28 June 2023, Volume 42 Issue 12
    

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  • SHENG Zhenxin1,2,LIU Jianhu1,2,WANG Haikun1,2,ZHANG Yongkun3,LI Liye1,2
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 1-7.
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    During shallow water explosion, the bubble motion is subject to the combined action of free surface and rigid bottom, therefore the existing theoretical models for bubble migration are not applicable. In this paper, the theoretical model of bubble migration for underwater explosion under the combined action of free surface and rigid bottom was established. At the same time, the underwater explosion experiment of TNT charge was carried out, and the evolution process of bubble motion was photographed with a high-speed camera, then the bubble migration law was obtained after intelligent processing. The results show that: the deviation of bubble migration between the theoretical calculation results and test experimental results were -11.7%~8.2%. The accuracy of the theoretical model could meet the requirement of engineering application, which could provide technical support for the damage assessment for ship structure.
  • ZHAO Lei,ZOU Dingfu,ZHANG Lijun,QI Xin,YU Zhixiang
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 8-17.
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    Only specific impact condition is considered in verification tests of flexible rockfall barriers, which may not be the worst-case scenario in practice. Field investigations show that part of the products which pass the verification tests do not effectively achieve the expected protection target. Therefore, an in-depth research on the mechanical response of a flexible rockfall barrier under different impact conditions was carried out by numerical simulations. Firstly, the full-scale impact test of a flexible rockfall barrier with auxiliary supporting ropes was back-analysed. The numerical model was verified by comparing the breaking distance, rope forces and the elongation of energy dissipators. On this basis, parametrical simulations were carried out to investigate the effects of span number, impact location and post ends sliding characteristics on the mechanical response of the flexible rockfall barrier. The results showed that: the mechanical response of the flexible rockfall barrier was less affected by the number of spans; under the same impact condition, the internal force of the side post was more than twice that of the middle steel post, and was significantly affected by the impact location. In term of the side post, the impact position located at the side span is most unfavourable, and it may buckle even when the system passed the standard verification test; the internal force of supporting ropes will grow significantly with the increasing of the friction coefficient of post ends, and a safety factor of 2.0 was recommended for the design of supporting ropes.
  • FU Bo1,CHEN Yuan1,SHENG Kai2,SUN Hao1,TONG Genshu3
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 18-28.
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    A low-cycle reversed horizontal load experimental research was conducted on two full-scale specimens of rectangular concrete filled steel tubular frame with full height opening stiffened thin steel plate shear walls (SPSW) and one non-opening SPSW specimen. The influence of the presence or absence of openings, and the opening positions was considered during the design of specimens. The frame columns were subjected to axial compression. The horizontal load-vertex displacement hysteresis curve and skeleton curve of each specimen are obtained through the study. On this basis, the failure mode, bearing capacity, ductility, energy dissipation capacity, stiffness degradation, strength degradation and other performance indicators of specimens were analyzed. The test results show that the specimens have good ductile deformation ability when the frame columns are subjected to vertical pressure. The ultimate drift ratio of the specimens can reach 1/51~1/29. Different from the failure mode of the non-opening wall, the failure of the opening wall starts from the failure of the stiffener at the edge of the opening. The side opening specimen retains certain shear failure characteristics, and the failure mode is the bending shear failure mode. The failure mode of the specimen with the middle opening is the bending failure mode. When the size of the opening is the same, the performance of the side opening specimen is better than that of the middle opening specimen. Finally, it is suggested that in addition to meeting the stiffness requirements given in the current code, the bearing capacity of the edge stiffeners should be checked as vertical members. The steel plate shear wall with full height opening is modeled by shell element. At this time, only the shear bearing capacity of the wall should be checked, and the axial force of the surrounding vertical members should be multiplied by 1.10~1.15.
  • XIE Hongwei1,2,LUO Qiang1,2,JIANG Liangwei1,2,YE Qingzhi1,2,FENG Guishuai1,2,ZHAO Mingzhi3
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 29-38.
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    Clarifying the dynamic response of the subgrade caused by the high-speed train is the key to the design of the subgrade structure. Applying the vertical coupling dynamic model of high-speed EMU train, CRTS III ballastless track, and soil subgrade, with the random irregularity generated by the high-speed railway ballastless track spectrum as the excitation, to analyze the subgrade surface dynamic stress characteristics and its statistical laws with respect to driving speed v and track spectrum cumulative probability λ, and to discuss the relations between dynamic stress coefficient ϕ's probability distribution parameters(position parameter μ and scale parameter β) and v, λ. Then a probability estimation model of ϕ is to be erected by dimensionless technology. The research shows that the train dynamic action on the subgrade surface has significant randomness, the dynamic stress coefficient ϕ obeys the Gumbel distribution, and the mode value μ and the discreteness β increase nonlinearly with v and λ. By introducing normalized indices Iμv, Iμλ, Iβv, and Iβλ, which are respect to probability distribution parameters μ and β of ϕ, the binary function expressions μ(v, λ) and β(v, λ) are derived. Based on the CDF of ϕ, a quantile value estimation equation ϕ(v, λ, p) with a guaranteed rate p is established. The relative bias is less than 5% compared with the calculated values of coupling dynamic simulation.
  • LIU Wentao1,XIONG Weili1,2
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 39-47.
