Home
About Journal
Editorial Board
Instruction
Subscribe
Advertisement
Contact Us
中文
Office Online
Journal Online
Current Issue
Accepted
Archive
Advanced Search
Download Articles
Read Articles
Email Alert
Links
2019 Vol. 38, No. 4
Published: 2019-02-15
1
Dynamic characteristics of a dual-rotor system with outer-rotor misalignment
XU MEI-PENG1 HOU LEI1,2 LI HONG-LIANG1 CHEN YU-SHU1
In this paper,a dual-rotor system model and its equation were established according to the structure and misalignment,which was transformed into equivalent bending-moment acting on out-dial.The Harmonic balance method was applying to solve equations with high-efficiency. The precision was verified by the Runge-Kutta algorithm.The misalignment resulted in fulcrum-offset,which was investigated by orbits and frequency spectrum.The results show that some new resonance region appeared when 2X frequency component plays an important role,which comes with the increase of the offset.Besides,with the increase of the offset,the rotor orbits get lager and twisted.These characteristics make help to failure diagnosis of misalignment.
2019 Vol. 38 (4): 1-6 [
Abstract
] (
533
)
HTML
(1 KB)
PDF
(1339 KB) (
745
)
7
A model test study on the time history of ship-ice impact loads
HUANG Yan, MA Gaoqiang, SUN Jianqiao
The ship-ice impact load is the governing load in the design of bow structures for ice class ships.A series of model tests were conducted in the ice tank of Tianjin University to investigate the time history of the ice impact loads.The tests were performed by towing the model ship striking large ice floes,and the ice impact loads on the model ship hull were measured by tactile sensors.According to the test results,the ice loading track on the ship hull during ship-ice impact was found to be parabolic,and the ice load increased firstly,then decreased.The maximum ice loading moment was found to be the moment when the ice deflected most.Furthermore,the maximum ice loading location was found near the 1/4 beam,and the time history of the corresponding local ice impact load was mainly characterized by a single-peak shape.
2019 Vol. 38 (4): 7-14 [
Abstract
] (
328
)
HTML
(1 KB)
PDF
(2050 KB) (
156
)
15
Analysis of frequency spectrum and the Fourier series convergence of the unit impulse train
DU Feng 1 TANG Lan 2
According to the shift theorem in the time and frequency domain,the unit impulse train has two frequency spectrum functions which were called the periodic spectrum and the series spectrum.The periodic spectrum is not rigorous for the lack of the analysis of the Fourier series convergence.According to the definition of the Dirac function,it proved that the series spectrum is in fact an impulse train in the frequency domain whose energy and period are equal to the angular frequency value.The sampling function characteristic,the limit and integral theory were made full use of.It shows that the Fourier series of the unit impulse train is convergent.The convergence was verified again by the analyses about the difference between the series spectrum and the Fourier series of the periodic spectrum.It failed to verify the miss of the Gibbs phenomenon.
2019 Vol. 38 (4): 15-19 [
Abstract
] (
497
)
HTML
(1 KB)
PDF
(579 KB) (
97
)
20
Parameter optimization of a maxwell model dynamic vibration absorber with negative stiffness
HAO Yan,SHEN Yongjun,YANG Shaopu，XING Haijun
The maxwell model of the viscoelastic material was applied to a dynamic vibration absorber (DVA) system to form a Maxwell model dynamic vibration absorber with negative stiffness spring,and the parameters of the model were optimized. At first,the analytical system solution was obtained based on the established motion differential equation. Then,three fixed points were found in the amplitude-frequency curves of the primary system. The design formulae for the optimal tuning ratio of the DVA were obtained by adjusting the three fixed points to the same height according to the fixed-point theory. According to the characteristics of negative stiffness elements,the optimal negative stiffness ratio was obtained and it could keep the system stable. The optimal damping ratio was obtained by minimizing the maximum value of the amplitude frequency curves. At last,the comparisons of the presented DVA with three other traditional DVAs under the harmonic and random excitations show that the presented DVA in this paper performs better in vibration absorption.
2019 Vol. 38 (4): 20-25 [
Abstract
] (
286
)
HTML
(1 KB)
PDF
(979 KB) (
192
)
26
Fault feature extraction of rolling element bearing based on improved infogram and MOMEDA
XIA Junzhong，YU Mingqi，BAI Yunchuan，LIU Kunpeng，L Qipeng
To solve the selection problem of the faulted period in the maximum correlated kurtosis deconvolution method,multipoint optimal minimum entropy deconvolution adjusted (MOMEDA) was introduced to enhance the faulted signal.Furthermore,improved infogram was combined to denoise for MOMEDA multipoint kurtosis (MKurt) spectrum.First,the spectral negentropy ratio of both faulted and healthy signals was considered to improve the average spectral negentropy algorithm.As a result,improved infogram based on filter banks was proposed.Second,in order to correctly identify the faulted period in the MOMEDA MKurt spectrum,the proposed method was employed to construct an optimal band-pass filter for noise reduction.Third,the weak fault characteristics were extracted by means of the square envelope spectrum after the MOMEDA being applied to enhance periodic impulses in the filtered signal of rolling bearings.The results of measured fault signals show that the improved infogram is better on denoising.Moreover,it can effectively improve the faulted period's identification and help MOMEDA adaptively with enhancing faulted signals.
