15 February 2024, Volume 43 Issue 3
    

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  • FENG Linzhao1,2, KANG Lixia3, LAI Liangqing1,2, CHEN Gaosheng1,2, ZHAO Xiaojian1,2, SU Zhengtao2, LIU Jia1,2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 1-6.
    Abstract ( 300 ) Download PDF ( 155 )   Knowledge map   Save
    In order to investigate the influence law of material performance parameters on the dynamic characteristics of the fluid-elastomeric damper, the variation of load-displacement curve, elastic stiffness, damping stiffness and loss factor of the fluid-elastomeric damper with the difference of rubber hardness and damping fluid viscosity were studied by electro-hydraulic servo dynamic testing machine. The test results showed that more than 91.5% of the elastic stiffness of the fluid-elastomeric damper is provided by the rubber part, and the elastic stiffness increases with the increase of rubber hardness. More than 84.8% of the damping stiffness of the fluid-elastomeric damper is provided by the damping fluid, and the damping stiffness and loss factor increase with the increase of the viscosity of the damping fluid and decrease with the increase of the shear amplitude. The greater the viscosity of the damping fluid, the greater the decrease of the damping stiffness and loss factor. When the viscosity of damping fluid increases from 2000 mm2/s to 10000 mm2/s, the damping stiffness of the fluid-elastomeric damper increases from 2420 N/mm to 5163 N/mm. when the shear amplitude increases from 0.2 mm to 1.5 mm, the damping stiffness decreases by 18.5% and 40.1%, respectively. The above conclusions can provide a basis for the selection of materials for fluid-elastomeric damper.
  • ZHANG Pengfei, WEN Yue, LI Zhaoquan
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 7-13.
    Abstract ( 241 ) Download PDF ( 106 )   Knowledge map   Save
    Long span cable-stayed bridges are prone to displacement and deformation due to beam flexibility in natural wind field, in order to study the distribution law of mechanical properties of bridge and track structures of CRTS double slab ballastless track continuous welded rails (CWR) on the long-span cable-stayed bridge under static wind load. taking a four line prestressed concrete cable-stayed bridge as the engineering background, a refined spatial coupling model of CWR on long-span cable-stayed bridge is established based on finite element method, and the mechanical properties of bridge system and track structures on the bridge under transverse static wind load are analyzed. The analysis results show that the maximum of the three direction forces (stresses) of the bridge and the track structures on the bridge is basically distributed in the middle span and near the side pier of the cable-stayed bridge; In the three direction forces (stresses) of each structures, the longitudinal stress peak of the base plate and bridge structure is the largest, about 8 times of the transverse stress peak, and about 7 and 13 times of the vertical stress peak, the transverse stress of track plate shows the maximum peak value, and the gap with the peak value of the other two direction stresses is small; In the three direction displacements of each structures, the transverse and vertical displacements reach the maximum at and near the middle of the span, and the longitudinal displacement reaches the maximum near the side pier of the cable-stayed bridge, among them, the peak value of lateral displacement is more than 20 times that of the other two directions; The vertical and longitudinal displacement directions of the structures on both sides of the bridge are opposite, that is, the bridge is inclined to overturn and bend under the action of static wind. The research results can provide a theoretical basis for the design, maintenance, and health monitoring of long span cable-stayed bridges in wind environment.
  • WANG Rui, DONG Zhiqian, LI Gang, YU Dinghao, ZHANG Han
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 14-26.
    Abstract ( 218 ) Download PDF ( 99 )   Knowledge map   Save
    With the rapid development of physical test technology, the structural model test can accurately obtain the dynamic response of the structure under environmental load. However, in the study of model test problems such as soil-structure interaction, regional group structure, complex structure wind tunnel,pseudo-static and shaking table tests, simple, practical and accurate simplified models of model tests are still the focus of research. In the existing model simplification methods, the calibration of nonlinear mechanical parameters is complicated, and the feasibility of test is insufficient. A simplified design method of high-rise structure test model considering nonlinear behavior similarity is proposed. The flexural and shear restoring force model simulating high-rise structures is decomposed into a combination of linear and nonlinear behaviors The nonlinear behavior of structure is simulated by Coulomb friction model. Because of its simple parameters, it has certain physical significance, it can be directly applied to model test. Based on the above theoretical methods, effective combination of flexural-shear model and flat-torsional friction device, and the physical model design method for the scale test and the calculation method of parameters such as stiffness, post-yield stiffness and bearing capacity are proposed, established the corresponding mechanical calculation model of "double shear and double flexural spring between layers". The test results can be used to predict the dynamic response of the structure in elastic and nonlinear stages. Taking a high-rise structure as an example, the feasibility and accuracy of the method proposed are verified by numerical simulation and shaking table test.
  • ZHAO Zhencheng1,2, ZHANG Hanke1,2, ZHENG Ling1,2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 27-36.
    Abstract ( 291 ) Download PDF ( 95 )   Knowledge map   Save
    Based on the characteristics of ABH (acoustic black hole) arc beam with small volume and rich modal frequencies, ABH (acoustic black hole) arc beam is periodically distributed on the straight beam as an additional structure and coupled with the straight beam to promote the local resonance effect and broaden the low-frequency band gap, and a new local resonance acoustic metamaterial is constructed. For local resonant metamaterials, the semi analytical theoretical analysis model is established by using the Gaussian expansion method. The internal connection and periodic boundary conditions are treated based on the null space method. The accuracy of the semi analytical theoretical analysis model is verified by the finite element method. The energy band structure is analyzed and calculated, and the influence mechanism of structural parameters and ABH effect on Bragg band gap and local resonance band gap is studied. The results show that the semi analytical theoretical model can effectively calculate the band gap of the structure, and the notch mechanism with arc ABH can promote the local resonance effect of the structure and effectively reduce the vibration of the main beam.
