15 September 2018, Volume 37 Issue 19
    

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  • WANG Chao1,2,ZHU Hongping2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 1-6.
    Abstract ( 324 ) Download PDF ( 135 )   Knowledge map   Save
    For multi-layer shear time-varying structures, local structures with time-varying happening were extracted as sub-structures using the sub-structure method, internal forces on interfaces were exerted on substructures as external loads, and then the dynamic differential equations of substructures were built.Based on wavelet transform, time-varying parameters were expressed with wavelet expanding coefficients, and then dynamic differential equations of substructures were converted to linear algebraic equation sets, so problems for identification of time-varying parameters were converted into ones for time-invariant wavelet coefficients solving.Decomposition layers of different time-varying parameters were determined using Akaike information criterion.Time-varying parameters were reconstructed using the solved wavelet coefficients.Finally, a model for a multi-layer shear time-varying structure was numerically stimulated, and the analysis results showed that the proposed method can be used to identify time-varying parameters of multi-layer shear structures with response data of local substructures and this method has a certain anti-noise capacity.
  • JIANG ShuJie12,2 LIU FeiFei1,2 CHEN Gang2,3
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 7-13.
    Abstract ( 329 ) Download PDF ( 220 )   Knowledge map   Save
    In conventional aero-acoustic investigations, wing structures are usually treated as a rigid body not coupling with flow.Actually external flow induces wing structure’s vibration, and vibration causes flow field to change and aerodynamic noise variation.Neglecting this fluid-structure coupled vibration noise effect on wing structures with larger elasticity leads to numerical simulation results deviating from actual situations.In order to investigate influences of the fluid-structure coupled vibration effect on predicted results of aerodynamic noise, taking the NACA0012 airfoil model as a study object, the CFD/CSD coupled numerical method was used to solve unsteady responses of the airfoil flow field and the structure field, and evaluate the far-field radiated aerodynamic noise of the airfoil.The simulation results indicated that when considering fluid-structure interaction effects, the airfoil aerodynamic noise is significantly larger than that of the rigid body model, and the directivity of the noise source changes obviously; the vorticity analysis for the wing surface reveals that the wing vibration changes its surface pressure distribution and causes the turbulence kinetic energy to enhance on the wing surface, and make the wing aerodynamic noise radiation increase; the radiated aerodynamic noise of the elastic wing increases with decrease in its stiffness.
  • SONG Jindong, JIAO Congcong, LI Shanyou, HOU Baorui, WANG Yuan
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 14-22.
    Abstract ( ) Download PDF ( 80 )   Knowledge map   Save
    Here, a new approach to predict 40 cm/s2 with 4-level based on seismic early radiated P-wave energy was proposed with predicting accurately and rapidly the magnitude 1 earthquake alarm of high-speed railways taken as the objective.This method used Japan K-net strong ground motion data, based on the linear statistical relation between the ground motion parametric squared velocity integral IV2 to characterize earthquake rupture radiation energy and the peak ground acceleration (PGA), to predict if PGA reaches 40 cm/s2 using the magnitude 1 earthquake alarm threshold corresponding to IV2 of P-wave.Meanwhile, a parametric characteristic period τc being able to stably estimate the seismic magnitude M was introduced.The threshold of P-wave τc was used to characterize the large seismic magnitude event, and reflect the influence of seismic magnitude on the predicted results.Based on thresholds of IV2 and τc, the method model to predict the magnitude 1 earthquake alarm with 4-level was built.Using the strong ground motion data of 14 April 2016 Kumamoto earthquake (Mj=6.5) recorded at K-net stations along Kyushu Shinkansen, analyses were done for correctness and timeliness of the magnitude 1 earthquake alarm.The results showed that the magnitude 1 earthquake alarm can be predicted within 1 second after P-wave triggers at the station nearest the epicenter; this prediction time is 3.34 s and 4.84 s earlier than Kyushu Shinkansen derailment time and the emergency earthquake report time issued by the meteorological agency, respectively.
  • Yu Jianbo1 Liu Haiqiang1 Zheng Xiaoyun1 Zhou Binhai1 Cheng Hui2 Sun Xiwu2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 23-29.
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    Aiming at problems of early faults of rolling bearings having the feature of periodic impacts and very difficult to extract due to being submerged by strong noise, a new method for fault feature extraction of rolling bearings based on the time scale decomposition (ITD) and the sparse coding shrinkage (SCS) or ITD-SCS was proposed here.ITD could be used to adaptively decompose non-stationary and nonlinear vibration signals into several intrinsic rotation components or proper rotations (PRs), some of them were effectively selected to highlight impact features of original signals.Furthermore, the singular value decomposition (SVD) was used to perform noise-filtering for each effective PR, and SVD was taken as the pre-filtering noise unit of SCS to improve signals’ sparsity.Finally, SCS used the maximum likelihood estimation to extract impact features in synthetic signals.Numerical simulation results and testing ones for rolling bearings’ fault vibration signals showed that ITD-SCS method can be used to effectively extract impact features of bearing fault signals under strong background noise.
