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2020 Vol. 39, No. 23
Published: 2020-12-15
 
1 Limiting performance of a new nonlinear spring
CHEN Zhengqing1, ZENG Jiongkun1, PEI Bingzhi2, ZHANG Menzhe3
Flexible structures with low damping may have large-amplitude displacements under excitation of external loads, which cause damages of the components, and even structural failure in severe cases.Here, the buffering and limiting performance of a bi-directional nonlinear spring restrictor for flexible structures was studied, and the theoretical calculation formula for force and deformation of the device was derived and verified with pseudo-static tests.Finally, based on a single-DOF main structure model, buffer limit performances of linear and nonlinear restrictors were compared and analyzed, and effects of the nonlinear spring stiffness on its performance were studied.Results showed that the calculated results with the theoretical calculation formula of the nonlinear spring do not agree well with test ones, then a theoretical calculation formula considering initial displacement is proposed; when the initial displacement is smaller, both two theoretical calculation formulas can be a theoretical basis for practical application; the nonlinear spring restrictor has characteristics of quasi-zero stiffness, when it starts to work, it can reduce the main structure’s motion speed more gently; under random loads, the nonlinear spring has the same limiting capacity as that of a linear spring, and can significantly reduce recoil action on structure; the reasonably setting of its stiffness not only can effectively control displacements of the main structure, but also reduce its recoil force on the main structure.
2020 Vol. 39 (23): 1-7 [Abstract] ( 451 ) HTML (1 KB)  PDF (1418 KB)  ( 199 )
8 Sensitivity of twin-tower’s aerodynamic forces and their correlation to spacing
SHI Junyang, XIE Jiming
Aerodynamic interference and load correlation between twin-tower are important parameters to describe wind loads and do wind-resistant optimization, and the spacing between twin-tower has important effects on these parameters.Here, using the synchronous pressure integration (SPI) method, wind tunnel tests were performed to determine the function relationship between aerodynamic forces on twin-tower under conditions of different wind directions and spacing.Wind load correlations under different spacings were studied in time domain and frequency one, respectively by means of correlation coefficient and coherence function.Results indicated that in most cases, with decrease in spacing, wind load on each tower, in particular, cross wind fluctuating load tends to decrease; cross wind loads on twin-tower under multiple spacings reveal negative correlation, the negative correlation is more obvious when the twin towers are arranged forward and backward along wind direction; the selection of spacing plays an important role in twin-tower’s wind resistance optimization, and has a guiding significance for the design of conjoined body.
2020 Vol. 39 (23): 8-16 [Abstract] ( 196 ) HTML (1 KB)  PDF (1539 KB)  ( 68 )
17 Compression performance of closed-cell aluminium foam under different temperatures and strain rates
LI Xueyan, LI Zhibin, ZHANG Duo
SHPB and MTS machine were employed to conduct quasi-static and dynamic compression tests to study mechanical performance of closed-cell aluminum foam with different densities under different temperatures and strain rates.The test results showed that the crushing strength of aluminum foam increases with increase in its relative density under quasi-static and dynamic conditions, the crushing strength has a power exponential relationship with the change of relative density; closed-cell aluminum foam has a very strong temperature softening effect, its crushing strength drops with increase in temperature and has a linear relationship with variation of temperature; aluminum foam has an obvious sensitivity to strain rate, its crushing strength increases with increase in strain rate.Finally, an empirical formula for crushing strength of closed-cell aluminum foam related to relative density, temperature and strain rate was obtained through fitting.
2020 Vol. 39 (23): 17-20 [Abstract] ( 206 ) HTML (1 KB)  PDF (1051 KB)  ( 61 )
21 Semi-active control of air suspension considering pavement preview information and parametric uncertainty
ZHANG Zhiyong1,2, WANG Jianbo2, HU Lin1,2, HUANG Caixia3
Aiming at the semi-active control problem of vehicle air suspension with throttle damping hole and additional air chamber, based on the robust control theory, a semi-active control strategy for vehicle 1/2 air suspension considering parametric uncertainty was proposed.The mapping relationship between expected control force and orifice area was established based on the switch control method to realize the damping force’s tracking expected control force.The pavement information of the front axle wheel was taken as the preview information of the rear axle wheel to establish an augmentation system containing pavement preview information.Numerical simulation for the air suspension semi-active control system considering road surface preview information and parametric uncertainty was performed.Results showed that the proposed control strategy can not only improve the ride comfort of the air suspension, but also have stronger robustness to parametric uncertainty.
2020 Vol. 39 (23): 21-29 [Abstract] ( 200 ) HTML (1 KB)  PDF (1023 KB)  ( 172 )
30 LQG control of active suspension based on adaptive road surface level
KOU Farong, GAO Yawei, JING Qiangqiang, PENG Xianlong, WANG Xing
In order to solve the problem of poor ride comfort and handling stability of vehicles on mixed level road surfaces, a LQG control strategy of active suspension based on adaptive road surface level was proposed.The road surface level was identified according to the relationship between pavement power spectral density and international roughness index.Three kinds of control objectives were determined with different road surface levels taken as thresholds, and the variance of judgment value of average taste concentration after each iteration was calculated to determine next iteration step length to solve problems of premature convergence and long iteration times of Drosophila algorithm.The corresponding fitness functions were set up under different control objectives, and the improved Drosophila algorithm was used to optimize the weighting coefficient of LQG control under different fitness functions to improve the control performance under mixed level road surface.The dynamic performance of the suspension under different levels of road surface was simulated and analyzed, and real vehicle tests were conducted on road.The simulation results showed that compared with the traditional LQG control, the proposed suspension system based on pavement level adaptive LQG control can reduce the RMS value of the spring loaded mass acceleration by 16.34% under A-level road surface, and the RMS value of the tire dynamic load by 6.51% under D-road surface; RMS values of spring loaded mass acceleration and tire dynamic load can be reduced by 9.59% and 7.54% under B-road surface, and 11.32% and 9.4% under C-road surface, respectively; test results are basically consistent to simulation ones.
