25 November 2014, Volume 33 Issue 22
    

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  • WANG Pu;GAO Liang;CAI Xiaopei;YE Jun
    . 2014, 33(22): 1-6.
    Abstract ( 333 ) Download PDF ( 216 )   Knowledge map   Save
    An elaborate heavy haul train-track coupling dynamic model is established, taking into account multiple vehicles. Various components and interactions between components (e.g. contact friction) in the vehicle and coupler buffer device are modeled detailedly. The wheel-rail contact interactions are calculated based on Hertz’s theory and Kalker’s FASTSIM algorithm. The track model is established with the help of field parameter experiments conducted through self-developed devices. Dynamic characteristics of train-track system in curve sections and influence regularities of curve parameters on dynamic characteristics are investigated and the following conclusions are drawn: 1) The wheel-rail interactions are complicated in transition curve sections. Forces of different wheels present different variation trends and amplitudes, and wheel-rail interactions are also definitely different in front and rear transition curve sections. This is mainly caused by the superelevation slope and the vehicle structure. It is rather adverse for the train operation if the length of transition curve is too short. There usually exists an inflexion in the influencing curves of transition curve length on dynamic characteristics. It is suggested the smallest length of transition curve be determined according to the inflexion value. Lengthening the transition curve can effectively decrease the wheel-rail interactions and decrease the total wear mainly through reducing the wear of the leading vehicle and guide wheelsets. However, as the length of transition curve increases, the improvements of dynamic characteristics become less obvious. 2) The superelevation of the outer rail in small-radius curves is generally large in heavy haul railway of China. It is suggested to reduce the superelevation properly and set an inadequate superelevation of 10%-20%, which is conductive to decreasing the wheel-rail interactions and wear. 3) Increasing the radius of curve is advantageous for improving the wheel-rail interactions. While the improvement becomes smaller with the radius increasing larger.
  • Deng Kailai;Pan Peng;Ran Tianran;Su Yukun Xue Yantao
    . 2014, 33(22): 7-12.
    Abstract ( 363 ) Download PDF ( 277 )   Knowledge map   Save

    Stoppers are often installed with the isolation bearings in bridges to avoid that the upper girder drop from the pier during earthquakes. In this paper a novel energy-dissipation stopper is proposed. The stopper remains elastic and provides reaction force to restrain the displacement of upper girder during small earthquakes. On the other hand when large earthquakes occur it can yield and dissipate energy, and reduce the seismic responses of the bridge. To verify the performance of the stopper, 5 specimens are designed and the experiment study is carried out. The results show that a reasonable designed stopper has reliable strength and can provide adequate energy dissipation capacity.


  • WANG Fu-sheng;JI Yao-yao;LIU Zhi-qiang YUE Zhu-feng;ZHANG Qing-mao
    . 2014, 33(22): 13-20.
    Abstract ( 289 ) Download PDF ( )   Knowledge map   Save

    3D FE model of long air gap and composite laminate was built.Positive streamer growth probability model of along rod-plate gap is a stochastic dischargeone based on the traditional streamer theory. The detailed simulation process includes potential calculation of each grid point in air gap, routes list of all streamer developed around the pole, growth time calculation of route developed for each streamer and route definition with the minimum growth time as the selected priority one. When the streamer reaches composite plate, cross point of the streamer and plate is regarded as the attachment pointof lightning strike. Potential, temperature and heat stress distribution of composite plate can be obtained under high voltage wave of lightningstrike through direct effect analysis. The results show that high potential, temperature and heat stress produced instantaneously by fast streamer mainly spread out symmetrically along direction with the maximum conductivity on top plate. But the study in this paper only provides the preliminary analysis results as a quality description. In order to more accurately simulate the process of composite discharge effect under lightning strike, damage mechanism of ablation and heat mechanics for composite laminate needs to further take into account.