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    Fast Tool Servo (FTS) system is a key component to realize the machining of micromachined parts. Taking the piezoelectric ceramic type FTS system as the research object, the hysteresis state delay model, the time varying delay model and the unmolded dynamic nonlinear model are introduced into the FTS system model design to describe the chattering phenomena. Based on neural network control, an active disturbance rejection composite control scheme with hysteresis delay compensation function is proposed to realize the chattering control of FTS system. The linear active disturbance rejection control (LADRC) considers the internal uncertainty, delay nonlinearity and other disturbances as total disturbance and estimates compensation in real time, and the adaptive BP neural network is used to approximate the disturbance estimation error among them. Compared with the traditional model inversion method, the composite control scheme is easy to be designed initially without precise mathematical model. Compared with the LADRC, the composite control scheme reduces the number of parameters that need to be adjusted, has higher tracking accuracy under the same bandwidth. The simulation results show that the designed composite control has better robustness, can effectively realize fast and precise tracking control of piezoelectric ceramic type FTS system.
  • WANG Zhimin1,2,JIN Guoguang1,2,LIANG Dong1,2,CHANG Boyan1,2,ZHOU Yang1,2
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 48-58.
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    Taking the four-bar mechanism as the research object, the Monte Carlo algorithm is used to simulate the generation of uncertain geometric parameters and clearance size, the nonlinear dynamic equation of the four-bar mechanism with multi-clearance joints and uncertain parameters is established, and an analysis method for nonlinear dynamics of mechanisms with multi-clearance joints and uncertain parameters is proposed. Firstly, the effects of clearance joints and uncertain parameters on the kinematic accuracy of the mechanism are studied under different conditions, and the kinematic error of the mechanism is quantified. Then, the influence of uncertain parameters, crank speed, clearance size and clearance position on the bifurcation and chaos of the four-bar mechanism are investigated. The analysis results show that the kinematic accuracy of the mechanism is reduced due to the influence of clearance joints and uncertain parameters. At the same time, the dependence and sensitivity of systems bifurcation and chaos behavior on crank speed and clearance size are proved by using bifurcation diagram. The changes of crank speed and clearance size are the main factors that cause the bifurcation and chaotic behavior of the mechanism, and the influence of uncertain geometric parameters on the overall bifurcation phenomenon of the mechanism is limited.
  • ZHANG Li1,TAN Jian2,ZHANG Yulong3,XU Jin2,HUANG Shimiao1,DUAN Qingfeng2,DUAN Menglan2
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 59-68.
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    Large flow induces vibration and instability in pipe during conveying. To reveal the dynamic response of pipe conveying seawater, based on the Euler-Bernoulli beam model, the calculation and analysis model is established under marine condition. The semi-analytical solution of the vibration equation is solved by using Generalized Internal Transform Technique, and the time-dependent solution of structural dynamic response is given. The results show that structural damping only reduces the pipe amplitude in default of outflow. The effect of internal flow velocity on pipe amplitude is greatest under fixed-free boundary condition and least under pinned-with clump weight boundary condition. However, under the action of external flow, the internal flow velocity only influences the pipe amplitude under fixed-with clump weight boundary condition. The pipe has different natural frequency and critical velocity under different boundary conditions. With internal flow velocity increasing, the natural frequency of the pipe decreases gradually while approaching to zero.
  • XIANG Ling1,HU Yanan1,CHEN Kaile1,BING Hankun2,HU Aijun3
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 69-76.
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    The nonlinear dynamic model of a dual-rotor system with inter-shaft bearing is deduced and established, which the unbalance of dual-rotor system and the nonlinear factors of inter-shaft bearing are considered. The nonlinear dynamic characteristics of dual-rotor system subjected to internal and external excitations are studied. Firstly, the amplitude frequency responses of dual-rotor system are presented and the primary resonance characteristics of high and low pressure rotor are obtained, basing on the nonlinear dynamic model of dual-rotor system with inter-shaft bearing. Then, considering the influence of nonlinear parameters of dual-rotor system, the nonlinear dynamic responses of dual-rotor system are analyzed under internal and external excitations. Through the bifurcation diagram, axis orbit diagram, Poincare cross-sectional diagram, time-domain waveform diagram and spectrum diagram, the motion state and frequency characteristics of high and low pressure rotor under the influence of nonlinear parameters are obtained with the changes of excitation frequency. Finally, the influence of unbalance on the nonlinear response characteristics of dual-rotor system is analyzed, and the evolution law of dynamic characteristics of high and low pressure rotor under the change of unbalance is investigated. The research results can provide reference for the dynamic characteristic design of dual-rotor system and the fault diagnosis of high and low pressure rotor.
  • HU Liangpeng1,SUN Yangyang2,YUE Songlin2,MA Linjian2,CHEN Xudong1,NING Yingjie3,SONG Xiaohai4
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 77-87.
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    In order to gain insight into the damage characteristics and high strain rate mechanical response of high-strength concrete materials in assembled precast bridge structures under near-field impact loading, uniaxial impact compression tests were conducted on C60 and C80 high-strength concrete using a 100 mm large-diameter split Hopkinson pressure bar (SHPB). Dynamic parameters such as stress-strain curves, dynamic modulus of elasticity and dynamic increase factor of the concrete were obtained. The high-speed digital image correlation (DIC) technology was used to study the strain field on the concrete surface and analyze the crack propagation process during the failure process. The test results show that: the dynamic compressive strength of high-strength concrete specimens under high strain rate shows obvious strain rate effect, but its modulus of elasticity remains constant. And the logarithmic function model can better characterize the dynamic strength evolution pattern of high-strength concrete under high strain rate. Macroscopically, the observed damage patterns can be classified into four modes: intact specimen, axial splitting, concrete bursting and crushing. At high strain rates, the instability of crack and its expansion rate increases with strain rate increasing.
  • YANG Yalei1,DU Lijie2,LI Qingwei1,WEI Fei3,ZHANG Xiongwei4,ZHAO Xiangbo3,WANG Zhe3,LIU Yang4
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 88-97.
