of a submarine. Due to the special cavity structure in the acoustic covering layers, cavity structures will distort and absorb energy when encountering underwater explosive shock waves. This will greatly affect submarine’s anti-shock performance. The anti-shock performance of a submarine covered with acoustic layers is studied in details based on composite element method. Influence of acoustic tiles to the destroying environment and impact environment of submarine is thus obtained. Study shows that the covering of acoustic tiles would help submarine absorb energy from underwater explosive shock waves, and worsen the destroying and impact environment of submarine. Study may provide reference for relative researches.
  • ZhangXiqing; XiangChangle; LiuHui
    . 2011, 30(4): 109-112.
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    Abstract: The Pre-test Analysis and the Modal testing theories is introduced, on this basis, Taking certain complicated gearbox housing as the object of research, sets up the FEM model and carries on Pre-test analysis, and optimizes the measuring and exciting points of modal experiment; by the hammering modal testing, Housing structure modal parameters are identified; through analyzing testing Frequency Response Function(FRF) and Modal Assurance Criterion(MAC), and comparing with Pre-test analysis, It indicates that Pre-test analysis results is reasonable, the identified modal parameters of modal testing is believable.
  • ZhangXiqing; XiangChangle; LiuHui
    . 2011, 30(4): 109-112.
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    Abstract: The Pre-test Analysis and the Modal testing theories is introduced, on this basis, Taking certain complicated gearbox housing as the object of research, sets up the FEM model and carries on Pre-test analysis, and optimizes the measuring and exciting points of modal experiment; by the hammering modal testing, Housing structure modal parameters are identified; through analyzing testing Frequency Response Function(FRF) and Modal Assurance Criterion(MAC), and comparing with Pre-test analysis, It indicates that Pre-test analysis results is reasonable, the identified modal parameters of modal testing is believable.
  • Guo Li;Li Zhao-xia;Han Xiao-lin
    . 2011, 30(4): 113-118.
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    Abstract:Pseudo static model updating method is presented to reduce the algorithmic complexity in dynamic model updating process. With characteristic force concept, a dynamic model is transformed into a static model to update, and Eigen analysis is avoided. Spline interpolated method is adopted to match measured messages with computed ones. Using complex variable differential method, an efficient parameter sensitivity analysis technology is developed. Statistic formula also is constructed to calculate the errors in model updating process. With numerical verification, the developed method is efficient and reliable for model updating. As a case study, the model of the Run Yang Bei-Cha Yangzi cable stayed bridge tower is updated with the pseudo static model updating method. With the updated parameters, the computed results of the bridge tower coincide well with the measured ones.
  • CHEN Xin;ZHU Xi;MEI Zhi-yuan;WANG Xiao-qiang
    . 2011, 30(4): 119-123.
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    Abstract: Ultra-high molecular weight polyethylene (UHMWPE) laminate, plane sandwich and spherical sandwich are researched by ballistic penetration experiments, and lower anti-penetraion performance of convex spherical structure is found than that of plane structure. Disadvantage of initial curvature of spherical structure is elementarily analyzed based on experimental phenomena. Ballistic penetration of UHMWPE laminates with different curvature is numerically simulated by DYTRAN FEM software, and curvature influence on ballistic properties is analyzed. Main cause of ballistic performance degradation is considered to be deformation restriction and the induced stress concentration due to initial curvature.
  • Wang Fu-tong;Tao Xia-xin;Zheng Xin;Cui Gao-hang;Chen Xian-mai
    . 2011, 30(4): 124-126,.
