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  • WANG Jianjun1,LIU Honghui2,CAO Yalei1,FU Xuanming3,LI Weijie3,LUO Mingzhang4,LAN Chengming2
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (625) PDF (122)   Knowledge map   Save
    A type of metal corrosion probes was proposed using piezoelectric tube stack and electro mechanical impedance (EMI) technique. The probe consists of a piezoelectric tube stack and a metal bar. The transfer matrix model of the multilayer structured probe in longitudinal vibration mode was established, and the electrical impedance was derived to solve the first resonance and anti-resonance frequencies. The theoretical results were validated by comparing them with those of the special cases in the published literature. In addition, the probe performance was studied systematically through theoretical analysis, artificial uniform corrosion experiments, temperature-sensitive experiments, accelerated corrosion tests, and wireless impedance measurement experiments. The results show that the first resonance and anti-resonance frequencies of the probe are increased with the decrease of the bar length, the increase of the corrosion days, and decreased with the increase of temperature. The measured impedance spectra of the wireless impedance measurement system are very consistent with the test results of the traditional impedance analyzer. The present study provides an important reference for developing the novel metal corrosion probes of wireless quantitative measurement.
  • ZOU Penglai1, CAI Lujun1, ZHANG Wei1, 2, 3, LI Yanhui1, ZHONG Dongwang1
    Journal of Vibration and Shock. 2024, 43(18): 1-11.
    The thin-walled metallic tube-core sandwich structures with convenient preparation, low cost and the ability to form significant plastic deformation have broad application prospects in the field of impact protection. In this paper, the novel metallic tube-core sandwich panels with geometrically asymmetric face-sheets and transverse density gradient distribution of tubes are designed. The dynamic response and energy absorption mechanism of the sandwich panels are studied numerically. The dynamic response process and characteristics of metallic tube-core sandwich panels are obtained, and the effects of detonation height, explosive mass, mass distribution of the panel and transverse density gradient distribution of the tubes on the deformation and energy absorption are discussed. The results show that the dynamic response process of the metallic tube-core sandwich panels can be divided into three stages: core compression, overall deformation, and elastic deformation recovery. With the increase of explosive mass and the detonation height, the central displacement of the back face-sheet of the sandwich panel increases and the energy absorption ratio of the tube-core layer decreases. When keeping the total thickness of the face-sheet unchanged, the sandwich panel with thick front face-sheet and thin back face-sheet has strong ability to absorb energy and resist deformation. The sandwich panel with positive density gradient distribution of cores has strong ability to resist deformation, and the sandwich panel with the negative density gradient distribution of cores has strong ability to absorb energy. The application of the metallic tube-core sandwich panel with an appropriate increase in the thickness ratio of the front and back face-sheets and a positive density gradient distribution of the tubes can better disperse the blast shock wave, enhance the energy absorption efficiency of core layer, and obtain better anti-blast effect.
  • SONG Yubing, TI Zilong, YANG Ling, LI Yongle, LI Zeteng
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (458) PDF (230)   Knowledge map   Save
    During the construction of twin decks, the long-span asymmetrical twin parallel decks represent a unique design, where both the highway and railway are arranged side by side at the same elevation. Due to the disparate dynamic characteristics of the highway bridge and the railway bridge, the considerable variation in wake characteristics of the decks, as well as the pronounced and consequential aerodynamic interference between the asymmetrical twin decks, the vortex-induced vibration (VIV) characteristics of the asymmetric twin decks become considerably more intricate. To comprehensively investigate the impact of interference effects on the VIV behavior of decks, a series of wind tunnel tests and fluid-structure interaction numerical simulations were conducted on twin decks. These experiments and simulations were conducted in the context of a long-span asymmetrical twin separated parallel deck configuration, where the highway deck was designed as a Π-type superimposed deck and the railway deck was a streamlined box deck. The research findings indicate the following: (1) The Π-type highway deck exhibited significant vertical bending and torsional vibrations when exposed to the windward side, showing typical VIV "lock-in" characteristics between the wind speed range and the structural vibration frequencies. However, these vibrations diminished when the deck was on the leeward side. (2) The streamlined railway deck showed no significant vibrations when positioned on the windward side, but substantial vibrations were observed on the leeward side, with amplitudes rapidly rising and falling, without a distinct "lock-in" range. (3) The numerical flow field indicates that the scale and distribution of vortical structures near the deck vary significantly when the highway is located at different positions (windward and leeward sides). The presence of large-scale vortices in the cavity below the bridge deck and the periodic variation of vortical structures are the main reasons for vortex-induced vibration on the windward side. On the leeward side, influenced by the disturbance effect, the scale of vortices in the cavity below the bridge deck decreases, the oscillation frequency of lift changes, and the phenomenon of vortex-induced vibration lock-in disappears. (4) Flow fields and pressure distributions near the railway revealed stable flow patterns when positioned on the windward side, with self-excited lift forces approximating steady forces. However, when positioned on the leeward side, the railway surface experienced a larger negative pressure area due to the interference of the highway wake, leading to significant vibrations caused by the pulsation of the highway wake and resulting in oscillations of the railway's aerodynamic lift. This study systematically investigated the aerodynamic interference effects between asymmetrical twin parallel main girders and their impact on VIV performance. The underlying VIV and aerodynamic interference mechanisms were revealed, providing valuable insights for the engineering design of similar bridges.
  • HUANG Qunxian1,2,LIN Congying1,2,LIU Yang1,2,HUANG Jun3
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (436) PDF (243)   Knowledge map   Save
    Based on the strongback mechanism, damage control, and replaceable concept, an innovative earthquake resilient strongback-frame structure is proposed to minimize earthquake-induced damage and facilitate quick and economical post-earthquake repairs. To investigate the seismic performance and resilience of the strongback-frame structure, pushover analysis on five structural models was conducted with Sap2000 software. Particular emphasis was taken on the damage mechanism, damage evolution, deformation characteristics, seismic performance, and seismic resilience of the strongback-frame structure. A two-stage calculation method for the residual deformation is proposed to evaluate the seismic resilience of structures subjected to different magnitude earthquakes. The results show that the strongback system can effectively control the lateral deformation pattern of the structure, and the story drift ratio and damage distribute uniformly, which can avoid the formation of the weak-story failure mechanism and improve the seismic performance and collapse resistance of the structure. The strongback system can also effectively mobilize the reserve capacity of the overall structural components, which enhances the overall performance. The stiffness, strength, and energy consumption capacity of the strongback frame are significantly improved, and the pushover curves do not appear the strength softening behavior. After reasonably graded damage design, the replaceable energy dissipation components set in the strongback frame play the first line of defense role to reduce the structural damage and residual deformation, effectively improving the structure's seismic resilience.