  • ZHANG Long1,2,3, CHENG Junliang2,LI Xinglin3,YANG Shixi1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 30-38.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Fault quantitative evaluation of rolling bearings is a basis to realize their effective residual life prediction and condition-based maintenance.The present fault quantitative evaluation method based on distance and probabilistic similarity measure has disadvantages of complicated calculation and easy premature saturation, and is unfavorable to on-line monitoring application.In traditional time domain, the statistical index of root mean square (RMS) has advantages of simple to calculate and good consistency with fault development trend, and it is widely used in engineering practice.Unfortunately, RMS is insensitive to incipient faults.Here, a new fault quantitative evaluation index named shock value of selected frequency band (SVSB) was proposed.Firstly, the crest of envelope spectrum (EC) was used to optimally select the central frequency and band width parameters of Morlet wavelet filter to obtain the adaptive optimal filter and do filtering for the analyzed signals.SVSB was defined as the product of RMS and EC of the filtered signals, RMS and EC represented the signal’s total intensity within the filtered frequency band and the ratio of fault induced impact components to the former, respectively.Thus, SVSB revealed effectively the strength of cyclic impact fault in rolling bearings to quantitatively evaluate their impact fault level.The test data for artificially introduced faults and rolling bearings’ fatigue test data showed that SVSB can trace rolling bearings’ fault development trend; it is sensitive to incipient faults.
  • YU Jianda1,2,PENG Linfeng1, ZHANG Xiangqi1, PENG Jian1,2,CHEN Zhengqing3
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 39-44.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    High-rise structures’ large amplitude vibrations and collapses easily happen under the action of earthquake, strong wind or other excitation.High-rise structures’ vibration reduction effect is not efficient using dampers directly at present due to the lack of ideal installation position of dampers.Sag damping cable is used to amplify the relative displacement between ground and high-rise structures and drive dampers for dissipating vibration energy of high-rise structures.This is a new attempt to reduce vibration of high-rise structures with dampers.Here, in order to investigate vibration reduction performance of sag damping cable for high-rise structures, an eddy current damper with adjustable viscous damping coefficients was developed, and the relationship between viscous damping coefficient and magnet number was obtained with test results.Then a sag damping cable was made with a main cable, an occurrence reset spring and an eddy damper.Vibration reduction test was conducted using the sag damping cable for a model structure.The results showed that the vibration reduction effect of the sag damping cable for high-rise structures increases with decrease in its main cable’s sag and increase in damper’s viscous damping coefficient; the additional damping ratio supplied by the sag damping cable for high-rise structures can reach more than 30%, this ratio is much larger than that provided by current other vibration reduction measures.
  • NIU Jiamin1,2, WU Jiuhui2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 45-49.
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    Low frequency sound wave control is a challenging subject, and membrane-type acoustic metamaterials for current hot research can deal with it.However, the sound-absorbing resonant frequency’s dropping is at the expense of resonant bandwidth.Here, the sound-absorbing membrane-type acoustic metamaterials were taken as the study object to study the effects of a resonance mass’s asymmetry on structure’s low frequency wide band sound-absorbing performance.The results showed that the sound absorption performance of a whole structure significantly increases under structural asymmetric mode, and the sound absorption bandwidth is widened; the frequencies for zero equivalent mass density are corresponding to peak values of sound absorption coefficient; a structure with asymmetric modes has higher elastic strain energy than that with symmetry modes does within a full frequency range; each sound absorption peak frequency caused by structure’s asymmetry is adjusted by the mass of a resonant block and reveals a certain law; according to this law, a sound-absorbing structure is designed to achieve the sound absorption effect with low frequency and wide band through numerical calculation.This study provided a theoretical guide for improving low frequency wide band sound-absorbing performance of membrane-type acoustic metamaterials.
  • CAI Yannian1, YU Hongliang1,2, YAN Jin2,LIAO Jianbin2,YU Wanneng2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 50-55.
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    In order to study influence laws of statistical energy parameter uncertainties on uncertainty of vibro-acoustic responses, Fourier amplitude sensitivity test (FAST) was applied to perform the parametric sensitivity analysis for a statistical energy vibro-acoustic model with three subsystems.It was shown that the most important parameter is the resonance coupling loss factor within a wide frequency band; the non-resonance coupling loss factor has a certain influence within a low frequency band; the coincidence effect changes the influence level of each parameter on the uncertainty of the output function under the critical frequency.The proposed method and conclusions could be used to identify the source of vibro-acoustic response uncertainty and contributions of different parameters.They provided a reference for designs of vibration and noise reduction based on SEA.

  • XU Yazhou1, LIU Kedong1,LIU Zhangjun2,SU Ningfen1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 56-61.
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    In order to investigate seismic responses of shear wall structures subjected to stochastic ground motions, a 1/5 scaled 12-layer shear wall model structure for shaking table tests was fabricated.34 non-stationary ground motion samples of frequent earthquake suitable to fortification of magnitude 7 earthquakes were generated based on the spectral representation-random function method.Variations of vibration modal shapes and damping coefficients of the model structure were analyzed through the model structure’s dynamic characteristics measurement.Means, variances, variation coefficients and probability density functions of structural dynamic magnification factor, inter-layer shear force and inter-story drift angle under stochastic ground motions were analyzed according to shaking table testing results.The results showed that the model structure random seismic responses has an obvious discreteness, the discreteness of acceleration magnification factor increases with increase in floor height, while that of inter-layer shear forces decreases with increase in floor height; the measured model structure’s random seismic responses and their probability information can be used to verify numerical simulation of a shear wall structure’s random seismic responses and its dynamic reliability evaluation.