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    Relying on a major water conservancy tunnel project in Xinjiang, a full-face rock tunnel boring machine (TBM) is being drilled, and the field test of TBM main beam vibration under different working conditions is carried out. Through time domain and frequency domain, the vibration characteristics of main beam of TBM under different surrounding rock and different tunneling parameters are comprehensively analyzed. The results show that the change of vibration acceleration of main beam can accurately reflect the working cycle process of TBM starting, stable tunneling, stopping and changing steps;With the increase of the excitation source distance, the vibration of the main beam shows a fluctuation attenuation, but the axial vibration fluctuation is small, the attenuation amplitude is 36.68%, followed by transverse, vertical attenuation is the largest, up to 81.88%.The vertical vibration of main beam caused by tunneling thrust is larger than the axial and transverse vibration. The fluctuation range of the effective value of axial acceleration is -5~+5m/s2, horizontal acceleration is -3~+3m/s2 and vertical acceleration is -10~+10m/s2. Geological conditions (rock integrity and the uniaxial compressive strength, etc.) have a great influence on the main beam vibration.The key tunneling parameters of TBM are cutter-head speed (n), penetration (P) and thrust (F), which are significantly correlated with the vibration of the main beam. The vibration frequency of the main beam is generally distributed below 150 Hz. Under different tunneling conditions, vibration peaks may appear at some frequency points in the three directions simultaneously, indicating that there is a coupling vibration in different directions.The field test reveals the vibration characteristics of the main beam of TBM under different surrounding rock and different tunneling parameters, which provides test data and theoretical basis for the structural analysis of TBM main beam, the optimization of TBM tunneling parameters and the identification of geological conditions.
  • KOU Farong,LI Mengxin,HE Jiajie,XU Jianan,WU Jianghao
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 98-108.
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    In order to ensure the damping performance and improve the energy recovery performance of active suspension, a self powered active suspension system based on electromagnetic hybrid actuator is proposed, which adopts hierarchical coordinated switching control strategy, including upper controller and lower controller. Considering the motor loss, the energy flow state of the actuator is analyzed, and the self energy supply criterion is obtained. The lower nonlinear double closed-loop controller is designed to control the actuator through the energy feed / energy supply circuit; According to the analysis of the lower system, the upper coordinated switching controller with active, semi-active and energy feedback modes is designed. The effectiveness of the control strategy is simulated and verified in Matlab / Simulink environment, and the performance of electromagnetic hybrid active suspension is analyzed. The results show that the dynamic performance of the proposed suspension system is basically consistent with the active suspension without energy recovery function, and the average power of the energy storage module is less than 0, which conforms to the self energy supply criterion. Under this control strategy, the suspension system can realize self energy supply.
  • JIAO Lingling1,CHEN Jie1,2,LIU Lianhua1
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 109-117.
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    Aiming at problems of health indictor construction depending on prior knowledge and prediction accuracy being low for rolling bearing performance degradation trend prediction method in rotating machinery, a prediction method for rolling bearing degradation trend based on convolutional auto-encodes(CAE) and attention gated recurrent unit(AGRU) was proposed.Firstly, the method converted the rolling bearing time domain signal into frequency domain signal with fast fourier transform(FFT), and the features were extracted adaptively from frequency domain signal with convolutional auto-encodes.Then, the health indicators werw constructed from encoding features with evaluating and delsting. Finally the health indicators were input into the attention gated recurrent unit mode, and the pruning algorithm optimized the parameters to predict the performance degradation trend of rolling bearings. Results showed that the proposed method can obtain more accurate prediction results for rolling bearing performance degradation trend.
  • WAN Ruoqing,ZHANG Chun,JIANG Huiqiang,LI Yinbin
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 118-125.
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    In order to reduce the dependence of traditional vibration signal denoising methods on the prior information in time or frequency domain, a blind vibration signal denoising method based on deep autoencoder was proposed. In the absence of clean signals as the training target of the neural network, the adjacent sampling and expansion strategy was used to construct the training sample pair of the denoising deep neural network from the original signal. The deep neural network that can effectively denoise the original signals was obtained through self-supervised learning. And the applicability evaluation index was proposed to guide the setting of signal sampling frequency in practical engineering application. The denoising analysis of simulation signals and measured signals shown that the proposed method does not depend on the prior information of real signals and has great adaptive denoising effect for both steady and unsteady signals.
  • FANG Jiachang1,HUANG Tianli1,LI Miao2,WANG Yafei3
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 126-134.
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    To rapidly construct and accurately predict the strain responses of the main girder induced by temperature in the long-span cable-stayed bridge for structural condition assessment, based on the measured temperature and strain data on the main girder of a long-span cable-stayed bridge over 1 year, a method of constructing the temperature-strain mapping model by using the transfer learning technique and the bidirectional long short-term memory (Bi-LSTM) neural networks is proposed in this study. Firstly, the analytical mode decomposition (AMD) is adopted to denoise the strain data to obtain the temperature-induced strain. Secondly, the temperature and the strain data at a particular measurement point were selected to form a dataset, and were fed to a Bi-LSTM neural network. Then a well-fitting neural network baseline model is constructed by optimizing the network structure and hyperparameters. Finally, using the transfer learning method, some parameters from the trained Bi-LSTM neural network model are transferred to other temperature-strain datasets to construct the transferred temperature-strain mapping models. Compared with the temperature-strain Bi-LSTM neural network models constructed directly from the datasets, the transferred temperature-strain Bi-LSTM neural network models built by using the transfer learning technique have higher fitting accuracy, shorter training time and smaller prediction error.
  • WANG Yanbing1,2,REN Bin1,GENG Yanjie1,LI Zhengkuan1
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 135-144.
