15 April 2020, Volume 39 Issue 7
    

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  • XIE Juntai, FENG Longfei, GAO Jianmin, GAO Zhiyong, GAO Xu
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 1-7.
    Abstract ( 200 ) Download PDF ( 67 )   Knowledge map   Save
    Aiming at features of strong noise and chaos existing in monitoring data of process industrial production systems, a signal de-noising method based on the local projection (LP) method and wavelet packet was proposed. Firstly, LP method was used to perform several iterations for a signal’s de-noising from the point of view of dynamic system embedding manifold, and judge iteration termination using correlation dimension number. Then, the wavelet packet method was used to do noise reduction for a noisy signal from the point of view of frequency, suppress inference of high-frequency noise, and obtain better de-noising effect. Lorenz time series was used to do simulation verification. Different levels of noise were added to the time series, and phase space, SNR and the maximum Lyapunov exponent obtained with wavelet packet, LP and the proposed method, respectively were analyzed contrastively. The results showed that the proposed method has better noise reduction effect for medium-high intensity noise. Finally, the proposed method was used to reduce noise of actual monitoring data of a certain compressor unit, and the three methods’ noise reduction effects were evaluated to further verify the superiority of the proposed method.
  • ZHONG Guoxiang1, WEI Duqu1, ZHANG Bo2
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 8-13.
    Abstract ( 270 ) Download PDF ( 39 )   Knowledge map   Save
    Previous studies showed that chaotic oscillation behavior occurs in a single motor under some certain parameters and operating conditions. On the other hand, in the modern industrial production process, multiple motors are often required to operate in coordination and synchronization. At present, there are many studies on chaotic oscillation synchronous analysis and control of motor systems and networks at home and abroad, but investigations on synchronous interruption analysis and control of motor systems and networks due to parametric disturbance are less. Here, on the basis of conventional diffusion coupling mode, vibration characteristics of permanent magnet synchronous motor (PMSM) systems and networks after parametric perturbation were studied by introducing a unidirectional cross coupling mode. It was proved that unidirectional cross coupling has synchronous robustness to parametric perturbation in PMSM systems and networks. PMSM systems with 3-node, 4-node and multi-node networks were adopted to verify cross coupling having important actions of global stability and synchronization for multi-node motors and networks. The study results showed that establishing a suitable unidirectional cross coupling mode can effectively control synchronous interruption caused by parametric disturbance in motor networks, and recover their synchronous operating.
  • WEI Xingchun, WANG Zhiming, GUO Junfeng, ZHANG Yafei, SONG Yalong
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 14-20.
    Abstract ( 324 ) Download PDF ( 123 )   Knowledge map   Save
    Gears pair is one of key components of mechanical transmission. To analyze its reliability, based on the improved checking point first-order second-moment (IFOSM) reliability method, Taylor series expansion and Hermite polynomial approximation were used to derive gear performance function’s checking point first-order fourth-moment (FOFM) method, analyze gear transmission reliability with two major correlated failure modes of tooth root fracture and tooth surface corrosion, and give two modes’ correlation coefficient and gear reliability. On the other hand, due to many factors affecting gear failure, when either IFOSM reliability method or FOFM reliability one was used to estimate gear reliability, the computation amount was large and they were easy to make mistakes. Aiming at this problem, a classified variation difference coefficient checking point first-order fourth-moment reliability analysis method was proposed. This method was used to classify and integrate gear performance function’s basic random variables, significantly reduce design variables and computation amount, and solve the difficult problem mentioned above. Finally,the proposed method was used to estimate the reliability of a transmission gear pair in a certain lathe spindle box. The results showed that there is a certain correlation between tooth root bending fatigue strength and tooth surface contact fatigue strength of the gear pair; the proposed FOFM method can further improve estimation accuracy due to its containing higher order statistical information of skewness and kurtosis.

  • ZHAO Xiaoqiang1,2,3, ZHANG Qingqing1,2, CHEN Peng1, ZHU Qixian4
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 21-28.
    Abstract ( 320 ) Download PDF ( 99 )   Knowledge map   Save
    Actual working conditions of rolling bearing are complex and varying, and bearing faults can’t be diagnosed effectively. Here, a novel rolling bearing fault diagnosis method based on improved Alexnet, i.e., the second generation of convolution neural network, and particle swarm optimization and bacterial foraging algorithm (PSO-BFA) was proposed. Firstly, this method was used to simplify Alexnet structure, and two local normalization layers respectively followed Alexnet’s first two pooling layers and were added to reduce training cost. Then, small batch samples softmax’s cross entropy was taken as a loss function, and Adam iterative optimization method was used to train the improved Alexnet with a small number of samples and a few iterations. The diagnosis accuracy of variable-load samples was designed as swarm intelligence algorithm’s fitness function, it was combined with the updating method of particle movement velocity in PSO to update bacterial swimming direction in BFA, and search improved Alexnet’s structure parameters. Finally, according to parameters obtained with PSO-BFA, the same training method was used to train improved Alexnet with large samples and multiple iterations, and realize rolling bearing multi-state fault diagnosis under complex working conditions. Test results showed that the proposed method is feasible for diagnosing rolling bearing’s 16 fault states under complex working conditions; it has higher diagnostic accuracy, better anti-interference and generalization performances.

  • DENG Wangqun1,2, WU Shizhi1, LIU Wenkui1,2, SUN Yong1, TANG Hubiao1
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 29-35.