  • REN Hongyi1, LIU Xiangyu1, XIAN Ganling1, LAN Jingyan1,2
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (426) PDF (62)   Knowledge map   Save
    At present, there are some defects in seismic wave filtering methods of earthquake engineering research field, such as human experience interference, peak spike, noise interference, etc. In this paper, a new adaptive filtering method is proposed by combining recursive least squares (RLS) algorithm and recurrent neural network (RNN) model. The results show that the new method performs filtering by setting adaptive adjustment filter parameters and the self-iteration algorithm. It is superior to the traditional filtering method recommended by the United States Geological Survey (USGS) in noise recognition ability and filtering speed, and can effectively reduce the distortion, damage and phase advance of the original waveform after filtering. At the same time, the adaptive filtering method was applied to near-field seismic records containing velocity pulses at different site classification of stations. The adaptive filtering method has been further proven to be effective. The research results provide a new idea and method for filtering analysis in the field of Earthquake engineering, and can also provide reference for seismic record processing and related applications.
  • LOU Wenjuan1, ZHOU Weizheng1, BIAN Rong2, CHEN Keji2, HUANG Zenghao3
    Journal of Vibration and Shock.
    Accepted: 2024-07-05
    Abstract (422) PDF (331)   Knowledge map   Save
    To investigate the difference of wind-induced swing characteristics between long span conductors and jumper lines, a refined finite element model coupling the jumper lines, long span conductors and insulator strings is constructed. The research elucidates the different dynamic characteristics, included mode and aerodynamic damping ratio, between the conductors and jumper lines. Combining with the frequency-domain method, multiple cases are calculated to analyze the effect of wind field and line parameters on the dynamic response of conductors and jumper lines. Results show that: The fundamental frequency of jumper lines is approximately 1.5~2.0 times that of conductors. The effect of aerodynamic damping on jumper lines is much smaller than that of conductors. The dynamic response of conductors is dominated by the background response, while the resonance response is not significant. However, the resonance response increases the wind -induced swing response by more than 30%, which should be considered in the wind-resistance design of jumper lines. The resonance response characteristics of jumper lines are determined by their own dynamic characteristics, and are relatively less affected by the upstream wind. The fundamental mode plays a decisive role in the resonance response of jumper lines. Based on the quasi-static and inertia force method, this paper derives the resonance part of peak fluctuating wind force for jumper lines, introduces the resonance factor, and amend the gust response coefficient. The amended gust response coefficient increases by about 9%~12% compared to the code.
  • WANG Weijing1,2,ZHANG Weiming2,GUO Mengfu3,YANG Jinshui1,MA Li2
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (419) PDF (138)   Knowledge map   Save
    Negative Poisson’s ratio structures have considerable application prospects in the field of energy absorption due to their abnormal deformation mechanism. This paper designs and characterizes a novel negative Poisson’s ratio structure with adjustable parameters. The static/dynamic mechanical properties and energy absorption characteristics are systematically studied using a combination of theoretical and numerical simulation research methods. The research results show that the new structure has excellent mechanical properties and adjustable parameters. Under static compression conditions, the new structure has higher stiffness and better energy absorption performance, with a specific energy absorption value 2.64 times that of the concave honeycomb structure and 3.89 times that of the star-shaped honeycomb structure. Under dynamic impact conditions, the energy absorption performance of the concave-star structure is better than that of two traditional honeycomb structures (concave and star-shaped) at low velocity, and its energy absorption advantage degrades at medium and high velocities, which is equivalent to the concave honeycomb structure but much higher than the star-shaped honeycomb structure.
  • HAN Yan1,2,BU Xiumeng1,WANG Lidong1,2,3,LUO Ying1,2,LI Kai3
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (395) PDF (133)   Knowledge map   Save
    Track unevenness is one of the primary sources of excitation that induces coupling vibrations in the vehicle-bridge system. The sensitive wavelength of the coupling vibration in the system has been identified, which holds significant reference value for line management. Firstly, a spatial model of the high-speed maglev train-track beam coupled system is established. In this model, the maglev train is simulated as a multibody dynamic model with 537 degrees of freedom, while the track beam is simulated as a spatial finite element model. The two are coupled through the magnetic track relationship based on PD control theory. Secondly, the Shanghai high-speed maglev is used as the research background, and a 5-car marshalling train crossing a 20-span simply supported girder bridge is selected as the calculation condition to verify the correctness of the model by comparing it with the measured results. Finally, considering the uneven excitation of track harmonics, the effects of different combinations of track unevenness in various directions, different amplitudes of track unevenness, and different vehicle speeds on the sensitive wavelength of dynamic response and ride stability of trains and bridges are discussed. The results indicate that the coupling of lateral and vertical vibrations in the maglev-bridge system is weak. At a design speed of 430 km/h, the sensitive wavelengths of the car body in vertical, roll, and pitch accelerations are 140-180 m, 60-100 m, and 120-160 m, respectively. The sensitive wavelengths of the car body in lateral and yaw accelerations are greater than 200 m. Resonance in the body roll, yaw, lateral, pitch, and vertical directions can be triggered at wavelengths of 80 m, 105 m, 115 m, 140 m, and 160 m, respectively. The response amplitudes of the car body and main beam are generally linearly related to the amplitude of track unevenness. When the amplitude of track unevenness is 1 mm, the peak roll acceleration of the car body does not change significantly with vehicle speed, while the peak accelerations in the other four degrees of freedom decrease with increasing vehicle speed. The vertical acceleration amplitude of the main beam increases linearly with vehicle speed. The lateral and vertical Sperling indicators of the car body indicate that the Sperling index of the car body is less than 2.5, indicating good ride stability for the maglev vehicle.
  • WANG Xuan1,2,SHI Yuankun1,CHEN Xiang1,LONG Kai2
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (367) PDF (169)   Knowledge map   Save
    An effective reliability-based topology optimization method is proposed for the design problem of continuum structure considering the uncertainty of load amplitude and frequency of harmonic excitation. A reliability design optimization model of minimizing structural volume ratio under probabilistic reliability constraint is established, in which the limit state function is the sum of the amplitude squares of the degrees of freedom concerned. The analytic sensitivity formulations of limit state function with respect to design variables and random variables are derived using adjoint variable method. The Performance Measure Approach (PMA) is used to achieve reliability analysis, and the method of moving asymptotes (MMA) is used to update design variables. Finally, three numerical examples and Monte Carlo simulation are tested to verify the effectiveness and stability of the proposed method for the design problem of continuum structure under uncertain harmonic excitation. The influences of the uncertainty of amplitude and frequency of harmonic excitation, reliability index, and coefficient of variations on the optimization results are also discussed.