2019 Vol. 38 (4): 26-32 [
Abstract
] (
291
)
HTML
(1 KB)
PDF
(2018 KB) (
190
)
33
Dynamic modeling and optimization of the supporting structure of a propulsion shaft system by an FRF-based substructuring method
HUANG Xiuchang 1，2，3 SU Zhiwei 1 NI Zhen 1 ZHANG Zhenguo 1 HUA Hongxing 1，2，3
A FRF-based substructuring method was proposed for dynamic modeling of a propulsion shaft system.The method took into consideration of cross stiffness of oil film,the excitation of both propeller and propulsion machine.The dynamic model of the coupled system was based on two synthesis processes for substructures,i.e.,propeller- propulsion shaft,bearings,coupling,propulsion machine,isolators and hull.FRF-based substructuring sensitivity analysis was employed to evaluate the optimal stiffness of bearings,coupling and isolators under the objective function of mean-square forces and power flow transmitted to the foundation.The proposed method is of great efficiency.For the studied model,the stiffness of the bearings and the isolators should be lowered; the stiffness of coupling should be increased to obtain small vibration transmission.
2019 Vol. 38 (4): 33-39 [
Abstract
] (
294
)
HTML
(1 KB)
PDF
(1834 KB) (
107
)
40
Direct multiscale analysis of the stability of an axially moving compressible sandwich beam with time-dependent velocity
YAN Ting1,YANG Tianzhi1,2,DING Hu1,CHEN Liqun1,3
The motion stability of a composite and soft-cored compressible sandwich beam was investigated,which is different from the traditional incompressible sandwich beam.The direct multiscale method was applied to the analysis process of an axially moving sandwich beam with time-dependent velocity,then the natural frequency and solvability conditions were obtained.Based on the conditions,the stability boundaries of subharmonic resonance and combination resonance were obtained.The numerical examples were presented to show the effect of mean velocity and the ratio of the elastic modulus to shear modulus on the stability boundaries,and the difference between the compressible sandwich beam and the ordinary incompressible beam was compared.
2019 Vol. 38 (4): 40-44 [
Abstract
] (
235
)
HTML
(1 KB)
PDF
(1559 KB) (
123
)
45
A study on the hydropower station units' vibration based on the second-order perturbation
ZHI Baoping1,2,WANG Yu1,QIN Jingjing1,YU Yang1,ZHANG Hongzhan3
At present,most analysis methods for solving the problem of parameters’structural dynamical response are limited to the first-order.If the uncertainty of one parameter (such as oil seal,etc.) is slightly large,then the first-order analysis method does work.This paper derived a second-order perturbation analysis method with second-order partial derivative calculations on the basis of the first-order perturbation method.This method analyzed structural vibration transfer efficiency in the frequency domain.The method was validated through a simple example and a vertical vibration transfer analysis example.However,there was a big error,when using the second-order perturbation in the vibration analysis of hydroelectric units,especially in the natural frequency.This research provided a method to solving large disturbance parameters in hydropower station units' vibration analysis,but only for the non-natural frequencies.It also offers basis for further research on complicated structural transfer paths.
2019 Vol. 38 (4): 45-49 [
Abstract
] (
201
)
HTML
(1 KB)
PDF
(1055 KB) (
66
)
50
Sliding mode robust control of a bearingless induction motor suspension system based on the HJI theory
SUN Yuxin，TANG Jingwei，ZHU Huangqiu，SHI Kai
To realize the dynamic decoupling control of a bearingless induction motor suspension system,a sliding mode robust control method based on the HJI (Hamilton-Jaeobi-Issaes) theory for a bearingless induction motor suspension system was proposed.In modeling the suspension system,the system uncertainty and the external disturbance were considered,and the stability of the control system was ensured by satisfying the HJI inequality robust condition by designing an appropriate sliding mode control law.Finally,the method realizes the dynamic decoupling control of the bearingless induction motor suspension system and improves the stability and anti-disturbance performance of the system.Simulation and experimental results show the effectiveness of the method,which can realize the decoupling control of two degrees of freedom bearingless motor.
2019 Vol. 38 (4): 50-55 [
Abstract
] (
232
)
HTML
(1 KB)
PDF
(1317 KB) (
60
)
56
Mine microseismic signal denosing based on variational mode decomposition and independent component analysis
HUANG Weixin,LIU Dunwen
Microseismic signal denoising plays an important role in P and S phase arrival picking,seismic event location,focal mechanism inversion,and so on.To handle this problem,a variational mode decomposition (VMD) and independent component analysis (ICA) based method was proposed.Firstly,VMD was applied to decompose microseismic into certain number mode functions,then correlation coefficient between each mode function and original microseismic signal was used to remove mode functions which have a large noise.For noise and useful signal mixed mode functions,the ICA method was adopted to extract the useful signal,then the extracted useful signal was combined with the rest low frequency mode functions,which was called the VMD_ICA denoised signal.In addition,a Sine function was used to remove the power frequency noise which remained in the VMD_ICA denoised signal.A signal test shows that both the VMD_ICA method and the VMD_ICA_Sine method can retain microseismic signal local features effectively,and their signal to noise ratios (SNRs) are higher than that based on removing some mode functions directly.The mine microseismic signal application further indicates that the VMD_ICA method and the VMD_ICA_Sine method can improve microseismic signal's SNR and P phase arrival picking quality of the PAI-K method,and the VMD_ICA_Sine method has a better denoising performance than the VMD_ICA method.In conclusion,the VMD_ICA_Sine method provides a good way for mine microseismic signal denoising.