    Abstract ( 216 ) Download PDF ( 56 )   Knowledge map   Save
    A support stiffness modification method for a cantilever power turbine rotor of a turbine shaft engine with flexible transition section was studied. Firstly,a power turbine simulated rotor was taken as the study object to establish its finite element analysis model. The rotor’s first three critical rotating speeds and modal shapes were computed based on the software SAMCEF, and the rotor’s dynamic characteristics tests within the full rotating speed range were completed on a high-speed rotating test rig. The test results showed that the flexible transition section is the main reason to cause big calculation errors of the rotor’s first two critical rotating speeds. Based on critical rotating speed test results, a method for rotor support stiffness modification was proposed to modify the simulated rotor’s support stiffness, and obtain the flexible transition section’s lateral support stiffness through reckoning. Secondly, an actual power turbine rotor was taken as the study object, its support stiffness was modified according to the proposed method. After modification, the actual rotor first two critical rotating speeds’ computation errors were considerably reduced to verify the correctness of the proposed method. It was shown that the modified computation model can reflect the practical situation of the actual rotor; the study results can provide a guide for modifying similar high-speed rotor’s support stiffness, and effectively improve modeling precision of high-speed flexible rotors of aero-engines with flexible stator.
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  • ZHANG Longwen1, LU Zhaohui2
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 36-42.
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    In order to study aseismic reliability of bridge piers under their non-linear seismic responses, the random function-spectrum representation model and high-order moment method were introduced to propose a bridge pier’s aseismic reliability analysis approach based on first four moments of extreme structural responses. Firstly, a three-line restoring force model was considered to establish a single column model of bridge pier. Secondly, the random function-spectrum representation model was used to generate non-stationary seismic acceleration time-history samples, and non-linear time history analysis was conducted for the bridge pier’s structural responses. Then, the calculation framework for first four moments including mean, standard deviation, skewness and kurtosis of extreme structural responses was established. Finally, the pier displacement limit was considered to deduce the pier displacement’s performance function, and the high-order moment method was used to calculate the bridge pier’s aseismic reliability index. Through the bridge pier’s structural analysis, the effectiveness and precision of the proposed method were verified. The results showed that compared with the simulation results using Monte Carlo method, the maximum relative errors of first four moments, aseismic reliability index and failure probability calculated using the proposed method are 0.28%, 1.92% and 4.92%, respectively; the proposed method provides an effective way for evaluating aseismic reliability of bridge piers.
  • YANG Qiuwei, LU Chen, LUO Shuai, LI Cuihong
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 43-50.
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    The ill-conditioned least squares problems often appear in structural damage recognition using noisy data to cause calculation results being fully distorted. Here, to significantly improve calculation accuracy, a feedback ridge estimate (FRE) technique was proposed to obtain accurate and stable damage recognition results. The proposed method has three steps. Firstly, the first ridge estimate (RE) calculation was done for linear equation set in structural damage evaluation to obtain the rough solution to damage parameters. Secondly, a new diagonal matrix was designed to be used in the second RE calculation according to the rough solution to damage parameters. Thirdly, the second RE calculation was done with FRE technique for linear equation set in structural damage evaluation to obtain damage parameters’ high-precision solution. A beam structure was taken as a numerical example to explore the effectiveness of the proposed method under 10% noise level. The calculation results were compared with those using the ordinary RE method and the singular value truncation (SVT) one. The results showed that the proposed FRE method can significantly improve calculation accuracy; even under 10% noise level, it can be used to obtain calculation results with very high precision.
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  • FANG Zhiyuan1, WANG Zhisong1,2, LI Zhengliang1,2
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 51-58.
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    In order to study frequency domain characteristics of wind pressure on a high-rise building under thunderstorm downburst, an impinging jet device was used to simulate thunderstorm downburst, and pressure tests were conducted on a rectangular high-rise building model under simulated thunderstorm downburst. According to test data, power spectral density, correlation coefficients in horizontal and vertical directions and coherence functions in horizontal and vertical ones of fluctuating wind pressure were analyzed in detail. Effects of radial position of the model on fluctuating wind pressure’s frequency domain characteristics were discussed. The results showed that power spectral density of fluctuating wind pressure on the model’s windward surface at radial position is basically consistent to that of incoming flow wind speed spectrum; energy of fluctuating wind pressure on sides and leeward one is mainly concentrated at vortex shedding frequencies; correlation of wind pressures decreases with increase in distance between measured points; coherences in horizontal and vertical directions of wind pressures on windward side are stronger, and synchronization of fluctuating wind pressures is better; horizontal coherence of wind pressure on sides is more significant when the reduction frequency is less than 0.2, and its vertical coherence is relatively better within the whole frequency range; coherences in horizontal and vertical directions of wind pressure on leeward side are stronger when the reduction frequency is less than 0.1, and coherence quickly weakens with increase in the reduction frequency; there is a stronger horizontal coherence between wind pressures on windward side and leeward one near the reduction frequency of 0.06; when phase angle difference is about 180°, fluctuating wind pressure reveals the opposite phase characteristics.
  • XU Xunqian1, YANG Wei1, HUANG Wei2, JI Tao1, LI Xuexue1, CHU Liu1
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 59-66.