2020 Vol. 39 (23): 30-37 [Abstract] ( 173 ) HTML (1 KB)  PDF (1432 KB)  ( 78 )
38 Incipient fault diagnosis of rolling bearing based on VMD with parameters optimized
WANG Hengdi1, DENG Sier1, YANG Jianxi1, LIAO Hui2
Aiming at the problem of incipient fault features being difficult to extract in original vibration signals of rolling bearing, an incipient fault diagnosis method of rolling bearing based on variational mode decomposition (VMD) with parameters optimized was proposed.Firstly, Beetle antennae search (BAS) algorithm was used to search the optimal parameter combination of VMD algorithm.The reciprocals of kurtosis values of intrinsic mode functions (IMFs) obtained with VMD were taken as fitness functions in the search process. The number of IMFs and the quadratic penalty factor of VMD algorithm were set up according to the obtained results after search.Then, the bearing vibration signal was decomposed using VMD algorithm with parameters optimized, and the optimal IMF component was chosen with the kurtosis criterion.Hilbert envelope demodulation calculation was done for the optimal IMF component to gain its envelope spectrum.This envelope spectrum could reveal more obvious fault impulse features to realize incipient fault diagnosis of rolling bearing.The results were compared with those obtained using EMD, VMD with fixed parameters and tests results showed that the proposed method can more effectively extract incipient fault features of rolling bearing.
2020 Vol. 39 (23): 38-46 [Abstract] ( 248 ) HTML (1 KB)  PDF (1247 KB)  ( 114 )
47 Overall self-adaptive precision integration method for solving an undamped system under arbitrary excitation
CHEN Dongliang, WANG Lianfu, ZANG Rui, ZHOU Changhe, GONG Chen, ZHANG Jindong
Aiming at calculation precision and efficiency problems of solving an undamped system, the overall self-adaptive precision integration method was studied.Padé approximation and Simpson formula were used to analyze the relationship between matrix exponent and fine parameters of Duhamel integral term in solving differential equations, and then the overall self-adaptive precision integration method for solving a vibration differential equation set was proposed.It was shown that thismethod can be used to do self-adaptive integration according to different precision requirements, and keep its computational accuracy under high frequency excitation; this method is beneficial to solve vibration responses under high frequency excitation and improve computational efficiency.Numerical examples verified the effectiveness of the proposed method.
2020 Vol. 39 (23): 47-51 [Abstract] ( 169 ) HTML (1 KB)  PDF (652 KB)  ( 52 )
52 Denoising measures against aeolian noise of smooth circular cylinders
SHEN Guohui1, ZHANG Yang1, ZHENG Chong2, SONG Gang3, WANG Yiwen3
In order to reduce aeolian noise of smooth circular cylinders, multiple denoising measures were systematically studied.Aeolian noise characteristics of smooth circular cylinders were obtained with acoustic wind tunnel tests.Three kinds of noise suppression measures including winding spiral, protruding pitch diameter and adding axial additional line were tested for noise reduction effect of multiple groups of parameters.Wind noise spectrum and A-weighted total sound pressure level of cylinder before and after adding noise suppression measures were compared.Finally, suggestions for noise reduction measures of smooth cylinder were proposed.Results showed that the predominant frequency of cylindrical wind noise increases linearly with increase in wind speed, Strouhal number of inverse calculation of predominant frequency is 0.197-0.200; for noise suppression measures of smooth cylinder, the noise reduction effect of winding disturbing streamline is the best, followed by that of adding pitch protrusion, and the noise reduction effect of adding additional line along axial direction is the worst, and even wind noise increases; for smooth cylinder with diameter of about 24 mm, it is recommended to use a single circular spoiler with diameter of 4 mm and a spacing of 10 cm; if two disturbing streamlines are arranged side by side, better noise reduction effect can be obtained.
2020 Vol. 39 (23): 52-57 [Abstract] ( 186 ) HTML (1 KB)  PDF (1673 KB)  ( 50 )
58 Natural characteristics of PMS with random and interval hybrid uncertainties
L Hui1, YANG Kun1, OU Tingjun1, SHANGGUAN Wenbin1, YU Dejie2
In engineering practice, various uncertainties inevitably exist in powertrain mount system (PMS) of vehicles.Here, aiming at cases of parts of PMS parameters’ information being sufficient while other parts of PMS parameters’ being deficient, firstly, PMS parameters with sufficient information were taken as random variables, while PMS parameters with deficient information were treated as interval variables.Then, the hybrid Monte-Carlo method (HMCM) was proposed to solve natural characteristics hybrid response of a PMS.Furthermore, the hybrid perturbation-central difference method (HPCDM) was proposed to quickly solve natural characteristics hybrid response of a PMS through combining Taylor expansion, random moment method and central difference one.Finally, the effectiveness of the proposed methods was verified with a numerical example, and effects of hybrid uncertainties on natural characteristics of PMS were analyzed.
2020 Vol. 39 (23): 58-63 [Abstract] ( 198 ) HTML (1 KB)  PDF (928 KB)  ( 97 )
64 Compensation control-based stochastic resonance characteristics and their application
FAN Zhigang, LIN Min, HUANG Yongmei, XU Ming
Here, a stochastic resonance control method based on compensation control was proposed.The stochastic resonance phenomenon of a bi-stable system excited by periodic signals and correlated multiplicative and additive Gauss white noise based on compensation control was studied.By introducing the corresponding generalized potential function, the analytical expression of signal-to-noise ratio (SNR) was derived.Taking the SNR as an index, the effect laws of control parameter r and correlation coefficient λ between two noises on the resonant output of the bi-stable system were studied.The results indicated that the SNR is non-monotonically related to control parameter r or correlation coefficient λ.The theoretical analysis and numerical simulation results showed that the compensation control can enhance the resonance output of the bi-stable system, adjusting control parameter r can cause the generation of stochastic resonance, and effectively control the intensity of the resonance effect; in a single peak curve of SNR versus correlation coefficient λ, the peak value and its position vary with the change of control parameter r.Test results indicated that the proposed method can effectively extract the characteristic frequency of a vortex street signal with small flow rate.