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    In order to explore the impact dynamic characteristics of soft and hard media composite rock mass, which is common in rock breaking and supporting engineering, granite and sandstone with large difference in protodeacon coefficient are used to splice into soft and hard media and single media composite rock mass. The split Hopkinson pressure bar (SHPB) test system is used to carry out the impact compression test of composite rock mass, respectively. The fluctuation characteristics, peak strength of stress wave into soft and hard media and single media composite rock mass are compared and analyzed, and the crack propagation morphology of composite rock mass is recorded by high-speed camera. Through the numerical simulation of discrete lattice spring method (DLSM), a comprehensive inversion analysis is carried out to study the variation law of stress time history curve of rock on both sides of cemented surface of soft and hard medium composite rock mass, and the ' soft and hard combination coefficient ' is used to characterize the damage evolution law of soft and hard medium composite rock mass. The results show that the wave characteristics of composite rock mass have obvious wave impedance effect. The better the wave impedance matching effect between composite rock mass and incident rod, the smaller the amplitude of reflected wave and the larger the amplitude of transmitted wave. At the same impact velocity, the peak strength of soft-hard rock mass is close to that of single medium soft rock mass. The failure degree and failure mode of soft-hard medium composite rock mass are obviously different from that of single medium composite rock mass. The crack of soft-hard medium composite rock mass first occurs at the end of sandstone far from the cementation surface, while the crack of single medium composite rock mass first occurs at the cementation surface. The single medium composite rock mass is mainly shear failure, supplemented by local tensile failure, and the failure is more complete. The soft sandstone in the soft-hard rock mass has shear failure, while the hard granite has no obvious damage. The rock stress on both sides of the cementation surface of the soft-hard medium combination rock mass presents a repeated phenomenon of rise-decrease-rise-decrease with time. The stress of the rock on both sides of the cemented surface of the single medium composite rock mass begins to decrease after reaching the peak stress, and there is no stress recurrence. The damage degree D of rock mass composed of soft and hard media is quadratically related to the coefficient γ of soft and hard media: D=-0.85γ2+2.80γ.
  • ZHANG Wanxuan,LU Zhe,ZHANG Jian,ZHANG Nan
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 145-151.
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    Vibration signals of a liquid rocket engine represent nonstationarity and strong noise, which brings difficulties in characteristic frequency component extraction. In order to solve the problem, a time-frequency analysis method called Second-order Multisynchrosqueezing Transform(SMSST)was proposed. The mathematical derivation of this method and the proof of its convergency was completed. Then a rotation frequency component extraction method based on adaptive band filtering and ridge extraction was presented. The SMSST was compared to traditional time-frequency analysis methods using generated signal. finally the SMSST-based rotation frequency component extraction method was applied with actual data in rotation speed identification and fault diagnosis . Result shows that the SMSST has better accuracy in time-frequency analysis compared with traditional methods. The method proposed provides an effective, reliable, redundant way to measure rotation speed. And the method is able to support fault early warning.
  • ZHANG Yibo,ZHOU Jin,SHEN Quan,ZHANG Yue,JIN Chaowu
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 152-163.
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    Active Magnetic Bearing (AMB) has limited ability to suppress the base excitation. When the vibration of the rotor caused by the base excitation is greater than its suspension gap, the rubbing damage between the rotor and stator of the magnetic bearing system will occur, resulting in equipment damage. In view of the above problems, the base excitation vibration suppression method combining the isolator and the active controller of magnetic bearing is proposed. On the basis of establishing the magnetic bearing rotor model under the base excitation, further considering the mutual coupling effect of vibration isolator, base and magnetic suspension bearing stator, the coupling relationship of the three is transferred to the stiffness and damping matrix of the magnetic rotor system equation in the form of generalized force, and the electromechanical integration model of the magnetic suspension rotor-vibration isolator coupling system is established. According to the coupling model, the influence of vibration isolator design parameters on rotor amplitude under different harmonic excitations is analyzed. Based on the variation of rotor amplitude, the maximum deformation, maximum acceleration and rotor stator clearance of vibration isolator are taken as the design objectives, and the appropriate stiffness range of vibration isolator is derived. Combined with the coupling vibration suppression effect of isolator-high stiffness active controller, the vibration suppression effect of the coupling system on the base excitation is analyzed theoretically and experimentally. The results show that compared with the magnetic suspension rotor system without isolator, the maximum amplitude of the rotor can be reduced from 0.052 mm to 0.011 mm by using isolator-high stiffness controller coupling control, and the overall amplitude of the rotor is less than 10 % of the protection gap (0.125 mm).
  • HU Yuchao1,2,WANG Xing1,2,LI Wenyin1,2,HU Jinghua1,2,CHENG Siwei1,2,WANG Dong1,2
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 164-171.
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    In motors, the electromagnetic forces and mechanical forces are usually considered as independent vibration sources. However, in engineering, the two factors both act on the rotor of motors and cause more complicated dynamic response due to their coupling effect. In this paper, the influence of unbalanced magnetic pull (UMP) caused by static air-gap eccentricity (SE), mechanical forces caused by asymmetric rotor with mass eccentricity and their coupling effect on rotor vibration are studied for the permanent magnet synchronous motors (PMSM). For a chosen 10 kW PMSM,the Jeffcott rotor model is used for numerical simulation. The results reveal that static air-gap eccentricity has little influence on rotation frequency vibration caused by mass eccentricity. Combined asymmetric stiffness of rotor and mass eccentricity, the component of three times rotation frequency vibration (3fr) occurs and its amplitude increases with ratio of asymmetric stiffness. When considering the coupling of UMP in asymmetric rotor with mass eccentricity, the components of double rotation frequency vibration (2fr) and its harmonic (4fr) occur, and the amplitude of 2fr component has a positive correlation with SE. This conclusion is verified by experiments on an air-gap adjustable permanent magnet synchronous motor.
  • DONG Zhiqiang,WANG Hongtao
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 172-177.