  • LEI Wei1,2,WANG Qi1,2,LIAO Haili1,2,LI Zhiguo1,2
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (367) PDF (172)   Knowledge map   Save
    The steel bridge tower is one kind of tall and slender structure which is highly sensitive to wind loads and prone to vortex-induced vibrations (VIVs). To investigate the VIV characteristics of a 217-meter-high steel bridge tower, 1:100 scale free-standing aeroelastic model wind tunnel tests were conducted. The experimental results show that in-phase VIVs occur in the low wind speed ranges, and out-of-phase VIVs occur in the high wind speed ranges at the wind directions range of 0° - 30°. The most unfavorable wind directions of in-phase and out-of-phase VIVs are 0° and 10°, respectively. In-phase along-wind displacement and out-of-phase torsion angle are 609.5 mm and 4.3°, respectively. Furthermore, the VIV triggering mechanisms were studied by computational fluid dynamics (CFD). The numerical simulation results show that the frequency of alternating vortex shedding near the two tower columns is close to the fundamental natural frequency, and the periodic pressure difference generated by this phenomenon leads to in-phase and out-of-phase VIVs. The findings and conclusions of this study provide some reference for the wind-resistant design of similar steel bridge towers.
  • ZHANG Fan1,2, YAO Dechen1,2, YAO Shengzhuo1, YANG Jianwei1,2, WANG Yanliang1,2, WEI Minghui1,2, HU Zhongshuo3
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (366) PDF (178)   Knowledge map   Save
    Bearing is an important component in rotating machinery. Due to the working conditions, materials, and processing methods, the lifetimes of bearing have large fluctuations. Traditional parallel or serial neural network prediction methods have seriously dependent on the data sets. Therefore, there is a need for bearings RUL prediction network that can be applied to different data lengths. To overcome this challenge, a Transformer-LSTM serial-parallel neural network prediction model is proposed, which can predict the RUL for bearings with different lifetimes. By reconfiguring the Transformer decoding layer and fusing it with the LSTM network structure, the serial-parallel prediction processing of bearing life data is achieved. The experimental results show that the Transformer-LSTM neural network can accurately predict the bearing failure time for different lifetimes, including: long, medium, and short. Moreover, the model has a stronger generalization ability which also indicates that the proposed method can improve the prediction accuracy of bearing life.
  • CUI Yue, YANG Na
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (361) PDF (44)   Knowledge map   Save
    The Potala Palace is a famous world cultural heritage in our country. And its area is located with active faults and frequent major earthquakes. Reliable seismic risk assessment can provide a basis for seismic protection of Zang-style ancient buildings in the study area, including the Potala Palace. Compared with the shortcomings of traditional seismic hazard analysis methods, this paper proposes a systematic process of seismic hazard assessment by using the seismic physical prediction method based on the multi-locking segment rupture theory. According to the relationship between seismic intensity and the attenuation of ground motion parameters, considering the conditions of the site itself, the seismic risk assessment of the area where the Potala Palace is located was carried out. The results show that the study area is located in the Linzhi selsmic zone, and the seismic risk of the study area in the next 100 years is mainly the next M8.5 main shock or M7.8 landmark earthquake in the Linzhi selsmic zone. The seismic fault is located in the southeast bank fault of Namco near the middle section of the Yadong-Gulu fault, and the epicenter is near 30.3°N and 90.1°E. The Potala Palace complex is located in bedrock, regardless of the magnification of the mountain site, and the seismic action at the ground end of the structure is equivalent to that of bedrock. The research conclusion provides a theoretical basis for the seismic study of the structure of the Potala Palace complex.
  • LIU Yong1,2,LI Xing1,2,GUO Xinhui1,2,WEI Jianping1,2,SONG Dazhao3
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (350) PDF (112)   Knowledge map   Save
    In order to reveal the influence of the confining pressure on the formation and expansion mechanism of rock fissures under particle impact, particle impact rock-breaking experiments and micro-nano industrial CT scanning experiments were carried out, which clarified the influence of the confining pressure on the characteristics of the rock fissure expansion under the action of particle impact; and numerical simulations were carried out on the particle impact under the conditions of different confining pressures, to analyze the evolution process of the rock's stress and fissure fields, and to reveal the intrinsic mechanism of the confining pressure influencing the expansion of fissures. The results show that after the particles impact the rock, a fracture zone and intergranular main crack propagation zone are thus formed in the rock. The shear stress and tensile stress caused by compressive stress are the main reasons for the formation of the fracture zone, while the formation of the intergranular main crack propagation zone is mainly due to tangential derived tensile stress. The confining pressure induces prestress between rock particles such that the derived tensile stress needs to overcome the initial compressive stress between the particles to form tensile fractures. And the increase in the confining pressure leads to increases in the proportion of shear cracks and friction effects between rock particles, resulting in an increase in energy consumption for the same number of cracks,which inhibits the formation of the fracture zone and intergranular main crack propagation zone.
  • MIAO Wei1,YIN Qiang1, QIAN Linfang1,2
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (347) PDF (207)   Knowledge map   Save
    It is of great significance to study the contact phenomena between bourrelet and bore for understanding the in-bore motion of projectile. Hence, a bourrelet-barrel contact model is proposed. It is assumed that the contact stress between a bourrelet and a rifling land only varies longitudinally along the rifling. The surface of a rifling land is simplified as a spatial curve. The geometry of the bore is then described as a cage consisting of rifling lands. An algorithm is proposed for detecting the contact between the bourrelet and rifling lands. The contact stress is calculated with an analytical solution to a 2-D contact problem by spreading the projectile and barrel out in a circular direction. The Chebyshev-Gauss quadrature is adopted to calculate the contact load on the bourrelet and rifling lands because of the square-root singularity of the contact stress. The fitting method and identification method of determining the model parameters are presented. Theoretical analysis suggests that the contact stiffness between the bourrelet and bore varies with in-bore travel of the projectile. The influence of variance of the projectile mass-center on bourrelet-bore contact type and formation of wearing grooves on the bourrelet is analyzed through numerical simulations. It is found the equivalent contact point on the bourrelet does not locate at the bourrelet center or on the bourrelet edges.
  • KANG Yuxiang1, CHEN Guo2, SHENG Jiajiu1, WANG Hao3, WEI Xunkai3
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (342) PDF (221)   Knowledge map   Save
    Aiming at the problem that the faults of aero-engine rolling bearings are difficult to detect at low speed, a deep support vector description method based on Transformer framework was proposed to detect the faults of low speed rolling bearings. Firstly, a vibration feature extraction backbone network based on Transformer model is constructed. Then, the extracted features are input into a three-layer autoencoder structure, which is used to calculate the loss function of the network model. In order to reduce the amount of network calculation and improve the training speed, the frequency spectrum results obtained by Fast Fourier Transform (FFT) of the vibration acceleration time domain signal of rolling bearing were used as the input of the network in the preprocessing, and the model training was completed only by normal data. Finally, the experiments were carried out on an aero-engine rotor tester with casing and a real aero-engine. The results show that the proposed method can accurately detect the faults of low speed rolling bearings, and the detection accuracy is 93% and 100%, respectively, which fully indicates that the proposed method has good anomaly detection ability and application value.