2020 Vol. 39 (23): 64-70 [Abstract] ( 148 ) HTML (1 KB)  PDF (848 KB)  ( 45 )
71 Chaotic characteristics of multi-frequency band of centrifugal pump inlet pressure under cavitation condition
LIANG Chao, ZHOU Yunlong, YANG Ning, LIU Qichao
Pressure fluctuation signals of a centrifugal pump inlet under different effective net positive suction head available (NPSHa) conditions were measured using dynamic pressure sensors.The3-layer 8-band wavelet packetdecomposition was done for the pressure signals.Wavelet packet decomposition coefficients were taken as time series to calculate 3 chaotic characteristic parameters including the maximal Lyapunov exponent, correlation dimension and K2 entropy.These parameters’ features and changelaws were analyzed and discussed.Results showed that the first 3 of decomposition coefficients in 8-band all have typical chaotic features; 3 chaotic characteristic parameters can be used to describe the system’s chaotic characteristics from different angles, and divide cavitation conditions corresponding to different NPSHa values into 4 different cavitation stages.
2020 Vol. 39 (23): 71-77 [Abstract] ( 149 ) HTML (1 KB)  PDF (933 KB)  ( 64 )
78 Effects of anti-hunting shock absorber on stability of high-speed train
BAI Jinyu, ZENG Jing, SHI Huailong, WU Yi
Here, firstly, a piecewise linear Maxwell model for anti-hunting shock absorber considering unloading characteristics, joint stiffness and internal oil stiffness was established.Effects of joint stiffness on dynamic characteristics of anti-hunting shock absorber were analyzed and the model verification was done with bench tests.Then, the non-linear dynamic model of high-speed train trailer was established and simulated.It was shown that with increase in equivalent conicity of wheel tread, the optimal joint stiffness value of anti-hunting shock absorber required to ensure the motion stability of high-speed train also gradually increases.Finally, motion stabilities of high-speed trains with multiple kinds of joint stiffness of anti-hunting shock absorber were contrastively analyzed.The choosing strategy for joint stiffness of anti-hunting shock absorber considering variation of equivalent conicity was explored.
2020 Vol. 39 (23): 78-83 [Abstract] ( 173 ) HTML (1 KB)  PDF (1304 KB)  ( 163 )
84 Extreme wind speed estimation of mixed climate combined with typhoon full path simulation
LI Qiang1, MAO Jianghong1, HUANG Mingfeng2
In order to reasonably determine the wind-resistant design wind speed in mixed climate area, an extreme wind speed estimation method in mixed climate area based on typhoon full pathsimulation was proposed.Based on the best-path dataset of CMA-STI tropical cyclones, a typhoon full-path model suitable for northwest Pacific Ocean area was established by using Vickery empirical regression model.The model parameters were modified for local area of northwest Pacific Ocean to generate 100 000-year random samples of typhoon track and intensity in line with characteristics of historical samples.The wind field was simulated with Yan Meng model, and based on statistical analysis of extreme value, extreme wind speeds of typhoon in return period of 10 cities along southeast coast of China were determined.Combined with the measured data of good wind near ground in Hangzhou area, extreme wind speedsin mixed climate return period of Hangzhou area were estimated.Results showed that effects of different climate models should be considered in the design wind speed estimation of mixed climate regions; using the proposed method, a conservative estimation of extreme wind speed of mixed climate can be given.
2020 Vol. 39 (23): 84-89 [Abstract] ( 136 ) HTML (1 KB)  PDF (1207 KB)  ( 31 )
90 Longitudinal vibration reduction of ship propulsion shafting based on quasi-zero-stiffness isolator
ZHAO Han1, YANG Zhirong2, TA Na1, RAO Zhushi1
Based on static characteristics study of two quasi-zero-stiffness (QZS) isolators, effects of the two isolator models’ structural parameters on displacement range of low dynamic stiffness were contrastively analyzed.The dynamic model for longitudinal vibration of ship propulsion shafting based on QSZ isolator with its restoring force taken as one end’s boundary condition was established using the finite element (FE) method.The force transmissibility of the system was solved with the harmonic balance method.Combined with simulated ship working condition parameters, vibration isolation effects under excitation of blade frequency for ship propulsion shafting based on different isolator models were contrastively studied.Analysis results showed that the QZS isolator can realize longitudinal vibration reduction of ship propulsion shafting under excitation of blade frequency based on an equivalent linear system; choosing a suitable QZS isolator model and damping can avoid jump phenomenon occurring during main resonance and keep low frequency vibration isolation effect.
2020 Vol. 39 (23): 90-95 [Abstract] ( 216 ) HTML (1 KB)  PDF (1089 KB)  ( 56 )
96 Deformation, heating and performance degradation of lead rubber bearings for highway bridges under near fault ground motions
SHI Yan, WANG Haohao, QIN Hongguo, HAN Jianping, XIONG Lijun
Lead-rubber bearings (LRBs) are extensively used seismic isolators in bridges.The cyclic deformation of LRBs under earthquake can cause heating accumulation and temperature rising.As a result, variations of mechanical properties of LRBs including dropping of hysteretic energy dissipation, characteristic strength and stiffness threaten seismic safety of bridges.Here, according to the code of the lead rubber bearing isolator for highway bridge (JT/T 822—2011), 22 types circular LRBs were taken as objects to establish 40 single bearing isolation structure models with different periods.40 bilateral near-fault ground motion records suitable to transportation field structure aseismic design were input into models to perform nonlinear dynamic time history analyses.Effects of lead core heating on LRBs’ displacement, temperature, characteristic strength and hysteretic energy dissipation were studied.In addition, relations among increment of lead core temperature, characteristic strength reduction rate and near-fault ground motion were discussed to establish fitted relation expressions among bearing displacement ductility coefficient, shear strain and Qd/W.Results showed that for the isolated systems with medium-long periods (1.5~3 s) under near fault ground motion, lead core temperature rising and characteristic strength dropping are obvious, the increase in lead core temperature is 50 ℃-80 ℃, characteristic strength drops 20%-40%; displacement responses of LRBs can be under-estimated by 15% not considering lead core heating.