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    Abstract: Background vibrations typically reside in field observation data for recording traffic-induced environmental vibration in surrounding areas, and may disturb the true vibration signals excited by traffic transportations. A method of PSD revising is suggested here to remove the background vibration from field observed records. Based on the assumption that the true vibration and the background vibration are mutually uncorrelated stochastic processes, calculating formulae of the method were deduced. A group of data was then taken as an example to demonstrate the capability of the method. First, a vibration curve was set as the true vibration data, and was superimposed on a background one to synthesize a filed observation record. Then the true vibration was supposed to be unknown, and was estimated by the vibration level revising approach, the Fourier amplitude revising approach and the proposed PSD revising approach, respectively. The feasibility and accuracy of these approaches were examined by comparing the true vibration setting data with the estimated ones. The results of the example show that the time history and the PSD obtained with the PSD revising approach resemble their setting curves very well, and the errors are smaller than that of Fourier amplitude revising approach. The vibration level calculated by the PSD revising approach or the vibration level revising approach is almost the same as its setting value, but the calculated value by the Fourier amplitude revising approach is relative smaller. It can be concluded that the proposed approach behaves more accurately than the Fourier amplitude revising approach, and produces more types of true vibration data, i.e., time histories and PSDs, than that obtained by the vibration level revising approach.
  • He Shaohua;Wu Xinyue
    . 2011, 30(4): 127-130.
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    Abstract: A shock response spectrum method for multi-body systems was presented. Take a rigid-flexible-multi-body system under base shock excitations for example, the theoretical foundations of that method were described, including: firstly, to obtain the system state vectors and natural modes by transfer matrix method; secondly, to build differential equations of system bodies in a coordinate relative to base, and then to decouple equations by the orthogonal of augmented eigenvectors, the maximum responses in each modes were thus obtained by the definition of shock spectrum; lastly, the time –varying responses were obtained by mode combination. The utility and validity of the proposed method were confirmed by an application example at last.
  • Liu Zhansheng; Qian Dashuai; Sun Liquan
    . 2011, 30(4): 131-134.
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    Abstract: To study the periodic solution stability problems of inclined rotor-journal bearing system, the dynamic equation of inclined rotor system is established considering the change of radial load of journal bearing based on finite element method. The response of inclined rotor-journal bearing system is obtained by using Newmark method. The influences of inclination angle on rotor unstable threshold and width of unstable area are analyzed. Simulation results show that the increase of inclination angle lead to the decrease of unstable threshold and broaden the unstable area, while the upper boundaries of unstable areas change little. The experimental researches validate the simulation results.
  • Zhou Wenbo;Chen Lifeng;Yang Qiongliang;Tang Guoan
    . 2011, 30(4): 135-138.
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    Abstract: To simplify the aeroelastic analysis by utilizing the general CSD program, an approach to transform the aerodynamic to the desired formation is presented in this paper. For a flow-flexible structure coupling model, the aerodynamic is given in the frequency-domain formula, and then can be expressed as rational polynomials. Through the equivalent transformation, the aerodynamic can be deduced to a second order ordinary differential equation. Then aeroelastic analysis can be achieved under the framework of computational structural dynamics. This approach combined the general CSD program and aerodynamic model, which is derived from numerical analysis or experiment, to simplify the aeroelastic analysis and improve computational efficiency.
  • JIANG Zhigang;SONG Dianyi; Zeng Shouyi
    . 2011, 30(4): 139-143,.
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    ABSTRACT:A Finite Cylindrical Cavity Expansion(FCCE)theory was proposed to the penetration onto thick metal targets with finite planar dimensions. The cavity expansion process in elastic-plastic material with free boundary was divided into elastic-plastic and plastic stages,and the analytical solutions of the radial pressure on the cavity wall were obtained. Based on the Tate's eroding rod model,an engineering model for the penetration of long-rod project onto cylindrical thick metal targets with finite diameters was presented by using the FCCE theory for the target's resistance to penetration. Comparisons between the presented model and previously published ballistic experiments show that the penetration depths from the presented model are in good agreement with those from the ballistic experiments.
  • Kang Jian; Tang Li-wei; Zuo Xian-zhang;Li Hao Zhang Xi-hong
    . 2011, 30(4): 144-149.