  • Chen Qiang;Xu Zhike
    . 2014, 33(22): 21-25.
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    Operation mechanics of a new type linear ultrasonic motor is analyzed in this paper. It uses bimorphs and double-driving feet. The motor has the attribute of simple structure, no frequence degenerate and easy to miniaturize. The construction, vibration mode and operation principle are described. The vibratory response finite element model of the stator is established. The computation method of input impedance of the stator is presented, and the input impedance of the stator is computed. The vibration amplitude of the driving-feet’s contact points near the harmonic frequence is computed by the above model. The movement locus of the driving-feet’s contact points are carried out. The impedance characteristic of stator has been surveyed by using impedance characteristic analysis instrument, and the experimental results are compared with the theory analysis.
  • GUAN De-bao;HUANG Wei-ping;SONG Hong;TIAN Hui-yuan;GENG Ao-xiang;WEI li-bo
    . 2014, 33(22): 26-29.
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    In order to research upstream riser’s effect on downstream riser different conditions, we design a device which can inhibit the upstream vortex by model test method. The experiments concentrate on the vortex-induced vibration of isolated upstream riser and it with improved variety equipment under different flow rate, different spacing conditions. Analysis the impact on downstream riser result from upstream riser through researching vortex shedding and measuring model vibration with inhibit vortex device or not. After that, we conclude that downstream riser is different to isolated standpipe under the influence of upstream standpipe. The lateral vibration of the downstream riser have minimum like arch with tube spacing increases without any inhibit device, while it become stable after some tube diameter with the improved variety equipment.
  • . 2014, 33(22): 30-34.
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    According to the aerodynamic brake wing made up of composite material on a high-speed train, the finite element model of the bird and brake wing was established. Based on contact-collision theory and by using non-linear dynamic analysis software LS-DYNA the process of bird impact on the aerodynamic brake wing was simulated. Through the comparison of the experiment and numerical simulation results, the rationality and feasibility of the model were verified. The simulation results showed that the designed brake wing could withstand the bird strike with a speed of 500km/h and the limiting case was the bird velocity reaching about 625km/h. In the impact process, the deformation of the brake wing had a characteristic of shock wavetransmission. The peak stress mainly distributed in surrounding of the impacted area and the part area connected to the bottom case and rockerarm also can appear stress concentration.
  • Jiang Dong;;Wu Shaoqing;;Shi qinfeng;;Fei Qingguo;
    . 2014, 33(22): 35-40.
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    Study on finite element modeling and parameter identification of bolted joints which are widely applied in engineering is conducted in this paper. By adopting the basic theory of the thin-layer element with isotropic constitutive relationship, a method based on parameter identification for recognizing the mechanical characteristics of contact surface in bolted structures is proposed. Finite element modeling for single and multiple bolted structures are investigated respectively, ignoring the hole and the mass of the bolt, and the contact surface is modeled by using of thin-layer element. An optimization problem is formulated using experimental modal data for identifying the constitutive parameters of thin-layer element. When the identify parameters are adopted in the finite element model, the maximum error of the computational modal frequencies compared with the experimental data is reduced reasonably. It is shown that thin layer element with the identified parameters can be used for accurately simulating the normal and tangential stiffness of the contact surface. The proposed approach in this paper is available for precisely simulating the single and multiple bolted structures.


  • Zhou Pan;Li Wan-you;Shuai Zhi-jun
    . 2014, 33(22): 41-45.
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    Adaptive delayed inverse model of mechanical system is adopted to determine time histories of multiple input forces aimed at the shortcoming that existing inverse system method relies on the state-space model. Adaptive algorithm is applied to identify delayed inverse model, followed by time domain force estimation using operational response combined with inverse model of mechanical system. Multi-input forces of simply supported beam were reconstructed by dynamic accelerations without and with noise disturbance. Simulation results illustrate that reconstruction accuracy decrease under noise condition but relatively satisfied and the method for multi-input identification is feasible. Furthermore, this method is validated experimentally.

  • WANG Qing-tao;WU Ke-gang;LI Bi-hong;CHEN Zhi-yang
    . 2014, 33(22): 46-50.
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    The numerical simulation way studied hypervelocity impact has been discussed. Damage mechanism and the process of the debris cloud forming has been studied with the SPH method of ANSYS/AUTODYN code when spherical projectile hypervelocity impact thin shield. Tungsten alloy and RHA(Rolled Homogeneous Armor) material models and parameters have been given, using the methods, material models and parameters of the numerical simulation results in good agreement with the experimental results. fragmentation-initiation threshold velocity of the projectile, the average fragment size and the distributing of fragment size have been researched including its relation with the impacting velocities when the projectile hypervelocity impact the target.