  • WU Siyuan 1,2,WANG Zhengzhong 2,WANG Yue 2,Xu Chao 2,LIU Jiliang 3,WU Shoujun 2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 62-68.
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    In order to obtain an accurate dynamic finite element (FE) model of a radial gate, a rapidly modeling method based on combining Isight-MSC Patran/Nastran simulation and Eigen-sensitivity optimization was proposed.The main idea was that under the condition of ensuring the radial gate’s geometric features and its dynamic characteristics being consistent, mass redistribution is realized through combined calling software to derive the corresponding dynamic FE model.Here, the perturbation method was used to establish the target model for the main frame of the radial gate, and prove the validity of this method through iteration and approaching using the Eigen-sensitivity optimization method.Furthermore, through comparing this method with existing parametric optimization methods, it was shown that the proposed method can be used to get a more precise FE dynamic analysis model under the condition of guaranteeing the minimum variation.Using this approach, a dynamic FE model was constructed according to the actually measured data for the full hydro-elastic model of a radial gate.Example calculations showed that the proposed method needs fewer iteration steps to realize accurately modeling.
  • WANG Qingfeng, XU Gang, WANG Shuqi, ZHU Renqing
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 69-73.
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    The traditional frequency domain method has large limitations to simulate liquid sloshing in a tank.It only can be used to calculate a system’s response of each frequency under linear condition.The system’s responses under irregular excitations can be obtained with the spectral analysis method.Here, a method called DBIEM (de-singularized boundary integral element method) was proposed.Based on DBIEM, a liquid dynamic numerical model was built to solve liquid sloshing problems in a tank.A calculation program was developed using FORTRAN to simulate liquid sloshing in tanks with arbitrary shape and size.Firstly, a liquid tank sloshing problem was simulated under a single direction excitation.Its result was compared with its analytic solution, and the correctness and accuracy of the proposed method were verified.Then, liquid tank sloshing problems were simulated under irregular excitations.The results showed that the proposed method can be used to effectively simulate liquid tank sloshing problems.
     
  • WU Song1,2,GUO Qiwei1,2,ZANG Xu1, XU Teng1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 74-78.
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    For a suspended ultra-low frequency modal test system, its theoretical calculation models in vertical direction and horizontal one were established, respectively and Rayleigh method was used to solve fundamental frequencies of the system in both vertical and horizontal directions.The equivalent relationship expression between fundamental frequency test values and the true ones was built.Mechanism causing error, influencing factors and variation trend of fundamental frequency measurement in both directions were analyzed.The results showed that the system’s fundamental frequency test value in vertical direction is on the low side and that in horizontal direction is on the high side; the method and procedure to calculate the true fundamental frequency of products are proposed using their fundamental frequency test values; the correctness and effectiveness of the equivalent theoretical calculation models in both vertical and horizontal directions are verified with a standard bar’s fundamental frequency test and finite element simulation analysis.

  • TIAN Xiaochao1,2, YANG Zhigang3, WU Yue3,WANG Rui4, YANG Shuchen4, LI Qinghua2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 79-82.
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    Aiming at track matching failure phenomena appearing in design and use of linear piezoelectric vibration feeders, a prototype for tests was designed, and tests were conducted for different tracks and their installation ways.Two laser displacement sensors were used to measure vibrations of different positions during track failures.The results showed that amplitude of track endpoint is large, amplitude of track central position is small, motion directions of track’s two ends are opposite, i.e., track has both a translational motion and a rotation; the measured point near track gyration center has a displacement of 8.2 μm, the endpoint displacement can reach 67.8 μm; dynamic equations for both translation and angular motions of track under the condition of no damping are established, the effective condition for track matching is amplitude component of end angular motion being smaller than that of its translational motion.Theoretical analysis results indicated that decreasing track length, installation angle of vibrator and supporting points’ asymmetry degree are helpful to solve problems of track matching failure.
  • XIA Junzhong, L Qipeng, CHEN Chengfa, LIU Kunpeng, ZHENG Jianbo
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 83-88.
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    Fault feature extraction is the key of bearings’ health state description, however, features extracted with currently common methods may have higher dimensions or they are lack of information and unable to reflect bearings’ health state monotonously, and the predicted results cannot effectively reveal the degradation trend of bearings.Here, the cumulative sum and Mahalanobis distance (MD-CUSUM) was adopted to realize feature dimension reduction, obtain the health index (HI), and reflect monotonously health state of bearings with lower dimensions.Furthermore, a time delayed support vector regression (TD-SVR) model was constructed to improve the prediction accuracy for health state of rolling bearings.The advantages and disadvantages of MD-CUSUM and those of the isometric feature mapping were compared through test data analysis.The results showed that the combination of MD-CUSUM and TD-SVR has a better effect on predicting health state of bearings.

     
  • TIAN Jialin1,2,ZHANG Tangjia1, CHENG Wenming1,2,YUAN Changfu3, YANG Lin1, DONG Yi1, LIN Xiaoyue1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 89-96.