  • BAO Yingchao1,2,XIANG Yu1,2,CHEN Jie1,2,SHI Ziyu3
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (341) PDF (54)   Knowledge map   Save
    Aiming at the problem of non-uniqueness of solution and singular integral in acoustic boundary element method, based on the idea of CHIEF method, the conventional boundary element equation and the equivalent source equation are combined, and the coupling equivalent relation between the coefficient matrix of the two equations is used to indirectly replace the singular coefficient matrix in the conventional boundary element method, and then a coupled CHIEF method with unique solution in full frequency domain, high computational accuracy and high stability is proposed. In this method, the equivalent source equation is used as the supplementary equation, which not only solves the failure of the interior point supplementary equation of the traditional CHIEF method, but also avoids the direct calculation of singular integrals by the indirect substitution of matrix, which significantly improves the computational efficiency and accuracy. Through typical examples of acoustic radiation and scattering, the results of the proposed method, conventional boundary element method, conventional Burton-Miller method and equivalent source method are compared. The results show that not only the unique solution can be obtained in the full wavenumber domain, but also the calculation accuracy and efficiency of the proposed method are better than those of the conventional boundary element method and the conventional Burton-Miller method, and the condition number of the coefficient matrix is much lower than that of the equivalent source method.
  • LU Yixiang1, 2, QIAN Dongsheng1, 2, ZHU De1, 2, SUN Dong1, 2, ZHAO Dawei1, 2, GAO Qingwei1, 2
    Journal of Vibration and Shock. 2024, 43(17): 203-213.
    Abstract (340) PDF (52)   Knowledge map   Save
    In practical engineering, fault diagnosis of rotating machinery often faces various complex situations such as noise interference, limited fault samples and variable working conditions, which pose new challenges to the application of data-driven deep learning methods that lack prior knowledge. Traditional fault diagnosis methods based on wavelet analysis can extract rich prior knowledge of faults, but a fixed (structured) or single wavelet basis is difficult to directly adapt to complex fault scenarios. To address these issues, a multiscale wavelet packet-inspired convolutional network (MWPICNet) was proposed for fault diagnosis of rotating machinery in this paper, inspired by traditional multiscale wavelet packet analysis. The proposed MWPICNet internally coupled the time-frequency domain conversion with filtering denoising, feature extraction and classification. First, the multiscale wavelet packet-inspired convolutional (MWPIC) layer and soft-thresholding activation (ST) layer were alternately used for signal decomposition and nonlinear transformation, extracting multiscale time-frequency fault features and filtering out the noise layer by layer. Each MWPIC layer could be approximately seen as a single-layer wavelet packet transform of the signal under multiple learnable wavelet bases, and learnable thresholds in the ST layer were used to sparse the wavelet coefficients. Then, the frequency band weighting (FBW) layer was designed to dynamically adjust the weights of each frequency band channel. Finally, a global power pooling layer (GPP) was introduced to extract discriminative frequency band energy features that were helpful for fault identification. The efficacy of the proposed MWPICNet is verified through case studies designed for different complex scenarios on three fault diagnosis datasets.
  • ZHENG Huadong1, 2, ZHENG Haodong1, 2, WANG Zhen1, 2, XIE Weiping1, 2, WU Bin1, 2
    Journal of Vibration and Shock.
    Accepted: 2024-07-05
    Abstract (329) PDF (182)   Knowledge map   Save
    To study the extreme wind pressure distribution in semi-closed stations, the wind pressures induced by high-speed trains passing through railway stations are simulated. The accuracy of the numerical model is also verified against the field-measured data. Based on this validated numerical model, the extreme wind pressure distribution at the train head and tail is analyzed for the two typical station regions (near platform Region I and far from platform Region II) under the traveling train speed of 250km/h, 300km/h and 350km/h, respectively. The corresponding empirical equations are established. The results show that there is a nonlinear relationship between extreme wind pressures and train speeds. At the same train speed, the extreme wind pressures in Region I and Region II decrease exponentially with the horizontal distance, whereas the decrease rate is inversely proportional to the vertical distance. When the horizontal distance is less than 15m, the positive extreme wind pressures due to train head in Region I are always larger than those in Region II at the same vertical distance, while the absolute values of the negative extreme wind pressures due to train head in Region I are always smaller than those in Region II. When the horizontal distance exceeds 15m, the extreme wind pressures gradually tend to be steady, and the corresponding steady values in Region I are larger than those in Region II. The empirical equations developed in this paper can accurately describe the extreme wind pressure distribution in the semi-closed station. The research results can provide reference for the structural design of semi-closed stations.
  • WANG Min1,2,DENG Aidong1,2,MA Tianting1,2,ZHANG Yujian1,2,XUE Yuan1,2
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (323) PDF (157)   Knowledge map   Save
    Regarding the problem that the diagnosis accuracy of rolling bearing fault diagnosis model decreases under the variable working conditions and environmental noise interference, a rolling bearing fault diagnosis method (DAMSCN-BiGRU) composed of Multi-scale Convolutional Network based on Dual Attention mechanism (DAMSCN) and improved Bidirectional Gated Recurrent Unit (BiGRU) was proposed. Firstly, using multi-scale feature fusion module with different kernel sizes to obtain a variety of receptive fields and extract the multi-scale feature information of the original vibration signal of the bearing, which were fused adaptively according to their importance. And the multi-scale features were weighted and fused using a dual attention module composed of channel attention and spatial attention to weaken the redundant features in the fused features. Then, the attention layer was added and the segmented activation was used to improve BiGRU to mine the time-domain features of the signal to improve the performance of the bearing fault diagnosis. Finally, the classification of different faults was completed by Softmax layer. The experimental results show that compared with other intelligent diagnosis models, DAMSCN-BiGRU can achieve an average diagnostic accuracy of 98.2% under variable working condition and still has an accuracy of 85.3% in the strong noise background, and the effect is better than other commonly used models under different levels of noise intensity, which is beneficial to promote the research and practical application of intelligent fault diagnosis of rolling bearings.
  • ZHANG Yongliang, SUN Peng, HUANG Yanbo, LIU Pei
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (320) PDF (235)   Knowledge map   Save
    The rectangular hollow section pier of a railway high-pier long-span simply-supported beam bridge is taken as the research object,calculation model for four kinds of pier heights were constructed, and factors such as the position of truncation and the number of reinforcement bars were considered. IDA analysis is carried out by using Opensees software to build a single pier calculation model, and the elastic-plastic seismic response characteristics of railway high piers are summarized and suggestions on seismic design is put forward. The results show that when the ratio of longitudinal reinforcement is between 0.63 and 0.89%, the pier height is less than 42 meters and the longitudinal reinforcement length is arranged over the pier, the section of hollow pier bottom is weak.When the height of the pier is greater than 67 meters and the longitudinal reinforcement is divided into sections, the section at the bottom of the hollow pier, the section at the truncation of the longitudinal reinforcement and a section in the pier may be the weak part, but the section at the bottom of the hollow pier is the area where the plastic hinge appears first.The plastic hinge in pier shaft can be produced only when it is stimulated by strong ground motion. The influence of ground motion peak acceleration should be considered in the selection of longitudinal reinforcement.Increasing the number of reinforcement bars at pier bottom is beneficial to reducing the plasticity of pier bottom section in general, but it may not improve the seismic performance of the whole pier under strong earthquakes. For high piers, when there are two or more plastic hinge areas in pier shaft, it is suggested to use the coefficient of curvature ductility as the evaluation index.