2019 Vol. 38 (4): 56-63 [
Abstract
] (
240
)
HTML
(1 KB)
PDF
(2482 KB) (
203
)
64
In-situ dynamic shear modulus and decay characteristics of silty clay under cyclic freezing-thawing
CHEN Shufeng1, 2, KONG Lingwei1, 2, LI Jingjing1, 2
According to the actual soil state of geotechnical structures in deep seasonally frozen region,systematic in-situ seismic dilatometer tests and laboratory resonant column tests were conducted.The in-situ G-γ decay characteristics of silty clay were investigated based on the in-situ maximum shear modulus and laboratory decay characteristics.The results show that freezing and thawing cycles exert great impacts on the G-γ decay characteristics of silty clay.The maximum dynamic shear modulus Gmax drops from 97.9 MPa to 53.6 MPa over successive freezing-thawing cycles.The maximum attenuation occurs in the prophase of cyclic freezing-thawing process.After several freeze-thaw cycles,the normalized Gmax-γ curves shift upwards.The G/Gmax-value of the specimens subjected to freezing and thawing cycles is relatively higher,which indicates that cyclic freezing and thawing can relieve the shear modulus decay.On the other hand,the in-situ dynamic shear modulus G0 by in-situ SDMT was greater than the Gmax from laboratory RCT.This is due to the soil disturbance during sampling and transportation,and suggests the necessity of in-situ tests.G0 decreases with freezing and thawing cycles.Moreover,the influence of freezing and thawing decreases with shear strain and is negligible when the shear strain exceeds the working strain γDMT.Rational selection of the value of soil modulus with the consideration of actual strain level and freezing-thawing is the key for the engineering design in deep seasonal frozen area.
2019 Vol. 38 (4): 64-69 [
Abstract
] (
363
)
HTML
(1 KB)
PDF
(1120 KB) (
117
)
70
Wind field characteristics on slope terrain under thunderstorm downburst
FANG Zhiyuan1，WANG Zhisong1, 2,WU Yanjun1，WANG Chao1，LI Zhengliang1, 2
Downburst often occurs in the mountainous and hilly areas.At present,the research of downburst mainly concentrates on the steady wind field in flat terrain.To investigate the effects of slope terrain on downburst wind field,an impinging jet physical experiment and the large eddy simulation (LES) were used to test and simulate the wind field in flat and three different gradient slopes.The results indicate that the large eddy simulation capture the transient characteristics of wind field,and the maximum wind speed of the wind field during the whole life cycle of downburst appears when the vortex structure first arriving the crest of the slope.Except the crest of the slope has significant speed-up effect,other positions were not found this effect.Compared with the wind field on flat terrain,both horizontal and vertical wind speed have increased,and the wind speed-up factor,Mt,near the ground reached about 1.3.The position where turbulence intensity increases obviously including the foot of the slope and the area behind the crest,and other positions do not have the obvious increasing effect.With the increasing of the gradients,the amplification factor of turbulence intensity at the crest increases slightly.
2019 Vol. 38 (4): 70-76 [
Abstract
] (
210
)
HTML
(1 KB)
PDF
(1813 KB) (
259
)
77
Frequency estimation for densely intervaled components based on all-phase filtering
YANG Jundong1，YU Jiang1，HUANG Ming1，ZHANG Guo2，GE Fuhua1
To enhance the frequency estimation accuracy for densely-intervaled components,this paper proposed an all-phase filtering based spectrum correction method.Firstly，a factor reflecting the phase linearity deviation of 3 spectral lines centered with the spectral peak was constructed,which can identify whether dense components exist around the frequency position of interest.Secondly,substituting this frequency component into the analytic formula of all-phase narrow-band filter yields all the filter tap coefficients.Lastly,the estimation results were acquired by implementing an existing spectrum correction operation (such as the ratio correction) on the effective sample segment of the all-phase filter’s output.Numerical results show that,the proposed estimator can greatly remove the inter-spectra interference errors and thus achieves a higher accuracy than the existing spectrum method,which possesses a vast potential of applied prospects.
2019 Vol. 38 (4): 77-82 [
Abstract
] (
181
)
HTML
(1 KB)
PDF
(1067 KB) (
75
)
83
An experimental study on flow-induced vibration of the VIVACE converter for harnessing ocean flow energy beneath a free surface
XU Wanhai1, LUO Hao1, SUN Hai2
In this paper,a series of experimental studies on FIV of single cylinder with low mass ratio and large Reynolds number were carried out in a low turbulence free surface water channel.Cylinder response was measured by a virtual spring-damping system (Vck).It can be found that a single cylinder near free surface with Passive Turbulence Control (PTC) generally behaves three typical response types,i.e.vortex-induced vibration (VIV),transition region and galloping.The influence of the free surface is not obvious when the cylinder responds as VIV.In addition,significant effect of the free surface can be observed when the cylinder vibrates as galloping.The experimental results can provide strong support for the application of VIVACE (VIV for Aquatic Clean Energy Converter) which is one efficient device for extracting clean and renewable hydrokinetic energy from ocean flow.
2019 Vol. 38 (4): 83-89 [
Abstract
] (
174
)
HTML
(1 KB)
PDF
(1685 KB) (
116
)
90
A study on the cavitation expansion related characteristics induced by horizontal water entry of projectiles
GUO Zitao1，CHEN Tuo2，GUO Zhao1，ZHANG Wei2
In this paper,the horizontal water-entry experiments of flat,hemispherical,truncated-ogival and spherical projectiles at the velocity range of 100—300 m/s have been conducted with a light-gas gun.The whole water entry and cavitation expansion processes were recorded by a high-speed camera.Variation laws of the pressure difference Δp along the penetration distance were indirectly investigated by the principle of energy conservation.Moreover,the average cavity wall velocity at different cavity sections which are along the penetration distance was also studied.Two variation laws were found for the pressure difference Δp,and results show that the average cavity wall velocity remains consistent basically for different cavity sections along the ballistic trajectory which is in the same water-entry condition.Good agreements were observed between experimental and analytical results.
