28 February 2024, Volume 43 Issue 4
    

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  • BA Zhenning1,2,3,FU Jisai1,WANG Fangbo1,LIANG Jianwen1,NIU Jiaqi1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 1-11.
    Abstract ( 433 ) Download PDF ( 1974 )   Knowledge map   Save
    The site-city-interaction (SCI) effect will drastically modify the seismic wave field and the response of buildings. Based on the development status of SCI effect simulation approach, taking advantages of the spectral element method (SEM) and the multi-degree of freedom (MDOF) model, (i.e., SEM can efficiently simulate the three-dimensional seismic wave field propagation, and MDOF can simulate a large number of buildings at the same time), and combining with the frequency wavenumber domain (FK) method to input the seismic wave field by applying equivalent seismic loads, the FK-SE-MDOF approach is established. This approach can simulate the oblique incidence input of multiple wave-types (P, SV and SH) in the SE-MDOF coupling model, and solved the problem that the influence of nonlinear characteristics of buildings, spectrum characteristics, seismic wave-type and incidence angle cannot be considered simultaneously in previous three-dimensional SCI effect simulations. Firstly, the theory of the approach is introduced; Then, the correctness of the approach is verified by simulating an existing shaking table test; Furthermore, a series of ideal site-city-interaction models are established, and the influence of incident angle and wave-type on SCI effect is mainly discussed; Finally, some useful conclusions are obtained. The approach can realistically reflect the impact of SCI effects while reflecting the influence of building foundation contours on the seismic wave field. It is suitable for community-scale buildings where it is necessary to consider foundation contour information and can provide quantitative guidance for urban planning, seismic design, risk assessment and post-earthquake rescue.
  • Lv Xiaohong,WANG Jipei,ZHANG Jintao
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 12-19.
    Abstract ( 280 ) Download PDF ( 107 )   Knowledge map   Save
    A mechanical impact oscillator with a pre-compressed spring is considered. The Poincaré map composed of smooth flow map and discontinuous map is constructed, and a numerical calculation method of Floquet multipliers is given. The periodic attractor patterns and their parameter regions of the system in the two-parameter plane are obtained by numerical simulation. The bifurcation characteristics of period-1 attractors and the discontinuous bifurcation behaviors, such as discontinuous grazing bifurcation, bifurcations induced by grazing and period-doubling, subcritical period-doubling bifurcation and crisis, are studied by applying continuation shooting method and cell mapping method, and the formation mechanism of hysteresis and subharmonic inclusions regions is revealed. In the transition between adjacent 1–m and 1–(m+1) attractors, the hysteresis and subharmonic inclusions regions are created by discontinuous grazing bifurcations. However, they are respectively created by grazing induced saddle-node and period-doubling bifurcations as the pre-compression is equal to 0. The results can provide guidance for the parameter design and optimization of mechanical impact system with a pre-compressed spring.
  • DING Taotao1,2,3,GUO Yu1,2,XIANG Yanxun3
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 20-26.
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    In the process of ultrasonic guided waves detection, the interaction between different modes of guided waves and various types of damage is different, which directly affects the reliability of damage detection and localization imaging. Therefore, the excitation method of target mode of guided waves is systematically studied to obtain the ideal guided waves, which is helpful to realize the accurate detection of multi-types damage and obtain high resolution positioning imaging. In this paper, the excitation method of target mode of guided waves is studied in theoretical analysis, finite element simulation and experimental measurement. The excitation condition of target mode of guided waves is analyzed theoretically, and two-dimensional multi-physical field simulation models are constructed to verify the method. The comb transducer and PZT wafer were compared during the experiment of guided waves. The results show that the comb transducer has better mode selection ability than PZT wafer. In addition, the quarter omnidirectional and omnidirectional comb transducers are designed to excite the target mode and control the propagation direction of guided waves.
  • LIU Zhongxian1,2,WANG Jianxu1,JIN Liguo3
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 27-37.
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    In this paper, a high-precision indirect boundary element method (IBEM) is used to study the dynamic interaction between aboveground building group and subway tunnel group under SV wave excitation. The results show that there is a significant interaction between the building group and tunnel group, and its basic law is closely related to the nature of the incident wave, the number of buildings and tunnels. By analyzing the influence of building numbers on tunnel response, it can be found that The low frequency wave action amplifies the dynamic response of the building to the underpass tunnel. In contrast, the high frequency wave action weakens the dynamic response of the tunnel by up to about 37.5%. From the frequency domain analysis, it can be seen that the tunnel has a strong shielding effect on the seismic waves, thus reducing the seismic response of the buildings. The presence of the aboveground building group reduces the dynamic response of each individual building, but the building located on the incoming wave side of the group produces a larger dynamic response during high-frequency wave action. The research results of this paper provide some guidance for the dynamic response analysis of urban building-group and the construction of the underground subway tunnel-group.
  • GAO Peng1,YAN Ming1,ZHANG Quan2,DU Zhipeng3
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 38-44.
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    In order to analyze the deformation and damage of stiffened plate for ship subjected to underwater explosion shock wave load, the scaling law of boundary tearing damage of the plate under uniform load was studied by using simulation and data fitting methods. Firstly, we combine theory and data analysis to find that the initial response velocity is closely related to the failure mode, and can clearly describe the damage mode of the stiffened plate. At the same time, the simulation results show that the fracture strain, plate thickness and length width ratio are the important parameters that affect the boundary tear of stiffened plate. Finally, a fitting function is established to determine the tearing damage of stiffened plate, and the effectiveness of the function is verified by a warship damage case. The results show that the method of constructing the tearing damage criterion of the plate boundary based on the initial response velocity and the dimensionless number considering the parameters such as the fracture strain is feasible, which provides a reference for the scaling research on the damage of the ship’s stiffened plate.