  • XIANG Huoyue1,2, TAO Yu2, WANG Zhen2, ZHONG Jinkun2, LI Yongle1,2
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (309) PDF (116)   Knowledge map   Save
    To enhance transverse stiffness of a long-span railway suspension bridge, a composite-spatial cable structure consisting of main and secondary diagonal cables is proposed. Then, the parameters of diameter of composite-spatial cables, anchorages of main diagonal cables with stiffening beams and the surface, and the number of secondary diagonal cables on transverse deflection-span ratio of the bridge are optimized by the effective utilization of the materials and static analysis method. Finally, the analysis method for coupling vibrations of wind-vehicle-bridge system is used to obtain the limit of transverse deflection-span ratio of the bridge based on the driving performance, and the influence of the main and secondary diagonal cables on the enhancement rate of the limit of transverse deflection-span ratio is analyzed. The results show that on the basis of considering the effective utilization rate of composite-spatial cables, anchorages of main diagonal cables and stiffened beams should be located near 1/4 of the main span, and it is optimal when the vertical distance between anchorages of main diagonal cables with stiffening beams and the surface and the tower is equal, and it is enough to set a secondary diagonal cable for each group of composite-spatial cables; in the optimal layout of composite-spatial cables, transverse deflection-span ratio of the bridge can be reduced by 14.18%, the limit of transverse deflection-span ratio can be increased by 16.79%.
  • YANG Zheng1,WANG Shibo1,2,RAO Zhushi3,YANG Shanguo1,2,YANG Jianhua1,2,LIU Songyong1,2,LIU Houguang1,2
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (303) PDF (73)   Knowledge map   Save
    Aiming at the problem that it is difficult to recognize the caving coal gangue in the process of fully mechanized caving mining under the background of strong noise, a coal and gangue recognition method fusing low-level auditory feature Mel spectrum and high-level auditory feature auditory neurotransmitter firing rate is proposed. Firstly, according to the frequency spectrum characteristics of the sound signal of the tail beam of collapsed coal and gangue impact hydraulic support, an auditory model suitable for the coal gangue recognition task is established based on the auditory neural filter bank model. Then, the auditory model is used to analyze the sound signal of collapsed coal and gangue to obtain auditory neurotransmitter firing rate. Afterwards, the auditory neurotransmitter firing rate is fused with the peak feature extracted by Mel spectrum to obtain the auditory perception diagram of coal and gangue sound. Finally, coal and gangue were recognized with the ConvNeXt model based on the fusion auditory features constructed. The experimental results showed that the proposed coal and gangue recognition method with fusion auditory features had high recognition accuracy under different signal-to-noise ratios, and its superiority was particularly evident under the condition of large background noise (signal-to-noise ratio of -5dB), with accuracy reaching 91.52%, which was significantly superior to the method using low-level auditory features and spectrum as recognition features and using time-frequency domain features combined with machine learning, verifying the robustness of the proposed method to noise.
  • CHANG Yuanjiang, WANG Shichao, LI Jian, LIU Xiuquan
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (299) PDF (166)   Knowledge map   Save
    In the process of deepwater drilling, the riser and blowout preventer system are an essential part of the entire operation process. Due to many risks involved in the operation process, therefore, establishing an accurate mechanical analysis model of the coupling system between riser and BOPs, accurately analyzing its mechanical behavior and performance, is of great significance for guiding the safety of drilling operations. At present, most people only focus on independent modeling of the riser and ignore the potential impact of the blowout preventer group, which will lead to differences between the established model and the actual situation, and making it difficult to accurately analyze the mechanical properties of the riser system. This paper puts forward the rigid-flexible coupling concept of riser and BOPs, derives the kinetic energy and potential energy of the coupling system, establishes the theoretical model by Lagrange method, and uses Newmark- β Perform numerical calculations on the dynamic model using the direct integration method. A simulation modeling was established using ADAMS software to conduct comparative analysis of dynamic response under different operating conditions. The results indicate that the lateral displacement envelope and bending moment envelope of the riser obtained from the theoretical model in this paper, as well as the lateral displacement time history curve and bottom bending moment time history curve of the middle node of the riser, are in good agreement with the ADAMS simulation results, indicating the importance of the theoretical model in this paper, which can provide reference and support for the design and analysis of risers in China.
  • ZHANG Benxi1,WANG Xiaoming1,MEI Yulin2
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (292) PDF (26)   Knowledge map   Save
    The transfer function model of acoustic structural unit is established through the time-domain simulation method of three-dimensional finite element analysis, and is accurately expressed as the function of structural parameters. The transfer function representation can simplify the design process of acoustic structure. First, two acoustic structural units are established, and their amplitude-frequency characteristics are simulated. And meanwhile, the simulated amplitude-frequency characteristics are verified by experimental measurements. Next, based on the amplitude-frequency characteristics, transfer functions of the two structural units are fit by adopting different zero-pole matching schemes. The results show that the fitting accuracy is the highest when matching 7 poles and no zero to fit the transfer function of the expansion chamber unit, and matching 2 poles and 2 zeros to fit the transfer function of the Helmholtz resonator unit. Then, the influence of the structural parameters of the acoustic unit on the amplitude-frequency characteristics is analyzed. Subsequently, based on the high accuracy form of the fitting function, the transfer function model of the acoustic structural unit is established by numerical simulation and fitting calculation. Finally, a composite acoustic structure composed of an expansion chamber and a Helmholtz resonator is constructed, and its transfer function is calculated based on the transfer function models of the units. The results of COMSOL and transfer function model are compared to verify the established unit transfer function models.