  • HAN Yueyang1,2, ZHU Xiang1,2,3, LI Tianyun1,2,3, ZHANG Shuai1,2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 37-45.
    Abstract ( 158 ) Download PDF ( 117 )   Knowledge map   Save
    The liquid-filled cylindrical shell structure widely exists in practical engineering. Under the action of external excitation, the cylindrical shell and the fluid will generate coupled vibration, and the unfilled liquid surface will also slosh. This coupled vibration response analysis is of great significance in engineering. This paper presents a semi-analytical method for solving an elastic cylindrical shell's vibration response considering internal liquid sloshing. Firstly, a shell-based structure coordinate system and a free liquid surface-based liquid coordinate system are established to describe the internal liquid's structure and movement, respectively. Based on the Flügge shell theory, the motion control equation of the cylindrical shell is established. Considering the liquid as an inviscid and incompressible ideal fluid, the velocity potential function of the internal liquid is obtained according to the linear water wave theory and the boundary conditions of the liquid free surface motion. The motion governing equations of the fluid-structure interaction interface is obtained through the continuity condition of the fluid-structure interaction system and the coordinate transformation. The vibration response of the shell under radial harmonic excitation is studied, and the corresponding liquid surface sloshing response is obtained. By changing the system parameters, the vibration response characteristics of the elastic cylindrical shell considering the internal liquid sloshing are discussed.
  • ZHAO Wu1, ZHANG Quanbin1, LI Yamin1,2, JING Shuangxi1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 46-57.
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    The lateral random dynamic behavior of BTA deep-hole boring bar with axial flow fluid under stochastic excitation is studied by using stochastic method. The bending, stretching and torsional deformation of the boring bar under fluid-structure coupling were considered in the modeling, and the Galerkin method was used to discretization the model. The effects of characteristic values and frequency on vibration characteristics of BTA boring bar with and without stochastic excitation are analyzed. The critical speed and critical instability frequency of the lateral vibration of the deep-hole boring bar were analyzed by using the maximum value of the response variance and spectral density. The influence of parameters such as rotational speed, stiffness, initial total axial force and shear modulus on the vibration characteristics of the system is clarified. The effect of the speed change of boring bar on the stability of the system is no longer monotonous, with the increase of the BTA boring bar speed, the system will undergo two critical instabilities of rotational speed, namely the systematic motion modes transfer in the order of instability, stability, instability and stability; Increasing the equivalent stiffness and equivalent shear modulus of the system will promote the stability of the working process; The effect of changing the axial force on the stability of the working process is not obvious; The agreement between the analysis results and the experimental results is verified by the power spectrum of stochastic vibration physical experiments. This study reveals the complexity of the motion state of BTA deep hole process system to a certain extent, and this research mode provides more possibilities for further analysis of the motion evolution in the complex state. The research conclusion provides a basis for better understanding the random dynamic behavior of BTA deep-hole boring bar when it works, and also provides a theoretical basis for vibration control and parameter optimization of BTA deep-hole process.
  • ZHANG Jianbo1, CHEN Ce2, DENG Zhifang1, ZHANG Kun1, JIN Hailiang1, CAO Yitao1, SU Zhimin1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 58-68.
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    In this paper, the method of “separation of variables” (MSV) is utilized to solve laminar boundary-layer equations of aerostatic thrust bearing with single orifice and study the performances of the flow field behind orifice. Then the pressure depression phenomenon is caused by the inertial effect and the influences of the aerostatic bearing geometry and flow parameters on the pressure depression are studied. Moreover, the critical condition of the pressure phenomenon generation is the critical pressure ratio 0.9409, i.e. that is, when the pressure ratio is greater than the critical pressure ratio, the pressure depression phenomenon disappears. Moreover, based on the principle of the equal mass flow rate, a new numerical method which combines the MSV for solution of laminar boundary-layer equations and analytical solution of Reynolds equation is proposed to study the discharge coefficient. The influences of flow and geometry parameters on discharge coefficients are investigated. The results show that there exists parameters insensitive and sensitive regions in discharge coefficient analysis, which is caused by that discharge coefficient tends to be constant 0.86 when pressure ratio is approximately less than 0.6.
  • HUANG Dawei, CHEN Likun, GAO Yadong
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 69-76.
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    The strain produced by impact load on a structural is much greater than the static load. It is of great significance to identify the impact load accurately. The method proposed aims at the prominent contradiction of inconsistent sample length between impact load and response signal. The method was based on linear model and the experiment was carried on a steel pylon structure. Firstly, the feature extraction of vibration signals was carried out based on the impact response signal decomposition theory. Then, the load and response signal sample characteristics are mapped to realize the impact load identification based on the long short term memory neural network (LSTM). The results show that the correlation coefficients between the true and predicted load are more than 94% and the RMSE (root-mean square error) are less than 0.6.
  • ZHAN Jinqing1, WANG Xiao1, PU Shengxin1, LIU Min1,2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 77-85.