2019 Vol. 38 (4): 90-94 [
Abstract
] (
176
)
HTML
(1 KB)
PDF
(1163 KB) (
105
)
95
Design and analysis of shaking table test of a small radius curved bridge
ZHANG Zhi1，LI Xiaojun1,2,LAN Riqing2
Focusing on a small radius curved bridge,the shaking table test of a 1/16 scaled model considering pile-soil-bridge structure dynamic interaction was accomplished.The model design and implementation of the shaking table tests were demonstrated.The vibration response of pile-soil-bridge structure was obtained preliminarily using test data and observed phenomena,and the failure features and modes of the scaled model were investigated.The results showed that the frequencies were in a downtrend but damping ratios tended to increase with the intensity of input ground motion; from the bottom of pile to the bridge deck,acceleration responses of structure tended to increase; the strain and dynamic soil pressure amplitudes of pile top were maximum,and the strain of pier column was larger than pile; torsion phenomenon was observed in the test,and a series of earthquake damage phenomena,such as girder falling,bearing failure,crack penetration and local concrete crushing,were demonstrated during the test.
2019 Vol. 38 (4): 95-102 [
Abstract
] (
228
)
HTML
(1 KB)
PDF
(1803 KB) (
103
)
103
A study on a space deployable telescopic mechanism
GUAN Fengwei1,2,CAO Nailiang1,2
A one-dimensional deployable mechanism based on thin-walled open tube was proposed.First,the deployable principle of the thin-walled open tube was introduced,the section characteristics of the thin-walled open tube was analyzed,the stability condition of bistable characteristic based on the classical laminated plate theory was derived,and a steady configuration point was gave.Secondly,different diameters and angles open tube buckling stiffness was derived through the finite element analysis.Thirdly,the deployable mechanism of thin wall open tube driven by friction was proposed,which was closely fitted to the transition section wall of the thin-walled open tube by using roller driven.Finally,the prototype of thin-walled open tube deployable mechanism was manufactured,and the test verification was carried out.Test results show that the deployable mechanism can achieve stable motion under axial 50N load,and three deployable mechanisms were arranged uniformly and driven synchronously,a deployable test of the prototype under gravity unloading was realized.
2019 Vol. 38 (4): 103-109 [
Abstract
] (
269
)
HTML
(1 KB)
PDF
(962 KB) (
171
)
110
An optimal design of baffles for circumferential scan turntable laser communication
JIA Mei1,2,LI Xiaoming2，WANG Guibing1,2,TAO Tianqi1,2,ZHANG Lizhong1,2,3
The circumferential scanning and tracking system used for small satellite laser communication is installed outside the satellite,and it is subjected to huge impact load during the process of satellite launching and rising.The hood connected with the locking mechanism is a key component of optical locking,the stiffness and strength of the structure directly affects the reliability of the whole machine.This paper is based on the characteristics of the circumferential laser communication system.First,the external constraints of the hood were analyzed and calculated.Under the premise of ensuring the mechanical requirements,we optimized the design of the hood by combining topology optimization and free size optimization,so as to reduce the weight of the hood.The analysis shows that the quality of the hood is reduced by 17.08%,the maximum stress and the maximum strain are reduced by 45.45% and 54.93%,respectively,and the first three order modes are also significantly improved,which improves the usability of the hood and the reliability of the whole machine.
2019 Vol. 38 (4): 110-114 [
Abstract
] (
216
)
HTML
(1 KB)
PDF
(1022 KB) (
183
)
115
An analysis of the importance of structural earthquake demand based on random forest and least angle regression
WANG Xiuzhen1，QIAN Yongjiu1，SONG Shuai2
The nonlinear time history analyses of a reinforced concrete frame structure with viscous dampers under El Centro seismic wave were performed by OpenSEES software.The effect of damping coefficient and stiffness of viscous dampers,elastic modulus and yield strength of steel bars,damping ratio,compressive strength and elastic modulus of concrete and structure quality were considered.Three kinds of earthquake demand for reinforced concrete frame structures with viscous dampers were obtained respectively,namely,top displacement,the most story drift angle,and base shear.The application of random forest algorithm and least angle regression algorithm to the analysis of the importance of structural earthquake demand was proposed.The importance ranking to the three kinds of earthquake demand of each input random variable was obtained.The results were compared with the Monte-Carlo numerical simulation method.The results of structural seismic demand importance measure method based on random forest algorithm and least angle regression algorithm were basically the same as the Monte-Carlo numerical simulation method.These two methods are accurate and efficient,which can greatly reduce the number of samples.
2019 Vol. 38 (4): 115-120 [
Abstract
] (
170
)
HTML
(1 KB)
PDF
(1483 KB) (
97
)
121
Evaluation of bolted joints tightening force based on characteristic parameters
LUO Wenfeng1，YU Ling1,2
In order to solve the ill-posed problem in characteristic parameters identification of bolted joints,the positive problem solving idea was adopted that an objective function was proposed for parameters identification based on the dynamic equations.In addition,the characteristic parameters were used to evaluate the bolt tightening force quantitatively.Firstly,the linear model of bolted joint was constructed and frequency response functions under different bolt tightening force were measured in model test.After obtaining the objective function,the particle swarm algorithm was used to identify the characteristic parameters under different bolt tightening force.The fitting curve for characteristic parameters and bolt tightening force was obtained and used to evaluate the bolt tightening force quantitatively.Finally,the validity and applicability of proposed method was verified by a series of numerical simulations and experimental studies.The illustrated results show that the proposed method can identify parameters accurately,and the fitting curve can be used to evaluate the bolt tightening force reliably.