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    Aiming at SMA, GA and EP mixtures double-layer pavement structure adopted commonly in steel bridge pavement engineering, theoretical analysis and tests were conducted for fatigue damage characteristics of steel bridge surface and asphalt concrete pavement under cyclic vehicle loads. Based on the fatigue damage degree, fatigue damage failure behavior of steel bridge pavement and dynamic evolution mechanism of damage field, stress and strain ones in fatigue cracking process were studied, and calculation expressions for damage, stress and strain fields during fatigue failure were deduced. The fatigue life theoretical formula for steel bridge pavement was derived. Steel box girder bridge pavements of Runyang Yangtze River Bridge 2005, Nanjing Yangtze River Third Bridge 2005 and Sutong Yangtze River Bridge 2008 were taken as examples, fatigue tests and predictions using the fatigue life theory were conducted for composite girders under different pavement structure combination schemes. The actual examples’ study results showed that the prediction model for steel bridge pavement fatigue damage failure behavior is reasonable and feasible; compared with SMA and GA, EP has higher intensity and stronger low-deformation ability, and it is more suitable to meet anti-fatigue design requirements of long-span steel bridge pavement; the anti-fatigue performances of double-layer EP and "upper layer EP +lower layer GA" are superior to those of other pavement structure schemes, and their fatigue life is 1-2 times longer than other’s with the same thickness; double-layer EP is applied in pavements of the three bridges mentioned above, these bridges’ pavements operate successfully for more than 10 years, and their follow-up observation results are good. 
  • WU Wei, SHEN Yongjun, YANG Shaopu
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 67-73.
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    A pseudo phase plane method based on permutation entropy and its improved theory was proposed to extract weak periodic signal’s features in a nonlinear system. Through choosing a reasonable time delay and embedding dimension, the phase space of a Duffing system’s response signal was reconstructed to obtain primary permutation entropy and quadratic one. Then, displacement excitation, primary permutation entropy and quadratic one were taken as data sets to form two pseudo phase planes of displacement excitation-primary permutation entropy and displacement excitation-quadratic one. The proposed method’s extracting effect was compared with those of traditional methods including phase plane method, spectral analysis, permutation entropy, permutation entropy spectrum, quadratic permutation entropy and quadratic permutation entropy spectrum to verify the rationality of the proposed method. The study showed that the proposed method can extract characteristics of weak periodic signal in nonlinear systems, and achieve better effect.
  • XIANG Meijing, WANG Xiaochuan, LI Deng, CHEN Hao, QIAN Lei
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 74-80.
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    The software FLUENT was used to simulate a 2-D Helmholtz nozzle self-oscillating jet, and then effects of deep oscillatory cavity at the outlet protruding part of Helmholtz upper nozzle on its self-excited oscillation characteristics were studied. The results showed that upper nozzle outlet’s protruding part length and nozzle wall thickness have significant effects on self-excited oscillation characteristics; when protruding part length is 0-0.15D1, self-oscillating jet pulsation amplitude increases by 20%-80%; the lower the jet velocity, the more the amplitude increases; when protruding part length is 0.15-0.25D1, increase in jet amplitude drops gradually; when protruding part length is 0.25-0.3D1, jet amplitude is lower than that of ordinary nozzle, and jet stability drops; when protruding part length exceeds 0.3D1, self-oscillating jet fully disappears; when protruding part nozzle wall thickness is within  the range of 0-0.1D1, wall thickness has little effects on jet performance, but with increase in wall thickness, jet performance weakens; when wall thickness is larger than 0.15D1, self-oscillating jet can’t be formed.
  • PENG Jian1, XIANG Mingjiao1, YU Jianda1, SUN Hongxin1, SUN Ceshi2
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 81-85.
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    Here, the time-delay vibration reduction technique was used to do vibration control analysis for cable- beam composite structures. The dynamic governing equations for a cable-beam composite structure were established with Hamilton principle. The time-delay vibration reduction technique was introduced, and the multi-scale perturbation method was used to solve the dynamic governing equations, and obtain the approximate solution expressions to primary resonance and 1/3 subharmonic resonance. The results showed that two main parameters of the time-delay vibration reduction technique including time delay and control gain can be used to effectively adjust the system’s damping and frequency; through adjusting control gain and time-delay value, the system’s damping ratio can be increased, resonance fields can be avoided, and cable-beam composite structures’ vibration reduction can be realized.
  • DENG Yunfei, CAI Xiongfeng, ZENG Xianzhi, YANG Yonggang
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 86-92.
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    To investigate effects of projectile nose shape on anti-impact performance of carbon fiber reinforced plates (CFRPs),a one-stage gas gun was used to launch ogival-nosed projectiles, hemispherical-nosed ones and blunt-nosed ones on the target of a 2mm thick CFRP in impact tests. The test data were processed using the formula fitting method to reveal effects of projectile nose shape on the target plate’s ballistic limit and energy absorption, and analyze impact damage morphology and mechanism features of the target plate. The results showed that blunt-nosed projectiles’ ballistic limit is the highest, hemispherical-nosed ones’ is the second, and oval-nosed ones’ is the lowest; when projectiles impacting the target at low velocity, effects of projectile nose shape on target plate energy absorption rate are more significant; when blunt-nosed projectiles impacting target, target plate facing surface is subjected to uniformly distributed annular shear force, and fibers are cut at the same time, plate’s matrix has large area shear failure; when hemispherical-nosed projectiles impacting target, target plate facing surface is subjected to non-uniform distributed shear force and squeezing action, fibers have shear fracture and tensile fracture, and matrix has shear failure and attrition crushing; when ogival-nosed projectiles impacting target, fibers have single tensile fracture while matrix has attrition crushing; effects of projectile nose shape on target damage mainly focus on facing surface and middle fiber layers.