  • Yin Tao
    . 2014, 33(22): 51-57.
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    It’s found from the literature that the discrete-coordinated systems following the FE technique are generally employed by almost all works for investigating the optimal sensor placement problem. Although the discrete-coordinated systems can provide a convenient and practical approach to the dynamic response analysis of arbitrary structures, the solutions obtained can only approximate their actual dynamic behavior. This will affects the results of optimal sensor placement, and the sensors are confined to be placed at only a very limited number of discrete locations. For the distributed-parameter system, the sensor locations are identified by their coordinates that are continuous within the region of interest. In such situation, the continuous-coordinated models are more suitable than the FE-based discrete-coordinated models for investigating the optimal sensor placement problems. For the purpose of structural model updating, this paper is intended to develop a sensor/actuator configuration methodology for the distributed-parameter system based on both the Bayesian statistical system identification method and information entropy. In the proposed methodology, the Bayesian statistical system identification method is firstly adopted to identify the optimal values and associated uncertainties of the structural modeling parameters, wherein the information entropy is employed as a scalar measure to quantify the uncertainty of the identified structural modeling parameters. Then, the problem of optimal sensor/actuator placement is formulated as a continuous optimization problem, in which the information entropy is minimized by using the genetic algorithm, with the sensor/actuator configurations as the minimization variables. Maximum amount of information about the structural modeling parameters would be obtained if the sensors/actuators are placed at their optimal locations, indicating the uncertainties of identified modeling parameters being minimum. The proposed methodology is verified through a set of numerical simulation cases for a three-span continuous bridge model with two elastic supports at top of piers.
  • CHU Qin;JIANG Hui;WANG Baoxi
    . 2014, 33(22): 58-66.
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    Because of the existence of velocity pulse, the dynamic response of structure under near-fault and far-field earthquake may be different. Taking the equivalent pier of a typical railway bridge built in deep-water as an example, the vibration characteristic and dynamic response under the two kinds of earthquake were contrasted based on the potential-based fluid method from fluid-structure interaction theory. The research results show that, the vibration characteristic of pier is changed because of the water around it. With the increase of the depth of water, the natural vibration period of pier becomes larger and the first period increases by 10.4% when the water depth is 30m. The distribution of hydrodynamic pressure along the pier is parabolic, which is larger by near-fault earthquake, and the difference becomes more obvious with the addition of water depth. There is also significant difference between the dynamic response under near-fault and far-field earthquake, in addition, the dynamic response under near-fault ground motions is greater than that of far-field earthquake.The diplacement at the top of pier, the moment and shear force at the bottom of pier increase by 34.5%, 37.8% and 51.3% respectively under near-fault earthquake; while these three indicators are 17.0%, 21.8% and 40.0% for far-field earthquake. In summary, the destructive capacity of near-fault ground motions with obvious velocity pulse is far greater than far-field earthquake, so special attention should be paid to those bridges surrounded by deep-water in near-fault zone.

  • Wu Feng;Xu Xiaoming;Zhong Wanxie
    . 2014, 33(22): 67-71.
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    For the generalized eigenvalue problem, a method based on the fast Fourier transform (FFT) is developed. In the proposed method, the dynamical structural response is viewed as a signal which contains all information about the vibrational frequencies. Using FFT to the signal, the vibrational frequencies can be obtained. The method is a kind of direct solution method which could compute all eigenvalues without the matrix inversion. The numerical example manifests the correction of the proposed method.
  • HE Yu-yang;YUAN Quan
    . 2014, 33(22): 72-77.
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    The shaking table test of a 1/6 scale multi-rib composite wall supported on frame, the test structure has undergone elastic stage, cracking up the whole process of destruction, the dynamic characteristics and the dynamic response of the structure in the various stages, inputting the El Centro wave, Taft wave, artificial seismic wave input, according to the seismic fortification intensity of 7 degree frequent, basic, rare, very rare and 8 degree frequent, basic, rare, very rare earthquake test,to study the model structure in each phase under the action of earthquake acceleration, displacement and strain responses, as well as the structure of the failure mode and failure mechanism. The results showed that: frame supported ribbed composite wall structure of its conversion layer shear failure mode of destruction, plastic deformation is mainly concentrated in the conversion layer; frame supported ribbed composite wall structure layers absolute acceleration response depends primarily on the first two bands formation, formation of a small order, wherein the first phase formation plays a role in absolute control.