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    A method for dynamic topology optimization of continuum structures with multiphase materials using the equivalent static load method is proposed to meet the dynamic performance requirements. The ordered solid isotropic material with penalization (SIMP) interpolation is used to penalize the stiffness matrix and mass matrix. The objective function is developed by minimizing the total dynamic compliance of a multi-material structure under multiple dynamic loads subject to a mass constraint and a cost constraint. The dynamic topology optimization model for multi-material continuum structures is developed. To reduce the complexity of sensitivity analysis, the equivalent static load method is used to transform the dynamic topology optimization problem into the problem for topology optimization under multiple static loads. The method of moving asymptotes algorithm is employed to solve the problem for dynamic topology optimization of multi-material continuum structures. The results of numerical examples demonstrate the effectiveness of the proposed method. In comparison to the traditional topology optimization method, the method for dynamic topology optimization of multi-material structures based on the equivalent static load method reduces solution time by 75% and significantly improves calculation efficiency. The structures obtained by dynamic topology optimization with multiple materials have better dynamic performance than those obtained by topology optimization with single phase material.
  • LI Buyun1,2, SHUAI Changgeng1,2, MA Jianguo1,2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 86-92.
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    Low-frequency vibration affects the acoustic stealth performance of underwater equipment. A novel nonlinear floating raft vibration isolation system is proposed based on air spring. The structure design makes the lateral air spring provide negative stiffness to the system and improve the low-frequency vibration isolation performance. The new system consists of "lateral air spring-universal joint-vertical air spring" nonlinear vibration isolator group and floating raft. The mechanism of the negative stiffness generated is analyzed, the six-degrees-of-freedom dynamic model of the nonlinear floating raft vibration isolation system is established, the prototype of the new system is designed, and the related performance tests are carried out. Theoretical analysis and experimental results show that the vertical first order natural frequency of the new system is approximately reduced to 50% of that of the original system, and the vertical vibration isolation performance is improved by about 6dB, and the lateral vibration isolation performance is similar to that of the original system. In addition, the rolling stability of nonlinear floating raft vibration isolation system is also studied. The results show that the new system can have good rolling stability under heavy load.
  • CHEN Gongqing, WU Hao, L Jinxian, CHEN De
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 93-104.
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    As non-structural members, masonry infill walls are often neglected in the blast-resistant analysis of structures. However, serious damage occurs to masonry infill walls in explosion accidents, which affects the propagation of blast wave, its interaction with structures and the degree of damage to the structure. This paper aims to evaluate the effect of masonry infill walls on damage and failure of RC frame structure under external blast loadings based on refined numerical simulation approach. Firstly, the finite element software LS-DYNA is used to reproduce the near-range explosion tests of typical masonry infill walls and masonry-infilled RC frame, which verifies the applicability of the simplified micro-modelling approach, material models and parameters, as well as the blast loading applied approach based on Arbitrary Lagrangian-Eulerian (ALE) and the Fluid-Structure Interaction (FSI) algorithm. Furthermore, combined with the structural hybrid element modelling approach, the numerical simulation was carried out on the dynamic behavior of the typical 6-story bare and masonry-infilled RC frame structure with 6-, 7- and 8-degrees seismic precautionary intensities under the explosion of sedan bomb (454kg equivalent TNT specified by Federal Emergency Management Agency) at the bottom edge column. The propagation of blast wave, as well as dynamic response, damage pattern and collapse-resistance mechanism of the structures were examined. It derives that: the masonry infill walls can effectively block the inward propagation of blast wave and reduce the peak overpressure on the adjacent internal column by 95%, and thus relieve the damage degree of the internal structural members. However, the structural damage at the head-on blast face is aggravated, e.g., compared with bare frame, the horizontal displacements of target column in masonry-infilled RC frame with three seismic precautionary intensities increase by 21.4%, 31.1% and 14.8%, respectively. The vertical displacement of target column at top floor in the bare and masonry-infilled RC frame with different seismic precautionary intensity is basically same. Therefore, the effects of seismic design and masonry infill walls on the overall collapse behavior of structures can be ignored under the external explosion of sedan bomb.
  • YANG Qingshan, ZHANG Yuanhao, LIU Gang, WANG Hui
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 105-109.
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    In view of the low efficiency of the revision due to the numerous nodes of the solid finite element model of the ancient masonry pagoda, a fast revision method of the finite element model combining the solid model and the cantilever model is proposed. Based on the test output signal, the natural frequencies were obtained by using Stochastic Subspace Identification method. Based on ABAQUS platform, the finite element model is established by using the overall continuous method, based on the measured results, the Firefly Algorithm is used to modify the elastic modulus and density of the pagoda. The calculated results of the modified finite element model are close to the measured results, it shows that the modified model is reliable and can be used as the basis for subsequent seismic performance analysis.
  • XU Hongda, WANG Yu, JIAN Ze, LI Xuehui, YU Xiaoguang
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 110-119.
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    Based on Halpin-Tsai micromechanical model and transfer matrix method, the traveling wave vibration characteristics of a rotating dual-functionally graded graphene platelet reinforced composite(DFG-GPLRC) cylindrical shell were investigated. The material properties of metal-ceramic functionally graded matrix and five types of distribution patterns of graphene platelet were analyzed. Based on the Love’s shell theory and transfer matrix method, the ordinary differential equations and the global transfer matrix relation for any cross section state vector were derived considering the influence of rotational speeds. The dynamic differential equations were solved based on clamped-free (cantilever) boundary condition mainly, which verified the rationality of the analytical method. The research shows that the low-order modes are dominated by the first axial half-wave number and the circumferential mode vibration for the free end, and the coriolis force caused by rotating speeds makes the traveling wave curve separate. The traveling wave frequencies increase with the increase of graphene material weight fraction, and the distribution patterns have little effect on the mode shape order. The volume fraction exponent of the matrix has some obvious effects on the vibration characteristics, while the number of graphene layers has little effect, and different excitation frequencies have different effects on resonance characteristics.