2020 Vol. 39 (23): 96-106 [Abstract] ( 190 ) HTML (1 KB)  PDF (1740 KB)  ( 41 )
107 Parameter Optimization of MDVA Applied in Box Girder Based on Multi-modal Control Theory and the Analysis of Effect on Low Frequency Vibration
ZHOU Li, ZHANG Tianqi, LUO Yanyun
As multiple dynamic vibration absorbers (MDVA) have features of good vibration reduction effect and mass dispersion, here, MDVA’s parameters were reasonably optimized to reduce vibration of box girder’s components within multi-frequency bands under vehicle loads.Firstly, based on the fixed-point theory of a single-DOF system and the multi-DOF multi-mode control theory, the MDVA parametric optimization method for multi-objective mode was deduced.Secondly, the vehicle-rail-bridge finite element model was established.According to vibration spectrum and modal characteristics of box girder obtained with simulation, MDVA parameters and installation location were reasonably set up.Finally, the differences (1-250 Hz) between vibrations of box girder with and without MDVA were compared.Results showed that MDVA have better vibration absorption effect on multi-band responses of box girder; dynamic response results of rail and wheel reveal MDVA have a certain suppressing effect on their low frequency vibration.
2020 Vol. 39 (23): 107-113 [Abstract] ( 53 ) HTML (1 KB)  PDF (1268 KB)  ( 8 )
114 Numerical analysis method and vibration characteristics analysis of complex composite structure de cotton rotor
LI Huijuan, GENI Mamtimin
In order to reveal vibration characteristics of complex composite structure (CCS) de cotton rotor of a cotton picker, firstly, a 3-D microstructure fiber model including nylon fiber was established for brush strip part of CCS de cotton rotor.At the same time, the brush strip was simplified and an anisotropic microstructural composite model was established considering characteristics of composite material.Elastic modulus ratio of composite model was changed, and modal analyses were performed with finite element method.Vibration characteristics of the fiber model and the composite model were contrastively analyzed to obtain elastic modulus ratio of the model close to the actual brush strip, and determine composite material properties of composite model.At the same time, influences of element type and size were studied contrastively to verify the effectiveness of the proposed modeling method and numerical algorithm.Secondly, numerical models of CCS de cotton rotor with and without brush strip were established and modal analyses were performed to obtain the rotor natural frequencies and modal shapes.Results showed that the brush strip has a larger influence on vibration characteristics of the CCS de cotton rotor, the first six natural frequencies range is 52.63~249.00 Hz, but the rotor’s first natural frequency is higher than the rotor’s actual working frequency of 25 Hz to avoid the resonance.Finally, the rotor’s natural frequencies were obtained with a rotor test platform and Laser Doppler vibrometer.It was shown that both the numerical results and test ones agree well with each other, and can correctly reflect vibration characteristics of the CCS de cotton rotor to verify the effectiveness of the proposed modeling method and related algorithms; the results can provide a reference for design and optimization of CCS de cotton rotor.
2020 Vol. 39 (23): 114-121 [Abstract] ( 147 ) HTML (1 KB)  PDF (1912 KB)  ( 25 )
122 Automatic identification of modal parameters based on interval perturbation and double-layer fuzzy clustering
QIN Xianrong, LIU Jiahui, YU Chuanqiang, WANG Yulong, ZHANG Qing, SUN Yuantao
The traditional stochastic subspace identification method is difficult to determine the reasonable order of system, the results of parametric identification are easy to be disturbed by environmental noise.The stability diagram method relying on subjective judgment can not automatically identify structural parameters.Here, aiming at above problems, interval perturbation and double-layer fuzzy clustering algorithm were proposed to identify modal parameters automatically based on stochastic subspace identification.A natural frequency identified of a high-order system was taken as the central frequency to do perturbation by ±2%, and natural frequencies identified within this perturbation interval were regarded as the same order frequency.Natural frequencies were automatically identified by combining with the stability diagram method.The double-layer fuzzy clustering algorithm was used to cluster damping ratios with larger discreteness, and damping ratios were automatically identified by combining with the stability diagram method.The results of modal parametric identification of engineering examples based on monitoring data of quay crane showed that the proposed method can effectively eliminate false modes, improve the efficiency of parametric identification, and achieve better automatic identification of natural frequencies and damping ratios.
2020 Vol. 39 (23): 122-127 [Abstract] ( 115 ) HTML (1 KB)  PDF (1241 KB)  ( 28 )
128 Wet modal tests and numerical simulation for a rigid-liquid-flexible coupled structure
CAI Kelun1,2, LIU Yuhong1,2, ZHU Yaqiang1,2, HUANG Cheng1,2, ZHANG Lianhong1,2
Based on physical model tests and finite element simulation, modal characteristics of a rigid-liquid-flexible coupled structure, a miniature model of “haiyan” underwater glider, was studied.Using hammering method, this structure’s wet modal frequencies and modal shapes characteristics under 3 different liquid-filled water pressures were measured.It was found that the structure has good vibration absorption action.Meanwhile, based on the acoustic-structure coupled algorithm of ANSYS Workbench software platform, the wet modal analysis of this structure was performed under different internal and external pressures to study variation of its wet modal frequencies and modal shapes.Analysis results showed that liquid additional mass effect can’t be ignored during modal analysis of this structure; increase in internal and external pressures can cause the structure’s wet modal frequencies to drop; the study results can provide a reference for wet modal analysis of relevant structures.
2020 Vol. 39 (23): 128-134 [Abstract] ( 201 ) HTML (1 KB)  PDF (1876 KB)  ( 70 )
135 Artillery launch dynamic simulation based on ADAMS
ZHOU Jun1， GAO Yuefei1， WANG Deng1， XIAO Jianguang1， WANG Zhenrong2
Aiming at problems of during using the software ADAMS to simulate gun launching dynamics, loading process of propellant gas pressure being cumbersome and simulation calculation time being not synchronized with change of propellant gas pressure, a launch dynamics simulation method based on ADAMS self-defined functions was proposed to synchronously solve interior ballistic process and gun recoil motion inside ADAMS during gun launching.Based on the classical interior ballistic equation and the force analysis of recoil part, the load needed in dynamic analysis was added with displacement, velocity and other functions, and the simulation process was controlled by sensors and scripts.The launching dynamic simulation was done for a certain 122 mm artillery to verify the correctness of the simulation method.It was shown that the proposed simulation method can make motion of projectile, generation of propellant gas and motion of recoil part be related to each other, the three problems can be solved within the same software to improve the efficiency of simulation calculation.