  • ZHOU Jun-wei;HE Lin;XU Rong-wu;CUI Li-lin;
    . 2014, 33(22): 78-82.
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    The traditional response estimation model is based on force-response relationship. According to the transmissibility concept in linear time invariant system, a new response estimation method-transmissibility function (TF) method is provided based on response-response relationship. First, the principle of the method is interpreted in mathematic formula and the restriction condition is presented. Then, an engineering technique called operational conditions combination is presented for calculating the transmissibility function (TF) of vibration responses, and the guideline on how to devise the scheme of working conditions is discussed. Finally, the performance of the developed transmissibility function method is validated by a cylindrical double-shell exciting experiment.
  • Chen Long;Shen Yujie;Yang Xiaofeng;Wang Ruochen;Zhang Xiaoliang;Shi Dehua
    . 2014, 33(22): 83-87.
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    In order to further broaden the design thought of vehicle suspension applying inerter, two types of vehicle ISD suspension have been designed based on the two parallel elements‘inerter and spring’ by using the anti-resonance of the inerter-spring-mass structure. Using genetic algorithm to get the optimized structural parameters of suspension, analysis in frequency showed that, compared with the passive suspension, the designed suspension structures can suppress the vibration at the offset frequency of the body resonance. Experiment on the second generation suspension has been carried out, a quarter vehicle suspension test bench including the second suspension structure has been built. In the random road input, the suspension working space square mean root has improved by 16.24%, the dynamic tire load square mean root has improved by 6.75%, and the body acceleration square mean root has also improved. The results show that the designed suspension structure can effectively improve ride performance and control stability.

  • WU Chang;WANG Xiu-li;MA Xiao-tong;Liang Ya-xiong;
    . 2014, 33(22): 88-96.
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    In order to analyze the dynamic response mode of Kiewitt-6 single-layer reticulated shell with the substructure under impact, the shell with steel pipe column for numerical analysis was established by the ANSYS/ LS-DYNA program. Four dynamic response modes were put forward according the dynamic response. The influences of the impact energy, impact location, the stiffness of ring beams were studied. The impact test on single-layer reticulated shell model with steel pipe column was conducted. The dynamic stress, dynamic displacement and acceleration were measured and analyzed, and the damage patterns of impact columns were studied. The results show that the typical characteristics of response mode are the damage patterns of impact columns(slight damage, local dent, press-bend failure, shear failure).The dynamic response of reticulated shell with impact energy increases in addition to the response mode 4. The most unfavorable impact position is central column. The dynamic response of reticulated shell decreases with the increase of the stiffness of ring beams. And the numerical model is also proved to be reasonable by comparing the theoretical and experimental results.