  • ZHANG Leike1, NIE Liang1, ZHANG Jinjian2,3, WANG Xueni1,4, MA Zhenyue2
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (291) PDF (146)   Knowledge map   Save
    Aiming at the rotor-runner system with rubbing problem of hydro-generator set, the Magneto-Rheological Fluid Damper ( MRD ) is adopted to control the shaft vibration, in order to investigate the influence of MRD on vibration pattern of unit shaft system and corresponding effect on suppression of system rubbing faults. Firstly, the unit axial position function is introduced into MRD nonlinear dynamics model, and the dynamic model of MRD-rotor-runner system with axial distribution parameter under rubbing fault is established. Secondly, based on numerical simulation method, the nonlinear dynamic behavior of rotor-runner system with or without considering MRD is comparatively analyzed using unit speed as control parameter. Finally, the effects of different MRD axial arrangement parameters on the dynamic behavior of rubbing rotor-runner system are investigated. The results show that the addition of MRD has a good restraining effect on unsteady motion of rotor and runner, which can significantly reduce vibration amplitude of rotor and runner, and effectively avoid the occurrence of rubbing faults in unit shaft system. The vibration dampening effect of MRD on the system is the best when damping parameters s1 and s2 are taken to be 0.25 and 0.95, respectively. By reasonably arranging MRD in unit shaft system, the system vibration can be effectively improved, thus providing useful guidance for vibration control of hydro-generator set.
  • HE Keda1, LI Qing1, 2, LIU Lei1
    Journal of Vibration and Shock.
    Accepted: 2024-08-05
    Abstract (289) PDF (176)   Knowledge map   Save
    A large number of scientific instruments and equipment in the space station need to be locked by unloosening bolts. Aiming at the problem of frequency drift induced by unloosening bolt locking during the development of active vibration isolator for space station, the dynamic mechanism modeling and experimental verification of nonlinear connection of active vibration isolator for space station in locking state are explored.The mechanical analysis of the locking release device of the isolator based on the unloosening bolt is carried out, and the equivalent dynamic model of the system based on the Iwan model is established according to the nonlinear distribution of the stress on the contact surface of the unloosening bolt, and the nonlinear characteristics of the dynamic response are analyzed.The prototype of the active vibration isolator of the space station is developed for sinusoidal vibration test to verify the accuracy and effectiveness of the established dynamic model, which provides a reference for the environmental adaptability design of the space station precision scientific equipment.
  • WANG Zhaodong1,WANG Zifa2,3,LI Zhaoyan2,MIAO Pengyu1,WU Luyuan1
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (286) PDF (125)   Knowledge map   Save
    Two liquefaction discrimination methods are proposed. The first method is to establish a machine learning model with sand liquefaction prediction function based on 519 sets of static penetration test data from the New Zealand Geotechnical Database (NZGD). First, three machine learning classification models, namely, Support Vector Machine (SVM), Random forest (RF), and XGboost (eXtreme Gradient Boosting (XGB), are established. After super parameter optimization using GridSearchCV, the performance of the model is evaluated using the overall accuracy (OA), accuracy (P), recall (R), and F1 values, Conduct model validation on historical liquefaction data and compare the results with domestic and foreign methods. The second method is based on historical earthquake damage data and uses empirical judgment to determine the initial judgment conditions for static penetration testing. The results show that Random forest can be used as a liquefaction Discriminative model with strong prediction ability. By comparing with the domestic Geotechnical investigation and the international Olsen method, Random forest with simple elements and rapid calculation can achieve the accuracy close to the above two power methods, which is a feasible liquefaction Discriminative model; In addition, based on the historical liquefaction database, the conic resistance threshold method with the limitation of liquefaction burial depth under different intensities is summarized. The accuracy rate of the method is good in the 7 intensity zone, 8 intensity zone, and 9 intensity zone through data verification. Compared with the Code for Geotechnical investigation, it has the advantages of good operability, strong interpretability, and wide applicability. The established model has strong applicability for predicting soil liquefaction, and the initial judgment conditions of static cone penetration can also serve as reference values for rapid liquefaction discrimination. The combination of the two methods can provide good reference value for scientific research and engineering construction.
  • CHEN Bing, ZHANG Yangkun, REN Jiang, YIN Zhongjun
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (285) PDF (159)   Knowledge map   Save
    The Acoustic Black Hole (ABH) effect can generate strong energy concentration, which can convert low-quality vibration energy of high frequency and low amplitude into high-quality vibration energy of high amplitude, so as to facilitate utilization. A piezoelectric energy harvesting device for a circular two-dimensional acoustic black hole is proposed. The finite element analysis results show that the annular two-dimensional ABH structure can significantly improve the energy collection efficiency in the wide band domain. The experimental test platform of circular two-dimensional acoustic black hole piezoelectric energy collector is built, and the correctness of the simulation results is verified by experiments. Compared with the classical two-dimensional ABH structure, the annular two-dimensional ABH structure has better energy collection efficiency and structural strength. The influence of the geometric size of the piezoelectric plate on the energy collection efficiency of the device was analyzed, and the geometric size range of the higher output power was obtained. The orthogonal test design was carried out to study the comprehensive influence of the truncation thickness, the size of the piezoelectric plate, the diameter of the central platform, the power exponent, and other factors.
  • LI Xuzhe1, LI Wenjie1, BI Zhigang2, LIANG Bin1
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (281) PDF (115)   Knowledge map   Save
    In order to study the influence of blasting excavation on the stability of surrounding rock in the tunnel with a small clear distance, taking the Yidong high-speed Fangjun tunnel project in Zhejiang province as the engineering background, the calculation formula of surrounding rock vibration velocity during blasting construction was derived according to the law of energy attenuation. The finite element software MIDAS GTS NX was used to simulate the change law of surrounding rock vibration velocity and stress under different clear distance conditions. The numerical results of vibration velocity in surrounding rock are compared with the theoretical values to verify the accuracy of the formula. According to the relation between vibration velocity and stress, the threshold value of vibration velocity is proposed to ensure the safe construction of tunnels. The results show that: (1) The maximum relative error between the theoretical value and the simulated value is 5.9%, and the maximum relative error between the theoretical value and the field monitoring data is 7 %, which verifies the accuracy of the theoretical formula. (2) There is a negative correlation between the peak vibration velocity of the rear tunnel and the distance between the blasting center of the first tunnel, and the peak vibration velocity of the monitoring point on the blasting side of the surrounding rock is greater than that on the back explosion side. 2D is the minimum safe clear distance of the anti-military tunnel during blasting construction (D is the clear distance of the tunnel), at this time, the maximum peak vibration velocity of the excavation of the upper step is about 1.20 times that of the lower step. (3) After blasting excavation, the peak stress and vibration velocity of the surrounding rock are mainly concentrated near the arch waist and arch foot. With the increase in the clear distance, the influence of the advance tunnel on the rear tunnel gradually weakens and is eventually ignored. (4) Under the action of blasting, there is a certain linear relationship between the peak stress of surrounding rock and the peak vibration velocity, and the vibration velocity control threshold to ensure the safe construction of tunnel blasting is 1.9 cm∙s-1. The research results can provide a reference for the blasting construction of similar small clear-distance tunnel projects in the future.