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    As a key problem in drill string dynamics, drill pipe stick slippage in deep wells and large displacement horizontal wells may cause drilling tool performance dropping and tool failure to lead to underground accidents.Therefore, studying sticky slip reduction technology has important guiding significances for effectively improving machinery’s rotating speed, shortening well-built period and ensuring safe operation.Here, based on the dynamic model of sticky slip process with longitudinal-torsional vibration coupled, a new constant torque tool was proposed.This new tool was taken as the study object to study its working mechanism.According to production data, the theoretical method established was used to do example analysis including longitudinal and torsional dynamic results.The example results were compared with the field data.The study showed that due to the constant torque effect produced by the new tool with longitudinal-torsional coupling, the torque fluctuation of the new tool can be effectively reduced to avoid the hysteresis phenomenon and make effective rock breaking behavior be continuous and stable when drilling for rock breaking in soft and hard inter-leaving zones.The proposed new constant torque tool provided a reference for improving techniques of sticky slip reduction and increasing speed and efficiency.The established theoretical dynamic model promoted the development of drill string dynamics under new drilling conditions.
  • LI Guojun1,BAI Junqiang1,TANG Changhong1,LI Yufei1,LIU Nan2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 97-103.
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    The unsteady Reynold averaged Navier-Stockes (URANS) equation was adopted to simulate unsteady aerodynamic force in stall flutter.Coupled with a structure’s dynamic equation, the time domain aero-elastic analysis method was established.The structure’s dynamic equation was solved in time domain using the fourth order implicit Adams linear multi-step method based on the prediction-correction technique.Firstly, the aerodynamic response of dynamic stall and the prediction accuracy of frequency locking region were verified to ensure the CFD solver being suitable to stall flutter simulation.Then, this aero-elastic analysis method was used to simulate the flutter boundary of NACA23012 airfoil.The results showed that the flutter velocity boundary predicted with the proposed method agrees well with the test results.Through analyzing structural motion responses and flow characteristics in stall flutter, it was found that the generation of leading edge vortices and wake shedding in stall flutter is an energy conversion and an injection mechanism to keep the constant amplitude oscillation of the airfoil; meanwhile, the frequency locking phenomenon occurring in stall flutter is the main reason to cause flutter frequencies abruptly dropping when the initial attack angle are 15°, 16°and 17°, respectively.
  • CAI Xiangyang1, SU Xiaoyang2, KANG Houjun2, GONG Ping1, LIU Haibo3, HU Jianhua3
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 104-111.
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    Here, a new dynamic model named a double-beam system with discrete springs was proposed for an inclined tower cable-stayed bridge without backstays based on cables’ elastic support effect on bridge deck beam in a cable-stayed bridge.In the model, cables were taken as springs without masses, tower and deck were regarded as two Euler-Bernoulli beams considering influence of axial force.Then, based on the basic principle of the transfer matrix method, the fundamental theory for evaluating the vertical bending stiffness of the inclined tower cable-stayed bridge without backstays was derived.Finally, Hongshan bridge of Changsha city was taken as an example, and its natural frequencies and modes were calculated.Meanwhile, influences of ordinary steel cables replaced with CFRP ones on the vertical bending rigidity of the bridge were studied.The results showed that the proposed model can be used to effectively evaluate the vertical bending rigidity of an inclined tower cable-stayed bridge without backstays; CFRP cables can improve the bridge’s overall rigidity to some extent compared with the traditional steel ones.

  • LEI Jiping1,2,YU Jianwu1, LI Chengbo3, CHEN Jianmei2,LI Wei2, LUO Hong1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 112-117.
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    Trace Sr+Sc and ultrasonic vibration (UV) were added in A380 alloy to implement modification processing and study effects and action mechanism of UV and trace Sr + Sc on microstructure and mechanical performance of A380 alloy.The results showed that the microstructure of A380 alloy can be refined significantly due to adding UV and trace Sr+Sc; the optimal refinement for the microstructure of A380 alloy is obtained when adding 0.15% Sr + 0.3% Sc and UV, its grain size is the smallest (about 27 μm) and its shape factor is the largest (about 0.8) with the highest hardness of 113BHN and the largest elongation of 4.7%; A380 alloy reaches the highest strength with its tensile strength of 302 MPa and its yield one of 272 MPa when adding 0.2% Sr + 0.4% Sc and UV.Through simulation analysis of ultrasonic cavitation field in melted A380 alloy, the influence mechanism of ultrasonic acoustic flow effect and cavitation one on alloy microstructure refinement and improvement of mechanical performance was explored.
  • JI Fang1, ZHANG Huadong1,2,LI Guonan1,3,WU Ming1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 118-123.
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    Tests for the correlation between ship vibration isolator installation parameters and vibration isolation effect are a key to support vibration isolator acoustic quality measuring.Here, typical ship vibration isolators were taken as a study object, their installation parameters being sensitive to vibration isolation effect in ship building process were found.Furthermore, the influence laws of vibration isolator’s mounting surface clearance and pre-tightening moment on vibration isolation effect were analyzed through series of process tests.Based on a great amount of actual ships test data, each installation parameter’s contribution to vibration isolation effect was obtained based on the multi-variate statistical analysis.The results showed that the BE300 vibration isolator’s vibration isolation effect is complexly related to its pre-tightening moment and bottom bonding clearance; its installation after removing bottom rubber and choosing proper pre-tightening moment is suggested; its vibration isolation effect is strongly correlated to its underwater deformation, its deformation after connecting pipes and gasket thickness at central frequencies of several 1/3 octave paths.