  • LI Jin-jun HAN Lei
    . 2014, 33(22): 97-100.
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    A two-probe Laser Doppler Vibrometer(LDV) system is used for detecting the vibrations of the cantilever and the base. Compare the velocity spectrum curve of cantilever and base, acquire the dimensionless frequency response curve of the cantilever, and acquire the phase difference between the cantilever and the base, then accurately estimate the resonant frequency of the cantilever by observing the dimensionless frequency response curve and the phase difference. This paper analyzes the cantilever’s impact to the base when the cantilever is resonating, and the influence between the two cantilevers.
  • YANG Yi-qing LIU Qiang
    . 2014, 33(22): 101-105.
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    Machining chatter is an important factor of restricting high speed cutting, and chatter stability prediction is an effective method to avoid chatter by measuring the tool tip frequency response functions (FRF) in the X/Y directions of the machine tool coordinate system. As the complexity of the machine structure and uncertainty of tool path, the tool tip FRF is varied during the cutting process which therefore causes the variation of the stability charts and cutting parameter selection. The stability charts with different feed directions and spindle positions are investigated based on the modal test, and the machining performance of two machine tools of the same model are compared. Cutting tests are carried out in the end, and the machining stability performance along different feed directions is verified by collecting the sound signals of the machining. The results are beneficial to the chatter avoidance and cutting parameters selection in the real manufacturing process.
  • Li jiyong Li Shunming CHEN Xiaohong JIANG Xingxing
    . 2014, 33(22): 106-110.
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    Rotor-stator rub-impact response de-noising and its characteristics extraction are key problems of fault diagnose, a piecewise smooth threshold function was constructed for wavelet de-noising, the non-stationary signal is de-noised separately by Wavelet, Wavelet Packets and Dual-tree Complex Wavelet Transform(DTCWT), take SNR (Signal to Noise Ratio)to evaluate the de-noising effect, the results reveals that the constructed threshold function is high active in de-noising. Then single rotor rub dynamic response was calculated, decomposed by DTCWT, the dynamic response was exactly extracted due to dual tree wavelet approximate analytical and sampling interpolation complementary. The simulation and experimental results show that the proposed methods are effective.
  • Shi Zhi-biao;Miao-Ying
    . 2014, 33(22): 111-114.
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    In order to solve the problem that the selection of the kernel function parameters and penalty factor parameters in the support vector machine(SVM)algorithm is blindfold,we use the fruit fly optimization algorithm(FOA)to optimize the parameters in SVM.A fault diagnosis algorithm of SVM based on FOA is put forward,and then we use it to execute the pattern recognition of the turbine failure experimental data.This algorithm could optimize the SVM parameters automatically,and achieve ideal global optimal solution.Comparing with the SVM which optimized by the common used methods of the particle swarm optimization(PSO) and the Genetic Algorithm (GA) currently,the results demonstrate that FOA-SVM has the fastest recognition speed and the highest recognition rate.
  • ZHANG Lijie Chang Jiadong Wang Jiong
    . 2014, 33(22): 115-120.
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    Since the critical demand for time response of MR damper for gun recoil buffering applications, experimental studies of MR recoil control system are carried out on an impact test rig with the special designed MR damper. Impact performance of the MR damper under fixed operating current is obtained, which is described by a physical model. Time response of the MR damper’s coil current and the damping force are respectively tested, then trajectory tracking control scheme for MR recoil system is put forward, so that the MR adjustable damping force can accurately track the ideal reference curve. Experimental results with 3g and 4g powders under double close-looped feedback control, as well as the fixed damping curve without feedback are obtained. By comparisons, the feedback control can efficiently reduce the response time of the damping force and provide more rapid tracking ability. With the same displacement, smaller peak of recoil force is produced, while with the same peak of recoil force, more less displacement is achieved. Finally, for decline of the damping force curve with 4g powders, it’s suggested the adjustable coefficient of the damping force, as an important parameters must be large enough in MR dampers’ structural design.
  • LIU Hai-biao;SONG Han-wen
    . 2014, 33(22): 121-126.
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    Active structures can be found in several engineering contexts, including active control or a variety of self-excited chatter. The dynamic characteristics of active structure are analyzed. Active structure is classified from different perspectives and discussed from several typical examples. Thus, active structure and non-self-adjoint structure are distinguished. Besides, frequency response feature of active structures is studied and the relationship between frequency response functions of active structure and its corresponding passive structure are elaborated. Based on a simulation system, the differences between frequency response functions of active and passive structure are revealed and the left and right eigenvectors of active structure are shown. Through experiments and data processing, the frequency response functions of an active structure constructed by a free-free beam are obtained and frequency response characteristics are verified experimentally.
  • WANG Feng;FANG Zong-de;LI Sheng-jin;JIANG Jin-ke;WANG Kanwei
    . 2014, 33(22): 127-130.
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    In order to reducing the vibration of herringbone gear transmission system more effectively, vibration reduction design methodsare put forward respectively from vibration excitation source of herringbone gear transmission system (tooth meshing quality) and vibration transmission path (box structure). Tooth surface three-dimensional modification is choosen to optimizing the vibration between the herringbone gear meshing teeth under multi-loads. Topology optimization is carried out target with static (box deformation) and dynamic (lower natural frequency) in order to improve the gearbox dynamics structure, and the optimization results can indicate which parts of redundant material and which structure needs to be strengthened. Accordingly, gearbox structural size is optimized to obtaining minimum acceleration of gearbox feet. Example calculations and experimental results show that the method of tooth three-dimensional modification reduce vibration of 18.9% by experiment test and 20.5% by theoretical analysis,the method of gearbox structural optimization reduce vibration of 12%. The better effect of 27.3% decline is obtained by combination of two methods.