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    Abstract: In order to reduce the amount of data of non-stationarity and nonlinearity signal sent throughout the sensor network, a grey morlet wavelet kernel partial least squares (GMWKPLS) model is proposed. In this model, grey prediction theory is firstly introduced into kernel partial least squares (KPLS). Then the input-output data are mapped to a nonlinear higher dimensional feature space by morelt kernel transformation. Finally, a prediction fusion model is constructed by linear partial least squares. Moreover, moving widow method is utilized to update samples continuously in this dynamical prediction model. The model is validated with vibration signals of gear tooth breakage in the speed of rising. The results show that the model can execute dynamic multi-step prediction, and it has high precision prediction. Thus, it can observably reduce the amount of sending data throughout the sensor network and save energy. Comparing with grey RBF kernel partial least squares (GRBFKPLS) and RBF kernel partial least squares (RBFKPLS), GMWKPLS is best in prediction performance, and the prediction errors are around ±0.4%.
  • Guo Weiliang;Teng Jun;Rong Baisheng;Li Zuohua;ZHANG Hao
    . 2011, 30(4): 150-155.
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    Abstract: Diagrid tube structures have advantages on constructing high-rise buildings for their great rigidity and are built in and aboard, however their seismic behavior researches are limited. Models of concrete filled steel tube diagrid tube-concrete core tube structure were analyzed by Modal Pushover method using Perform-3D program. The structure plastic development process and the component yield order were summarized. The diagrid tube components yield path was researched and the reasons of force redistributions between inner and outer tubes were explained by analyzing the development of diagrid tube forces. The reason for structure lateral stiffness degradation was discussed based on the development process of diagrid and core tube lateral stiffness.
  • Liu Zu-jun; Ge Yao-jun; Yang Yong-xin
    . 2011, 30(4): 156-160.
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    Abstract: Based on fluent software redevelopment, the motion of the structure was described by UDFs and moving grids was also used to realize fluid-solid coupling from the view of the loosely coupled model. A new method of multi-moving grids technique was proposed to resolve the problem of structure movement by fluid meshes size restriction and large deformation of grids leading to failure calculation under the conditions of the velocity of dynamic meshes meeting the Space Conservation Law . In hydrodynamic calculations, the method of large eddy simulation was used to solve N-s equation in order to consider the impact of turbulence. Numerical simulation of the flow field around the single degree of freedom forced vibration plate was give. The aerodynamic derivatives were acquired by fitting aerodynamic time-history curve with the least-squares method. The results were in better agreement with Thodorsen theoretic solutions.
  • Duan Xiang-yang; Wang Yong-sheng; Su Yong-sheng
    . 2011, 30(4): 161-165.
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    Abstract:. Vibration signals of cavitation in centrifugal pump were acquired by acceleration transducers mounted on different positions in order to find out the cavitation characteristics. The test results showed that the measuring point B mounted on pump case was more sensitive to cavitation and more suitable to act as monitoring point. The signals appeared a up-down trend, and emerged obvious peak values in 6kHz and 8kHz. The band vibration acceleration levels in 5~8 kHz and 8~12 kHz, and the broadband vibration acceleration levels in 5~12 kHz had about 10dB uprising after cavitation, which could clearly reflect the vibration tendency of cavitation, and could be used as indicators for cavitation monitoring.
  • Li Zhanfang;Tong Junling;Li Wei
    . 2011, 30(4): 166-172.
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    Abstract: The optimal design of a single chamber hydro-pneumatic spring used in a certain military off-road vehicle was studied. First, the mathematic model of the hydro-pneumatic spring was established, then, a half-car model of the hydro-pneumatic suspension system was obtained. Based on the model, considering the characteristics of the off-road vehicle, the suspension system performances of ride quality and road adhesion were chosen as the objective functions, the main parameters of the fore and rear hydro-pneumatic springs such as volume and pressure of the auxiliary gas room and the accumulator at equilibrium position, diameter of the main piston, hydraulic diameter of the damping hole and check valve were chosen as design variables, and with the constraint conditions the mathematic model of the optimal design was achieved. Then the Particle Swarm Optimization(PSO) algorithm was employed to solve this optimal design problem. The result shows that the combination property of the hydro-pneumatic suspension system has increased by 37.33% after the optimization.