2019 Vol. 38 (4): 121-128 [
Abstract
] (
193
)
HTML
(1 KB)
PDF
(1227 KB) (
132
)
129
Effect of dynamic loading rate on crack propagation velocity and dynamic fracture toughness in tunnels
ZHOU Lei，ZHU Zheming，DONG Yuqing，YING Peng，WANG Lei
In the process of tunnel blasting excavation,blasting activities may induce radial cracks in the surrounding rock of tunnels.In order to investigate the propagation velocity and dynamic initiation toughness of cracks in a tunnel under different impact loads,impact experiments by using green sandstone tunnel models with a mode I crack were carried out by the middle-low speed drop weight impact test system.In the tests,the crack propagation velocity and crack initiation time were measured by crack propagation gauges (CPGs),and the measuring results were analyzed.The dynamic stress intensity factors were calculated by using ABAQUS code,and the dynamic initiation toughness under different dynamic loading rates was obtained by using an experimental-numerical method,and the property of initiation toughness was analyzed.The studying results show that: ① Crack propagation velocities increase with dynamic loading rates,and as loading rate is larger than a certain value,it gradually tends to be a constant value.Crack propagation velocity is slightly less than 0.38 times of the P-wave velocity of sandstone.② Crack initiation time decreases slowly with the dynamic loading rates,and the range of reduction is about 50 μs.③ As the dynamic loading rate increases,the dynamic initiation toughness increases gradually.
2019 Vol. 38 (4): 129-136 [
Abstract
] (
224
)
HTML
(1 KB)
PDF
(1211 KB) (
213
)
137
Analysis dynamic mechanical characteristics and fracture breaking characteristics of coal mine mudstone
WANG MengXiang WANG HaiBo ZONG Qi
In order to study the influence of dynamic load on surrounding rock of soft rock roadway in coal mines,a diameter 50 mm separated Hopkinson test device was used to test the dynamic mechanical characteristics and fracture characteristics of common mudstone under impact loading in a coal mine under different impact pressures.Combined with the failure modes of specimens,the dynamic mechanical parameters of specimens under different impact pressures were analyzed.The results of the study show that: the growth rate of stress,strain and the maximum strain of the mudstone increase with the impact pressure; the dynamic uniaxial compressive strength of mudstone show exponential growth with the strain rate,which shows strong strain rate effect; the shale test specimen is in the reflection stress wave and transmission stress; under the combined action of the reflected stress wave and the transmission stress wave,the mudstone specimen produces circumferential failure and axial splitting failure.
2019 Vol. 38 (4): 137-143 [
Abstract
] (
241
)
HTML
(1 KB)
PDF
(1109 KB) (
219
)
144
Seismic fragility analysis of an AP1000 shield building considering the fluid-structure interaction of a passive gravity water box
LI Jing, CHEN Jianyun, XU Qiang, QU Yaqing
:Non-active cooling system plays an important role in improving the security of an AP1000 nuclear power plant.But the fluid-structure interaction in gravity water box has great effects on the earthquake response of a NI shield building.In this paper,the seismic fragility analysis of a NI shield building with different water levels in a gravity water box were performed based on the ALE fluid-structure coupling algorithm and the effects of different water height on seismic fragility curves were compared.The seismic fragility curves were also obtained for proposed four kinds of baffle design schemes and the effects on seismic fragility curves were analyzed.The results show that,when there is no water in the gravity water box,the fragility of the NI shield is the highest; and the next is in the condition of normal water level which could guarantee water supply for 72 hours.NI shield buildings possess the lowest fragility when water level is 2/3 of normal water level; and the setting form of the baffles also has great effects on the fragility of the shield building.
2019 Vol. 38 (4): 144-150 [
Abstract
] (
182
)
HTML
(1 KB)
PDF
(1963 KB) (
75
)
151
An experimental study on pounding response of a self-anchored suspension bridge with single tower under pulse-like ground motions
ZHENG Qinfei,YAN Weiming, LUO Zhenyuan, XU Weibing
In order to explore the seismic response of a self-anchored suspension bridge when considering the collision effect under the action of pulse-like ground motions,a self-anchored suspension bridge with single tower was taken as a prototype to design the test model with a reduced scale of 1∶20,and three near-fault pulse seismic waves of different pulse periods were selected to perform comparative tests under uniform excitation and traveling wave excitation on a multiple-earthquake-simulation-shake-table system.According to the test results,the collision effect has significantly aggrandized the deformation of side pier bottom but reduces the displacement response of the support in varying degrees; the collision effect at ends of the model bridge first heightens and then recedes as collision gap widens while the traveling wave excitation has intensified collision at bridge ends so that the collision effect significantly amplifies the deformation of side pier bottom and deformation of main tower bottom; the closer the pulse period of pulse-like ground motions is to the basic cycle of model bridge girder,the more intense the collision effect and the more significant amplifying effect on the deformation of side pier bottom and main tower bottom,but less effect on the reduction of support displacement.Therefore,factors such as collision effect,traveling wave effect and pulse characteristics of ground motions should be considered at seismic or aseismic design of a self-anchored suspension bridge.The findings will provide references for studying bridge structure collision response.