  • Li Shaohua;Yang Shaopu;Chen Liqun
    . 2014, 33(22): 131-138.
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    The coupling relationships of vehicle motions in different directions are analyzed first. A three-directional coupled heavy vehicle model with 23-DOF is built and the equations of motion of this vehicle are deduced. The nonlinear tire forces in different directions are calculated by the nonlinear Gim model and vertical single dot contact model. Six one-order ordinary differential equations are obtained to calculate wheel rotate speed at real time and slip ratios. Taking the turning-braking combined condition, the uniform straight running and the steering wheel angle step input as examples, the dynamic responses of the coupled vehicle are simulated by numerical integration. The validity of this new vehicle model is verified by comparing with the traditional handling and stability model, the traditional ride comfort model, the Functional Virtual Prototyping model and test data. The effects of coupling action on vehicle responses are also analyzed. The results show that the proposed three-directional coupled model is suitable to research the ride comfort, handling stability and brake properties of vehicles in complicated driving conditions simultaneously.
  • HUANG Lei LIU Li-qin TANG You-gang
    . 2014, 33(22): 139-145.
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    Natural vibration characteristics study of a two dimensional rectangle moonpool is performed in this paper. Based on the linear potential theory, the equations are converted into eigenvalue problem by Galerkin method. Via solving the coefficient matrix of potential function, the semi-analytical solution of a two dimensional rectangle moolpool natural frequencies and shapes is obtained to present the geometric parameters influence on natural vibration characteristics. The results showed that, the natural frequencies occur in two catalogues as the mass flux at bottom: piston mode and sloshing mode. The piston mode frequency in vertical decreasing as the liquid height increased is largely determined by the liquid height, whereas sloshing mode frequencies decreasing as the moonpool width increased is mainly depended by the moonpool width. The piston mode shape presents crest in low liquid depth, and vanishes as the liquid depth increases. The CFD method is carried out to verify the semi-analytical solution, the free surface curves in two results fit well.
  • LIANG Feng;BAO Ri-dong;JIN Ying;SU Yong
    . 2014, 33(22): 146-151.
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    An external periodic load is considered to act on a fluid-conveying pipe clamped at both ends, and the nonlinear forced vibration for such a system is explored by the multidimensional Lindstedt-Poincaré (MDLP) method. According to the analysis, when the second natural frequency of the system is nearly thrice the first one, and the excitation frequency is near the middle of first two natural frequencies, a combination resonance with internal resonance may occur. The characteristics of this response are discussed, where the motions of first two modes are investigated in detail. The influence of excitation amplitude on the internal resonance is analyzed. Numerical examples reveal rich and complex dynamic behaviors caused by internal resonance and show that the occurrence tendency of internal resonance will die down and the response forms will vary with the excitation amplitude increasing. The convenience and efficiency of the MDLP method in predicting nonlinear dynamics are as well demonstrated by the results of the study.


  • QI Hui;CHEN Dong-ni;CAI Li-ming
    . 2014, 33(22): 152-156.
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    The solution of scattering of SH-wave was given by the method which to use an circular boundary of large radius to approximate the straight boundary of surface layer. With the theory of Helmholtz, the general solution of the Biot’s wave function was achieved. Utilizing the complex function method and the boundary conditions, we could transform the present problem into the problem in which we needed to solve the infinite linear algebraic equations with unknown coefficients. Numerical results of the ground motion were provided. The effects of incident wave number, incident angle, buried depth, stiffness of inclusion and layer on ground motion were analyzed qualitatively. The results in numerical examples show that greatly impact on ground motion can occur due to strong interaction between the surface layer, circular cavity and inclusion.