  • WANG Qingsong1, ZHANG Yu1, ZHANG Hongyu1, CHEN Baihua2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 120-127.
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    Aiming at the problem that it is difficult to observe the internal interface debonding damage of carbon fiber composite (CFRP) strengthening steel structures, a method for interface debonding prediction using Lamb wave and neural networks was proposed. The experimental platform for the CFRP strengthening steel plate signal analysis based on Lamb wave was built. The electromechanical coupling finite element model was established using ABAQUS software, and the accuracy of the finite element model was verified by experiment. The signals obtained from the models with rectangular and circular debonding shapes were analyzed in the time and frequency domain. Based on the Elman neural network improved by the adaptive genetic algorithm, the prediction model for the debonding area of steel plate reinforced with CFRP was established. The signal feature data with a high correlation with the debonding area was used as the feature data for the prediction model. The performance of the prediction model is verified, and the mean absolute percentage error of the predicted debonding area for rectangular and circular debonding shapes is 3.03% and 8.06%, respectively, which show that the improved Elman network has better prediction accuracy for debonding.
  • WU Shaowei1, XIANG Jinghui2, LI Jianzhong1, CHEN Xu1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 128-135.
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    A direct displacement-based design procedure for isolated bridges with irregularity in height is proposed, which can be incorporated into a performance-based design philosophy. This method can be used to determine the reinforcement ratios of piers and the properties of bearings. Under longitudinal seismic motions, all piers can perform elastically, and all bearings can achieve the same damage state. Furthermore, a uniform distribution of shear forces or base bending moments among all piers can be achieved. An example bridge is designed using this method, and the finite element model of the bridge is established to perform nonlinear time history analysis. The comparison of design results and time history analysis results shows the effectiveness of this method. In addition, the seismic response of the bridge designed by this method under two seismic force distribution modes (i.e., uniform shear force and uniform base bending moment) is compared. The result shows that for the bridge with the same section size and reinforcement at each pier, the uniform distribution of base bending moment is recommended. This distribution mode can optimize the use of materials and reduce construction costs, but special attention should be paid to the shear capacity check of short piers.
  • LI Jiaxiang1,2,3, WANG Wenrui1, FU Xing2, JIANG Wenqiang3, DONG Zhiqian2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 136-146.
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    The icing disaster seriously threatens the safe operation of transmission lines. In the process of ice disaster, it is often accompanied by the effect of wind load. In order to improve the ability of transmission towers to resist icing disaster, this paper proposes a failure probability evaluation framework of transmission towers based on Jones icing model. Firstly, based on the meteorological station data of Chenzhou, Yongzhou and Shaoyang in Hunan Province, the superstation is established. On this basis, the Copula function is used to establish the joint probability distribution considering the correlation of ice thickness-wind speed and wind speed-wind direction. Finally, taking an actual transmission line as an example, the collapse failure probability of the tower under the coupling of ice wind load is calculated. The results show that the method proposed in this paper can effectively evaluate the failure probability of transmission towers under ice-wind coupling. After considering the correlation of ice thickness-wind speed and wind direction-wind speed, The calculation of failure probability of transmission towers is more scientific and reasonable. Affected by the probability of wind direction, the value of transmission towers failure probability may appear at any angle. This paper can provide reference for the design of transmission line ice disaster resistance.
  • LI Jiaxin1,2, WANG Dong1,2, SUN Wei1,2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 147-157.
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    In order to reduce the harmful vibration of aero-engine pipeline in service stage, this paper describes a method to reduce the vibration of pipeline by attaching viscoelastic damping layer locally on the surface of pipeline, which mainly includes dynamics finite element modeling of damping layer-spatial pipeline system and position optimization of damping layer. In the modeling, based on ANSYS platform, a parametric finite element model of damping layer-spatial pipeline is established to satisfy the calling of optimization algorithm. At the same time, two kinds of damping are introduced into the whole model, which are the support damping of clamp and the material damping of viscoelastic damping layer. In the aspect of position optimization, an optimization model with the attaching position of damping layer as the design variable and the minimum of first-order maximum resonance response as the optimization objective is created, and the solution flow for the optimization model is given by genetic algorithm. Finally, a case study is carried out, and the rationality of the damping layer-spatial pipeline analysis model is verified by the experimental system of spatial pipeline with damping layer. Based on this, the position optimization of damping layer is carried out, and the damping layer attaching position scheme which minimizes the resonance response in the movable range is obtained. The rationality of the optimization results is proved by numerical comparison with five random schemes.
  • NING Fangli, WANG Ke, HAO Mingyang
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 158-163.
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    To the characteristics of small amount of data and non-stationary fault signal of bearing fault diagnosis, a bearing fault diagnosis method combining short-time Fourier transform, convolutional neural network and vision transformer is proposed. Firstly, the origin acoustic signal is converted by short-time Fourier transformer into a time-frequency image containing timing information and frequency information. Secondly, the time-frequency image is used as the input of the convolution neural network, which is used to implicitly extract the deep features of the image, and its output is the input of the vision transformer. And the vision transformer is used to extract time series information. Finally, the output layer is used to realize the pattern recognition of multiple faults of the bearing using Softmax function. The experimental results show that this method has a high accuracy rate for bearing fault diagnosis. In order to better explain and optimize the proposed bearing fault diagnosis method, the classification features are visualized by the t-distribution domain embedding algorithm.