  • FENG Han1, ZHANG Xuemin1, WANG Lichuan1, 2, HUANG Qinwei3,OU Xuefeng1, ZHANG Cong1, ZHOU Xianshun1
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 93-100.
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    Charge structure is one of main factors affecting blasting vibration effect. Aiming at a common water-sealed charge structure in tunnel drilling and blasting construction, theoretical solution to far-field mass point motion excited by Heelan short column charge was taken as the foundation, this charge structure was divided into explosive section and water medium one, it was assumed that blast source far-field mass point’s maximum vibration velocity is caused by superposition of hole wall pressures of the two sections, then the analytical solution to vibration velocity at far-field position was solved and verified with the actual field measured data. Meanwhile, factors affecting blast vibration were analyzed. The results showed that there is a certain error between theoretical calculation values and the actual measured data, but the former can meet engineering requirements, and be used to guide the construction; the action of water medium section on surrounding rock mainly depends on length of this section and radial pressure on hole wall; the ratio of water medium section length to explosive section one directly affects blasting vibration value caused by water medium section action and its proportion in the total effect of blasting vibration; as the action intensity of water medium section is smaller, this action is not obvious in far-field, so it is suitable to predict and evaluate blasting vibration velocity in near-field.
  • WANG Jiaxia1, YUAN Shijie1, LIU Kun1, ZHANG Yanchang2
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 101-107.
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    Coupling phenomena between bubble and neighboring rigid/flexible boundaries were tested, monitored and studied using an electric spark air bubble device and a high-speed camera. The bubble pulse test data under conditions of flat panels of different materials and different distance parameters were collated to perform mechanism analysis for bubble dynamic characteristics including bubble splitting phenomenon, bubble jet direction property and bubble migration features, etc. The software MATLAB was used to develop an image digital recognition program. A flexible plate’s overall motion response mode under the whole bubble pulsation load and the structure center measured point’s response features were analyzed and summed. The test results showed that when bubble contracts near a flexible plate, bubble changes into a "wooden club" shape or splits into two small ones, and jets away from opposite directions occur; the motion response mode of the flexible plate under the whole bubble pulsation load is explored, the flexible plate reveals the one-order response mode during bubble expanding, while when bubble contracts, the plate reveals the third-order response mode and two-peak values migration phenomenon.
     
  • ZHANG Kongliang, XIAO Zhengming, ZHANG Yuandong, GUO Zhiting
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 108-115.
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    The multi-rigid-body model of gear transmission system was established by using LMS Virtual.Lab, and the time-varying meshing stiffness of the gear pair was obtained by simulation calculation, and compared with the time-varying meshing stiffness of the gear pair calculated by finite element method. Considering the flexibility of the gear box, through the dynamic simulation analysis of the rigid-flexible coupling model, on the basis of obtaining the Craig-Bampton mode of the box, the box-bearing-gear coupling dynamic model was established. The dynamic meshing force of the gear pair, the surface vibration response cloud diagram of the gear box and the vibration acceleration, velocity and displacement of the key points were calculated, and the bench test and verification analysis were carried out.The gear meshing force and the dynamic response of the gear box were simulated by the rigid-flexible coupling method.It was shown by the result that The energy mainly concentrate in the gear meshing frequency and its frequency doubling. The simulation results of the rigid-flexible coupling method are in good agreement with the experimental results in terms of vibration acceleration and vibration displacement, which verifies the correctness of the rigid-flexible coupling model of the gear system.
  • CUI Xuhao, XIAO Hong, JIN Feng
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 116-124.
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    In order to study dynamic response and deterioration law of ballast bed under long-term repeated train load, the discrete element analysis software PFC was used to establish the discrete element computation model of ballast bed considering ballasts’ true shape, crushing and degradation to analyze vibration responses of ballast bed, forces exerted on ballasts, ballasts’ friction energy-dissipating and crushing behavior under cyclic loads with different frequencies and amplitudes. The results showed that ballasts’ vibration acceleration increase nonlinearly with increase in dynamic load’s frequency and amplitude; contact forces exerted on ballasts are mainly affected by load amplitude, load frequency has a smaller influence on them, the larger the load amplitude, the bigger the ballasts’ contact forces; increase in load amplitude or frequency can add ballasts’ friction energy-dissipating, in initial stage of load acting, ballasts’ friction energy-dissipating has a sudden growth process; load amplitude is the dominant factor on crushing behavior of ballasts, ballasts stay at a lower crushing level when load amplitude is lower; when load amplitude is higher, ballasts’ crushing phenomenon intensifies and is affected by load frequency, the higher the load frequency, the more serious the ballasts’ crushing this moment.
     
  • LIANG Dong1, KANG Jian1, ZHAO Wenzhong2, LIU Jing1
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 125-131.
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    In order to study problems of cable-beam coupled vibration and cables’ interaction under nonlinear geometric conditions, a two-cable and a single beam combined system was taken as a simplified model. D’Alembert principle was used to establish the cable-beam system’s dynamic partial differential equation considering cables’ initial sag, and it was discretized into a two-order ordinary differential equation using Galerkin method after setting cables’ first two vibration modes and beam’s first one. The 4-5 order Runge-Kutta method was used to solve and analyze the cable-beam system’s vibration responses. The results showed that in the 2-cable and a beam combined system, the first mode is strongly coupled with beam, and the second mode is coupled with beam at a lower level under specific frequency condition; compared with a single-beam and single-cable structure, multiple cables make beam frequencies increase, cables’ interaction makes cable amplitude increase and beat frequency decrease; the system’s in-plane first mode is more sensitive to cables and beam changes; when cables and beam frequencies are unchanged, cables’ interaction obviously suppresses cables’ large amplitude vibration caused by coupled vibration; the system is more sensitive to beam initial displacement change.