  • HUANG Zhicheng1,HUANG Fan1,WANG Xingguo1,CHU Fulei2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 45-51.
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    In this paper, the dynamic model of the damping cantilever structure of the intelligent constraint layer is established based on the dissipative coordinates and the GHM model, and the vibration active control of the cantilever structure of the intelligent constraint layer is studied. Aiming at the problem of excessive freedom of the structural model, the joint order reduction treatment of the structural model is carried out in the physical space and modal space. The correctness of the modeling method in this paper is verified by specific examples, and then the influence of the laying position of piezoelectric sheet and viscoelastic layer on the vibration control effect and control cost of the system is compared. Finally, the universal applicability of the structural simplification model is verified. The results show that under the condition of the same feedback gain of the controller, the closer the position of the piezoelectric sheet and the viscoelastic layer to the fixed end, the better the system control effect and the smaller the control cost. The simplified model also has a better control effect on noisy input signals.
  • TANG Jia1,CHI Maoru1,YANG Chen1,MA Zikui2,YAO Xuesong2,LUO Yun1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 52-60.
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    As an optimal state estimation algorithm, Kalman filter can be applied to the inversion of high-speed train axle box bearing loads. While accurately establishing the inversion model, the selection of filter parameters is also the key to the inversion. In this paper, a 17-degree-of-freedom vertical and lateral vehicle dynamics model of the pivoting arm axle box device is derived, a bearing load inversion method based on the Kalman filter algorithm is proposed and verified, and the selection of key parameters of the model is analyzed and determined. The niche genetic algorithm performs multi-objective and multi-parameter optimization on the key parameters, and finally uses SIMPACK to establish a consistent vehicle dynamics model, calculates and simulates the vehicle running at a constant speed on a straight line with random track irregularities, and verifies the inversion effect. The results show that the optimized parameters can greatly improve the inversion effect, which verifies the correctness of the bearing load inversion model and the adaptive niche genetic algorithm for the filtering parameter optimization method, and provides a basis for the high-speed train axle box bearing load inversion and key parameter setting. Optimization provides methods and experience.
  • CHENG Yuqiang1,2,CAI Cunguang1,2,GAO Hua1,2,SHUAI Changgeng1,2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 61-68.
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    The bellows mechanical model of the air spring under preload conditions is constructed and solved, and a parametric calculation method of the transverse stiffness characteristics of the air spring is proposed. The bellows mechanical model is constructed under the condition of preload, and the transfer matrix between the bellows state vectors is derived by introducing the intermediate displacement vectors and using the precision integration method. The coupling relationship between the state vectors of the bellows, the internal pressure and the structural parameters is analyzed by the iterative method. Based on the boundary conditions, the parametric solution of the capsule stiffness is completed, and the calculation and analysis of the transverse stiffness characteristics of the air spring are completed by combining with the perfect pneumatic stiffness model. The correctness of the calculation method of transverse stiffness characteristics is verified by comparing the test results, and the influence law of the main design parameters on the stiffness characteristics is investigated.
  • DU Linlin1,YUE Fangfang1,WANG Jinpei1,WANG Hao1,SHAO Xiaoyan1,HU Yunxia2,LI Weike2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 69-75.
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    1000MW ultra-supercritical double reheat units have significant advantages in reducing energy consumption and pollution, and the number of units in operation has increased significantly in recent years. Turbogenerator is the key equipment of power plant and its infrastructure vibration control is important to ensure the safe and reliable operation of the power plant. The turbogenerator shaft system of the double reheat units is long and the rotor is heavy. In order to reduce the influence of vibration and ensure the stable and safe operation of the units, the spring vibration isolation foundation is widely used in the turbogenerator foundation of 1000MW ultra-supercritical double reheat units. In this paper, numerical analysis and model test are carried out on the dynamic performance of rigid frame foundation of turbogenerator for 1000MW ultra-supercritical double reheat unit. The results show that the turbogenerator rigid frame foundation of 1000MW ultra-supercritical double reheat units has good dynamic performance. In the normal operation stage, the amplitude of the vibration displacement response of each disturbance point is not more than 20 μ m, which meets the requirements of the national standard limit. The research results can provide technical support for the turbogenerator infrastructure design of 1000MW ultra-supercritical double reheat units.
  • LI Weibo1,WANG Weimin1,2,LI Ming3,WANG Wei1,ZHANG Shuai1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 76-86.
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    The combined rotor shafting structure is the main structure of rotor systems in aero-space power equipment. The existence of contact surfaces in shafting makes the rotor dynamic characteristics difficult to be grasped, and a design risk arises when rotor working speed margin is involved. Considering the nonlinear connection parameters between different contact surfaces based on the characteristics of single spindle multi components axial preloading structure of combined rotor shafting, a two-step model correction method based on thin-layer elements and zero-length elements modeling was proposed. The nonlinear analysis of static structure based on response surface optimization and the contact analysis of rough surface based on stochastic statistical model were used to identify the material parameters of thin-layer elements and the contact stiffness coefficients of zero-length elements, then the rotor dynamic model was established. According to the structural characteristics of an engine hydrogen-turbopump rotor , a rotor test piece was manufactured, and its free mode was experimentally studied to obtain the effects of different thread pre-tightening states and axial preloads on the first two orders of modal characteristics of the combined rotor shafting. Comparing with the experimental data, the proposed model optimization method can well reflect the variation trend of the first two orders of modal frequencies of the combined rotor shafting under different axial preloads, and the calculation error is less than 1% in the range of linear variation of rotor modal parameters, which verifies the correctness and validity of the method and provides a reference basis for the refined modeling of combined rotor shafting.