  • LI Heng, ZHANG Qin, QIN Xianrong, SUN Yuantao
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 124-131.
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    Aiming at fault vibration signals of rolling bearings with features of stronger non-stationarity and easy to be disturbed by strong background noise, a fault diagnosis method based on the short-time Fourier transform (STFT) and the convolution neural network (CNN) was proposed to realize the end-to-end fault pattern recognition.Firstly, STFT was performed for vibration signals of rolling bearings to get their time-frequency spectrum samples divided into a training set and a test one.Then, the training set was input into CNN to do learning and update parameters of CNN.Finally, the CNN model with updated parameters was applied in the test set to output the fault recognition results.Through simulation tests of rolling bearing faults, the feasibility and effectiveness of the proposed method were verified.The results indicated that the proposed method has higher recognition accuracies for different types of faults; the robustness of this method can be improved with increase in amount and type of fault data; it is a fault diagnosis method suitable for dealing with big data.

     
  • LIU Linya, QIN Jialiang, LEI Xiaoyan, SONG Rui, LIU Quan, ZENG Feng
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 132-138.
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    The low frequency noise radiated by trough girder structures in rail transit under dynamic load of trains is very harmful to human health.Taking a 30 m long rail transit trough girder simply supported as the study object, based on the vehicle-track coupled dynamic model, the vibration response of the trough girder under the action of train loads was calculated using the finite element method.Then, characteristics of the radiated noise of the trough girder structure were analyzed with the acoustic transfer vector method.Finally, contributions of the trough girder’s panels to radiated noise were studied.The results showed that both the peak frequency of the vertical vibration velocity level of the trough girder’s bottom deck and that of the transverse vibration velocity level of the trough girder’s web are 63 Hz, and the bottom deck’s vertical vibration response is the largest; the peak frequency of the linear sound pressure level of the trough girder structure-borne noise is near 63 Hz, its radiation region is the widest and its attenuation is the slowest at 63 Hz; the noise radiation main region is on the top and bottom of the girder, the noise on the top of the girder is larger than that on the bottom of the girder; the contribution of the girder bottom deck to noise is the largest, the second one is the girder web, and the influence of the girder flange slab on structure-borne noise is very small.
  • HAO Yaodong 1.2.3, PAN Nenggui1, HE Zhicheng1, GU Chengbo4
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 139-145.
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    Damping sheet is one of main means to control vibration and noise of vehicles, the robustness of its loss factor and manufacturing thickness is one of main factors causing vehicles’ NVH performance fluctuation.Here, the damping sheet was studied to control vehicles’ NVH performance fluctuation.Firstly, a four-factor model for damping material was built, Marquardt method was used to solve the model’s parameters and obtain damping material loss factor’s uncertain distribution characteristics.Then, the modal strain energy method was adopted to determine laying location of damping sheet.Finally, taking thickness of damping sheet as the design variable and loss factor as the random variable, the combined optimization method of the genetic algorithm (GA) and the sequential quadratic programming (SQP) one was applied to do the robustness optimization design and reduce the fluctuation of vehicle interior noise under the condition of ensuring the sound pressure level inside vehicle.Taking a MPV model as an example, the optimization design was performed.The results showed that the mean value of the single objective function (SOF) is 0.465 and its standard deviation is 0.004 7; the reliability reaches 99.8%, it’s almost double the initial design value.
  • ZHANG Lieshan1, ZHANG Xiaolin1, LIU Gang2, TANG Wenyan1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 146-152.
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    An optical coherence method based on low-frequency phase modulation of reference arm was proposed to detect nanometer level weak vibrations with medium and high frequencies.The model and its spectral distribution characteristics of weak vibration coherence detection signals were analyzed under condition of low-frequency phase modulation of reference arm.Then, the demodulation calculation method for weak vibration frequency and amplitude was proposed.Simulation study showed that the proposed method can correctly demodulate the frequency and amplitude of weak vibrations with a stronger anti-noise and anti-disturbance capacity.An optical heterodyne coherent system was developed to do tests and detect nanometer level weak water surface waves excited by underwater acoustic source.The test results showed that the proposed method can accurately measure the frequency of weak vibrations; it can detect the amplitude of weak vibration with a good repeatability; the detection method based on low-frequency phase modulation of reference arm provides a new solving scheme for parametric detection of weak vibrations with medium and high frequencies.
  • XU Kun,ZENG Jing, QI Yayun,YAN Yong
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 153-158.
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    In the traditional vehicle system dynamic analysis, the influence of harmonic torque of traction motor is rarely considered.In fact, the harmonic torque can cause the motor rotating speed’s oscillation, and then generate dynamic action forces exerted on the vehicle system.In order to calculate harmonic torque of a traction motor and its effects on dynamic performance of high-speed trains, according to traction motor’s parameters of a certain type high-speed train in China, the first four order components of its harmonic torque were calculated and added to the vehicle system dynamic model.After calculation, it was found that the harmonic torque has a larger influence on the comfort, wear and dissipation work indexes of a vehicle system; it has little effect on the system’s critical velocity, transverse and vertical ride indexes, derailment coefficient and maximum axle lateral force; it also causes longitudinal acceleration root mean square values of gear box and traction motor to increase, the harmonic torque’s effect on them increases with increase in the traction motor’s rotating speed.