  • LI Binbin1, KOU Xiping1,2, L Binbin1, YU Li1, YANG Xinghua1, LU Bo1, ZENG Kaichun1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 164-170.
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    Aiming at the low frequency and large vibration of the test model caused by the interference of shock vortex and shock boundary layer during the transonic wind tunnel test, the adaptive LMS filter algorithm developed based on Wiener filter was used to systematically test the test model. After identification, the filter coefficients of the first and second-order modes of vibration in the pitch direction of the test model are obtained, which can be used to design the digital filter of the test model and the active vibration control algorithm. The actual collected wind tunnel test data has multi-modal coupling, and the vibration energy of the model is mainly concentrated in the first two modes in the pitch direction, therefore, in order to accurately identify the first two-order modal transfer functions in the pitch direction, the fast Fourier transform is used to modally decouple the measured vibration signals of the filtered active vibration reduction ground debugging system model. The first-order modal signal containing only the pitch direction and the second-order modal signal only containing the pitch direction are obtained through the decoupling matrix. The first-order and second-order modal signals are identified by adaptive LMS filtering algorithm, and compared with the traditional transfer function model identification algorithm and polynomial model identification algorithm. The results show that the adaptive LMS filtering algorithm is not only simple in structure and easy to implement, but also has higher robustness and identification accuracy. It provides a new theoretical method for the system identification of the wind tunnel model, and provides support for the design of the subsequent active vibration control algorithm.
  • CHEN Yinghang1,2,3, XU Chi1,3, HUANG Weichun2, XIE Longxiang2, ZHANG Jianxiang1,3,WANG Shuangjun1,3, SUN Weiwei1,3
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 171-178.
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    How to achieve low-frequency broadband sound absorption and design sound-absorbing metamaterials with sub-wavelength thickness has always been a challenging task. A micro-slit folded space metamaterial structure was proposed. The theoretical analytical model and numerical simulation model of the structure were established. The acoustic characteristics and sound absorption mechanism were deeply studied. The influence of typical structural parameters on sound absorption characteristics was analyzed. Based on these, the possibility of realizing low-frequency broadband sound absorption was explored. The results show that by adjusting the thickness of the folded space and the number of folded channels, the peak frequency of the structure can be adjusted in a large frequency band without changing its near-perfect sound absorption performance. Finally, a broadband sound absorption metamaterial was proposed to obtain a continuous and efficient sound absorption bandwidth with an average sound absorption coefficient of 0.931 in the frequency range of 500 Hz ~ 2000 Hz. The thickness of the structure was 5.68 cm, which was only 1/12 of the wavelength corresponding to the lowest resonance frequency. The experimental results were good. The research results can provide reference for realizing broadband sound absorption.
  • REN Guanghui1, ZHAO Xin2, DENG Yunfei2, YANG Xiaoyue2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 179-188.
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    In order to study the impact performance and damage characteristics of aluminum alloy triangular corrugated sandwich plates against blunt-nosed projectile, the impact test on the aluminum alloy triangular corrugated sandwich plates was carried out with the one-stage gas gun system. According to the test data, the ballistic limit velocity and energy consumption of triangular corrugated sandwich plate and monolithic plate are analyzed, and the dynamic damage process, dynamic load response and damage mechanism are analyzed combined with finite simulation. The results show that the damage modes of triangular corrugated sandwich plate are shear failure, tear failure and bending deformation. The impact resistance of the corrugated plate is lower than that of the monolithic plate, and the impact resistance of the corrugated plate at node position is higher than the base position. At low impact velocities, the energy dissipation of the corrugated plate is lower than that of monolithic plate. As the impact velocity increases, the energy dissipation at the node position of the corrugated plate is higher than that of the monolithic plate, and the energy dissipation at the base position is similar to that of the monolithic plate. In addition, the dynamic load response and the failure mechanism of the corrugated plate are affected by the impact position.
  • TAN Xin
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 189-193.
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    Aiming at the difficulty of vibration isolation for heavy machines with low-frequency, the vibration isolator of solid and liquid mixture (SALiM) companying with additional mass of solid element is proposed. Based on the dual-mass vibrator model of solid element, the dynamic equation of the SALiM vibration isolation system is established first. Then the theoretical expressions of isolation transmissibility are derived under both conditions of force excitation and base motion. As a result, the extreme value points on transmissibility curves are found. Further, the effects of the additional mass of solid element on transmissibility are investigated, and results show that the element’s additional mass does not affect the static load-bearing capacity of isolation device, but it reduces the resonance frequency, and thus such vibration isolator has the high static and low dynamic stiffness (HSLD) characteristics, which is a completely different mechanism to generate HSLD from the traditional nonlinear quasi-zero stiffness. More importantly, the minimum extreme point can be observed on transmissibility curve due to the existence of additional mass. Hence, the isolation effectiveness around the ‘anti-resonance’ frequency band has been improved greatly. Besides, the ratio of effective areas and solid element quantity are important parameters to dominate vibration isolation performance.
  • CHEN Renxiang1, ZHANG Xiao1, ZHU Yuqing1, XU Xiangyang1, YANG Baojun2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 194-200.