  • YIN Song1,2,LIU Pengfei2,SUN Yuzhou2,LI Xinming2,YAN Pan2,WANG Zhiliu2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 87-95.
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    In order to study the influence of stress and humidification conditions on the cumulative deformation characteristics of compacted granite residual soil under train load, cyclic hollow torsional shear and cyclic directional loading tests were carried out on compacted granite residual soil with confining pressure, dynamic stress amplitude and water content as variables. The results show that the rotation effect of principal stress axis under cyclic torsional shear stress path increases the cumulative deformation and even changes the development mode of the cumulative deformation, and the effect degree increases with the increase of the water content of the sample. Sample rate of accumulated strain development at the beginning of the load (N < 100) complete greatly attenuation, the increase of confining pressure can accelerate the development of accumulated strain velocity attenuation, the increase of the dynamic stress amplitude will extend the accumulated strain development rate decay time, cumulative strain development of cyclic torsional shear loading when the sample rate attenuation degree directional load is less than the cyclic triaxial test, The higher the moisture content, the more significant the effect. The prediction model can fit the development curves of stable and developed cumulative.
  • XIAO Wangqiang1,HUANG Zijie1,LIU Hanwu2,QIAN Haikun2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 96-104.
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    The exposed platform, as a component equipped with precision instruments such as pyrotechnic separation devices and load adapters, is an important component of aerospace vehicles. Under pyrotechnic impact environments, the exposed platform will generate high-frequency, transient, and high-order pyrotechnic impact responses. High level pyrotechnic impacts can easily cause damage to sensitive components in onboard equipment, resulting in incalculable losses. Therefore, effectively controlling the high-frequency impact of the satellite rocket exposure platform in pyrotechnic environments is of great significance in the aerospace field. This article uses the honeycomb core type flexible bag damping technology to conduct impact reduction research on the exposed platform. Through discrete element energy dissipation simulation design of the flexible bag damping system model, the influence of particle material, particle size, filling rate, and bag film thickness on the impact reduction performance of the flexible bag damper is analyzed, and the optimal characteristic parameters of the flexible bag damper are obtained. The impact response spectra of the exposed platform with flexible bag dampers with different parameters were obtained through impact experiments and compared with simulation results, verifying the correctness of the model and the effectiveness of flexible bag damping technology. The simulation and experimental results show that the flexible bag damper with a filling rate of 95% and a film thickness of 0.2mm and a material of iron based alloy with 2mm particles has the best impact reduction performance. The optimal parameter of the flexible bag damper has an impact reduction effect of 58.13%, meeting the impact reduction requirements of the Mengtian Load Warehouse Exposure Platform.
  • WEI Lulu1,2,XU Shiwei1,ZHU Guohua2,ZHAO Xuan2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 105-114.
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    Quasi-static in-plane compression tests were used to reveal the tunable stiffness characteristics of star-triangular honeycomb (STH). The tunable mechanism of compression stiffness for STH with non-homogeneous cell-wall thickness was investigated via finite element simulation, and the influences of different cell-wall thickness ratios (("t" _"1" "=" "t" _"3" ))⁄"t" _"2" and cell-wall angles on the in-plane compression stiffness were analyzed. The results show that the stress-strain curve of STH shows two linear elastic stages under in-plane compression loading, and the strengthening stiffness is significantly higher than the initial stiffness. Appropriately increasing the thickness of re-entrant and vertical cell-walls can significantly improve the initial stiffness and strengthening stiffness of STH. When (("t" _"1" "=" "t" _"3" ))⁄"t" _"2" >"1.575" , the initial stiffness continues to increase while the strengthening stiffness gradually decreases, and finally the strengthening stiffness phase disappears. When "α"≤"40°" , increasing the cell-wall angle can improve the initial stiffness and strengthening stiffness of STH. On the contrary, the initial stiffness and strain corresponding to strengthening stiffness gradually increased with the increase of cell-wall angle, while strengthening stiffness gradually decreased and tended to disappear. This study is expected to provide a novel path for design of auxetic honeycombs with tunable stiffness.
  • WU Haipeng1,CUI Shurong1,ZHONG Zhiwei1,WANG Xiaomeng1,GAN Mai1,CAO Wanlin2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 115-124.