  • Yang Haiyang Zhong Tieyi Xia He
    . 2014, 33(22): 157-163.
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    Based on the general finite element software ANSYS, seismic responses under non-uniform excitations of a long-span railway suspension bridge are studied in this paper. Two different input methods, traveling seismic wave excitation and multi-support excitation, are used to analyze the seismic responses of the bridge, and then response regulations are discussed. By studying differences of the response control modes, the influence mechanisms of the non-uniform excitations are discussed, thus the fundamental differences between effects of the two input methods are revealed. These results can provide an important basis for the seismic analysis of the suspension bridge.
  • Yang Bin Cheng Junsheng
    . 2014, 33(22): 164-167.
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    To extract the sensitive damage features directly from the structural vibration responses, the singular value decomposition and the proper orthogonal decomposition are applied to decompose the structural vibration response matrix into a set of proper orthogonal mode, which can represent the structure natural properties. The singular value decomposition is firstly applied to the structural vibration power spectral matrix to figure out the modal frequencies, then the correlation matrix can be calculated at each modal frequency. The proper orthogonal decomposition method is applied on the correlation matrix, so that the proper orthogonal mode can be got, and the proper orthogonal mode converges to the normal structural mode, so the proper orthogonal modes can be used to construct a damage locating vector, and the damage can be located through the different stress distribution of each elements. The experimental results show that the proposed method can detect and locate the damage effectively.

  • JIA Hai-tao;WANG Feng;FANG Zong-de
    . 2014, 33(22): 168-171.
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    In order to effectively calculate the helical gear tooth surface contact stress under dynamic conditions, six degrees of freedom helical gears meshing type bending-torsion-axis coupling vibration model is established by considering time-varying mesh stiffness excitation and meshing impact excitation under the rolling bearing supported, and meshing dynamic load is calculated. Helical gear tooth contact dynamic stress calculation method is put forward considering the proposed dynamic load tooth, teeth and tooth surface load distribution, and the Hertz contact theory, but also the dynamics dynamic stress of tooth contact is get by use of Abaqus finite element analysis software. Dynamic contact stress under three load torques of 800N•m, 1200N•m and 1600N•m is calculated out, the results show that the maximum contact stress between loaded tooth contact analysis method and AGMA standard method is have the maximum difference of 11.6%, and the maximum difference between Abaqus finite element method and AGMA is 13.8%. The two methods of tooth contact dynamic stress curve maximum deviation of 11.3%, it is shown that the method proposed in this paper is reasonable and effective.
  • ZHU Xiu-yun;PAN Rong;LIN Gao;HU Meng-qian
    . 2014, 33(22): 172-177.
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    In order to resist the impact of aircraft crash, Reinforced concrete (RC) or Steel plate concrete (SC) structures are usually used in the design of external walls in nuclear island buildings. For comparing the im-pact resistance performance of the above two types of structures, comparative simulation analyses of a group of 1/7.5 scale aircraft model impact tests are carried out by applying nonlinear finite element code AN-SYS/LS-DYNA based on force time-history analysis method in this paper. The damage modes of the walls and the residual velocity of the scattered debris and the deformation of rear-face steel plate calculated by this paper are compared to the impact test results and the results based on the missile-target interaction analysis method of RC and SC walls, respectively. Of course, it is important that the simulation results with the same thickness walls of different types (RC/HSC/FSC) are compared either. The results indicate that the FEM si-mulation results based on the force time-history analysis method are in good agreement with the test results and the impact resistance performance of SC walls is better than RC walls, especially the rear face steel plate is very effective in preventing the perforation and scabbing of concrete. Therefore, the thickness of SC structures can be reduced in important structures like nuclear power plants against impact of aircraft com-pared to RC structures.