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    Aiming the diagnosis of rolling bearing faults in complex operating conditions with strong noise and different speeds. Rolling bearing fault diagnosis method under complex working conditions based on deep residual shrinkage transfer network (DRSTN) was proposed. The domain adaptation layer is added to the deep residual shrinkage network to construct the deep residual shrinkage migration network with noise reduction and adaptation ability, so as to reduce the interference caused by noise and the distribution difference caused by speed change. Firstly, a set of thresholds are automatically set by using the attention mechanism to learn the importance of each feature channel after convolution layer, and the features in the threshold range are set to zero by soft threshold to reduce the interference caused by noise. Then, the feature distribution of the two domains is aligned by edge distribution to reduce the distribution difference caused by speed change. Finally, the fault diagnosis of rolling bearing under end-to-end complex conditions is realized under Softmax classification layer. The experimental results of rolling bearing fault diagnosis under complex conditions verify the feasibility and effectiveness of the proposed method.
  • LI Qi1, WANG Xiaoming1, MEI Yulin2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 201-208.
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    A low-frequency acoustic structure is designed by means of electric-acoustic analogy, and an optimization strategy of the acoustic structure is constructed by combining transfer matrix method and simulated annealing method. First, a band-stop electric filter is designed based on the fourth-order Chebyshev high-pass filter through adopting the normalization method. Second, according to the acoustic-electric analogy, a silencing structure is obtained by respectively substituting a tubule and a cylindrical cavity for the inductance and capacitance in the circuit. And then, the mathematical model of the silencing structure is established by using the transfer matrix method, and an expression calculating transfer losses of the silencing structure is derived. Finally, based on the mathematical model, an optimization strategy is proposed by using simulated annealing method, and is implemented to optimize structure parameters of the silencing structure. The results show that, it is feasible to use the circuit of electrical filter to guide the structural design of silencing structure; the silencing structure’s mathematical model established by transfer matrix method can accurately describe the state of sound wave propagating in the silencing structure; compared with the initial acoustic structure, the optimized silencing structure has better filtering effects, including a wider attenuation band with transmission losses above 20dB, covering 410Hz-2165Hz and extending by 202% , and an obvious increase of transmission losses.
  • SHI Huirong, ZUO Cunsheng, GAO Quanfu
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 209-217.
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    The piezoelectric energy harvester with magnetic coupling can realize wide-band vibration energy harvesting, but the output power is greatly affected by the excitation direction. In order to make the energy harvester obtain large mechanical energy in real time, a new type of energy harvesting device is designed, which uses the inertia force of pendulum to adjust the relative position of piezoelectric coupling cantilever beam and magnet in real time. The dynamic model of the system was established by the energy method, and the multiscale method and numerical computation method were used to get the solution of the system. The combination resonance characteristics of the system were analyzed under the action of the external excitation, and the effects of the external excitation amplitude, the distance between magnets, the length of the swinging arm, the length and width of the cantilever beam on the effective harvesting frequency band width and output voltage were discussed. The results show that the swing arm can make the system obtain higher mechanical vibration amplitude under the excitation of larger acceleration, and the energy harvesting frequency band can be expanded effectively. The performance of energy harvester can be improved effectively by changing the distance between magnets, the length of the swing arm and the structural parameters of the cantilever beam.
  • SUN Chenjin1, ZHOU Mengde1, REN Yuhang1, ZHANG Xinyu1, ZHAO Qi1, YAN Huanhuan2, LIU Wei1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 218-226.
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    To address the problem of poor control effectiveness due to unknown vibration characteristics of wind tunnel model-support system, firstly, the structure and principle of wind tunnel model-support system are analyzed, and the identification scheme of system vibration characteristics is proposed. Secondly, the equivalent dynamics model of the system is established, and the pitch and yaw dimensional vibration characteristics of the system are analyzed theoretically by introducing dynamic stiffness. Then, a vibration characteristics identification method is proposed, including sinusoidal sweeping, spectrum refinement, and frequency response function. And the vibration state estimation model is established based on the identification results, which is introduced into the closed-loop control resulting in the identification-based control method. Finally, the impulse response experiment and hammering experiment are conducted, and the vibration suppression results of the conventional control method and the identification-based control method is compared. The experimental results show that the root mean square error of the frequency response discrimination in pitch and yaw dimensions is 0.0840 g/V and 0.0075 g/V, respectively. Compared with the conventional control method, the identification-based control method improves the equivalent damping ratios of pitch and yaw dimensions by 1.48 and 3.00 times, respectively, which has obvious advantages over the conventional control method.
  • WANG Haiwen, XU Dan, CHEN Molin, YE Renchuan, REN Peng
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 227-232.
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    In order to improve the protective performance of fiber lightweight structures subjected to hail impact, the numerical model of bionic sandwich structure was constructed based on the leaf epidermis cell wall bionic structure (bio-ITCLC) with high vertical stiffness. The influence of nose shape, impact velocity and multiple impacts on the mechanical behavior and dynamic damage of bio-ITCLC structures were analyzed. The results showed that the impact force between hail and bio-ITCLC structure was changed with the changing of nose shape of hail. The peak value and raising rate of initial force increased with the contact areal increasing between hail and structure, meanwhile, the loading time of the force was decreasing. The peak value of impact force caused by the cylindrical and conical nose hail linearly increased with the velocity of hail increasing, and the parabolic relation was found between the peak value of impact force generated by the hemispherical nose hail and impact velocity. The main damage modes of bio-ITCLC structures impacted by the cylindrical, conical and cylindrical nose hail were fiber breakage with buckling and crushing, fiber breakage and matrix crack caused indentation, and delamination between bio-core and upper face-sheet, respectively. The damage modes were not changed under the multiple impact of hail, and the delamination of matrix and the area of accumulated damage of the structure were obviously enlarged with the multiple impact increasing.