2019 Vol. 38 (4): 151-157 [
Abstract
] (
315
)
HTML
(1 KB)
PDF
(2532 KB) (
250
)
158
A compound fault features separation method of rolling bearing based on spectral kurtosis combined with maximum correlated kurtosis deconvolution
HU Aijun,ZHAO Jun,SUN Shangfei,HUANG Shenshen
Aiming at the problem that the compound fault features in vibration signal is difficult to be separated accurately,a compound fault separation method was proposed based on spectral kurtosis (SK) and maximum correlated kurtosis deconvolution (MCKD).Firstly,the fault signal was analyzed by spectral kurtosis,and resonance band was selected to carry out band-pass filtering to extract several fault signals.Secondly,the envelope demodulation method was used to analyze the extract vibration signals,complete the separation process for the vibration signal that can extract single fault feature.Finally,the maximum correlation kurtosis deconvolution was applied to the vibration signals that can separate single fault feature.The effectiveness of the method was verified by the improved compound fault simulation model.The analysis results of measured fault signals of rolling bearing show that the method can realize accurate separation of compound faults.
2019 Vol. 38 (4): 158-165 [
Abstract
] (
261
)
HTML
(1 KB)
PDF
(3131 KB) (
207
)
166
A dynamic model and modal analysis of a precision ball transmission system
ZHANG Yue，AN Zijun，LIU Ziqiang，BAI Xiaopeng
In order to reveal the inherent characteristics of a precision ball transmission system accurately,Considering the influence of the curvature of the cycloidal groove and the variation of meshing normal force on the mesh stiffness,the time-varying mesh stiffness of the meshing pair was obtained by the torque balance equation and the axial force balance equation.A translational-torsional coupling dynamics model of the precision ball transmission system was established,the dynamics of differential equations of the system were derived,the characteristic equation of free vibration of the system was obtained and the natural frequencies and vibration modes were solved.The results show that the natural frequencies of the transmission system are changed periodically.When the parameters of the prototype are given,loci veering occurs at the approach of respective natural frequency curves of low-order (1—10 order) and middle-high-order (27—29 order and 30—34 order) and there are changes between the linear vibration mode of the constant speed ball group 1 and the linear vibration mode of the constant speed ball group 2 at the intersection of the high-order (39—42 order) natural frequency curves with the increasing of the rotation angle.
2019 Vol. 38 (4): 166-174 [
Abstract
] (
191
)
HTML
(1 KB)
PDF
(2031 KB) (
107
)
175
Incremental dynamic analysis method based on force analogy method
HAO Runxia1,YANG Zuoxu1,LI Gang2,YU Dinghao2,JIA Shuo2
Incremental dynamic analysis (IDA) method is an effective method to evaluate the seismic performance of structures,but it needs a large number of nonlinear dynamic time history analysis,which requires a large amount of calculation work and time consuming,especially for large and complex structures.An incremental dynamic analysis method based on pseudo-force method (FAM) was proposed in this paper.By introducing additional fictitious loads,the global stiffness matrix of the IDA equation of motion was kept unchanged all the time when the equation of motion was solved nonlinearly.Under the excitation of multiple amplitude-modulated ground motions,by storing and calling the specific stiffness matrix,the reuse of the whole stiffness matrix in the whole process of IDA analysis was realized,and then the calculation efficiency was improved.The time complexity evaluation method was used to quantitatively compare the calculation efficiency of this method with that of the traditional IDA method.The calculation results and time complexity of the two methods were compared through the IDA analysis of the 8-story reinforced concrete frame structure.The accuracy and efficiency of the method were verified.
2019 Vol. 38 (4): 175-183 [
Abstract
] (
258
)
HTML
(1 KB)
PDF
(1467 KB) (
156
)
184
Simulation and experiments on shaped charge jets’ penetration into aircraft aluminum-alloy skin
DONG Shikang1,HU Fangyou1,CUI Aiyong1,HUANG Xudong2,LIU Qian2
Traditional cutting methods cannot meet the repair requirements of aircraft skin perforation damages under battlefield conditions.This article proposed a novel method to cut metal skin damage areas by taking advantage of the Munroe effect of charges.The authors conducted research on the new explosive cutting process using 2A12 aluminum plates of 2 mm thickness.The application carriers of the explosive cutting technology were lead-shell metal-pipe linear shaped charges with wedge-shaped grooves,and the cutters were filled up with hexogen (RDX).Based on the ANSYS/LS-DYNA,the finite element model of the linear shaped charge penetrating aluminum alloy plates was constructed.The cutting performances of linear shaped charges under different process parameter sets were analyzed using the orthogonal design method.Three influencing factors,including charge linear density,liner apex angle,and standoff were optimized.The numerical calculation results agree well with the experimental results,which indicates the favorable accuracy of the finite element model.In the end,the optimized explosive cutting process parameters were decided as a charge linear density of 1.5 g/m,a liner apex angle of 80°,and a standoff of 0.The prototype tests implies that new linear shaped charges adopting these parameters could meet the battlefield repair requirements of aircraft skin perforation damages in the aspects of cutting accuracy and abnormity cutting.
2019 Vol. 38 (4): 184-190 [
Abstract
] (
238
)
HTML
(1 KB)
PDF
(1342 KB) (
369
)
191
Ride and roll stability analysis of off-road vehicles with torsio-elastic suspension
CHAI Mu,RAKHEJA Subhash,SHANGGUAN Wenbin
A three-dimensional ride dynamic off-road vehicle model with torsio-elastic suspension was formulated to investigate the potential of ride comfort improvement as well as roll stability preservation for different suspension arrangements.The model validation was based on the field measurements of a rear-suspended vehicle with torsio-elastic suspension.According to the vibration response analysis near the operator seat and the roll angle of vehicle chassis,the results show that the torsio-elastic suspension could improve the ride performance as well as increase the roll stability of the vehicle.The results also illustrate that the fully-suspended vehicle could obviously decrease the vibration at the driver seat along all axes,and front-suspended vehicel could provide a batter ride performance,compared the rear-suspended vehicle.The loading effect was also analysed for vehicles with different suspension options,which illustrates that the torsio-elastic suspension is less sensitive to variations in the load.