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    Focusing on special-shaped bifurcated concrete-filled steel tube (CFT) column with multiple cavities of mega-frame structures in super high rise buildings, in order to investigate the influence of cross-sectional enhanced structures on the seismic behavior of the bifurcated short column, four specimens subjected to vertical axial load and horizontal twice loaded cyclic loading were tested. The upper part of the specimen includes two pentagonal CFT column branch with four cavities, while the lower part includes one octagonal CFT column branch with 13 cavities. As a result, a bifurcated column forms. The investigated cross-sectional structures are divided into four types: basic type, the type that the thickness of the whole tube steel plate is increased, the type that the thickness of local steel plate being far from the neutral axis is increased by welding steel angle, and the type that circular steel tube is encased in the cavities being far from the neutral axis. Based on the test results and the characteristics of section structures, numerical calculation was conducted. The test and simulation results show that for special-shaped bifurcated CFT short column, the failure mostly appears at the root part of the upper column branches on the bifurcated cross section. The main failure exhibits the tear of the steel plate far from the neutral axis and the tear of whole steel plate caused by the crack of local welding seam. The bearing capacity of the enhanced structure of encasing circular steel tube increases by 7.6%, while the deformability increases by 14.4%, and best energy dissipation ability shows. The bearing capacity of the enhanced structure of increasing thickness of local steel tube increases by 9.2%, but the deformability decreases by 18.7%. The bearing capacity of the enhanced structure of increasing thickness of all steel tube little increases, while the deformability significantly decreases. The proposed simplified finite element model for special-shaped bifurcated CFT short column with multiple cavities exhibits well efficiency. And the accuracy can full the demand of engineering design.
  • HU Changfu,ZHU Shunshun,ZHANG Xin,LUO Wenjun
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 125-133.
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    To derive the closed-form solution for the in-plane free vibration of non-circular arches, an approximate analytical method for the solution derivation of the variable coefficient differential equation is proposed. Based on linear strains of non-circular arches in the Cartesian coordinate system and the Hamilton principle, a variable coefficient equilibrium differential equation for the in-plane free vibration of non-circular arches is derived. The analytical general solution of the corresponding constant coefficient differential equation is substituted into the variable coefficient differential equation to yield the unbalanced deviation following by that the in-plane free vibration modes of non-circular steep arches and shallow arches are almost the same. The practical closed-form solution for the in-plane natural frequency is derived by setting the integration of the unbalanced deviation of the variable coefficient differential equation along the span being zero. The analytical solutions of the pin-ended and fixed arch in the Cartesian coordinate system are derived based on the proposed method, and the theoretical relationship of the in-plane frequency between non-circular steep arches, shallow arches and the straight beams with the same parameter are demonstrated. The numerical results of non-circular pin-ended and fixed arches show that, the basic assumptions has been strictly verified; the proposed method agrees well with the finite element method, the maximum relative error of the former tenth natural frequency are 7.71% and 4.34% for pin-ended arches and fixed arches, respectively; the theoretical relationship of natural frequency between non-circular arches and straight beam with the same parameter can be used in the code revision of arch bridges.
  • WU Fei,LUAN Tianyu,NONG Haoye
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 134-141.
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    A signal processing method based on sparrow search algorithm (SSA) and bistable stochastic resonance (BSR) was proposed for extracting the weak features in the transition phase of turning chatter. This method used signal-to-noise ratio as the optimization index to determine the optimal bistable stochastic resonance system parameters, which were used to filter the turning chatter signal and extract the chatter characteristic frequency. The simulation analysis showed that the SSA-BSR method can extract and enhance the weak feature signal in the strong noise background, while taking into account the advantages of optimization efficiency. The analysis of the chatter acceleration signal verified the correlation between the amplitude of the chatter characteristic frequency and the degree of chatter excitation. The comparison of the feature extraction effect of different models in the transition stage of chatter verified the effectiveness and superiority of the SSA-BSR model, and it can meet the requirement of real-time detection of chatter. This method provided a new idea for quantifying turning chatter and online monitoring of turning chatter.
  • WU Xu1,FANG Hui1,PAN Jiliang2,XI Xun2,SUN Jinglai1,ZHANG Yingcai3
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 142-149.
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    In order to investigate the mechanical properties and failure law of concrete specimens with cracks of different inclination angles under impact load, the Split Hopkinson Pressure Bar(SHPB) was used to test on concrete specimens, and the high-speed camera system was used to capture the crack growth and dynamic failure process in real time. The results show that the reflected wave amplitude of the crack specimens with 30° is relatively the largest, while the reflected wave amplitude of the crack specimens with 0° is relatively small. When the angle of the crack is 0°, the shock wave dissipation is less, and the transmitted wave amplitude is larger. When the angle of the prefabricated crack is 60°, the shock wave dissipates more, that is, when the angle between the stress wave propagation direction and the prefabricated crack is 60°, the specimen is most likely to failure. The newly formed cracks under impact load initiate, propagate and coalesce along the precast crack tip on the whole, and the failure mode is mainly tensile failure under compressive stress. Under the same width of the prefabricated crack, the failure mode of the prefabricated crack with a length of 20mm is simpler than that of the prefabricated crack with a length of 10mm. The number of new cracks is relatively small, and it is easier to crack outwards along the direction of the prefabricated crack tip. The failure modes of Brazilian disc specimens under impact load are closely related to the length of prefabricated cracks, but weakly related to the width of cracks.
  • GAO Yucai1,FU Zhongguang1,XIE Yucun2,WANG Shiyun1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 150-157.