  • SUN Feng, TANG Jinghu, LI Qiang, ZHAO Chuan, JIN Junjie
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 132-139.
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    Aiming at nonlinear varying feature of levitation force in a permanent magnet suspension system with variable magnetic circuit, the system’s stiffness characteristics were analyzed, a variation stiffness control method was proposed to decrease the system’s sensitivity to external disturbance. Firstly, effects of system structure and control parameters on suspension stiffness were analyzed based on the system mechanical model to propose a variable stiffness control method based on suspension object displacement. Then, change ranges of parameters were designed according to the presupposed load capacity and displacement variation to make the system stiffness vary according to the given control law. Finally, simulation and test analysis were conducted for the system’s floating up stability and sensitivity to external disturbance. The results were compared with those using the PID control method. The results showed that the proposed variable stiffness control method can ensure the system to stably float up; it can reduce displacement variation of suspension object by 50% under external load; it can greatly reduce the system’s sensitivity to external disturbance; compared with the traditional PID control method, its control characteristics are greatly improved.
  • ZHEN Man1,2, SUN Tao1, TIAN Yongsheng1, ZHANG Hualiang1,2, TAN Chunqing1,2
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 140-147.
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    In order to obtain the dynamic characteristics of rotor system under misalignment-rubbing coupling fault, the nonlinear dynamic differential equation of rolling bearing rotor system under holonomic constraints was established by Lagrangian undetermined multiplier method. The dynamic response of the system under misalignment-rubbing coupling fault was studied by Runge-Kutta numerical method. Time domain diagram, axis orbit diagram, bifurcation diagram, Poincare section diagram and FFT spectrum were used to analyze the effects of misalignment, rubbing stiffness and clearance on the vibration response of the rotor. The analysis results show that the misalignment increase will increase the vibration response of the system with 1-octave,and produce even-octave such as 2-fold and 4-fold, and the combined frequency response with VC (varying compliance) frequency at the same time. At low speed, the rubbing stiffness and clearance have little influence on the rotor system; at high speed,smaller rubbing stiffness and larger rubbing clearance would alleviate the nonlinear behavior of the system.
  • XIONG Weipeng, WANG Chao, FU Jiangyan, WANG Chunhui, CAO Chengjie
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 148-155.
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    In order to study the reliability of peridynamics method in simulating the failure behavior of ice at high strain rate, the numerical simulation of high-speed impact mechanical behavior of ice sphere was realized by self-programming based on the theory of peridynamics, and the calculated results were compared with the experimental results. The results show that the peridynamics method can accurately simulate the complete process of high strain rate failure during the impact process of the ice sphere, and the details of the surface crack diffusion of the sphere and the overall cracking of the ice sphere are well simulated, and the maximum amplitude error of the impact load prediction within the velocity range of 20-60 m/s is 18.2%, and the maximum mean error is 18.4%. At the same time, it is found that in the process of medium and low speed impact of 20-60 m/s, the destruction of the ice sphere takes the hemispheric section as the boundary, the lower hemisphere near the impact surface is crushed, and the upper hemisphere is fragmented, when the impact velocity is greater than 60 m/s, the damage degree of the upper hemisphere will increase sharply as the impact velocity increse; when the impact speed is greater than 100m, both the upper and lower hemispheres are crushed.
  • LEI Ronghua, CHEN Li
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 156-162.
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    Aiming at the space robot system of floating-based attitude-controlled flexible arm with partial actuator failure, the fault-tolerant control of actuator fault and the active suppression of residual vibration of flexible arm were studied. The dynamic differential equation of the system was established by combining the assumed mode method, the conservation theorem of linear momentum and the Lagrangian equation of the second kind. Based on the singular perturbation theory, the system was decomposed into a slow-varying subsystem representing the attitude of the base and joint trajectory tracking and a fast-varying subsystem representing the residual vibration of the flexible arm. Based on this, a compound controller was designed, which is composed of an adaptive neural network fault-tolerant controller of the slow-varying subsystem and a linear quadratic optimal regulator of the fast-varying subsystem. The fault-tolerant controller of the slow-varying subsystem makes the system insensitive to actuator faults and ensures the asymptotic convergence of the tracking error; the optimal regulator of the fast-varying subsystem can effectively restrain the residual vibration caused by the flexible arm and reduce the energy loss. The correctness of the theoretical derivation and the feasibility of the compound control strategy are verified by numerical simulation.
  • MENG Lingxia,XU Xiaoli,ZUO Yunbo
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 163-169.
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    The gearbox of wind turbine works under the condition of strong noise and time-varying speed and load, and its vibration signal is very complex. A vibration signal model of planetary gearbox with time-varying speed and load was established. A fault feature extraction method of time-frequency ridge order spectrum was proposed. First of all, the vibration signal was transformed by Wigner-Ville time-frequency transform, and then logarithmized and rearranged. Then, the peak ridge in the logarithmic rearrangement time spectrum was extracted by Crazy climber method. Finally, the ridge was converted into the time-frequency ridge order spectrum. The simulation signal and the experimental data of continuous fluctuation of rotational speed and load show that the fault characteristics of logarithmic time-frequency ridge order spectrum can provide an effective basis for fault early warning of planetary gearbox under time-varying complex conditions.