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    Many studies focus on the numerical correlation between the bearing parameters of spiral groove air bearing and its stability and bearing capacity, so as to provide data support for the design. As the application scope of spiral grooved shaft air bearing is wider and wider, more and more factors need to be considered to make the bearing work under the combustion condition of high temperature, high heat and full of flue gas. Quantitative analysis of these influencing factors is the key to improve the design. The falling particles and flue gas particles worn during the start and stop of the spiral groove bearing will have the effects of retention, deposition and erosion during the operation of the precision spiral groove bearing, and will accumulate for a long time, which will affect the performance and service life of the bearing. Based on the theory of gas-solid two-phase flow, the discrete phase model of Euler-Lagrange method is added to the CFD(computational fluid dynamics) equation. By solving the Navier-Stokes equation and the dynamic balance of particles, the motion trajectory and deposition law of particles in the spiral groove radial air bearing are studied, and the effects of radial bearing parameters and particle characteristics on particle deposition before and after its configuration adjustment are quantitatively analyzed, It provides a meaningful reference for exploring the self-cleaning structure of spiral groove radial air bearing.
  • HUANG Siqi1,TAN Zhiyin1,YANG Siguo1,ZHAN Yuxin1,WANG Xinglong2
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 178-186.
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    In order to overcome the problem that the Fourier decomposition method can easily obtain more similar boundaries during the spectrum scanning process, resulting in too many invalid components, an improved Fourier decomposition method (IFDM) is proposed. And this method is applied to the bearing fault diagnosis. First, based on the Fourier transform, several adjacent original components that are simultaneously larger or smaller than the feature mean are combined by establishing a neighborhood superposition criterion in IFDM, and a set of Fourier intrinsic mode functions (FIMF) is obtained by this method, thus reducing the invalid components. Secondly, some FIMF components with kurtosis value is greater than the mean value are reconstructed to extract sensitive fault feature information. Then, adaptive multi-scale weighted morphological filtering (AMWMF) is used to remove irrelevant components and background noise in the reconstructed component. Finally, the filtered signal is analyzed by spectrum. The effectiveness of the proposed method in bearing fault diagnosis is verified by the results of simulation and measured signals. At the same time, the superiority of the proposed method is verified in the comparison results with the existing methods.
  • ZHANG Longwei,YIN Shiding,CHEN Ning,WANG Jianqun,YUAN Luqi
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 187-193.
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    At present, the commercial bridge weigh-in-motion systems (BWIM) are generally based on the Moses algorithm. Although they can efficiently and quickly identify the axle weights of vehicles driving by bridges, the accuracy is low. To solve this problem, this paper presents a novel algorithm that finds axle weights using the bridge response subjected to the drive-by vehicles. Unlike Moses’ algorithm assuming all the bridge response have the same uncertainties, the proposed algorithm based on iteratively reweighted least squares (IRLS) considers the unequal uncertainties and can assign each observed response data its proper amount of influence over the axle weights estimates. Firstly, derive the formula of axle weights identification using IRLS; then, Numerical simulations are conducted to verify the IRLS algorithm using a simply supported beam-vehicle interaction model; finally, based on the field test of Wushui Fifth Bridge approach bridge, compares and analyses the axle weight identification of Moses algorithm and IRLS algorithm. Results show that IRLS algorithm reasonably allocates the contribution of different load responses to axle load identification and it can get more accurate axle weights than Moses’ algorithm.
  • LI Shutao,WEI Wanli,CHEN Yeqing,CHEN Longming
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 194-204.
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    It is difficult to distinguish the damage weights of penetration and explosion loads in the test of projectile penetration and explosion integration, at present, there is no mature method to simulate the whole process of projectile penetration and dynamic explosion integration. To solve this problem, a numerical simulation method of projectile penetration and explosion integration based on volume filling method is proposed, the explosive material is generated by volume filling in the background grid (ALE), and given the same initial velocity as the shell. The fluid structure coupling algorithm is set to restrict the cooperative deformation and movement of the shell and the explosive, and the static or dynamic explosive is charged after penetrating the target medium synchronously. The empirical formula is used to verify the model of inert projectile penetration process, and the numerical simulation of the whole process of penetration and dynamic explosion integration and penetration and static explosion integration is completed. The variation laws of medium internal pressure field, surface cratering and cratering depth are given, and the damage weights of penetration and explosion loads in the process of penetration and explosion integration are quantitatively analyzed. The results show that: when the penetration and dynamic explosion integration, the non dissipated penetration wave field in the target medium will be superimposed with the explosion shock wave field, and the pressure peak is higher than that of the single explosion wave field of charge static explosion after penetration, but it is not obvious; When the penetration and dynamic explosion integration, the dynamic explosive effect of the explosive makes the explosion shock wave field in the medium present an irregular spherical distribution, which has an influence that can not be ignored. When the target velocity is fixed, the later the initiation time is, the smaller the surface crater is and the greater the crater depth is; In the case of fixed initiation depth, the greater the target velocity, the smaller the surface crater and the greater the crater depth.
  • LU Junjie1,LIU Zhu1,2,DING Xuexing2,DING Junhua2,GAO De1
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 205-211.
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    According to the common problem of internal signal coupling and external interference factors a synergistic noise reduction method is proposed, which based on local characteristic-scale decomposition (Local Characteristic-scale Decomposition) and wavelet threshold in the low-speed stage of mechanical seals. Based on the information mapping relationship between local feature scale decomposition combined with wavelet threshold method and acoustic emission signal noise reduction, a cross-correlation coefficient, which is identification mechanism for noisy components, is established, and the pure components and the denoised noise components are reconstructed to achieve signal reduction. noise, and built a mechanical seal acoustic emission test bench. The test results show that the noise reduction effect of LCD-new threshold noise reduction method is better than LCD forced noise reduction and wavelet threshold noise reduction, and the signal-to-noise ratio of LCD-new threshold noise reduction is higher than LCD forced noise reduction and wavelet threshold noise reduction are 20% and 23% higher. Therefore, it is proved that the noise reduction technology based on the acoustic emission signal of the seal in conjunction with the wavelet threshold at the local characteristic scale maintains the availability of the signal, guarantees the fault characteristics of the signal, and lays a theoretical foundation for the full life cycle management of the mechanical seal.