2019 Vol. 38 (4): 191-198 [
Abstract
] (
169
)
HTML
(1 KB)
PDF
(2875 KB) (
65
)
199
Purification for a large rotor axis’s orbit based on the difference spectrum theory of singular value
ZHANG Jingrun,LI Weiguang,LI Zhen,ZHAO Xuezhi
Aiming at purification of rotor axis’s orbit in a large bearing testing platform,an approach was proposed based on the difference spectrum theory of singular value.The difference spectrum could directly describe the difference between the beneficial component and noise.The number of the useful components could be determined by the first peak of the difference spectrum.The Hankel matrix was constructed from original vibration signal and was decomposed by the singular value decomposition (SVD).The feature singular values were selected using the difference spectrum and feature components were obtained by the SVD reconstruction,and then the purified rotor axis’s orbit could be obtained with the feature components.The processing effect of SVD and harmonic wavelet packet algorithm was compared,and the results show that the axis orbit purified by the difference spectrum of singular value was much clearer.
2019 Vol. 38 (4): 199-205 [
Abstract
] (
158
)
HTML
(1 KB)
PDF
(3150 KB) (
319
)
206
Random vibration simulation analysis and an optimization design of analytical balance packages
MI Nannan, LI Guang
The finite element analysis method was used to analyze the modal and random vibration acceleration PSD of analytical balance package to obtain the stress distribution nephogram and the acceleration power spectral density response curve.The multi-objectives optimization design on cushioning pads were performed to obtain the cushioning structure of low cost and high property.The finite element model was established via Solidworks,and the dynamic simulation was done via Ansys Workbench.The deformation and vibration properties of the package in the transportation process were analyzed to find out the weak points of the package.The Optimal design of response surface was conducted the cushioning pad with acceleration,maximum deformation and mass of the package as the objective function.After response surface optimization analysis,the performance of the package was improved.Through the simulation analysis and the optimization design on the analytical balance package,the structure size of cushioning pad can be improved,the breakage rate of the product during transportation can be reduced,and the cushioning structure can be lightweight.
2019 Vol. 38 (4): 206-212 [
Abstract
] (
256
)
HTML
(1 KB)
PDF
(2092 KB) (
156
)
213
A numerical study on the effects of mass moment and moment of inertia on hydrofoil’s flow-induced vibration and noise
LIU Long ZHANG Huaixin YAO Huilan
The flow-induced vibration and sound radiation problem of three-dimensional hydrofoil with two-degree of freedom (2DOF) was studied in this paper with the URANS method.The hydrofoil’s vibration was implemented with calculating the hydrofoil’s motion equations,the flow field was calculated with the k-ω SST turbulence model.First of all,the mesh independent verification and time step verification were carried out.The method was validated by comparing the simulation results with that of experiment and the Theodorsen’s theory,which shows quantitatively agreement.Furthermore,the impact of mass moment and moment of inertia to the vibration and the sound radiation problems were calculated.The calculation results show that the effects of mass moment and moment of inertia to the vibration of hydrofoil are significant,and the hydrofoil’s vibration will increase the noise.
2019 Vol. 38 (4): 213-221 [
Abstract
] (
191
)
HTML
(1 KB)
PDF
(2480 KB) (
128
)
222
A study on the evolution of vortex in the draft tube of pump-turbine under the runaway condition
LI Qifei1,2,ZhAO Chao-ben1,LONG Shi-can1, QUAN Hui1,2
To study the hydraulic instability of pump-turbine under runaway condition with different guide vane openings,the pump-turbine of a certain pumped storage power station was employed.Based on the Realizable k-ε turbulent model,the unsteady flow of the whole passage of the pump-turbine with seven different guide vane openings was calculated.The pressure fluctuation of the inlet of the volute,blade free section,the region between the runner and the roof,and draft tube was monitored to study the evolution of vortex shape and pressure fluctuation on the draft tube with the effects on different guide vane opening.Results show that when the guide vane opening is different under runaway condition,there is a distinct difference of the shape of the vortex.In the small guide vane opening,the vortex is obvious and the shape of the vortex changes constantly.With the increase of the guide vane opening,the shape of the vortex tends to the pattern of geometric cone from the disordered status,as well as the screw vortex rope presents the thicker tendency gradually.In the large guide vane opening,the higher velocity distribution near the vortex rope wall leads to the great loss of turbulent kinetic energy and other forms of energy near the straight cone region.Meanwhile,the key reason why great pressure fluctuation is caused in the draft tube is that the vortex is transported continuously towards the downstream.
2019 Vol. 38 (4): 222-228 [
Abstract
] (
214
)
HTML
(1 KB)
PDF
(1653 KB) (
112
)
229
Analysis and design of a stiffness H∞ controller of electro-hydraulic rudder based on the LMI method
DONG Sheng,YUAN Zhaohui
The stiffness of a steering gear determines the control ability of the aircraft to the position of the rudder.When the aircraft is moving,with the change of the load disturbance frequency of the rudder,the stiffness characteristics are also changing.If the stiffness of a frequency point is minimum,the rudder surface is drastically jitter,and the safety of the entire vehicle will not be guaranteed.Therefore,a large number of simulation calculations are needed during the design of a steering gear controller,and the method of reducing the disturbance should be found at the beginning of the design phase.In this paper,the system model of an electro-hydraulic rudder was set up first,and the stiffness characteristics of the system were obtained by simulation.Then the H∞ controller was designed based on the Linear Matrix Inequality method,by solving the LMI optimization problem with constraint conditions.The designed controller can improve the dynamic stiffness of the system to a great extent.Finally,the simulation results show that the controller can improve the anti disturbance ability of the system.The stiffness of the system is constant in a certain range of disturbance frequency,and the control gain of the disturbance channel is reduced.When the system parameters fluctuate,the system can still keep good anti-disturbance ability and strong robustness,the design of the controller was verified by the actual project.