  • XIA Yankun,LI Xinyang,REN Junjie,KOU Jianqiang
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (281) PDF (39)   Knowledge map   Save
    Due to long-time high load operation, the insulation performance between turns of the stator winding of permanent magnet synchronous motor (PMSM) is prone to decrease, resulting in inter-turn short circuit. At this moment, the vibration intensity of the motor will change. In response to this phenomenon, this study proposed a CEEMDAN-HT nonlinear signal analysis method that combined complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and hilbert transform (HT) and utilized it for extracting fault features from vibration signal. Firstly, the vibration signal was decomposed using CEEMDAN algorithm to obtain a series of intrinsic mode functions (IMF), and the variance contribution rate in principal component analysis was applied to distinguish the IMF component containing fault feature information. Secondly, the IMF with high contribution rate was analyzed using HT, and the main fault features were obtained by presenting time, instantaneous frequency, and amplitude using three-dimensional joint time-frequency diagram. Finally, a short circuit fault simulation of motor was conducted using ANSYS finite element software, and a short circuit fault experimental platform was constructed. By comparing and analyzing the finite element simulation results and experimental results, the effectiveness and accuracy of the method proposed in this study were verified.
  • ZHU Hepeng1,2,3,DING Zhe1,2,3,ZHANG Yan1,2,3,LI Xiaobai1,2,3
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (271) PDF (83)   Knowledge map   Save
    The iterative process of topology optimization involves a large number of finite element analyses and sensitivity update steps. As the number of mesh divisions increases, the optimization process consumes a significant amount of computational cost. By using deep learning methods and establishing a mapping relationship between low-resolution intermediate configurations and high-resolution topological structures, cross-resolution topology optimization design of structures can be achieved, thus greatly improving computational efficiency. This article constructs a topology optimization method capable of cross-resolution prediction based on two different generative adversarial networks, and extends it to the optimization prediction of three-dimensional structures. Firstly, with the minimization of compliance as the objective function, a dataset of optimized structures under different loading conditions, initial displacements, and volume fractions is generated using the Solid Isotropic Material with Penalization method. Then, the Pix2pix and Esrgan networks are used to solve their cross-resolution prediction problems, where for the Pix2pix network, residual modules are used to replace the convolution modules inside the generator to enhance the reuse of low-level information. Finally, the effectiveness of the proposed method is verified through two-dimensional and three-dimensional examples, and comparative studies are conducted with existing methods based on the CGAN network. The results show that considering both calculation accuracy and computational efficiency, the method based on the Esrgan network performs better and is most suitable for cross-resolution topology optimization design.
  • LU Zhilong
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (269) PDF (136)   Knowledge map   Save
    In order to explore influence of different configuration parameters on a energy absorption performance of composite corrugated beams, the dynamic collapse tests were carried out for various configurations of corrugated beams, and the load-time curves and failure modes of various configurations of corrugated beams were given by analyzing the test phenomena and processing the test data. The transient impact process of the corrugated beam was simulated by the finite element software (ABAQUS), and the specific energy absorption (SEA) and the average load value were obtained, which were compared with the experimental results to verify the validity of the numerical model. Based on the experimental and numerical analysis results, the influence of the corrugated configuration on the peak load and energy absorption capacity of the corrugated beam is discussed, and the difference of energy absorption between different corrugated beams and the design of adding weak links is evaluated, which provides a reference for practical engineering design.The results indicate that when the critical stress equation of the corrugated beam under axial compressive load is used to set the height/amplitude ratio and wavelength/amplitude ratio of the corrugated beam in the corresponding relationship, the corrugated beam structure exhibits a relatively stable crushing process, which has certain application value;The R value of the corrugated web fillet not only affects the peak load and average load, but also has a certain relationship with the change of the failure mode of the corrugated beam. The R value of the weak fillet can better improve the peak load.
  • XU Haiwei1,LI Junlong2,HE Xuhui3,DU Hang1,DING Kunyang1,LOU Wenjuan1
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (268) PDF (131)   Knowledge map   Save
    The large-span photovoltaic support structure is light and flexible, and is vulnerable to wind-induced aeroelastic effects. In order to study the aerodynamic damping characteristics of this structure, an aeroelastic model wind tunnel test was carried out to a typical large-span flexible photovoltaic support structure with module inclination of 0° and 10° under different wind speeds and pretensions. Based on the aeroelastic test results, empirical wavelet transform (EWT) and variational modal decomposition (VMD) combined with the improved random reduction method (RDT) were used to identify the aerodynamic damping ratio of photovoltaic structure under different wind speeds and directions, module inclinations, and cable pretensions. The study results show that the aerodynamic damping ratio is sensitive to the change of wind direction angle. When the module has an inclination of 10°, the aerodynamic damping of a large-span photovoltaic structure shows a negative value under the windward wind azimuth of 180°. Increase of pretension may lead to decrease of aerodynamic damping ratio of a horizontally installed module under a high wind speed. The aerodynamic damping ratio generally decreases with the increase of wind speed, it basically shows positive values under low wind speeds but may become negative under high wind speeds. Although the aerodynamic damping ratios identified by different methods were not the same, both of them show consistent variation pattern of aerodynamic damping.
  • LI Xiaojun1,TIAN Chaojie1,HUANG Xuhong2
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (267) PDF (140)   Knowledge map   Save
    To consider the impact of time effects during collision on the vibration reduction performance and mechanism of non-packed particle damper (NPPD), an equivalent single particle mechanical model based on contact element method (EISM-CE) is proposed on the basis of existing mechanical model (EISM), and a corresponding solving algorithm of motion state of NPPD-single degree of freedom structure is suggested based on the Runge Kutta algorithm. The shaking table test of a single-layer steel frame structure with additional NPPD was also designed and conducted. The influence of filling ratio on the frequency response curve of structural displacement was explored. Further validation and comparative analysis of the EISM-CE model was conducted based on the proposed model parameter determination principle. On the basis of verifying the rationality of the equivalent model, the numerical analysis on the vibration reduction effect and energy change law under free vibration, harmonic excitation, and recorded strong ground motion was carried out subsequently. The results show that the EISM-CE model and the corresponding determination principle of model parameters are more reasonable and effective than the existing EISM. The results of the numerical analysis show that NPPD has good damping performance under different excitations. The damping performance and mechanism of EISM-CE are somewhat different from EISM after considering the collision time effect.
  • MA Chengshuai1, WU Hongbo1, WANG Yinjun2, LU Shaofeng3, LI Jirui3, CAI Xinyuan1, CHEN Zhengyan1
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (266) PDF (64)   Knowledge map   Save
    In order to study the attenuation characteristics of the bubble curtain on the underwater shock wave under different air flow rates, the morphological changes of the bubble curtain after the shock wave were explored by using high-speed photography, and the analysis was carried out based on the time-history curve of the shock wave pressure. The results show that the bubbles in the bubble curtain will expand and contract several times after being subjected to shock wave. With the increase of gas flow rate, the maximum diameter of bubble expansion increases and the first period of bubble expansion and contraction becomes longer. And the bubble curtain has a strong damping effect on the underwater shock wave pressure. The larger the gas flow rate rises, the more obvious the peak attenuation of shock wave pressure is. Under the gas flow rate of 40L/min, the peak attenuation of shock wave pressure is as high as 88.98%. When the gas flow rate is greater than 20L/min, the attenuation amplitude of shock wave impulse is greater than 50%. Based on the curve fitting of the relationship between the gas flow rate and the drop range of the peak pressure, the empirical equation suitable for the working condition is put forward in order to guide the practical engineering.