2020 Vol. 39 (23): 135-140 [Abstract] ( 206 ) HTML (1 KB)  PDF (731 KB)  ( 86 )
141 Split augmented lagrange contraction deconvolution algorithm for sound source identification
FAN Xiaopeng1, ZHANG Xin2,3, CHU Zhigang2,3, LI Li1
Here, a novel and efficient deconvolution algorithm with ultra-high resolution for sound source identification was proposed, it was called the split augmented Lagrange contraction deconvolution algorithm (SALCDA).In this method, the sparsity that the main sound source usually has and the idea of alternating directions for solving large-scale sparse recovery problems were used.Then a split variable equivalent to source strength was introduced into the mathematical model of beam forming deconvolution to establish the mathematical model of augmented Lagrange variable splitting for sound source identification.SALCDA was used to solve alternately and iteratively the split model, and gain the source strength.The results of simulation and tests showed that the source strength quantification ability of the proposed method is comparable to that of the classical deconvolution approach for mapping of acoustic sources (DAMAS); it has better convergence, ultra-high resolution within the whole analysis frequency range, and its iterative calculation speed is tens of times faster.
2020 Vol. 39 (23): 141-148 [Abstract] ( 145 ) HTML (1 KB)  PDF (1491 KB)  ( 61 )
148 Finite element modeling and dynamic analysis of passive constrained layer damping plate based on laminated theory
HUANG Zhicheng1, WANG Xingguo1, WU Nanxing1, CHU Fulei2， LUO Jing3
The finite element dynamic model of a passive constrained layer damping (PCLD) plate was established based on the laminated theory.A 3-layer plate element with four-node and 5-DOF per node was constructed to simulate interaction among base plate, viscoelastic damping layer and constraint layer.The frequency-dependent properties of viscoelastic material were described with Biot model, and they were introduced into the finite element dynamic equation of a PCLD plate by means of auxiliary coordinates, and then the latter was converted into the ordinary second-order differential equation form to simplify the solving process.The effectiveness of the proposed method was verified with the comparison between numerical examples and test results.Results showed that compared with the traditional finite element modeling theory, using the laminated theory can reduce the structure’s DOF and have good calculation accuracy.
2020 Vol. 39 (23): 148-153 [Abstract] ( 159 ) HTML (1 KB)  PDF (937 KB)  ( 50 )
154 Safety threshold of blasting vibration velocity of highway tunnel considering influence of stress wave transmission
CAO Feng1, LING Tonghua2, ZHANG Sheng3
Due to the existence of a large number of media interfaces in rock mass, complex phenomena of transmission and reflection occur in process of explosion stress wave propagation.Here, based on the theory of stress wave propagation, considering transmission and propagation laws of blast stress wave on different interfaces of media, the theoretical calculation formula for the relationship between vibration velocity and stress of tunnel lining structure with small clear distance incident by blast stress wave was derived.Then, combined with the dynamic tensile ultimate strength of tunnel surrounding rock and concrete, according to the ultimate strength criterion, the safety threshold of blasting vibration velocity was solved.Finally, the derived theoretical calculation formula was verified with engineering examples.Results showed that the calculation results of the theoretical calculation formula are basically consistent to the numerical simulation ones to verify the correctness of the theoretical calculation formula.
2020 Vol. 39 (23): 154-159 [Abstract] ( 156 ) HTML (1 KB)  PDF (941 KB)  ( 44 )
160 Complex mode pseudo excitation method for random seismic response analysis of isolated bridge structures
JIA Shaomin1, CHEN Huating2, WANG Ziqi2, ZHAO Lei3
Due to the constitutive relation of isolation bearing having significant non-linearity, nonlinear random seismic response analysis of isolated bridge structures has difficulties of complex theory and large amount of calculation.Here, to simplify analysis process and improve computational efficiency, the equivalent linear model of isolated bridge structures was established and the non-classical damping model was adopted to describe damping characteristics of isolated bridge structures.Based on the complex mode superposition method and the pseudo excitation method, the complex mode pseudo excitation method for random seismic response analysis of isolated bridge structures was established.Numerical examples showed that the established method has high computational efficiency, reliable results and convenient operation.
2020 Vol. 39 (23): 160-164 [Abstract] ( 144 ) HTML (1 KB)  PDF (928 KB)  ( 41 )
165 Design and performance tests of a new MR braking device for traction elevator
CHEN Kaifeng1,2, ZHENG Xiangpan1,2
With rapid development of urbanization construction, elevators play more and more important role.The existing traction elevator braking device adopts contact friction type electromagnetic one with large vibration impact, high noise and insufficient security protection, it can’t meet the requirements of higher ride comfort and safety.A new controllable brake based on magnetorheological (MR) effect with advantages of easy to control and lower working noise is very promising for engineering application.Here, according to braking working condition requirements of traction elevator, to improve the device performance and braking safety, based on MR effect and the principle of permanent magnet braking, a new type of elevator brake with self-protection and double-protection was designed.Through analyzing the working principle of the new MR brake, the braking moment mathematical model of the device was established and influences of different parameters on braking performance were theoretically analyzed.According to working characteristics of elevator zero speed braking and emergency braking, test contents were determined, and the braking performance test platform was built to conduct braking torque testing, temperature characteristics one and working noise study.The test results showed that the developed elevator MR braking device with self-protection and heat radiation has higher braking torque, lower temperature rising, lower vibration and noise level to meet the design requirements.