  • WANG Jianning1,2, FU Jisai3, ZHUANG Haiyang3, DOU Yuanming1, MA Guowei1
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 170-179.
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    Foundation liquefaction is one of the important causes for serious damage of subway underground station structure in earthquake. However,there is a little research on the seismic response of subway underground station structure in liquefiable sites at present. The research on the seismic response of large and complex underground station structures with unequal spans is even more rare. In this paper, by introducing the large deformation constitutive model of sand liquefaction and using the finite element mesh adaptive adjustment technique to overcome the distortion of soil mesh large deformation, a finite element numerical model of static and dynamic coupling nonlinear interaction between liquefied site soil and complex unequal span subway station structure was established. The distribution characteristics of site liquefaction, floating characteristics of unequal-span station structure, displacement settlement and vector characteristics of surrounding site, lateral deformation and seismic damage characteristics of the interaction system were analyzed. The seismic response law of the interaction system and the seismic failure characteristics of large-scale unequal-span underground structures in liquefied foundation were preliminarily revealed. The research results help to improve the understanding of the seismic response of unequal-span subway station structures in liquefied sites and the seismic design methods.
  • YANG Haixu1, SHI Ming1, WANG Haibiao1, FAN Dingjian2, ZHANG Maohua1, SHI Xinyu1
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 180-188.
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    In order to study the influence of NES shock absorber on the seismic performance of reinforced concrete frame structure joints, a new type of NES shock absorber was designed and manufactured, and a shaking table test of a five-story reinforced concrete frame structure with a scale of 1∶4 was carried out to analyze the changes of steel bar strain, joint failure mode, structural displacement and structural natural frequency at the joints of first and second floors of NES frame structure after earthquake damage. The test results show that the NES shock absorber can effectively reduce the strain of longitudinal hoop bars of reinforced concrete beams and columns, reduce the relative displacement of the structure, slow down the generation of plastic hinges at the bottom and top of the column, and there are beam end failure and in-joint shear failure at the joints, which basically fulfills the “strong column and weak beam” mechanism of the frame. The NES shock absorber can effectively reduce the shear stress of the concrete at the joint and thus alleviate the shear failure of the joint concrete. The final failure of the whole structure is caused by the yield of the steel bar at the bottom of the column, the crushing of the concrete at the foot of the column and the loose connection with the bottom plate. After setting up NES shock absorber, the decline rate of structural natural frequency decreases, and NES nonlinear shock absorber has a good control effect in reducing structural seismic response, improving structural anti-seismic capacity and reducing structural damage.
  • ZHOU Xiaolong1, LIU Weina2, JIANG Zhenhai3, MA Fenglei3
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 189-195.
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    In order to solve the problem of Hilbert-Huang transform (HHT), which has mode mixing and false intrinsic mode function (IMF), an improved HHT method combining ensemble envelop mean empirical mode decomposition(EEMEMD) and spurious mode function elimination algorithm was proposed. The method uses EEMEMD to accurately reflect the self-change of the signal after adding noise, neutralizes the residual noise contained in modal components partly, and obtains a purer IMF component without mode mixing. At the same time, the false mode function elimination algorithm based on normalized energy entropy can effectively eliminate noise interference components and iterative error components, so as to improve the accuracy of signal feature extraction. The simulation analysis and engineering examples of rotor misalignment fault diagnosis were compared.The result show that the improved HHT method can suppress the mode mixing problem better and effectively eliminate the false IMF, which is not related to the fault,to achieve effective fault diagnosis of rotating machinery.
  • ZHANG Fei1,2,3, ZHANG Chunhui1, ZHANG Lei1, WANG Zhijun1, LI Xudong1,2
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 196-201.
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    In order to study the anti-explosion and anti-shock ability of warship structure under multiple underwater explosion loads, several underwater explosion tests of marine A32 backspace steel plate and welding plate of 5mm and 12 mm were carried out based on the underwater explosion bulging test, the plastic deformation history of steel plate and welding plate was obtained, the deflection and thickness reduction rate of the points along radius in impact area of steel plate and welding plate  were measured and calculated. The plastic deformation law of steel plate and welding plate was analyzed. The results show that under the action of multiple underwater explosion loads, the plastic deformation morphology of welding plate and steel plate is in the shape of spherical crown, and their thickness reduction rate decreases at first and then increases from the center position to the boundary. But the deflection of the welding plate is less than that of the steel plate. The deformation mode of A32 steel plate is mainly bending and stretching, and the welding plate is mainly bending. The continuous increase of underwater explosion load leads to the tensile fracture at the center and boundary of the steel plate, while the brittle fracture occurs in the weld and its heat-affected zone of the welding plate.
  • YUAN Ke1, ZHANG Xiaoping2, HUI Yi3, CHEN Zhengqing1
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 202-208.