  • Yunlong Liu;ZhaoliTian;Aman Zhang
    . 2014, 33(22): 178-182.
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    As the classic form of submarine, dynamic responses and damage characteristics of cylindrical shell structure has always been concerned by researchers. In this paper, the damage caused by underwater explosion load is studied through Double Asymptotic Approximations method. By plenty analysis of cases, we found that the damage mode could be classified by the cause, such as local strength failure caused by direct impact load, dynamic buckling of local components, circumferential buckling of shell structure, and axial buckling of shell structure caused by whipping responses. Besides, the shockwave and bubble pulsation load are the dominating factor for far and near underwater explosion case.
  • Fan Pengxian Wang Mingyang;Feng Shufang Wang Derong Li Jie;
    . 2014, 33(22): 183-187.
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    The dynamic response of underground structure impacted by explosion is of great importance in the designing and evaluating of the protective engineering. The computational method for the dynamic response of straight-wall-round-arch structure to explosion seismic wave was investigated on the foundation of common deformation theory and matrix force method, and a rapid computation method is established. By the preseted method, the dynamic response of a typical straight-wall-round-arch structure was studied under different surrounding rock, subcrust and impact loading conditions. Results show that the rock grade, the thickness of subcrust and the loading mode all have notable influence on the structure’s dynamic response. The better the rock is, the lower the displacement and the internal force will be. And as the thickness of the subcrust increases, the peak value of the dynamic response decreases and delays.

  • JIA Guang-fei;WU Bo HU You-min
    . 2014, 33(22): 188-192.
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    Considering the nonlinear and non-stationary features of cutting chatter signals, this paper proposed a chatter recognition method based on Hilbert-Huang transform. By this method, firstly, a chatter signal is decomposed into a series of intrinsic mode functions (IMFs) by empirical mode decomposition (EMD), and then the IMF with rich chatter information is selected and filtered by a band-pass filter, and then the Hilbert spectrum of the filtered IMF is obtained by Hilbert transform, lastly, cutting chatter is quantitatively recognized by the standard deviation of amplitude of Hilbert spectrum. The effectiveness of the proposed method was validated by simulated and actual vibration signals. For comparison, the method by wavelet packet decomposition and wavelet spectrum analysis was also provided.


  • ZHAO Guo-wei;LI De-yong;CHEN-yong
    . 2014, 33(22): 193-197.
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    Based on the principles of cylindrical helical spring compressive deformation, dynamic equations of metal rubber vibration isolation system were derived. The metal rubber dynamic stiffness, frequency response and vibration characteristic were analyzed under the condition of a simple harmonic excitation. According to the method of harmonic balance, the influence of excitation frequency on metal rubber displacement amplitude, and the influences of metal rubber displacement amplitude and excitation frequency on metal rubber dynamic stiffness were analyzed. On the basis of the analysis of metal rubber vibration isolation system, the influences of metal rubber height, working face cross-sectional area and displacement compression on shock isolation coefficient were studied. Shock isolation coefficient could provide a reference on the design of metal rubber and its applications in engineering.


  • Wang Wei;Xu Hao;Ma Yue;Liu Haiping
    JOURNAL OF VIBRATION AND SHOCK. 2014, 33(22): 198-202.
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    Aiming at analyzing the self-loosening mechanism of bolted joints under vibration, a three dimensional FEA model of bolted joints , which had taken thread into consideration, was built with the application of APDL, and the preload was applied on the bolted joints by dropping temperature, then FEA transient analysis of the bolted joints under transverse cyclic excitation was conducted. Effect of transverse cyclic excitation’s amplitude, initial preload, thread and bearing friction coefficients, the joints’ surface friction coefficient on self-loosening was investigated. The results show that the complete thread slip occurs prior to the complete bearing surface slip under transverse vibration; the smaller amplitude is, and the greater initial preload, thread and bearing friction coefficients are, the more difficult self-loosening is to happen; the joints’ surface friction coefficient has little relationship with self-loosening, however, the larger joints’ surface friction coefficient makes the needed shearing force, which induces the transversal vibration, larger. These are of great significance for understanding of fasteners’ self-loosening and designing of bolted joints’ anti-loosening.