  • LIU Xiaofeng; BO Lin; ZHAO Lin
    . 2011, 30(4): 173-177,.
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    Abstract:Machine fault information generally includes multiple components with non-linear time-frequency (TF) relationship, whose wideband frequency spectrums are overlapped. This brings great obstacles for machine fault diagnosis. Based on the signal composition of elementary function one-dimension approximating and TF reassignment, an novel method of signal components extraction is developed. In this method, the component is modeled according to the characteristics of component extracted firstly. Afterwards, the TF distributions of the component model and the analyzed signal are computed separately. And then, the threshold of energy descending gradient is set to control the iterative times and the elementary functions fitted out are selected to reconstruct the useful signal components. Finally, with the nonlinear least square method, the elementary function parameters are determined by using elementary function TF curve surface to fit the analyzed signal’s reassigning TF. The simulation examples verifies using the above method that the component needed can be extracted with several fitting iterative times and the reconstructing result has high accuracy. This method is applied to extract bearing fault components. The experiment results show that the proposed method has good ability of Locating fault precisly and providing corresponding basis for judging fault cause and degree.
  • Lv Bangjun;Zhu Shijian;Peng Likun; Xing Jifeng
    . 2011, 30(4): 178-181.
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    Abstract:Based on influence coefficient method and principle of conversation of potential, stiffness mapping of Stewart mechanism is established, which takes into account the elastic deformation of active, passive joints and the effect of external wrench. Compared with the prevalent stiffness mapping model, the proposed model is more general and exact, not only considering the axis stiffness of actuator, but also considering the stiffness of passive joints and the change of Jacobian matrix brought about by tiny change of mechanism under external wrench. An example is analyzed combining stiffness matrix Reyleigh quotient to contrast the stiffness performance differences between the two models.
  • LIU Jing-xi;LIU Yao;Tang Hao-quan;LI Wei
    . 2011, 30(4): 182-187.
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    Key words: stiffened plates; blast load; failure mode; large deflections; dynamic plastic response
  • Wang Min[];Shi Shao-qing[];Yang You-kui[]
    . 2011, 30(4): 188-193.
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    Abstract: The ring-brake energy dissipater of the passive system consists of the tubular steel loops and the aluminum compression sleeves, and the cables drilled through the tubular steel loops are connected to the anchor rope and the support rope. The ring-brake energy dissipater used in the system is based on their great slip resistance capacity which can dissipate the kinetic energy and alleviates the impact load. Based on the effect of the ring-brake energy dissipater in the passive system, the static tensile tests and the dynamic FEM simulation are carried out. The numerical results with the ring-brake energy dissipater at the low speed load show the correlation to the static tensile tests. The slip resistance is increased and the energy dissipation performance is improved with the speed load increasing. In addition, the sliding force and the dissipated energy of the ring-brake energy dissipater which are influenced by the length of the aluminum compression sleeves are studied. The results show that: the energy dissipation capacity of the ring-brake energy dissipater begins to increase more singificantly, then no significant increase lately. The sliding force first decreases and then increases with the sleeve length increased. When the aluminum compression sleeves is in the context of appropriate length, the results of the ideal efficiency energy dissipation obtained by the dynamic simulation is closed to the static tests.
  • TANG Guo;Chen Anhua;Guo Yuanjun
    . 2011, 30(4): 194-197,.
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    Abstract: The nonlinear dynamics equation of a equal section beam under pure bending vibration was developed . According to theory of the nonlinear dynamics, the singular point and stability of the system was studied. Using theory of Chaos, the parameter condition of a equal section beam for occurred Chaos under pure bending vibration was explored. According to the parameter condition , the parameter condition of a equal section simply supported beam for occurred Chaos under pure bending vibration was studied., the parameter dividing line of occurred Chaos were obtained.
  • ZHU Xiao-jin; HUANG Quan-zhen; GAO Zhi-yuan; GAO Shou-wei; JIANG En-yu
    . 2011, 30(4): 198-204.