  • DU Linlin1, LIU Weining1, LIU Weifeng1, MA Longxiang2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 159-165.
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    How to model a curved railway track subjected to a moving harmonic load is very important to solve its dynamic responses.Here, a periodically supported discrete curved Euler-Bernoulli beam was used to simulate dynamic responses of a curved track taken as a part of a circular structure periodically supported.The problem to solve dynamic responses of a curved track could be changed into one to be solved within one basic cell of track based on the dynamic property of periodic structures subjected to moving harmonic loads.Through introducing a curved track’s vibration modes and using the modes superposition method in frequency domain, its dynamic response was expressed with a series of its bending modes displacements and torsional ones in frequency domain.The study results showed that frequency ranges for significant dynamic responses of a curved track under a moving harmonic load are near load excitation frequencies; with increase in the moving speed of load, the track’s displacement responses decrease within a very narrow range near load excitation frequencies, but the track’s displacement responses within most parts of the other frequency ranges obviously increase; with increase in the moving speed of load, the peaks of the track’s responses change little, but time durations for significant responses become shorter; the effect of load moving speed on discrete supports’ parametric excitation is significant; the vertical dynamic responses of the curved track obtained with a curved beam model agree well with those obtained with a straight beam one, so a straight beam model can be adopted to approximately study the vertical responses of the curved track; when the curved track was analyzed with a precise model, curve radius has a certain effect on the track’s torsional vibration, so a curved beam model is needed to study the curved track’s dynamic responses.
     
  • XIAO Yihua, DONG Huanghuang, ZHOU Jianmin
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 166-173.
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    A SPH model for blunt projectiles normally penetrating into Weldox 460 E steel targets was established.The model was verified with test data.The verified SPH model was used to simulate penetration processes of mono-layer targets with thickness of 2 to 12 mm to establish an empirical formula for the relation between ballistic limit velocitiesy and thickness.Also numerical simulations for blunt projectiles penetrating into multi-layer targets were performed to analyze effects of number of layers, total thickness and thickness combination on targets’ anti-penetration performance.Based on the established empirical formula for ballistic limit velocities of monolayer targets, an analytical model for predicting ballistic limit velocities of multi-layer targets was derived.The calculated results of ballistic limit velocity with the analytical model were compared with those obtained with SPH simulations.The comparison showed that both of them are close to each other, and their relative error is basically within 10%.
  • CHEN Zhiyong, LI Zhenhan, ZHANG Tingting
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 174-182.
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    The rigid trajectory tracking control and flexible vibration suppression for flexible-base, flexible-joint space robot systems were studied under effects of bounded external disturbances and uncertain pedestal attitude control input proportion.Combined with the system momentum conservation principle and Lagrange method, the flexible compensation and the singular perturbation technique were adopted to establish the singular perturbation dynamic equations of a flexible-base, flexible-joint space robot system.To eliminate influences of external disturbances and uncertain control input proportion on the trajectory tracking precision of a space robot system, a linear velocity observer and a fuzzy controller were introduced based on the traditional immune control algorithm to propose an improved fuzzy- immune hybrid control law, it was independent on controlled slow-varying subsystem models and realized coordinated motion between pedestal attitude and joints of manipulator.To actively suppress double flexible vibrations of pedestal and joints, an optimal control law based on a linear state observer was proposed for fast-varying subsystems.The improved fuzzy-immune hybrid control and vibration suppression scheme was obtained by combining the above two control laws.The proposed control scheme didn’t need measurement and feedback of related velocity signals of the space robot system in process of real time control and kept strong robustness to the system uncertainties.Simulation results verified the effectiveness of the scheme in control of the system’s rigid and flexible motions.
  • XIE Yunfei1,3, LIU Yang2, HE Wenfu3
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 183-189.
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    Near-fault earthquakes tend to cause isolation layer’s larger displacement of seismic- isolated structures.Larger displacement leads to impacts between seismic-isolated structures and earth-retaining walls.To study damage performance and damage control mechanism, the analysis model for a seismic-isolated structure considering structure damage was established.Damage control effects of the seismic-isolated structure with added viscous damping ratios, variable frequency isolators and added buffer limit devices were compared using the elastic-plastic time history analysis method.The study results showed that when displacement of isolation layer of the seismic-isolated structure under near-fault ground motions is beyond the isolation joint spacing, the larger the displacement value, the more serious the damage of the structure; when using the three methods above mentioned to control damage under near-fault earthquake, the seismic-isolated structure’s damage under the designed ground motion is slight, using added viscous damping ratio is the most effective approach to control structure damage under nearly-fault earthquake, using variable frequency vibration isolation system has the best effect.The results provided a reference for damage control of seismic-isolated structures under near-fault earthquakes.
  • HUANG Qiang1,2, HUANG Hongwei1,2, ZHANG Dongmei1,2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 190-197.