  • LI Lintao1, CAO Hengchao2, ZHU Guixiang2, LI Guoxing1, LIU Dong1, LIU Peiyu1, SHI Weiwei1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 233-240.
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    The differences in the vibration and noise response of multi-cylinder diesel engine lead to differences in liner lubrication, wear and cavitation. It causes differences in liner reliability and shortens engine lifetime. Research on these differences could help to optimise the maintenance and design of diesel engines. The main source of vibration noise in internal combustion engines is the combustion shock and piston secondary motion caused by the cylinder liner knock. The main source of cylinder liner vibration noise in multi-cylinder diesel engines is the piston knock. A heavy-duty six-cylinder diesel engine is used as the research object, and a retrospective analysis of the differences in multi-cylinder vibration response is carried out based on the variational modal decomposition(VMD). A piston dynamics model was established and the rationality of the parameter settings was verified through experiments. The main frequency components and associated modes were extracted from the vibration response by VMD. The results show that all cylinders of the multi-cylinder diesel engine have the same trend of vibration amplitude distribution, with the most intense vibration in the middle and upper part of the cylinder liner. The difference in vibration between cylinders is related to the modal characteristics of the body, and the difference in vibration between cylinder liners is consistent with the trend of the 7th order modal vibration pattern of the body, which is reflected in the strongest vibration of cylinder 6 and the weakest vibration of cylinder 2.
  • ZHAO Yan1,2, YANG Zhe1, WANG Xinwu2,3, LI Xiaolu3, CHEN Feng4
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 241-246.
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    With the increasing of the installed capacity and dimension of the wind turbine, its operating environment is more complex and the fatigue problem is prominent. So it is necessary to accurately predict the actual fatigue damage suffered by the wind turbine structure. Through long-term monitoring of tower bottom strain of 1.5MW wind turbine, the accuracy of different methods in dealing with residue series after rainflow counting is studied. First, the influence of transition cycles on fatigue damage was studied using different window lengths. The shorter the selected window length is, the greater the fatigue damage error is. When the window length was 10min, the error reached 20.7%. Then, residue concatenation methodology was used to process residue series. At this time, the damage values obtained by selecting different window lengths were the same as those obtained by taking all data in the monitoring period as continuous series, which proved the accuracy of this method in processing residue series. The results provide a solution for the online prediction of fatigue damage of wind turbine structures, and can obtain the fatigue damage in real time more accurately.
  • YAN Song, JIANG Yi, DENG Yueguang, YANG Baosheng, WEN Xianghua
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 247-254.
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    In order to reduce the weight of the missile launching system and reduce the cost of missile launching, a flexible airbag ejection system was researched to achieve work on the missile. Through a combination of theoretical analysis, experimental verification and numerical calculation, the working mechanism and ejection performance of the flexible airbag ejection system are studied. The results show that the results of calculating the deployment process of the flexible airbag by the corpuscular method are in good agreement with the experimental measurement results, and the error does not exceed 1.04%, which verifies the accuracy of the calculation of the deployment of the flexible airbag by the corpuscular method; the ejection performance and ejection working medium of the flexible airbag ejection system The type, temperature, range and area of the flexible airbag are related to other factors. In the study of the ejection working fluid and the structural parameters of the flexible airbag, it is found that the smaller the molar mass of the ejection working fluid and the higher the temperature, the better the ejection performance of the flexible airbag ejection system; When the action area is the same, the larger the aspect ratio of the flexible airbag, the better the ejection performance of the flexible airbag ejection system; When the operating distance is the same, the smaller the aspect ratio of the flexible airbag, the better the ejection performance of the flexible airbag ejection system, and the greater the kinetic energy obtained by the missile.
  • HAN Qinghua1,2,3, WANG Yue3, LU Yan1,2,3, LI Yaming4, XUE Yuan5
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 255-264.
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    To study the soil-structure interaction (SSI) and seismic response of single-layer reticulated dome under oblique incident wave, the equivalent nodal force and viscous-spring artificial boundary was used. The results show that the reticulated dome tilts at the seismic wave incident side and rotates along the incident direction. The maximum support displacement difference reaches 0.514m under oblique incident P-wave, which is 1/250 of the span. The vertex displacement in soft soil is larger than that in medium hard soil and medium soft soil, and first increases then decreases with the increase of incident angle under oblique incident P-wave. The vertex displacement in medium soft soil is larger than that in medium hard soil and soft soil, and increases with the incidence angle increasing under oblique incident SV-wave. Under oblique incident seismic waves, the maximum vertex displacement increase is 5.5 times after considering soil-structure interaction, and the displacement increase at the outer ring of reticulated dome is greater than that at the middle span.
  • DONG Shi1, LONG Zhiyou1, WANG Jianwei1, SHAO Yongjun2, YANG Chao2, ZUO Chen1, MA Shaohua3
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 265-275.