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    Abstract: In view of one of the key issues for active vibration control of flexible structures is the control strategy and method, this paper proposes a multi-channel FULMS algorithm for the adaptive feedforward control systems to solve the difficulties of obtaining the reference signal of FXLMS algorithm. Based on the controller architecture constructed and illustrated in this paper, the multi-channel FULMS algorithm procedure is deduced and described in generalization. To verify the feasibility and priority of the control algorithm proposed in this paper, simulation performance comparison of single-channel and multi-channel FXLMS and FULMS algorithm are made with MATLAB employed. The analysis results indicate that the multi-channel control performance is better than single-channel, while FULMS algorithm has better performance than FXLMS algorithm. Finally, taking a piezoelectric flexible epoxide resin plate to simulate solar panels, an active vibration suppression experimental platform is established with its relative measurement and control system built. The experimental results show that the proposed FULMS algorithm is feasible and efficient with excellent convergence and control performance.
  • Deng Yu-lin; Peng Tian-bo; Li Jian-zhong
    . 2011, 30(4): 205-210.
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    Abstract: Based on the pounding phenomenon at expansion joints of long-span subjected to longitudinal earthquake and in combination with a realistic engineering project of a long-span multi-tower suspension bridge, the complex nonlinear model that considered the elasto-plastic behaviors of piers and the pound responses between the main span and the approach span was developed. The effects of some pounding parameters such as pounding-stiffness, initial gap at expansion joint were studied. The results indicate that the pounding stiffness is not essential parameter and its effect on pound responses is not obviously. But the initial gap at expansion joint has important effects on pounding effect such as the relative displacement between main span and approach span and the displacement of main girder.
  • GAO Jing;Ge Jiping;LIN Tie liang
    . 2011, 30(4): 211-216.
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    Abstract: The similarities and differences of seismic performance between pre-cast segmental bridge column and cast-in-place bridge column were investigated with an experimental project including five kinds of concrete bridge columns. The existing of prestressing tendon, the construction method, the arrangement and the bonded state of prestressing tendons, and the existing of additional energy-dissipating bars were selected as experimental variables. Through the pseudo static test of the five kinds of concrete bridge columns, the development rule of failure mode, the failure area, the load-displacement hysteretic loops, the opening of the segmental joints, the residual displacement, the distribution of curvature, the energy dissipation ability, the viscous damping ratio, was gained. The experimental results show that the segmental column experiences opening-closing between the segmental interfaces under cyclic loading. The change of curvature is focus on the area of the segmental interfaces. The segmental bridge column has no plastic hinge mechanism at the bottom of the column, as commonly seen in conventional reinforced concrete bridge columns. The addition of energy dissipating bars crossing the joint could delay the gap opening, increase the strength and the hysteretic energy dissipation of the column, which will certainly help resist the earthquake. The residual displacement of segmental bridge columns with bonded or unbonded prestressing tendons is less, and the segmental bridge column with energy-dissipating bars exhibit bigger residual displacement, close to that of cast-in-place bridge column.
  • SHAO Yimin;XIAO Huifang
    . 2011, 30(4): 217-222.
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    Abstract: Research concentration on the transmission and attenuation principle of vibration and energy through multi-layered, discontinuous structure interfaces is lacked, especially in the consideration of interface roughness. The “single absolute smooth metal panel--rigid plane” and “single rough surface metal panel--rigid plane” models are established in this paper to investigate the force-deformation relation and energy loss characteristics on the interface on the effects of plasticity and interface friction during the loading and unloading process. Results for interface of different plastic material models,frictionless and friction are presented and comparisons are drawn. The energy loss coefficient is defined and the expression relates energy loss and interface prosperities is established. Future work will concentrate on the transmission principle and attenuation characteristics of vibration and energy through multi-layered, discontinuous, rough interfaces.
  • CHEN Xiao-bing;CHEN Chang-qing;ZHOU Yun;WANG Da-yang
    . 2011, 30(4): 223-229.