2020 Vol. 39 (23): 165-175 [Abstract] ( 177 ) HTML (1 KB)  PDF (4221 KB)  ( 44 )
176 Energy output efficiency of flat tube assembly based on deformable cylinder experiment
FENG Lina1, LI Dong2, TIAN Jiandong1, QU Zhanlong1, SUN Jing1
The expanding tube separation device is a commonly used linear separation device on space launch vehicle, whose energy source is a flat tube assembly including explosive cord, filler and a flat tube.Here, to study the energy output efficiency of the flat tube assembly, firstly it was inserted into a 1060 pure aluminum cylinder with the experiment method.Then velocity and displacement time histories of characteristic points on outer wall of the aluminum cylinder were measured.Wire cutting was done for specimens after experiment to measure their inner diameter’s variation.The above experimental process was simulated with the finite element method.The simulation results agreed well with experimental ones.The plastic strain energy of the aluminum tube was obtained by the finite element simulation, and taken as the effective energy output by the flat tube assembly, and its ratio to the total energy of explosive was the energy output efficiency of the flat tube assembly.Results showed that the energy output efficiency of the flat tube assembly is about 22.8%; within a certain filler’s material parameter range, the energy output efficiency of flat tube assembly increases with increase in filler’s density, modulus and Poisson’s ratio.
2020 Vol. 39 (23): 176-181 [Abstract] ( 148 ) HTML (1 KB)  PDF (1847 KB)  ( 68 )
182 Intelligent identification method using kernel extreme learning machine for rolling bearing multi-working condition multi-feature automatic selection
HU Aijun, ZHANG Junhua, LIU Suixian, XU Sha
There are many deficiencies in intelligent fault diagnosis of rolling bearing, especially, for fault diagnosis under complex working conditions, there are problems of insufficient feature extraction and low diagnosis accuracy.Here, aiming at fault diagnosis of rolling bearing under multi-working condition with different fault types, different levels of fault and different loads, an intelligent identification method using kernel extreme learning machine based on multi-feature automatic selection was proposed.Firstly, effective fault features were extracted in time domain, frequency one and time-frequency one, respectively.Secondly, Laplace score (LS) was adopted to automatically select sensitive features according to the importance of each feature, the goal was to eliminate some redundant information and improve computational efficiency.Finally, the kernel extreme learning machine with simulated annealing particle swarm optimization was adopted to realize multi-fault state recognition of rolling bearing.The method was applied in fault identification of rolling bearing under variable loads.It was shown that compared with other identification methods, the proposed method has higher recognition accuracy and faster classification speed.
2020 Vol. 39 (23): 182-189 [Abstract] ( 193 ) HTML (1 KB)  PDF (2046 KB)  ( 70 )
190 Drill string vibration analysis and pressurization scheme for medium-shallow horizontal wells
ZHU Xiaohua, ZENG Li, LI Ke
Medium and shallow oil and gas reservoirs are characterized by shallow buried depth, poor physical properties and low natural productivity, they are tight sandstone oil reservoirs and difficult to produce, they bring great challenges to horizontal well drilling.Among them, problems of drill string vibration, drag pressure and friction are urgent ones to be solved.Therefore, the simulation of drill string vibration and friction is very important.Here, taking the horizontal well in Ordos area as an example, based on the 3-D coupled vibration model, dynamic characteristics of drill string of two different well depth structures in Ordos area were described from 3 aspects of axial force, horizontal displacement of drill string and friction torque, and compared with those of medium-deep wells.In the process of using heavy weight drill pipe (HWDP) and hydraulic oscillator to solve the drag pressure problem, effects of number and size of HWDP, pulse force of hydraulic oscillator and installation position on dynamic characteristics and fatigue life of drill string were discussed.Results showed that compared with medium-deep horizontal wells, the WOB fluctuation of medium-shallow horizontal wells is only 1/8 of that of medium-deep wells, but the axial force fluctuation in oblique segment, especially, near neutral point is very large and reaches 20 kN, it is 1/3 of that of medium-deep wells, so drill string vibrations in oblique segment and near neutral point receive much attention; to solve the problem of supporting pressure, adding 10-12 or 18-20 114 mm or 127 mm HWDPs at place from the end of vertical segment to 25°-35 ° deviation segment can not only ensure smaller WOB fluctuation and friction, but also ensure high fatigue life of drill string in oblique segment.The conclusion was applied in site.In addition, a hydraulic oscillator was used together to further reduce friction.It was recommended that the hydraulic oscillator should be installed at 40 m away from the drill bit, and the pulse force should be 21 kN.
2020 Vol. 39 (23): 190-201 [Abstract] ( 129 ) HTML (1 KB)  PDF (6061 KB)  ( 109 )
202 Hole crack damage detection of CFRP plate based on super-magneto-strictive transducer
WANG Xiaoyu1, LIU Hailong1, GAO Sijia1, LI Jian2
Hole crack damage is the main damage form of carbon fiber reinforced plastics (CFRP) plate in service.Due to the anisotropy of CFRP material, ultrasonic guided wave signals are greatly attenuated and multiple mode wave packets are overlapped, so it is difficult to realize the quantitative detection of hole crack damage of CFRP bolted or riveted.Here, aiming at the damage quantification of CFRP hole cracks, Galfenol transducer was developed as the high-energy excitation source of ultrasonic guided wave, and PZT-5 was used as the receiving end to detect ultrasonic guided wave of hole cracks.The dynamic model of transducer was established, and the optimal excitation frequency was determined with the sweep frequency method combined with S0 mode capture comparison.Wavelet decomposition and short-time Fourier transform (STFT) were performed for the obtained ultrasonic guided wave signals, and the color threshold of the control cloud chart was calculated to highlight information of S0 mode and damage mode, and obtain the time-frequency cloud atlas.The mechanical model of CFRP plate was established, and the natural periodicity of Floquet boundary was adopted to gain the dispersion curve through scanning plate element wavelength Brillouin region.The time-domain location of crack damage was obtained by calculating the group velocity of dispersion curve on the cloud atlas.According to the threshold chromaticity of cloud atlas, the amplitude of wave packet was quantized, and the information of damage degree was obtained.The experimental results showed that there is a good discernibility between crack damage mode and the original mode; according to the obtained dispersion curve, the time errors for S0 mode to directly reach and reflect are 2.3 μ s and 0.6 μ s, respectively.