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    This paper explores the influence of surface horizontal partition on the local wind pressure of high-rise buildings. In this paper, rigid model pressure tests were carried out on four kinds of high-rise buildings with different forms of surface appendages, and the pressure measurement results were compared with those of high-rise buildings without appendages. The average wind pressure on each facade, the fluctuating and the peak wind pressure coefficient were analysed. The results show that the surface appendages have little influence on the positive wind pressure coefficient on the windward side, but can greatly reduce the negative wind pressure coefficient on the side wind surface. especially the negative peak wind pressure coefficient; And this reduction effect increases with the decrease of the horizontal spacing of the appendages, and the maximum reduction of the extreme wind pressure in the windward higher leading corner of the side wind surface can be up to 37%. The study on the probability density distribution and non-Gaussian characteristics of the fluctuating wind pressure on the side wind surface shows that the surface appendages can reduce the skewness and kurtosis of the probability density function of the larger negative pressure, thus weakening its non-Gaussian characteristics. this effect increases with the decrease of the horizontal spacing of the appendages, indicating that the appendages can effectively restrain the separation of the incoming flow on the side wind surface.

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  • LIU Zhiheng1, CHEN Xudong1, CHEN Chao2
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 209-215.
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    As the direct tensile test is difficult, reliable data are very rare. In this paper, the high stress axial tension reciprocating test of concrete was carried out by using hydraulic closed-loop servo material testing machine MTS322, and sine wave was loaded in the test. The hysteretic phenomenon caused by the phase difference between stress and strain of concrete was studied. The phase difference between strain wave and stress wave during loading is different from that during unloading, and the phase difference between loading and unloading leads to an asymmetric hysteresis loop. With the increase of loading frequency, the dissipation angle of concrete decreases, which is about half of the “X” angle of its tangent modulus.

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  • LIU Qingbo, REN Shunqing, WANG Changhong
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 216-222.
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    In order to improve the calibration accuracy of the second-order coefficient in the static error model coefficient of the floated gyroscope, the whole vibration period method of the linear shaking table was proposed to calibrate the floated gyroscope. On the basis of fully considering the parasitic rotation and verticality error of the linear shaking table, the angular vibration produced during the test and the installation error of the gyroscope, a calibration scheme of the six-position method was designed to calibrate the second-order coefficient of the gyroscope. This method suppresses the influence of the parasitic rotation of the linear shaking table, the small angular vibration produced during the test and the installation error of the gyroscope on the calibration accuracy, and can improve the measurement accuracy of the floated gyroscope on the on-line shaking table. Finally, the corresponding error analysis was carried out, and it is verified that the method can accurately calibrate the second-order error model coefficient of the gyroscope, and the calibration accuracy can reach the order of 10-4(°/h/g2).
  • GE Yang1,2Gnzhong1,2, NIU Shuguang1,2, DOU Yan1,2
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 223-231.
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    Aiming at the problem of remaining useful life prediction of rotating machinery, a prediction method based on t-Distributed Stochastic Neighbor embedding (t-SNE) and Long Short-Term Memory network (LSTM) was proposed. First of all, the t-SNE dimensionality reduction method was introduced into the feature extraction of rotating machinery vibration signals, and the example verifies that no matter for the  time-frequency domain features or energy features obtained by wavelet packet decomposition, the feature differentiation is more obvious after t-SNE dimensionality reduction, and the correct rate of fault mode recognition using the dimensionality reduction features is close to 100%. Secondly, it was proposed to use the divergence between samples as the degradation index of rotating machinery. the experimental results show that the divergence between samples has a more obvious performance on the performance degradation trend of rotating machinery than other indexes. Finally, the LSTM method was used to predict the remaining useful life with different training sample sizes. In order to verify the effectiveness of the LSTM method, it was compared with the BP neural network, grey prediction model, support vector machine and other methods. The results show that the LSTM method can predict the degradation trend of rotating machinery and significantly improve the prediction accuracy of the remaining useful life. It has a certain theoretical guiding significance for the health monitoring and life prediction of rotating machinery.
  • ZHANG Fan1, HUANG Yan1,2, LIU Qi3, HUA Chunrong1,2, YAN Bing1,2,DONG Dawei1,2, ZHENG Dong1,2
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 232-237.
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    In order to investigate the influence of the near-field term (reflector, end cover and stator) on the aerodynamic noise of the vehicle alternator, this paper studies the aerodynamic noise characteristics of the alternator based on the Lighthill acoustic analogy theory, large eddy simulation (LES) method and boundary element method. The results show that the main orders and amplitudes obtained by the simulation are in good agreement with the experiments, which verifies the correctness of the simulation method, and the order 4, 6, 8, 9, 10 and 12 are the main orders of this type of alternator. the reflection surface has influence on all the main orders, the end cover mainly affects the 10th order, and the stator mainly affects the 6th and 9th order. The reflection has a great influence on the sound pressure level of the left and upper measuring points, the end cover has a great influence on the left and right measuring points, and the stator has almost no influence on each measuring point. The influence of the near-field term on the five-point average total sound pressure level is in the following order: reflector>end cover>stator.
  • WANG Saisai1, CHEN Jie1,2, WANG Hua1,2, PAN Yubin1
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 238-244.
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    In order to solve the problems of large slewing bearing, such as large background noise, weak characteristic signal, and difficulty to identify the life state of slewing bearing, an identification method of slewing bearing life state based on improved deep belief network (DBN) was proposed. DBN network has strong deep learning ability and can effectively mine the running state information of slewing bearing, which solves the problem that traditional shallow network relies too much on the effect of feature extraction and low recognition accuracy. In DBN learning and training, a new optimized learning method,Free Energy in Persistent Contrastive Divergence(FEPCD), was proposed to solve the problem of the decline of approximation and classification ability of DBN in long-term learning. Then the superiority of the proposed method was verified by using the test data of test rig. Finally, the recognition results of the improved DBN algorithm and the shallow classification algorithm were compared. The results show that the improved DBN network can reflect the life characteristics of slewing bearing more accurately than the original DBN network and shallow algorithm, and the proposed method has the characteristics of stability and intelligence.