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    Abstract: Vibration control of a 98.93m high-rise building in wind and earthquake is studied in this paper. Three vibration control schemes with nonlinear viscous dampers are proposed to control structural dynamic responses under wind and earthquake excitations according to natural characteristics of the building. Dampers are installed in stories from 21st to 26th in scheme 1, from 12th to 14th in scheme 2 and from 3rd to 4th in scheme 3. The dynamic responses of the structure with the proposed control schemes in wind and earthquake excitations are investigated and their vibration control effects are analyzed comparatively. The study results show that dynamic responses induced by wind and earthquake excitations can be controlled effectively by the proposed schemes. Control effect of scheme 2 is superior to both scheme 1 and scheme 3 and scheme 3 is the worst in wind and earthquake. The peak top acceleration and story displacement can be reduced by 43% and 44% respectively for scheme 2 in wind-induced vibration. The top story displacement can be reduced by almost 10% for scheme 1 and 2 in earthquake excitations. Dampers are suggested to be installed in middle and up stories so as to achieve maximum control effect for cases of controlling structural responses under both wind and earthquake excitations.
  • ZHOU Yi;SUN Limin;MIN Zhihua
    . 2011, 30(4): 230-235.
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    Abstract: Strain data measured by the structure health monitoring system of the main navigation channel cable-stayed bridge of Donghai Bridge were analyzed. By using Empirical Mode Decomposition (EMD), a one-hour strain response of the middle section of girder was decomposed into an oscillation component (dynamic response) and a trend component (static response). The structural modal frequencies were obtained from the dynamic strain response and simultaneously the traffic flow was estimated based on the static strain response. It can be concluded that the separation between dynamic response and static response of measured strain by EMD is feasible and these two components are of great value in practice.
  • Shen Pingchuan; Wang Guoyan; Zhang Fang
    . 2011, 30(4): 236-240.
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    Abstract: This paper deals with wind-induced bending-torsional coupled vibrations of high-rise buildings with bi-asymmetric cross sections. The high-rise buildings are modeled as Euler-Bernoulli beams. The origin of the reference point of each cross section is chosen coincident with stiffness center of the cross section and X axis is parallel to wind directions. Natural frequencies and mode shapes of the bending-torsional coupled vibrations are calculated first; then a method for wind-induced 3D bending-torsional coupled vibrations of the beam model is developed base on stochastic vibration theory, and the expressions of top rise corner acceleration response are presented. An illustrative example is given and the results of this paper are compared with those from other related references. The effect of position of stiffness center and mass center on natural frequencies and acceleration responses is discussed.
  • XU Peng;ZU Jing;FAN Jing-biao
    . 2011, 30(4): 241-243,.
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    Abstract: According to the characteristic of acceleration test in the processes course of projectile penetration into hard target with high velocity, a kind of novel high g shock experiment equipment have been developed by us. It is composed of one-stage air gun, acceleration storage test and measurement equipment, shell, reflect type Laser velocimeter and Laser Doppler velocimeter, moreover the high g shock experiment on Onboard acceleration storage test and measurement equipment is carried out through with above experiment equipment. The foamed aluminum buffer cushion is employed used to protect the memory circuit modulus, and the grating is utilized as cooperative aim target, so Laser frequency shifting signal from external shell of the test equipment and the circuit modulus in high shock processes course are recorded synchronously by two sets of Laser Doppler velocimeters. Their acceleration –time curve are acquired and the buffer cushion effect are compared.
  • Sun Dan; Luo Songnan
    . 2011, 30(4): 244-247,.
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    Abstract:Base on first-order shear deformation theory and the small strain-displacement relations, the effects of shear deformation and the inertia rotation are considered and the governing equations for the wave propagation in the rectangular FGM plate are derived by using of Hamilton principle. The analytic dispersion relation of the FGM plate is obtained by means of the eigenvalue equations. A complete discussion of dispersion of rectangular FGM plates is given. The dispersion curves, the phase velocity curves and group velocity curves of the wave propagation in the FGM plates are plotted respectively. The influence of the parameter of the functionally graded materials on wave propagation is analyzed
  • TANG Zhiyin;HE Lin
    . 2011, 30(4): 248-253.