  • LIU Xun1,ZUO Weidong1,2,YNAG Ning1,LIN Kaiqi1,2
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 212-219.
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    Identification of time-varying cable force is an important content of structural condition evaluation and health diagnosis of a cable-stayed bridge. However, this problem has not been well solved by now. Based on the improved multisynchrosqueezing transform and efficient ridge extraction algorithm, a new method for time-varying cable force identification of stay cables is proposed in this paper. Firstly, the time-frequency spectrum is obtained by using the vibration acceleration response of the cable, and then the time-frequency ridge in the time-frequency spectrum is extracted to obtain the instantaneous frequency of the cable. Finally the time-varying cable force is calculated according to the tension string theory. The applicability and precision of the method are verified by a typical numerical case of cable-stayed bridge and a cable tests. The results show that:in the numerical case, under the noise level of 10%, the average error of time-varying cable force identification is less than 1.99%, and the maximum error is 5.09%; in the test, the average error of time-varying cable force identification is less than 2.52%, and the maximum error is 8.77%. The preliminary verifying results prove that the proposed method has good identification accuracy and noise robustness.
  • DANG Xuanju,LIN Zhiwu
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 220-226.
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    The consequence that the robot end’s six-dimensional force/torque sensor affected by the contact vibration of the grinding wheel causes the force measurement signal to be submerged by noise in robot grinding, so that real-time and effective extraction of the signal is the key to control force. From the characteristics of the force measurement signal after fast Fourier transform, its noise is a complex noise formed by the superposition of Gaussian white noise, vibration noise and colored noise. Double Kalman Filter(DKF) algorithm based on series structure was proposed. Including: 1)The Gaussian white noise and high-frequency vibration peak groups were filtered by the first Kalman Filter(KF) algorithm; 2) To analyze the characteristics of colored noise formed by the superimposition of unfiltered Gaussian white noise and low-frequency vibration noise, a single parameter was introduced to design the time-varying variance to describe them by exponential weighting, so that KF was improved as the second filtering algorithm;3) Two filters formed double Kalman filter in series. Taking the contact grinding process between eyeglass frame and grinding wheel as an example, the experimental results showed that the proposed algorithm is more effective than traditional KF algorithm in suppressing noise in force measurement signal, and has low computational complexity and strong practicability.
  • TU Wenbing,WANG Jiaming,YANG Benmeng,LIANG Jie,LUO Ya,ZHANG Guiyuan
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 227-235.
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    On the basis of considering the dynamic effect of bearing moving parts,the interaction between roller and cage was simulated by nonlinear spring,a dynamic analysis model of cylindrical roller bearing was established to research the internal contact characteristics of rolling bearing under variable load. The Runge-Kutta algorithm with fourth-order fixed step was used to solve the differential equations of motion. The contact characteristics between inner ring and roller and its influence law under variable amplitude and frequency, as well as the dynamic contact characteristics of cage under different forms of periodic fluctuating load were obtained.The results show that the collision between the roller and the front of cage occurred in load zone, reversely, the collision between the roller and the rear of cage occurred in non-load zone.With the increase of fluctuation amplitude, the contact force between roller and inner ring increases in load zone, but the influence is small when entering and leaving the load zone.Under the action of low-frequency load, the trajectory of inner ring centroid is relatively concentrated,with the increase of fluctuation frequency, the load of inner ring increases slowly,simultaneously,the inner ring tends to move upward.Under high frequency load the centroid trajectory of inner ring is disordered and dispersed and the contact between inner ring and roller is unstable,the inner ring vibrates in the vertical direction.When load fluctuates, the degree of collision between the roller and the front of cage intensifies. The peak value of cage collision force from large to small is square wave, sine wave, triangular wave and stable working condition.
  • HAN Wei1, FANG Hai1, ZHU Lu1, HAN Juan1, WANG Jian2
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 236-248.
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    In order to analyze the mechanical properties and energy absorption effect of foam-filled sandwich composite materials reinforced specimens, quasi-static compression experiments were carried out. The Glass fiber reinforced polymer(GFRP) was used on the surface and lattice webs of the specimen, and polyurethane(PU) foam was used for core material. The specimens prepared from these two materials include hexagonal (H) lattice and trapezoidal (T) lattice. The experiment results show that the load displacement curve of 45 º trapezoidal lattice specimen is the most ideal. The specimen not only avoids the problem of sudden drop of bearing capacity, but also greatly improves the elastic stroke. For hexagonal lattice specimens, the increase of foam density has great influence on the elastic ultimate bearing capacity and energy absorption characteristics of specimens. Based on the stress analysis of the matrix element intercepted by the trapezoidal lattice specimen, the equivalent compressive elastic modulus of the 45 ° trapezoidal lattice specimen is obtained. Based on the compression experiment of ANSYS / LS-DYNA simulation specimen, the simulation results are in good agreement with the experiment values. Finally, through the collision simulation of ship anti-collision device pier, it is found that the trapezoidal lattice composite anti-collision device has a greater reduction of ship collision force and better anti-collision protection performance.
  • YANG Juan1,2,XU Yan1,3,SHI Jinhua2,DING Shenghu1
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 249-255.