  • DAI Shijie1,2, LIU Ruojiao1,2, ZHANG Huibo1,2
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 245-252.
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    In order to analyze the vibration characteristics of omni-directional mobile wheelchair based on Mecanum wheel, the contact model between Mecanum wheel and ground and the mobile platform model with 7 degrees of freedom were established, and the coupling vibration equation between wheelchair and road surface was established by using the displacement coordination equation of the contact point between wheel and road and the balance relationship of interaction force between wheelchair and road surface. The effects of the starting position, rotational speed and load of the wheel in contact with the road surface on the vibration characteristics of the wheelchair were studied. An omni-directional mobile test rig was built, and the accuracy of numerical simulation was verified by experiments. The analysis results show that in order to improve the ride comfort, the initial contact position between the wheel and the road surface should be kept the same as far as possible. The vibration frequency and amplitude of the wheelchair increase with the increase of the rotational speed. When the rotational speed is between 150r/min and 200r/min, the vibration frequency of the wheelchair is close to the inherent biological wave (8Hz) of the human body, which will cause strong discomfort. The weight of the passenger has little effect on the vibration characteristics of the wheelchair, but has a certain inhibitory effect on the amplitude of the vibration.
  • XIE Xiaoping1, WANG Hongbo1, LIANG Yangyang1,2
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 253-259.
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    The increasingly fierce global automobile market competition and consumers’ higher and higher requirements for automobile comfort have forced automobile companies to speed up the development process of NVH, and automobile sound control has gradually entered the stage of sound quality control. In this paper, a transient sound quality analysis method and process based on time-domain transfer path analysis was proposed. Firstly, the time-domain deconvolution network was established by using the deconvolution filter method considering singular value truncation. Then the interior transient noise synthesis model was constructed, and the structural-borne acoustic contribution and air-borne acoustic contribution of the engine were decomposed and analyzed in time-frequency domain. Finally, through the audio-visual comparison of synthetic noise and measurement noise, in the form of subjective evaluation of the jury to verify the accuracy of the model. Furthermore, the subjective sound quality of the synthetic noise was evaluated, and the interior noise synthesis model was extended to the virtual interior sound quality prediction model. Based on this model, the paths with bigger contribution to sound quality were found, and the transfer function values of each path were virtually modified to optimize the sound quality in the vehicle, so as to provide guidance for improving the sound quality in the vehicle.
  • TIAN Yongjun1, XU Guosheng1, ZHANG Xiangyu1, DUAN Guolin2
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 260-267.
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    Based on the combination of sequential response surface model and hybrid optimization algorithm, an optimization method to reduce the sawing noise of diamond circular saw blade under complex load is proposed. In this paper, a mathematical model for the structural optimization of diamond circular saw blade under multi-variable and multi-constraint conditions was established, and the optimized circular saw blade which meets the requirement of stiffness was obtained by calculation. Through mathematical statistical analysis, the effects of size parameters on the acoustics, deformation and stress of the saw blade were obtained. According to the results, the diamond circular saw blade was prepared.The sawing experiments show that the optimized saw blade can effectively reduce noise, which shows that this method can be reference for the acoustic optimization of saw blade or such matter.
  • ZHANG Yanlong1, CHONG Fuquan1, WANG Li2, SU Cheng1
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 268-274.
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    The non-smooth factor was introduced into the volt-ampere characteristics of the voltage-controlled current-mode segment linear resistor to adjust the adjustable electronic components in the circuit. It makes a great difference between the system parameters and constructs a four-dimensional non-smooth fast-slow coupling cluster oscillation circuit system with two-scale effect. In order to analyze the equilibrium state and stability of the fast-varying system at each interface and the clustering mechanism of the system trajectory passing through the non-smooth interface, two sets of different parameters were selected, theoretical analysis and numerical simulation were combiled. The occurrence mechanism of different clustering phenomena and the influence of non-smooth bifurcation on the clustering mechanism when fast-varying systems crossing non-smooth interfaces were revealed. Finally, the fractional transformation of the two-scale fast-slow coupling cluster circuit system was carried out by using the R-L fractional calculus operator, and the single-scroll, double-scroll, three-scroll and four-scroll  chaotic control of the fractional circuit system is carried out.
  • JIA Baohua1, FENG Jinfei1, GU Yongqiang1, XU Zhenyang2
    JOURNAL OF VIBRATION AND SHOCK. 2020, 39(7): 274-278.
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    The finite element model of aramid / glass fiber composite laminates normal impacted by conical bullets was established by using Abaqus software. The reliability of the model was verified by comparing the simulation results with the experimental ones in the literature, and then the relationship between the initial velocity and the residual velocity of composite laminates with  bullets of different velocities impacting composite laminates of different ply angles and the failure characteristics of the laminates were studied. The results show that the relationship between the initial velocity and the residual velocity of the bullet is nearly linear when the ply angle of the laminate is constant and the bullet does penetrate the laminate.When it doesn’t,the anti-ballistic performance of the laminate with the ply angle of [0/90°] is the best, and when the bullet penetrates the laminate at a higher velocity from 600 m/s to 900 m/s, the energy absorption effect of the laminate with the ply angle of [45/-45°] is the best. The failure characteristic diagram shows that the ply angle has little effect on the damage area and failure mechanism of the laminate. This study can provide a reference for the design and optimization of protective equipment.