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    Abstract: Traditional algorithm on underwater vehicle radiated noise calculation could not satisfy real-time request in practical use due to long computing time. Aimed at this disadvantage, the problem can be converted into a pattern recognition problem based on multisensor data fusion, and a new method of fast evaluation acoustic stealth condition of underwater vehicle has been researched. The method has combined an improved D-S theory and image Euclidean distance model. Firstly, the power of each frequency band in analysis band was extracted as the feature vectors. And then the evidence was built with image Euclidean distance. At last, the rapid assessment was made by the improved D-S theory. The availability of the method was proved by computer simulation and an underwater experiment. The advantages have been researched in detail, and disadvantages have also been pointed out. A new approach to evaluation on acoustic stealth condition of underwater vehicle has been searched out.
  • Huang Fen; Han Xu;Gong Shuang; Huang Yonghui
    . 2011, 30(4): 254-258.
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    Abstract: The combination of reduced-basis method(RBM)、finite element method、Fourier transformation and Newmark direct integral method was introduced for the analysis of transient response of piezoelectric laminates subjected to coupled electro-mechanical loads. The laminates were discretized in the thickness direction by plate elements, and the governing equations were obtained. The governing equations in wavenumber domain were obtained by Fourier transformation. The Newmark direct integral method was employed to calculate the displacement responses and the potential responses in wavenumber domain. The reduced-basis method was introduced during the using of Newmark direct integral method and a reduced basis space was constructed. The equivalent stiffness matrix、mass matrix and load vector were projected into the space. The reduced Newmark formulation was obtained and the responses in wavenumber domain were calculated efficiency. The transient responses were obtained by using the inverse Fourier transformation. The results of the numerical example provide the transient responses excited by the coupled electro-mechanical line load in a PZT-5A/0°PVDF composite plate. The transient responses of piezoelectric laminates can be performed efficiently and accurately by employing the reduced-basis method.


  • HuXueke; MaShaojun; WangKuihua
    . 2011, 30(4): 259-264.
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    Abstract: This research bases on CAPWAP_C method and in the light of the limitations of present PDA method to deduce fitting F and v formula of high-strain pile driving where the sensor is in 4 units. According to the deduced formula, the research braids analyzing program. Then, a fitting F and Zv figure is drawn for a certain position of sensor, and analyses the influence of PDA results by the place of sensors. Further, this paper demonstrates advantages of the new approach over the old by comparing new fitting F and Zv figure with the old one and actual one , confirms the new approach is more suitable for real engineer project.
  • WANG Bo;HUANG Liang;XU Jian-guo;SUN Liping;HOU Yujie
    . 2011, 30(4): 265-270.
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    Abstract: Based on the pounding phenomenon at expansion joints of large-scale aqueducts during earthquakes, an analytical model that considers the effects of collision was presented, with the time history analysis method of the determining the nonlinear seismic responses, the pounding effects of adjacent girders at expansion joints on seismic responses of large-scale aqueducts were studied, and the influences on two-sided and one-sided pounding on structural responses were investigated. The results showed that the pounding changed the responding status of the aqueduct to a certain extent, the relative displacements between the girders were decreased when pounding occurred, but the huge pounding force will be harmful to the safe operation of the aqueducts. The results from the present study may serve as a reference base for seismic design of large-scale aqueducts.
  • Fan Shuli;Chen Mingyang;Chen Jianyun;Chai Huancheng
    . 2011, 30(4): 271-275.
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    Abstract: Nonlinear seismic analysis of concrete gravity dam is performed based on the plastic damage theory. The hysteretic characters, energy dissipation ability, failure mechanism and characteristics are researched. A seismic damage assessment model which can consider damage energy dissipation is developed for describing the damage degree of dams during strong earthquakes. The results show that the dam head are the vulnerable parts of gravity dam. The vibration energy and the earthquake responses of structure are reduced effectively by the structural damping, little amount seismic energy is dissipated by concrete damage and plastic dissipation. The seismic damage assessment model can quantitatively evaluate the damage degree of gravity dams during strong earthquake.