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    This paper proposes a semi-supervised learning method based on continuous wavelet transform and teacher-student network for fault diagnosis of rotating machinery, aiming to address the problems of network overfitting, low fault diagnosis accuracy, and underutilization of large amounts of unlabeled data when neural network models are used with limited labeled samples. The method is based on an improved Lenet-5 convolutional neural network model, which establishes a student network model and a teacher network model with the same structure and initialization parameters. First, the vibration signal of rotating machinery is transformed by continuous wavelet transform into a three-dimensional time-frequency image. Then, pseudo-labels are generated using the prediction results of the teacher model, and these pseudo-labels are combined with the real labels to train the student network. At the same time, the teacher network model parameters are updated using exponential weighted moving average algorithm. The experimental results show that compared with the pure supervised learning model, the proposed algorithm can significantly improve the stability of the model training process and the accuracy of fault diagnosis with limited labeled samples.
  • LI Shitu1,BAI Yujie1,2,YANG Xuan1,2,WU Tingwei1,2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 158-165.
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    A flexible connected two segment rotor-limiter system has been taken as the research object, the Lagrange method is used to establish the dynamic equation of the rotor system considering the gyro effect. The Hooke contact model and Coulomb collision model are used to describe the interaction between the variable stiffness limiter and the rotor, and numerical methods are used to solve the rub-impact response. The rub-impact behavior under different collision stiffness and friction coefficient is analyzed, and the concept of the rub-impact stability region is introduced and calculated. Rub-impact experiments under different excitation intensities are carried out, which are compared with results of theoretical analysis. The research shows that there are three typical rub-impact behaviors in the rotor rub-impact response: infinite rub-impact, restoring stability after finite rub-impact, and synchronous full annular rub-impact. Friction is the key factor leading to rotor instability, and there is an optimal range of collision stiffness of the limiter. The friction model of the limiter could provide a reference for engineering design.
  • YU Yanyan,DING Haiping,RUI Zhiliang
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 166-178.
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    A numerical method combined the spectral element method and multi-transmitting formula for simulating wave motions of 2D complex site under plane SV wave incidence. Based on this method, and considering 31 distinctive input waves, the additional aggravation features of 2D layered trapezoidal basin relative to the local 1D model, as well as the sensitivity with input waves are investigated. The results show that the proposed method has high accuracy and good stability performance in high frequency. The basin surface motion and aggravation features varies significantly with input signals. For horizontal component, the large-value average aggravation factor of response spectral (AFRS, with maximum value of 1.2) are concentrated in the basin edge region and at periods around 0.5~0.7 times the resonance frequency of the deepest part. While for the vertical component, large AFRS (maximum value of 0.9) regions are close to the basin corner and at 0.3 times resonance frequency. In addition, there exits considerable difference for aggravation features of basin in different periods, and for the changing trend of AFRS with frequencies. The basin edge effect is strongest for short-period motions, where the AFRS is most sensitive to incident motions, with its value varies in a large range. However, the aggravations decrease significantly for long-period waves, and the AFRS in the central part of the basin is quite insensitive to input waves, with a value changed in an obvious smaller range.
  • ZENG Shuhong,KANG Jie,SUN Jiabao,LUO Jie
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 179-189.
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    The frequency domain decomposition (FDD) method is a common method for structural operational modal analysis ( OMA ) under ambient excitation. However, the existing FDD methods have some shortcomings : (1) spurious modes caused by non-white excitation and harmonic excitation cannot be eliminated ; (2) It is impossible to distinguish between structurally closely-spaced modes and spurious modes generated by uncorrelated non-white excitations. It is found that the rank of power spectral density ( PSD ) matrix is the decisive factor for the performance of FDD method. On this basis, a new OMA method is proposed. This method combines the response PSD function matrix under different excitation conditions, and performs singular value decomposition on the response PSD matrix under a single excitation condition and the augmented response PSD matrix under multiple excitation conditions. By comparing the rank changes of the single-case PSD matrix and the augmented PSD matrix at the peak of the singular value, the structural modal parameters including the closely-spaced mode are identified, and the spurious mode generated by the non-white excitation is eliminated. The effectiveness of the proposed method is verified by a truss structure simulation example and the engineering data set of Guangzhou Tower.
  • CHEN Junhao,ZENG Xiaohui,XIE Youjun,LONG Guangcheng,TANG Zhuo
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 190-198.
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    In order to better understand the constitutive response of self-compacting concrete (SCC) applied in subway slab track filling layer under vehicle loads, the uniaxial compression test of SCC was carried out. The effects of different strain rates, rubber content and size on the stress-strain relationship and the energy evolution law of SCC were investigated, and a constitutive model was established. The results showed that the absolute value of the strain rate sensitivity coefficient of the peak stress was the largest, followed by the elastic modulus, and the peak compressive strain was the smallest. Because of rubber, the early energy growth of SCC was delayed, while after peak stress, the dissipation of elastic strain energy was hindered, and the rapid growth of total strain energy and dissipated energy were prolonged. The greater the strain rate, the greater the increase rate of total strain energy and dissipated energy, the greater the accumulation rate of elastic strain energy before the peak stress, and the greater the release rate after the peak stress. The established constitutive model can be used to describe the stress-strain relationship of SCC under different strain rate conditions.
  • LI Chunguang,LI Hejia,CHEN Sai,HAN Yan
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 199-206.