2020 Vol. 39 (23): 202-210 [Abstract] ( 124 ) HTML (1 KB)  PDF (2523 KB)  ( 41 )
211 Tests for fracture characteristics of fractured sandstone and micro-seismic and charge induced signal laws
ZHAO Yangfeng, JING Gang, CHENG Chuanjie, LI Bing
In order to effectively extract precursory information of instability failure of fractured sandstone, failure characteristics of intact sandstone and fissured one with different dips under uniaxial compression, and laws of charge induction signals and micro-seismic ones were tested and studied.Results showed that the existence of fractures is the main factor affecting uniaxial compressive strength and failure characteristics of sandstone; with decrease in fracture dip, the uniaxial compressive strength of sandstone decreases, and the fracture mode changes from tension-shear composite fracture to shear-lip one; micro-seismic and charge signals of intact specimens have high amplitude fluctuation only near peak stress, but they are lower in initial loading compaction stage and elastic one; if the occurrence time of micro-seismic and high-amplitude charge signals in fractured rock samples is in advance, the number of high-amplitude pulses increases; high-amplitude pulses only appear near peak stress in intact samples, if rock specimens have fractures, many high-amplitude pulses appear in rock elastic later stage; when fracture dip angle changes from 60° to 45° and then to 30°, micro-seismic and charge signals change from intensive ones to multiple isolated ones, micro-seismic signal and charge one are not completely synchronized, and better “synergistic” signals appear only in rock post-peak stage; stress drop of rocks is a sufficient and unnecessary condition to generate micro-seismic and charge-induced signals; combining micro-seismic and charge induction monitoring technique with stress field distribution of rock mass monitoring area to guide field practice is helpful to improve the prediction accuracy and reduce the occurrence of geological disasters.
2020 Vol. 39 (23): 211-219 [Abstract] ( 95 ) HTML (1 KB)  PDF (1643 KB)  ( 17 )
220 Optimal semi-active control for nonlinear random vibration of armored vehicle seat
HU Lingjun1, LIU Bin2, HUAN Ronghua1, ZHU Weiqiu1, LIU Yan3
When an armored vehicle drives on rough roads, its inside seat has violent vibration under random loads to significantly affect the comfort of crew members.Thus, it is of great importance to develop effective strategies for controlling seat random vibration.Here, an optimal semi-active control for nonlinear random vibration of armored vehicle seat was proposed.Firstly, the seat system of armored vehicle was taken as the study object, and its nonlinear stochastic dynamic model was established.Then, the stochastic average method and the random dynamic programming principle were applied to deduce the concrete form of the optimal semi-active control force.The statistics of the seat system steady-state response including probability density and mean square value, etc.under controlled and uncontrolled states were obtained.Finally, the correctness of the proposed method was verified with numerical simulation.Results showed that under controlled state, the control effect of the proposed control strategy on the mean square value of the seat system steady-state response reaches 85.0%, it has a good vibration reduction effect.
2020 Vol. 39 (23): 220-224 [Abstract] ( 176 ) HTML (1 KB)  PDF (1237 KB)  ( 32 )
225 Failure mode and damage assessment of segmental assembled pier under blast Impact
ZHANG Yuye1, YANG Xu1, FENG Jun2
In order to investigate failure mode and damage assessment method for segmental assembled piers under blast impact, 3-D solid separated models of integral pier with square section and segmental assembled pier under blast were established using the software ANSYS/LS-DYNA.The reliability of this simulation method was verified by comparing the numerical results and the blast test ones.By changing the blast’s TNT equivalent and blast distance, the stress variation, failure mode and damage mechanism of integral pier and segmental assembled one under different overpressure actions were contrastively analyzed, and the method for evaluating pier blast damage combined with pier section damage and its lateral displacement was proposed.Results showed that under combined action of blast impact and dead load, integral piers mainly exhibit shear failure and bending-shear failure, while segmental assembled piers present shear failure and local failure; under action of blast impact with different scaled distances, pier damage can be divided into 3 states of complete elasticity, partial elasticity and loss of elasticity; after segmental assembled piers are subjected to blast impact, larger relative rotating angle and displacement occur between segments to cause weakening of pier section and pier body lateral displacement; blast damage for both bridge piers of the two systems can be quantitatively evaluated with the combination method of section weakening and pier body lateral displacement.
2020 Vol. 39 (23): 225-233 [Abstract] ( 188 ) HTML (1 KB)  PDF (2357 KB)  ( 64 )
234 Hydraulic pump fault diagnosis method based on SGMD-autogram
ZHENG Zhi1, 2, LI Xianze1, ZHU Yong3, WANG Baozhong1
The symplectic geometry mode decomposition (SGMD) method has the problem of feature information distribution being too scattered, and Autogram method has the problem of the feature extraction ablility of the maximal overlap discrete wavelet packet transform (MODWPT) being not strong.Here, aiming at above problems, a new method based on SGMD and Autogram was proposed.Firstly, SGMD was applied to decompose measured multi-mode vibration fault signals of hydraulic pump.Secondly, aiming at the problem of too scattered feature information distribution after decomposition, the spectral  kurtosis method based on maximum unbiased autocorrelation was proposed.Some mode components containing rich operating feature information were screened out as the data source to replace MODWPT, and realize the extraction of the optimal fault features.Finally, the data source was processed with threshold, and the fault diagnosis of hydraulic pump was realized based on spectrum.By comparing and analyzing simulated and measured vibration fault signals of hydraulic pump swash plate, it was verified that the proposed method can effectively diagnose hydraulic pump swash plate faults.