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    Within the framework of quasicrystals linear dynamic theory, the dynamic fracture of a crack in a functionally graded one-dimensional hexagonal quasicrystals subjected to a time-harmonic elastic SH-wave was studied with integral transform technique. The material properties were assumed to vary continuously as an exponential function. Using the Fourier cosine transform, the boundary value problem of partial differential equation describing fracture problem was formulated to two pairs of dual integral equations, which were solved numerically with Copson method. The explicit expressions of phonon and phason elastic fields at crack face were determined and the dynamic stress intensity factors were obtained. Finally, numerical results showed the effects of gradient parameter, crack length , incident angle and normalized wave number on fracture characteristics of material. This study provides a theoretical basis for optimal design and nondestructive testing of quasicrystals.
  • ZHANG Ruiqi,SUN Yi,YU Yaoxiang,GUO Liang,ZONG Zhuyuxiu,GAO Hongli
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 256-263.
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    A dynamic adversarial adaptive bearing fault diagnosis method driven by a combination of simulation and data is proposed to solve the problem of low diagnostic accuracy of rolling bearings due to the scarcity of fault data samples and complex service conditions in real industrial scenarios. Firstly, a four-degree-of-freedom dynamics simulation model was proposed for the rapid generation of bearing fault characteristics with a well-defined time-frequency domain. Subsequently, the commonalities and differences between the measured data distribution and the dynamics simulation signal were explored. Finally, a dynamic adversarial adaptive network that can extract invariant features in the hidden domain and automatically align the distribution of data in the source domain of the simulation and the data to be diagnosed in the target domain was developed. The fault diagnosis experiment of rolling bearing was designed, and the source domain data composed of the signal with label information generated by the dynamic model, the measured signal of other dataset with label information and a small amount of signal in target domain with label information. The diagnostic effect of the neural network in the three categories of tasks was discussed, and the classification and recognition of a large number of unlabeled samples were completed. The results show that the simulated signal contains the characteristic information of bearing faults, which can characterize the real bearing data, and the proposed dynamic confrontation adaptive network can realize the bearing fault diagnosis more accurately than other diagnosis methods. At the same time, the source domain data contains very few labeled target domain data, which can greatly improve the recognition accuracy of the proposed method.
  • LIU Dongxu1,WEN Yaoke1,DONG Fangdong2,3,QIN Bin2,3,XIA Hailong4,LUO Xiaohao1
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 264-273.
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    The study of the dynamic mechanical response of ballistic plates under high-speed impact can guide the development of new personal protective, and provide a reference for the design of high-performance armor-piercing bullets. In this paper, the numerical model of the 5.56 mm SS109 rifle bullet impacting the NIJ Ⅲ SiC/UHMWPE ballistic plate was established. SiC ceramics and UHMWPE laminates were simulated by JHB constitutive and VUMAT based on Abaqus, respectively. And the accuracy of the numerical model was verified by comparing it with the results of the ballistic plate test by 3D-DIC technology. The dynamic response process of the back face deformation (BFD) of the ballistic plate was obtained. The bullet oblique impact of ballistic plates was also studied. The velocity of the bullet decreases from 810 m/s to 218 m/s after 40 μs of penetration into the ballistic plate. The ceramic in contact with the bullet in the ballistic plate was seriously broken, the bullet penetrated only two UHMWPE equivalent layers. And the fiber and matrix damage and delamination occur in the impact area of the UHMWPE laminated plate. BFD reaches a maximum of 18.72 mm at 700 μs. The shear strain on the back of the ballistic plate was distributed in "L-shape" on the center point of impact, and the equivalent stress field of the UHMWPE laminate was distributed in "diamond shape", and the equivalent stress level of the middle layer was the highest. When the bullet impacted at 30° and 45° angles, the peak values of BFD of the ballistic plate were 11.59 mm and 6.84 mm, respectively,
  • SUN Yanjie1, MA Ning2,YU Xueran1, SONG Zhibo2, ZHOU Caihua2, XU Shengli3, WANG Bo2
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 274-282.
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    The aero-engine casing should satisfy the containment requirements to resist the impact of high-energy fragments in order to ensure the safety of aircraft flight. The finite element analysis of casing containment was carried out by LS-DYNA to design the lightweight configuration of high pressure compressor casing, then the containment mechanism which dominated by absorbing blade kinetic energy through bulging plastic deformation of both smooth wall casing and stiffened casing can be obtained. Furthermore, it is necessary to propose an optimal design framework of stiffened casing to fully explore the structural performance. A containment mechanism based on the damage depth of casing thickness was proposed. Then, an optimization process combining parametric modeling, numerical simulation and containment evaluation was established. The software Deskopt which independently developed was used for optimization iteration and the optimal configuration was output. The results show that compared with the smooth wall casing, the optimal stiffened casing can reduce the weight by 20.86% on the premise of ensuring containment.
  • WANG Ruochan1, YAN Gang1, LI Yang2, SHI Yuan1, ZHOU Daheng1
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 283-289.
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    This paper proposes to extend Bayesian statistical inference method to flutter analysis for aircraft structures under excitation of atmospheric turbulence to consider the uncertainties in modal parameter identification and flutter boundary prediction. After the free decay responses are extracted from the structural responses under the excitation of atmospheric turbulence by natural excitation technique (NExT), based on Bayesian statistical inference, the posterior probability density functions of structural modal parameters are sampled and identified by Markov chain Monte Carlo (MCMC) algorithm. Then the probability density distribution for flutter velocity is obtained by Z-W flutter margin method to predict the flutter boundary and analyze the associated uncertainties. Numerical simulation studies are carried out to analyze the structural response data excited by atmospheric turbulence, and the effectiveness of the proposed method is verified.
  • MA Shaochun1,2, GU Yu1, BAO Peng1, GUO Chengchao2
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 290-298.