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    In order to study the effect of different locations of water supply pipes on the vortex-induced vibration (VIV) performance of wide streamline steel box girder and the suppression measures of VIV, a large-span flat steel box girder cable-stayed bridge was taken as the research object, and a rigid section model of steel box girder with a scale of 1:50 was made for wind tunnel tests and numerical simulation calculations. Firstly, the VIV characteristics of the main beam were compared and analyzed when the wind attack angle was 0 ° and ± 3 °, with the water supply pipe installed in the main beam wind faring (Type I) and on the bridge deck (Type II); And the mechanism of the effect of water supply pipes on the VIV performance of the main beam was explored through numerical simulation. Secondly, the influence of structural damping ratio on the VIV performance of I-shaped section main beams was studied; Finally, the effects of aerodynamic measures such as railing ventilation rate and railing flow suppression plate on the VIV performance of the I-section main beam were tested through experiments. The experimental results show that the water supply pipe is a vortex sensitive component, and for the I-shaped section, when the wind attack angle is -3 °, there is no VIV phenomenon in the main beam; When the wind attack angle is 0 °, there is a small amplitude of vortex response; When the wind attack angle is+3 °, there is a significant VIV phenomenon; There is no VIV phenomenon in the main beam of Type II section. The numerical simulation results show that placing the water supply pipe outside the main beam can effectively reduce the size of the upper surface vortex, thereby suppressing the generation of VIV. Increasing the structural damping ratio can effectively suppress the VIV of the main beam; The effect of changing the ventilation rate of the railing to suppress vibration is not significant; Setting up a flow suppression plate has a significant effect on vibration suppression.
  • GU Xingyuan1,2,NIU Yubo1,2,ZHENG Yang1,2,HE Peijie1,2,CHEN Qijuan1,2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 207-214.
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    This paper proposes a novel two-body wave energy converter (WEC). The WEC is composed of a buoy and a pendulum with a moveable mass block. A frequency-domain model was established by AQWA to calculate the hydrodynamic parameters of the WEC. A time-domain model with viscous terms and coupling of multi-degree-of-freedom was established. And the hydrodynamic parameters were substituted into the model. Then the simulation of regular and irregular waves was carried out respectively through the time-domain model to study the effects of the mass block position and PTO damping on the WEC. Finally, according to the real sea conditions, several irregular waves are simulated respectively to study the power generation performance of the WEC under the real sea conditions. The results show that: the WEC can generate power efficiently in waves of different periods by adjusting the position of the mass block, and the WEC can effectively utilize wave energy under the condition of wavelet height and has continuous power generation capacity.
  • CHEN Zaixian1,WANG Jiwei1,2ZHONG Weipeng1,LIU Cheng1,LI Minggang1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 215-221.
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    The model updating for hybrid simulation method based on global sensitivity analysis (GS) can effectively improve the accuracy of hybrid simulation with high computing efficiency. However, this always makes it fall into the local optimal value. To address this issue, this paper introduces momentum and adaptive step size, and proposes an adaptive (GS-A) model updating hybrid simulation method based on global sensitivity analysis. The steel frame model is used as the analysis object, and the eight parameters including both the constitutive and model geometric ones are identified. The uniform design test method is used to establish 11 model update cases and numerical simulations were performed for the hybrid simulation with no updating, GS method and GS-A method, respectively. The parameter identification process, displacement time course and hysteresis curves of the 33 sets of numerical simulation cases were analyzed and compared. The results show that the GS-A method, compared with the GS method, solves the problem of the parameters falling into the local optimal value , performs higher accuracy and stability of parameter identification, and improved the model updating effect.
  • ZHANG Shuai1,DING Junhua1,DING Xuexing1,LI Ning2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 222-229.
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    To address the problem that the acoustic emission signal was easily disturbed by external noise and the characteristic signal was difficult to be extracted during the operation of the aero-engine floating ring seal, an acoustic emission signal processing method based on Immune Algorithm (IA) and Variational mode decomposition (VMD) was proposed. Primarily the immune algorithm was applied to optimize the number of modes and penalty factors in the variational mode decomposition, and the sample entropy was used as the fitness function to obtain the best combination of parameters in the VMD algorithm. Moreover, the original signal was decomposed to obtain several modal components (Intrinsic mode function (IMF)) and the relative entropy of each component was calculated, and the components with small differences were selected for reconstruction to obtain the noise reduction signal. The simulation signal analysis shows that the IA-VMD method could obtain the best parameters and has obvious advantages in the anti-noise interference. Eventually, noise reduction and characterization of the acoustic emission signal of the floating ring seal show that the IA-VMD method could retain the maximum effective information while noise reduction, and obtain the acoustic emission signal characterizing the friction state of the main seal surface of the floating ring seal, laying the foundation for future fault diagnosis of the floating ring seal.
  • JIAO Xiaolong1, WANG Yuanjing1, WU Zongya2, XU Yuxin3
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 230-238.
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    To achieve high velocity and high integrity of the reactive fragment during explosive driving, the influence rule of lining structure on high-speed driving of reactive fragment was studied. Based on the law of conservation of energy, a new model of initial speed of preformed fragment was established by theoretical derivation, which considered the elongation of lining material. Three linings of 2A12 aluminum, 20 steel and 20 steel/aramid composite structure were selected. Based on the equation of state, the interfacial pressure on the contact surface between the lining and the fragment was analyzed. The breakage of reactive fragments and the new model were verified by the static explosion test. Results show that the elongation of 20 steel is 145.83% higher than that of 2A12 aluminum, the loading ratio of warhead with 20 steel/aramid composite lining is 14% lower than that of 2A12 aluminum lining, and the initial fragment velocity is 10.85% higher. The new model is well consistent with the experiment results, and its calculation accuracy is more than 8% higher than the existing model. Based on experimental results and theoretical analysis, it is shown that the reactive fragments remains integrity at a driving speed of more than 2300m/s by using 20 steel/aramid composite lining.