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    Floating slab track as an effective means is widely applied in urban rail transportation to reduce train-induced vibration.Here, a floating slab was simplified as a mass, an infinite Euler beam and a short beam, respectively.Three dynamic equations for a discretely supported floating slab track were derived using the mode superposition method, respectively.Its vibration responses were numerically solved with Runge-Kutta method.The calculation results showed that a floating slab modeled as a mas or an infinite beam are two extreme cases of a floating slab track model, the calculation result of the actual floating slab track model is between those of the two extreme track models; a floating slab has a critical length, when its length is equal to the critical one, the response result of the long beam-short beam model agrees well with that of the two-long beam model; when the length of a floating slab is very short (0—0.6 m), the floating slab can be modeled as a mass; when its length is larger than its critical length, it can be modeled as a long beam; when a floating slab is a short beam with a finite length, rail deflection and bearing force of the slab decreases with increase in the slab length.The vibration reduction characteristics analysis for floating slabs showed that increasing floating slab length, stiffness of rail pad, and flexural stiffness of floating slab or decreasing floating slab’s support stiffness is an effective method to improve its vibration reduction performance and train running comfort.
  • MA Jianguo1,2,SHUAI Changgeng1,2, LI Yan1,2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 198-204.
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    Active control of low frequency line spectrum is an important technique for vibration and noise reduction.Based on theoretical study and finite element analysis for a maglev-air bag active-passive hybrid vibration isolator, special force-measuring fixture for the isolator was designed to conduct active control tests of the isolator and obtain its output force characteristics.Then, aiming at mechanical line spectrum vibrations, an active control method taking force as error signal was proposed and it was verified with tests.The test results showed that under the condition of taking force as error signal, the low frequency line spectrum control effect on transmitted force of the active-passive vibration isolation platform is good and the active control test platform’s low frequency line spectrum vibration can be reduced significantly.
     
     
  • DANG Xuan1 GU Fengshou1, 2 WANG Tie1 LI Guoxing1 WANG Huanhuan1 ZHANG Hu1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 205-210.
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    In order to diagnose fault of a single-cylinder diesel engine, acoustic emission (AE) sensors were installed at different positions on the diesel engine’s surface.By comparing peak responses of abnormal AE signals at different measured points, the strongest abnormal AE signal was found to locate at the big end bearing bush of the engine connecting rod.After diagnosing the abnormal AE signal at the big end bearing bush of the connecting rod, the fault type of the bearing bush was determined with MATLAB simulation.Finally, through the disassemble inspection and replacement of the bearing bush, the sound emission diagnosis results were verified.The results showed that the fit clearance between the connecting rod shaft neck and the bearing bush is excessive large, so the connecting rod shaft neck and bearing bush have a collision and friction  when the diesel engine rotates each 90°, the AE signal at the corresponding crankshaft angle position is caused to have an abnormal peak response.AE technique provided a more accurate method for fault source positioning of diesel engines and collision friction fault diagnosis of diesel engine connecting rod big end bearing bush.
  • SONG Tao1,2,WANG Yulin3, ZHAO Mingfu1,2,ZHONG Nianbing1,2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 211-216.
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    Variable operation conditions of rotating machineries lead to unstable vibration characteristics to bring large difficulties to their fault diagnosis.Here, a method for variable conditions fault diagnosis based on the singular value decomposition interpolation (SVDI) was proposed.Firstly, vibration signal samples of rotating machinery were collected under a discrete operation condition.Then sample characteristic matrices were decomposed into singular vectors, rotation matrices and characteristic means with SVD.These singular vectors, rotation matrices and characteristic means were interpolated to reconstruct characteristic matrices under the actual measured operation condition.Finally, the fault diagnosis for rotating machinery was conducted with the feature reduction and pattern recognition method.It was shown that the proposed method can be used to estimate vibration characteristics of rotating machinery under any working condition to a certain extent when there is no complete sample base, and solve difficult fault diagnosis problems of rotating machineries under variable operation conditions.
  • WAN Lixiang1, LIU Xuelai2, CHEN Quanrui1, HOU Qiufeng3, ZHANG Chen3, WANG Shannan3, SHANGGUAN Wenbin2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 217-224.
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    The relationship between a clutch’s release force-displacement curve and its pedal force-displacement one was analyzed.The finite element (FE) model for estimating the clutch release force-displacement characteristics was built.The FE model contained the clutch’s pressure plate assembly and the driven disc one considering axial nonlinear characteristics of diaphragm spring and wave plate.Using the established model, the clutch’s release force-displacement curve was calculated.This curve was also measured with a test rig.The calculated results were compared with test ones to validate the correctness of the established model.The effects of diaphragm spring’s working point position and wave plate’s axial stiffness on the clutch’s release force-displacement curve were analyzed to improve the clutch’s pedal force-displacement characteristics.A clutch’s control system test platform was adopted to measure the clutch’s pedal force-displacement curve, and the test results verified the correctness of the calculated ones for improving the clutch’s pedal force-displacement characteristics.
  • ZHANG Shiming,ZHOU Yun, HU Heping
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 225-230.
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    Helicopter rotor blades’ first order lead-lag backward type mode is the main mode to affect its ground resonance stability.To identify the damping of this first order lead-lag mode, four different methods including FFT-based moving block (FFT-MB), Fourier series-based moving block (FSMB), Hilbert transform (HT) and Wavelet transform (WT) were proposed.Aiming at measured signals appearing dense frequency components and had signal-noise-ratio (SNR), a digital filter was added.Numerical simulation and recognition results based on test data indicated that both FSMB and WT methods can be used to effectively separate the first order lead-lag mode of helicopter bearingless rotor blades and the digital filter can be used to effectively improve the damping identification accuracy of this lead-lag mode.