2020 Vol. 39 (23): 234-241 [Abstract] ( 176 ) HTML (1 KB)  PDF (1252 KB)  ( 118 )
242 Progress and prospect of acoustic properties of metal rubber
BAI Hongbai1, 2, ZHAN Zhiqiang1, 2, REN Zhiying1, 2
As a fibrous porous sound-absorbing material, metal rubber has good environmental adaptability.Here, the preparation processing of metal rubber materials was introduced, and the development of theoretical and experimental research on acoustic properties of metal rubber was reviewed.The research status of sound-absorbing theoretical model and acoustic test of metal rubber were summarized.Aiming at metal rubber with different structures including single layer structure, series one and parallel one, and circular and square shapes, according to theoretical calculation and experimental research results, effects of processing parameters including wire diameter, porosity, thickness, etc., assembly parameters, such as, thickness of the back cavity, and using environment on the sound absorption performance of metal rubber were analyzed in detail.The prediction for sound absorption performance of metal rubber and the research status of metal rubber composite materials were discussed.Finally, the engineering application research of metal rubber as acoustic components was elaborated, and the future work on acoustic properties of metal rubber was prospected.
2020 Vol. 39 (23): 242-254 [Abstract] ( 178 ) HTML (1 KB)  PDF (5412 KB)  ( 223 )
255 Study on isolation simplification model and isolation response of LNG storage tank considering thermal insulation layer
LUO Dongyu1, SUN Jiangang2, LIU Chunguang1, CUI Lifu2, WANG Zhen2
To study the isolation response of LNG storage tank and the influence of insulation layer on base isolation effect, the base isolation simplified mechanical models of 16×104m3full-capacity LNG storage tank considering insulation were proposed, and the seismic responses of the tank were calculated by simplified mechanical model and finite element analysis platform ADINA.Compared the base shear, bending moment and sloshing wave height of the two methods, the following conclusions were obtained: The base shear and bending moment calculated by the simplified mechanical models are larger than those of by numerical simulation, but the sloshing wave height is smaller; the difference rate of the isolated model is smaller than that of the seismic model,  In the seismic and isolation design of LNG storage tank, the simplified mechanical model could be used to calculate the base shear and bending moment, which can ensure the fortification requirements.However, it is suggested that the sloshing wave height calculated by the seismic and isolation model should be expanded by 1-1.5 times and 2-2.5 times, respectively.In addition, insulation has an influence on the base isolation effect of LNG storage tanks, it is necessary to consider the effect of insulation on the base isolation design of LNG storage tank.
2020 Vol. 39 (23): 255-262 [Abstract] ( 160 ) HTML (1 KB)  PDF (2255 KB)  ( 39 )
263 Fault detection of electric booster based on fractional Fourier filtering
HUANG Ming, ZHENG Yongjun, WANGYANG Baihui
Due to the influence of strong noise environment, in order tracking analysis, vibration signal generated due to gears variable speed operation in an electric booster can’t accurately reflect fault signal.Aiming at this situation, the linear frequency modulation signal with noise was used to simulate the nonstationary signal produced by variable speed operation of the electric booster.The non-stationary signal was filtered with a fractional Fourier transform and a fractional Fourier domain bandpass filter.The signal spectra before and after filtering were compared to verify that the fractional Fourier filtering can filter out noise component of the non-stationary signal more accurately.Based on conclusions obtained with simulation, an optimization method for fault detection effect of vibration signal generated by variable speed operation of the electric booster was proposed.The fractional Fourier filtering was performed for the actually measured vibration signal generated due to decelerating operation of the electric booster motor.Comparing the signal’s order tracking spectra effects before and after filtering, it was verified that the proposed filtering method has a better filtering effect on gear fault signals measured under strong noise environment; it has a certain practical value and universality.
2020 Vol. 39 (23): 263-270 [Abstract] ( 131 ) HTML (1 KB)  PDF (2594 KB)  ( 49 )
271 Multi-crack location and degree identification of beam structure based on modal parameters
GUO Shuaiping1, WU Qiqiang1, LI Xuejun1,2, WANG Gang1
Aiming at multi-crack diagnosis problems of beam structure, based on natural frequencies of beam structure, a multi-crack diagnosis method to combine the sensitivity square matrix with the element subdivision was proposed.Firstly, natural frequency orders of a selected beam structure were equal to the number of elements divided in the beam, and the sensitivity square matrix of the beam was calculated based on the beam’s various modal shapes.Secondly, measured natural frequencies of the beam were used to solve the sensitivity square matrix equation, and determine cracked elements.The element subdivision method was employed to reduce crack area.Thirdly, aiming at the multi-crack beam, based on the return to zero inverse method, the beam’s natural frequency parameters were solved in turn when each crack exists alone.The multi-crack diagnosis problem was converted into multiple uncorrelated single-crack diagnosis problems.Finally, according to the beam’s single crack location and degree recognition method, within an element, cracks were further located and their degrees were recognized to realize multi-crack diagnosis.Numerical simulation and tests were performed.Results showed that the proposed beam multi-crack diagnosis method has higher accuracy; its effectiveness is verified; it can provide a theoretical basis for practical engineering application.
2020 Vol. 39 (23): 271-279 [Abstract] ( 168 ) HTML (1 KB)  PDF (1396 KB)  ( 60 )
279 Nonlinear dynamic behavior of impact capsule oscillator based on wireless endoscope application
LIAO Maolin
Here, to improve dynamic behavior of a capsule endoscope via introducing an impact oscillator structure, dynamic behaviors of an impact capsule oscillator with unilateral and bilateral elastic constraints were studied contrastively.The effects of two excitation parameters of frequency ratio and amplitude one and two structure parameters of mass ratio and stiffness one on dynamic behavior evolution laws of the impact capsule oscillator were investigated with numerical simulation.The study results showed that the capsule with unilateral constraint moves faster than the one with bilateral constraints does, and its propulsion efficiency under one-period one impact-vibration state is higher than that under other impact-vibration states; the capsule with bilateral constraints has lower propulsion speed but it can realize the two way movement forward and backward via adjusting the number of impact between the impact capsule oscillator and spring constraints at both left and right sides; this bidirectional movement provides the possibility of reciprocating looking back to key areas of human digestive tract; the study results have guiding significance for the structural design and vibration control of the impact capsule oscillator.
2020 Vol. 39 (23): 279-286 [Abstract] ( 116 ) HTML (1 KB)  PDF (2877 KB)  ( 56 )
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