  • XU Hong, LEI Bo, LIU Jinyang
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 239-249.
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    At present, the study of the coupling interaction between the granular matter and the complex mechanical systems is faced with challenges such as multiscale, large computational costs, and difficulties in contact detection on non-smooth surfaces. In order to investigate the interaction between the lunar rover and the moon soil, the coupled dynamic modelling and contact detection algorithm for the granular matter and the multibody system are studied firstly. The dynamics of the granular spherical particles and the constrained multibody systems are modeled by the discrete element method (DEM) and the Cartesian method of the multibody dynamics (MBD), respectively, and the contact forces between the granular particles and the rigid bodies are calculated based on the Hertz-Mindlin model. On this basis, a sequential coupling strategy is presented and DEM-MBD coupled dynamic model is established. Concerning the large-scale contact detection between the non-smooth surface of the rover’s toothed wheels and the particles, a sub-regional local detection strategy is proposed to handle the contacts between the objects with non-smooth shapes, which can reduce the scale of local detection. The accuracy of the proposed theoretical model is verified through the comparison of the experimental and simulation results of a rigid cylinder impacting granular matter. Based on the proposed coupled dynamic modelling and the contact detection algorithm, dynamics simulation for the driving process of the lunar rover with toothed wheels on the lunar soil is carried out to study the dynamic characteristics under different driving parameters and the influence of different tire shapes on the driving motion. The research results show that the lunar rover with staggered teeth has a 14% longer forward distance compared to straight teet and has higher forward efficiency, which provides some theoretical guidance for the design of the lunar rover.
  • YANG Weiguo1, GAO Yawei1, WANG Meng1, LIU Pei1, GE Jiaqi2, ZOU Xiaoguang1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 250-260.
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    In order to explore the seismic response and seismic effect of the Plum vase cultural relics fixed by fishing line in the actual museum, the typical Plum vase cultural relics were first selected to carry out shaking table test of three-layer reinforced concrete frame structure under 24 kinds of seismic excitation. Then the finite element model of Plum vase cultural relics used in the above test was established, and the accuracy of the finite element model was verified. Finally, incremental dynamic analysis was used to analyze the motion response of the relic under two common fishing line diameter protection measures. The results show that the cultural relics fixed by fishing line may slip, sway, overturn and break under the action of earthquake. The response of cultural relics varies greatly under different floors. Especially under the action of large earthquakes, the cultural relics fixed by fishing line in the upper floors are prone to capsize and breakage of fishing line. Therefore, attention should be paid to the pre-earthquake protection measures of the cultural relics in the upper floors. Under the action of strong earthquake, only increasing the diameter of fishing line can not play a key role in controlling the overturning of cultural relics, so it is necessary to take other measures to protect cultural relics.
  • WU Jigang, WEN Gang, YANG Kang
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 261-269.
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    Considering the harsh working environment of aero-engine, the hidden characteristics of the vibration signal of the fault and the serious noise interference, in order to strengthen the extraction ability of the network to the key features in the vibration signal, an intelligent fault diagnosis method for aero-engine rotor system with improved attention mechanism is proposed to diagnose the faults of aero-engine rotor system such as unbalance and friction. The proposed improved channel attention mechanism with partial pooling can solve the problem of insufficient information extraction capability of the existing channel attention mechanism for aero-engine rotor fault channels by pre-extracting local extreme values; the improved spatial attention mechanism with multiple scoring mechanism is proposed, which can solve the problem that the existing channel attention mechanism has insufficient ability to extract spatial information about aero-engine rotor faults by convolution scoring of different scales, The above methods are combined to build an improved attention mechanism module in channel space, and then imported into a 1D convolutional neural network to build a 1D convolutional neural network with improved attention mechanism to complete intelligent fault diagnosis, and the comprehensive performance of the network such as excellent detection performance, noise immunity and generalization performance as well as the feasibility of the attention mechanism improvement method are demonstrated by the comparative analysis of the aero-engine rotor system fault dataset.
  • ZHENG Zhi1, ZENG Kuikui1, HE Yuling2, LI Ke1, WANG Zhijun1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 270-278.
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    The multiple equipment components based on sufficient samples result in a large scale of multi-task learning network, and the slight and serious cross-component zero-sample problem has not been studied and is difficult. Under multiple sample sizes (sufficient samples and zero-sample), aiming at the problem that the scale of multi-component diagnosis network based on sufficient fault samples is too large, the MicroNet method is introduced to lighten the MTL network, and then the network is optimized by cosine annealing with warm restart algorithm, the lightweight MTL network model is proposed, thus the accuracy and efficiency of MTL network are improved. Aiming at the more difficult cross-component zero-sample problem, the meta-learning method is introduced to further improve the above MT-MN-CA, and then the improved lightweight MTL network model is proposed to solve the slight and serious cross-component zero-sample problem. The effectiveness and superiority of the proposed two network models are verified by the measured faults of hydraulic pump and rolling bearing, the experimental results show that the proposed network has high real-time performance and accuracy.
  • DENG Feiyue1, CHEN Zhe1, HAO Rujiang1, YANG Shaopu2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 279-287.