2019 Vol. 38 (4): 229-236 [
Abstract
] (
173
)
HTML
(1 KB)
PDF
(2349 KB) (
78
)
237
Closed-loop vibration control simulation of a helicopter active rotor with trailing-edge flaps based on the weighted-least-squares-error identification method
ZHOU Jinlong1,DONG Linghua1,YANG Weidong1,LIU Shiming2
An active rotor is effective active vibration control for helicopters.Focusing on closed-loop vibration control of an active rotor with active controlled flap (ACF),a coupled aero-elastic model with ACF was developed.Open-loop control simulation for the ACF was conducted through amplitude sweep,frequency sweep,and phase sweep,and their influence on rotor vibratory loads was studied.The higher harmonic control algorithm was employed in the closed-loop control simulation,while the weighted-least-squares-error (WLSE) method was used to identify the transfer matrix of the active rotor system.Actuator saturation was also taken into account using the auto-weighting method.The controller demonstrates satisfying control performance,and the vertical vibratory load of passing frequency is reduced by up to 87%.The simulation results will be useful to direct the engineering implementation of the closed-loop control system for the active rotor.
2019 Vol. 38 (4): 237-244 [
Abstract
] (
171
)
HTML
(1 KB)
PDF
(1479 KB) (
292
)
245
Pistol bullet impact soft body armor covered bionic human torso
TANG Liujian1, WEN Yaoke1, XUE Benyuan1, CHENG XU Cheng1，SONG Jiao2
In order to study the damage mechanism of blunt impact,the“gelatin-thorax”bionic human torso was built firstly.Then,the synchronous test system was designed to study the pistol bullet penetrating into armor covered bionic human torso.Pressure sensors were buried in the position of the heart and left lung to get dynamic pressure characteristics of these two places.When the heart was under blunt impact,the peak pressure in the position of the heart reached 2.40 MPa,the peak pressure in the position of the left lung reached 1.30 MPa; When the impact point was at the right lung,the peak pressures,which spread to the positions of the heart and left lung,were 0.39 MPa and 0.25 MPa,respectively; When the impact point was at the liver,the peak pressures,which spread to the positions of the heart and left lung,were almost equal to 0.10 MPa.The penetration process captured by a high-speed camera,presented that the soft body armor occurred very large transient deformations and then spring back with the elastic deformation of human torso.A 3cm height plastic bulge was formed on the back face of the soft armor.These results can provide references to blunt trauma evaluation and body armor design.
2019 Vol. 38 (4): 245-249 [
Abstract
] (
178
)
HTML
(1 KB)
PDF
(1233 KB) (
240
)
250
Pressure shock of hydraulic excited piping study based on a lattice Boltzmann method
YUAN Xin1,WU Wanrong1,HAO Qianhua1,2
In order to study the hydraulic vibration pipeline problem,a multi-relaxation-time lattice Boltzmann method was introduced based on the dynamic theory of mesoscopic particles.A multi-relaxation lattice evolution model was estabilished for hydraulic excited pipes.Pipe pressure shock caused by valve closing was simulated.Under the condition of different valve closing time and different flow velocities,the change law of pipeline pressure shock and the influence of velocity field on pressure were analyzed.The results show that the relationship between the time of closing valve and the period of pressure wave is the root cause of the pipeline pressure shock.By comparison with the simulation results of the traditional finite volume method,it is found that the Littice Boltzmann method can simulate the pressure shock phenomenon in hydraulic exciting pipe,and the results are in good agreement with the results of the traditional method and the operation efficiency is obviously higher.Analysis of the velocity field shows that velocity transients are the root cause of the pressure transients.The comparison of the two analysis methods shows that the lattice Boltzmann method has the advantages of easy programming and high computational efficiency and so on,thus can be applied to the analysis and research of a complex hydraulic exciting system.
2019 Vol. 38 (4): 250-257 [
Abstract
] (
142
)
HTML
(1 KB)
PDF
(1453 KB) (
59
)
258
A study on additional effective damping ratio of viscous dampers from time-uistory analysis
WU Xu1,ZHOU Meirong1,CHEN Xi2,ZHANG Xuemei1
To investigate additional effective damping ratio contributed by viscous dampers in structures during time-history analysis,by focusing on the work done by damping forces (damping energy),the paper established a relation between damping energy and equivalent damping ratio in time-history analysis,put forward theoretical formula of additional effective damping ratio,created finite element analysis models to testify the formula,and compared damping energies of the energy dissipation structure and an equivalent structure.The results show that the formula of equivalent damping ratio is more versatile and reasonable than other current formulae.It is applicable for calculating additional effective damping ratio of a energy dissipation structure in any time-history load case,and make energy dissipation structure and equivalent structure to have equal damping energy.
2019 Vol. 38 (4): 258-262 [
Abstract
] (
232
)
HTML
(1 KB)
PDF
(725 KB) (
317
)
Copyright © 2015 JOURNAL OF VIBRATION AND SHOCK
TEL: +86-21-62821366 http://jvs.sjtu.edu.cn E-mail: jvs@sjtu.edu.cn
Support by
Beijing Magtech
support@magtech.com.cn