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    The global positioning system real-time dynamic differential technology (GPS-RTK) is an important tool to solve the problem of roadbed slope safety monitoring, but the GPS-RTK signal is susceptible to multi-path error and common-mode error. Based on the wavelet transform (WT) and principal component analysis (PCA) can effectively remove multi-path error and common-mode error, respectively, the WT-PCA algorithm is proposed to remove the signal error. Firstly, the simulated signal is set up and the noise reduction effect of a single algorithm is further improved by parameter tuning. Secondly, the combined algorithm WT-PCA is proposed to improve the defects of the single algorithm and compared with other combined algorithms for analysis. Finally, the GPS-RTK monitoring data of the slope of the roadbed of the Shi-Tian highway is analyzed by example. The results show that the signal-to-noise ratio and root mean square error of WT-PCA algorithm are better than WT-VMD by about 66% and 50%, and the algorithm can effectively eliminate the influence of multi-path error and common mode error of GPS-RTK signal. It improves the accuracy of slope displacement monitoring signal processing and further evaluates the structural deformation and safety status of slopes.
  • ZHANG Cong1,2, LIU Shuang1,2, ZHAO Dingxuan3, JIANG Siyuan1, LIU Shiji1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 276-286.
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    Aiming at the driving leveling problem of special equipment vehicles, a dynamic reference-based low complexity control method is proposed. Firstly, the whole vehicle is decomposed into coupled suspension nodes driven by actuators. The dynamic model of the suspension node is established. And the hybrid control problem of position and attitude based on the vehicle vertical dynamics model is transformed into a simple displacement control problem based on the fully actuated node dynamics model. Secondly, the dynamic reference and its error are proposed and constructed. Then the technical bottleneck is solved which the existing method relies on and restricts the vehicle body’s vertical height, meanwhile, the passing ability of the vehicle is improved. Finally, the effectiveness of the proposed method is verified by the vehicle system simulation software Carsim. The results show that, compared with the classical constant-reference-based control method of the whole vehicle, the driving leveling accuracy is promoted by 1 order of magnitude under the effect of the proposed method; Especially when the road excitation amplitude exceeds the designed dynamic deflection of the actuator, the comfort and safety of the vehicle are both improved particularly.
  • PAN Wangbai1, L Liangliang1, WANG Donghua2, LIU Yu1, FANG Xianliang1, WU Linna1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 287-294.
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    Control moment gyroscope (CMG) is one important kind of actuators for on-orbit attitude control of the spacecraft. It stores the angular momentum by the high speed rotating flywheel and produces moment through rotating the gimbal by a servo mechanism. The vibration isolator can effectively reduce the influence on the high precision payloads caused by the unbalanced load from the rotating flywheel. A typical triple closed-loop control model of servo mechanism and an isolator with single degree of freedom are established to reveal that isolator can cause the instability of the speed loop in servo control system. Analysis and discussion on the influence of the stability, corresponding to the key design parameters of isolator, including frequency, damping ratio and inertia, are provided for detailed isolator design. Experiment results fully verify the entire design procedure and isolation effectiveness of a CMG isolator considering control stability, providing practical engineering experience for the design of similar products.
  • REN Zhiying1,2, LIU Rongyang1,2, HUANG Wei3, LI Chengwei1,2, SHI Linwei1,2, XU Caijun3
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 295-304.
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    In response to the problem of significant degradation of the performance of existing polymer damping mats used for traction machine damping due to environmental factors, this thesis is oriented to the engineering application requirements of elevator traction machine dampers, and after determining the stiffness of the damping elements required for the dampers, a high performance metal rubber/silicone rubber continuous interpenetrating phase damping material with environmental resistance is developed by filling the pores of metal rubber and forming an envelope using vacuum infiltration technology. composite vibration damping material (MR-SRC) that is resistant to environmental effects. Then the finite element numerical model of the elevator traction machine was established based on the actual structure. The modal analysis of the elevator traction machine before and after the addition of MR-SRC damper was carried out to determine the inherent frequency and vibration pattern of the overall structure. The impact response of the MR-SRC damper was analyzed to compare the effects of different MR-SRC materials and impact loads on the response, and the strength of the damper was calibrated. Then, based on the approximate equivalence of MR-SRC, the impact response of the damper system was theoretically calculated, and it was concluded that the MR-SRC damper with a metal-rubber density of 1.8 g/cm3 has the best effect on damping. Finally, the prepared MR-SRC shock absorber is installed in the actual elevator traction machine, and the acceleration and velocity changes of the elevator during operation are tested according to the requirements of the elevator vibration damping national standard, and the relevant characteristic parameters of the elevator operation are calculated and checked. The dampers proposed in this thesis provide a new way for safe and reliable operation of elevators.
  • SHANG Feng1, SONG Wenjie1, HAN Jinsheng2, YANG Bo1, FU Yao3, XU Longhai4
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(3): 305-310.
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    To obtain the actual acoustic emission signal of the corrosion fracture of prestressing steel in concrete beam, the galvanostatic method is applied to simulate the natural corrosion and artificially accelerate the process. High frequency acoustic emission sensors and distributed optical fiber monitoring system are used to collect the acoustic signals underwater when prestressed steel wires are broken. Signal are statistically analyzed in time domain and time-frequency domain. Test results show that only the time domain statistic characteristics below 20kHz can be used to identify the wire fracture, as the frequency dispersion occurs when the ultrasonic band of the wire-breakage signal propagates in the water. The fracture signal propagating in water can be received by the armored optical cable, which appears as a vertical band in the time-frequency diagram, and the energy is mainly concentrated in 100~ 200Hz. Small threshold should be set to intercept the signal from optical fiber monitoring system for the statistical analysis in time domain. For underwater condition, the signal-to-noise ratio of the peak index is low, and the margin and kurtosis index are more suitable for identifying fracture signal. This research lays the foundation for the development of underwater acoustic optical fiber monitoring system of prestressed concrete structure.