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    Remaining useful life (RUL) prediction is one of the key issues to be solved in prognostics and health management (PHM). Equipment components suffer from different failure degradation processes due to the influence of complex operating conditions, which poses a great challenge for accurate RUL prediction. This paper proposes a novel joint mode of multi-scale temporal convolutional network (MsTCN) and Transformer network (MsTCN-Transformer) for RUL prediction of rolling bearings under variable operating conditions. The method presents a new multi-scale dilated causal convolution unit (MsDCCU) that can adaptively mine the time-sequence feature information inherent in the whole-life signals of bearings. Then a Transformer network based on the self-attentive mechanism is constructed to accurately learn the mapping relationship between the time-sequence features and the bearing RUL by overcoming the memory degradation of the prediction sequence. In addition, the visual analysis for different stages of bearing failure degradation verifies that the proposed method has a better generalization performance of the extracted time-sequence features. The experiments show that the proposed method can achieve more accurate RUL prediction, and the accuracy of RUL prediction is higher compared with other current related methods.
  • WANG Jinhua1,2,3, MA Xuehua1, YUE Lianghui1, AN Yongsheng2, CAO Jie1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 288-296.
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    Aiming at the low diagnosis accuracy of some industrial equipment due to the lack of labeled fault sample data, a modeling method of multi fault network model based on PCA-BNs principal component analysis and Bayesian network (PCA-BNs) is proposed. The dimensionality of time series signals is reduced by PCA to obtain independent fault features and improve the ability of extracting key fault information; The method of fusing single fault Bayesian network to construct multi fault Bayesian network structure is used to solve the time-consuming problem of BN modeling process; The combination of Gaussian distribution and maximum likelihood estimation is used to determine the network parameters, improve the accuracy of BN modeling with a small amount of data, and realize fault diagnosis under small samples. The experimental results show that the PCA-BNs fault diagnosis method proposed in this paper can achieve high-precision fault diagnosis under the condition of small samples, and effectively reduce the running time of the algorithm.
  • ZHANG Kaiyin, SUN Qi, XIONG Sidong, JIANG Ziling
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 297-302.
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    Structural dynamic characteristics are widely used in structural vibration control, structural reliability design and health monitoring, from which some basic concepts of dynamics need to be further discussed. An example of transverse vibration of a simply supported beam is used to analyze and calculate the response amplitude of a multi-degree-of-freedom system by modal displacement method and modal acceleration method, respectively. the relationship between structural displacement response and first-order natural frequency and the relationship between structural displacement mode contribution and modal strain energy are discussed. Based on the modal orthogonality, by analyzing the displacement response of the multi-degree-of-freedom vibration system, the necessary conditions of the system resonance are discussed, that is, while ensuring that the vibration frequency of the system (a certain natural frequency) is equal to the excitation frequency, the displacement response should also show the corresponding modal shape, and the pure modal resonance of the multi-degree-of-freedom system can be used to accurately identify the modal parameters of the structure.
  • LIANG Gang1,2, LU Zhihan1, LIU Yunhe1,2, GUO Hongchao1,2
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 303-313.
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    To study the mechanical behavior of tube column and H beam welded joint with Q460 high strength steel (HSS) under earthquake, 11 specimens consisting of flange plate of H-shaped beams that were welded to rectangular columns at flange plates were tested under a cyclic tensile condition. The effects of the width ratio of the beam flange plate to the tube column, thickness ratio of the tube column on the failure mode, bearing capacity, ductility and energy dissipation capacity of the joint are studied. The results show that the failure modes of the tube column and H beam welded joint using Q460 HSS are mainly divided into three types after the cyclic tensile test: weld fracture at the connection, fracture failure of the tube column panel at the connection or tensile fracture of the beam flange; The width ratio α and the width thickness ratio λ have a greater impact on the mechanical behavior of welded joints with HSS, when α decreases from 25.0 to 18.75, the strain energy of the joint decreases by 134%; In addition, when a joint was damaged, the ultimate displacement of a welded joint with a new type of welded access hole construction is nearly two times greater than that of a traditional construction joint, and the former has better ductility. The research results can provide a basis for seismic design and further theoretical research of tube column and H beam welded joint with HSS.
  • LI Xinye1, LI Xingpeng1, LI Kai1, ZHANG Huabiao2, CHEN Tao1
    JOURNAL OF VIBRATION AND SHOCK. 2024, 43(4): 314-320.
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    In this paper, a new test system for simulating the axial-torsional coupling vibration of drill string is proposed. Based on this system, a single-factor experiment was designed, and the influence of driving speed, feed speed, drill bit diameter, rock sample strength and drill string stiffness on drill string vibration was studied, and the influence of the above factors on drill string vibration was explored through orthogonal experiments. The single-factor experimental results show that with the increase of rotational speed, the axial vibration amplitude first decreases and then increases, but the torsional vibration amplitude gradually decreases. With the increase of feed speed, the amplitude of axial vibration gradually decreases, but the amplitude of torsional vibration gradually increases. The increase in speed leads to a decrease in torque and drilling pressure, while an increase in feed speed leads to an increase in torque and drilling pressure; The use of small diameter drill bits, low strength rock samples, and low stiffness drill string all help to reduce the axial vibration amplitude of the drill string, but all lead to an increase in the torsional vibration amplitude. The orthogonal experimental results show that the speed has the greatest influence on the axial vibration, and the feed speed has the greatest influence on the torsional vibration. The experimental results are basically consistent with the prediction results of the numerical simulation of the axial-torsional coupling model of two-degree-of-freedom drill string.