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    A new composite wallboard joint of thermal insulation structure using U-shaped reinforcement was put forward to explore the seismic performance and seismic damage model of a new composite wallboard joint of insulation-integrated structure. Six experimental specimens were designed and made. With the low-cycle reversed loading test, the failure characteristics, hysteretic curve, bearing capacity, ductility coefficient and other indicators of this type of wallboard joint were studied. In addition, the research result shows that the commonly used Park damage model cannot reflect the damage development of the specimen. Therefore, an improved seismic damage model suitable for this type of specimen was proposed in this paper on the basis of experiments to accurately describe the development of seismic damage of new composite wallboard joint of thermal insulation structure. Through the case verification and analysis, it shows that this damage model can utilize more indicators to reasonably evaluate the damage, and the application prospect is extensive.
  • JIA Zichu, LIANG Daosen, CAO Zhifu, YAO Jianyao
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 299-308.
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    An improved substructure modeling and analysis method is proposed to reduce the computational cost in vibration analysis of a complex mistuned blisk. The blisk is divided into blade substructures and a disk substructure according to the geometric feature. Then, the reduced interfacial degrees of freedom are evenly selected and transformed into internal degrees of freedom of substructure by the coordinate transformation matrix. Finally, the substructure method is used to condense the internal degrees of freedom of the substructure and the interface, and the reduction model of the blisk is established. The mistuning level of the blisk was evaluated under typical hazardous excitation cases by using the improved substructure analysis model. The results show that this proposed method can efficiently analyze the dynamic response of the mistuned blisk while ensuring computational accuracy.
  • LI Wei1,2, CUI Junning1,2, ZOU Limin1,2, WANG Zhisheng1,2
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 309-316.
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    The electromagnetic force generators with a single magnetic circuit are in high demand in fields such as voice coil actuators and vibration metrology, where the key is to generate a strong magnetic field with high distribution uniformity in the magnetic circuit air gap through a rational structural design. This paper proposes an analytical modeling and structural design optimization method for the single magnetic circuit of electromagnetic force generator based on the equivalent magnetic circuit. The analytical theoretical model of the air gap magnetic induction intensity distribution with respect to the structure size is established based on the principle of equivalent magnetic circuit and the method of collective parameters, taking a typical single magnetic circuit as the research object. The accuracy of the theoretical model is verified by using finite element simulation, the relative error is about 2.5%, and the theoretical calculation can improve the calculation efficiency by about 2000 times. The influence of structure size on the average magnetic induction intensity of air gap and its distribution unevenness was analyzed, and better structure parameters were obtained by optimizing the design. The optimized analysis results show that the average magnetic induction intensity of the air gap can be increased by about 150%, and the distribution unevenness of magnetic induction intensity can be reduced by about 29% by using the proposed method.
  • SHI Dongyan1, ZHANG Ying1,2
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 317-325.
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    In this paper, the mathematical model of the vibration characteristics of the coupled structure of composite double-layer conical shell and annular plate under different boundary conditions is established by the spectral geometry method, and the displacement tolerance function is set by the improved Fourier series. The virtual boundary spring technique is used to simulate various boundary conditions by setting three sets of linear springs and two sets of torsional springs. The Hamiltonian principle is used to derive the characteristic equations of the vibration system of the cone-ring coupled structure by combining the continuity conditions at the connection of the coupled structure, and then the natural frequency and vibration response of the coupled structure are obtained. The correctness of the method in this paper is verified by comparing with the results obtained by the finite element method. Meanwhile, a relevant parametric study is carried out to analyze the influence of varied parameters on the vibration response of the coupled structure of composite double-layer conical shell and ring plate.
  • GONG Jingfeng, YANG Yangyang, XUAN Lingkuan, LIU Zhen
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 326-332.
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    In order to measure the dynamic transfer stiffness of elastic vibration dampers. Based on the indirect method measurement principle in ISO 10846 series standards, the dynamic transfer stiffness measurement bench of elastic damping elements is designed. Determination of block mass for a given effective test frequency; selection of decoupling spring based on effective test conditions. Study on dynamic transfer stiffness of a certain type of flexible pipe by the established measuring bench. The measurement results show that the abnormal fluctuation occurs in the frequency band of 200 Hz ~ 300 Hz. A finite element analysis model of the measurement bench is established, and numerical studies show that the fluctuation is due to the local mode of the integral transition plate between the block mass and the decoupling spring. Therefore, the optimization design of measuring bench. The results show that the non-integral transition structure can effectively eliminate the influence of the measurement bench on the test results.
  • ZHANG Jinliang1, 2, LUO Xingchen3, YANG Fengwei1, 2, FU Jie4, XIA Yimin3, LUO Nanchuan3
    JOURNAL OF VIBRATION AND SHOCK. 2023, 42(12): 333-340.
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    To compare the rock-breaking characteristics of disc cutter under abrasive water jet-assisted and conventional working conditions, rock-breaking experiments under two working conditions were carried out. The differences in the rock-breaking state, disc cutter load, and rock-breaking efficiency were compared and analysed. The results show that compared with conventional rock-breaking of disc cutter, the rock-breaking of disc cutter under abrasive water jet-assisted can improve the ability of disc cutter to penetrate the hard rock, promote the expansion of cracks inside the rock interior, thereby generating large-size rock chip. The vertical and rolling force of the disc cutter under abrasive water jet-assisted is significantly lower than that of the conventional disc cutter rock breaking, with an average decrease of 39% and 25%. In addition, the amount of rock-breaking by disc cutter under abrasive water jet-assisted increases, and the rock-breaking efficiency is further improved, which is 1-2 times that of conventional rock-breaking of disc cutter. The research results provide a reference for improving the rock-breaking performance of disc cutters under hard rock geological conditions and efficient excavation of TBM.