  • SHI Wenhui1,YUE Shuai1,LIU Zhou2,XIAO Yuzhi3,DU Zhonghua1,LIU Zhi2,GAO Guangfa1
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (254) PDF (52)   Knowledge map   Save
    Aiming at the impact on the satellite platform during the launch of the pyrotechnic device, a new launch buffer structure using an aluminum honeycomb was designed. Then the internal ballistic model of the pyrotechnic device and aluminum honeycomb crushing model was established through the closed bomb tests of gunpowder and the quasi-static tests of aluminum honeycomb. Then the launch recoil model was found on this basis. And the effects of the charge of gunpowder and the inner diameter of aluminum honeycomb on the recoil characteristics were studied. The results show that when the powder charge increased by 0.3 g, the average recoil increased by 1.95%, the velocity of the mass block increased by 5.10%, the recoil displacement increased by 7.64%, and the recoil duration decreased by 10.3%. When the inner diameter of the aluminum honeycomb decreases from 148 mm by 1 mm and 2 mm, respectively, the average recoil increases by 4.06% and 9.08%, the velocity of the mass block increases by 0.22% and 0.54%, and the recoil displacement rises by 3.38% and 15.24%. And the reasonable selection of the above parameters can effectively reduce the launch recoil and ensure the launch performance of the mass block.
  • LAN Chengming1, LIU Honghui1, WANG Jianjun2, LI Weijie3
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (254) PDF (107)   Knowledge map   Save
    The smart aggregate based on piezoelectric stacks is a new type of transducer, which usually use piezoelectric stacks as the core element. Compared with traditional smart aggregates, it has superior electromechanical coupling performance, which can effectively improve the accuracy and reliability of structural damage diagnosis and has important application prospects in the field of structural health monitoring. However, the current study mainly focused on the device design and theoretical modeling, the device performance based on electromechanical admittance needs to be further evaluated. A temperature-sensitive experiment was designed to analyze the variation of the resonant frequencies of the device under temperature gradient; a 28-day water immersion experiment was carried out to plot the variation of the resonant frequencies of the device with the number of water immersion days; three soil specimens with dimensions of 200 mm 200 mm 200 mm were prepared, and the devices were embedded into the soil specimens to conduct water content monitoring experiment. The water contents of the soil specimens were monitored by the quantitative indicators under different water contents. The results show that the resonance frequencies of the smart aggregates based on piezoelectric stacks decrease linearly with the increase of temperature; the maximum shift of the resonance frequencies do not exceed 10% during 28 days of water immersion, indicating good stability; the quantitative indicators calculated based on admittance signals all increase with the increasing moisture content of the soil specimens, which can effectively monitor the changes in soil moisture content.
  • XIE Jiaquan1,2, WANG Haijun1,2, SHI Wei2,3, ZHANG Jiale1,2, HUO Yiting1,2, CAO Jialin1,2, GAO Qiang1,2
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (253) PDF (98)   Knowledge map   Save
    The purpose of this paper is to study the resonance and chaos of Mathieu Duffing system with square damping term. The amplitude frequency and phase frequency characteristics of the main resonance of the system under the combined excitation of parameters and force are explored by using the multi-scale method. Based on Lyapunov's first method, the stability conditions of the steady solution are given and the periodic solution branches of the system are determined. According to the Parametric equation of the heteroclinic orbits of the system, the necessary conditions for the heteroclinic orbits to cross and the chaos of the system are derived. According to the bifurcation diagram, phase trajectory diagram, and Poincare cross-section were used to study the effects of excitation amplitude and frequency on the chaotic motion behavior of the system. It was confirmed that changes in excitation frequency and amplitude can lead to the system entering a chaotic state through period doubling bifurcation.
  • GAO Xuejin1,2,3,4, ZHANG Zhenhua1,2,3,4, GAO Huihui1,2,3,4, QI Yongsheng5
    JOURNAL OF VIBRATION AND SHOCK.
    Abstract (251) PDF (95)   Knowledge map   Save
    Aiming at the weak applicability of the traditional unsupervised domain adaptive method to multi-condition rolling bearing fault diagnosis scenarios, a Multi-source Domain Adaptive Residual Network (MDARN) was proposed. By aligning Correlated subdomains from multiple source domains, thus improving the fault diagnosis performance of the model under multiple operating conditions. First, the ResNeXt residual network is used to fully extract transferable features from the source domain and the target domain; then, the local maximum mean difference (LMMD) criterion is introduced to align the relevant subdomains in the target domain based on the subdomains of the two source domains, reducing The distribution difference between the relevant sub-domains and the global domain; finally, the proposed method is verified experimentally by using the bearing data set of Case Western Reserve University and the real bearing vibration data set generated by the MFS mechanical comprehensive fault test bench. The results show that the average fault diagnosis accuracy of this method is as high as 99.76% under multiple working conditions. Compared with the existing representative methods, the proposed method has better fault diagnosis effect.
  • YANG Fengli1, SHAO Shuai1, ZHANG Hongjie1, SU Zhigang1, FAN Rongquan2
    Journal of Vibration and Shock.
    Accepted: 2024-07-05
    Abstract (250) PDF (82)   Knowledge map   Save
    A four-point synchronous fluctuating wind speed measurement system with horizontal pair intervals of 10m, 20m and 30m was established in a plain landform terrain site of Nagqu town, Xizang, at an altitude of 4500m. Continuous records of wind speeds for 1.5 years at this high altitude site were obtained. The maximum average wind speed in 10 minutes and the fluctuating wind speed reached 33.6m/s and 45m/s, respectively. The measured mean values of longitudinal and transverse turbulence intensity are 0.134 and 0.123, respectively, which are between the turbulence intensity of the Exposure Category A and the Exposure Category B specified in DL/T 5551-2018. Based on the synchronous fluctuating wind speed of any two measuring points, the spatial correlation coefficient and turbulent integral scale of the downwind fluctuating wind speed component along the conductor direction were calculated. The generalized extreme value model can better reflect the probability distribution of turbulent integral scale based on high wind speed samples. The higher the field observation sample wind speed, the larger the average turbulence integral scale. When the wind speed sample limit is set as 8m/s and 20m/s, the difference between the average turbulence integral scale is 22.5%. The average turbulence integral scale with high wind speed samples above 20m/s is 106.96m, which is 2.1 times of the 50m specified by DL/T 5551-2018, and the wind load acting on the wires increases by about 6.1%. The wind load on the wires in the high-altitude plain landform may be underestimated.