  • NING Fangli 1.2 NING Shunshan 1 SHI Xudong 1 LIU Zhe 1WEI Juan3
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 231-238.
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    Cavity flow phenomena exist in various kinds of aircrafts.The cavity noise induced by cavity flow is easy to cause structures inside cavity resonance and acoustic fatigue failure of components carried inside cavity.Therefore studying mechanism and effective control methods of cavity noise has important practical significance in engineering.Here, a new active control method for deformable cavity noise was proposed using a mechanical device inside a cavity to adjust the inclination angle between the bottom surface and the rear wall of the cavity, and change the shape of the cavity with variation of flow velocity.Large eddy simulation and computational aerodynamic noise method were combined to simulate a typical open cavity noise.The results showed that the peak sound pressure level of pure tone noise main mode decreases with increase in the inclination angle   of rear wall, but the pure tone noise main modal frequency jumps to rise; increase in α causes the peak sound pressure level of pure tone noise main mode to drop with Mach number of 0.6 more significantly than it does with Mach number of 0.85; increase in α causes the frequency of pure tone noise main mode to rise with Mach number of 0.85 more significantly than it does with Mach number of 0.6; the proposed active control method for deformable cavity noise can not only significantly reduce the peak sound pressure level of pure tone noise main mode, but also make the frequency of pure tone noise main mode rise to keep away from the natural frequency of the cavity structure, and avoid the cavity’s resonance failure.This study laid a theoretical foundation for extending the engineering application of the active control method for deformable cavity noise.
  • WANG Jianlin1, GUO Yongqi1, WEI Qingxuan1, SUN Qiao2, HU Hongbo2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 239-244.
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    It is important to improve parametric recognition accuracy of accelerometer dynamic model for studying and improving accelerometer dynamic characteristics.Aiming at the problem of nonlinearity of accelerometer affecting its dynamic model parametric identification accuracy, an accelerometer dynamic model parametric identification method using the weighted least squares (WLS) and the support vector machine (SVM) was proposed.Aiming at the second order nonlinear dynamic model of accelerometer containing a linear part and nonlinear terms, parameters of the linear part of the model were identified using WLS, and the nonlinear characteristics of the model were estimated using SVM.Then the constructed error criterion function was iterated and minimized to realize the optimal identification for accelerometer dynamic model parameters.The simulation tests and the accelerometer calibration tests under shock excitation based on the absolute method showed that the proposed method can be used to reduce influences of nonlinearity of accelerometer on its dynamic model parametric identification accuracy; the identified results for accelerometer dynamic model parameters have a higher accuracy.
  • XUE Jianyang1, MA Linlin1, DONG Jinshuang1, GAO Weixin1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 245-253.
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    In order to investigate influences of brackets on mechanical performance of steel eave columns in an imitated ancient building, eight specimens of steel eave columns and brackets in an imitated ancient building with the scale of 1/1.5 were tested under low-cyclic repeated loading.On base of obtaining load-displacement hysteresis loops and skeleton curves of specimens, their rigidity degradation, strength decay, ductility, energy-dissipating capacity and failure mechanism were analyzed.The results showed that brackets not only change steel eave columns’ force transfer mechanism, but also affect their aseismic performance significantly; their yield and ultimate force-bearing capacity increase by 30.7% and 24.0%, respectively; their rigidities at yield point and ultimate one increase by 52.8% and 135.6%, respectively; the energy-dissipating capacity of eave columns with brackets at yield point is obviously higher than that of common eave columns, but the ductility of eaves column with brackets slightly decreases by average 8.5%.The finite element model for eave columns in imitated ancient building was established with the software ABAQUS based on the test study.The parametric analysis for influences of the thickness-width ratio of Ludou on eave columns’ aseismic performance was done.The results showed that with increase in the thickness-width ratio of Ludou within a certain range, the rigidity and strength of ease columns with brackets increase, while their displacement ductility decreases to a certain extent; the rigidity and force-bearing capacity of eave columns with brackets firstly increase and then decrease, when the thickness-width ratio of Ludou is within a range of 0.011—0.015, their rate of increase in the rigidity and force-bearing capacity is the maximum.
  • YAN Rongge 1,ZHAO Luna 1,BEN Tong 1,ZHOU Jie1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(19): 254-258.
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    Noise suppression is one of key factors which must be considered in manufacture and application of reactors, especially, in high voltage transmission networks.In order to solve problems of reactors’ vibration and noise, a vibration reduction method using negative giant magnetostrictive material (NGMM) was proposed.A single-phase iron-core reactor was taken as an example, and the reactor iron-core’s electromagnetic-mechanical coupled model was established.Based on the finite element method, the quantitative analysis was conducted to study vibrations of the reactor iron-core under magnetostrictive effect, Maxwell force and their combined action, respectively.The result showed that influence of magnetostrictive effect on the reactor vibration counteracts that of Maxwell force on the reactor vibration.Then NGMM was filled into air gaps of the reactor.The negative deformation produced by the material under the action of magnetic field was used to eliminate the original mechanical deformation of the reactor.The vibration displacements of the reactor with two different filled materials were compared, the results showed that the reactor’s vibration displacement is reduced by 13%; this study provides a theoretical support for the later design of low noise reactors.