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2020 Vol. 39, No. 21
Published: 2020-11-15
 
1 Bearing fault diagnosis method based on GRNN-SOFTMAX classification model
CHEN Jian1,2，LV Wuyang1，ZHUANG Xuekai1，TAO Shanyong1
Aiming at rolling bearing vibration signals under complex working conditions, a bearing fault diagnosis classification method based on the generalized regression neural network-SOFTMAX (GRNN-SOFTMAX) classification model were proposed to realize bearing fault mode identification.Firstly, the variational mode decomposition (VMD) was performed for rolling bearing vibration signals to do feature extraction and other pre-processing, and obtain a feature data set.The feature data set was divided into a training one, a verification one and a test one.Then, the training set and test set were used to train the GRNN-SOFTMAX classification model.The grey wolf optimizer (GWO) was introduced to optimize the key parameter’s smoothing factor of the above model, and obtain an ideal classification model.Finally, the trained model was applied in the test set to output the fault identification results.Through simulation tests, bearing fault data under different working conditions was collected to verify the effectiveness of the proposed method.Results showed that the proposed method can use a small sample training set to realize effective diagnosis of bearing faults under different working conditions; it is a fault diagnosis method suitable for actual working conditions.
2020 Vol. 39 (21): 1-8 [Abstract] ( 258 ) HTML (1 KB)  PDF (1542 KB)  ( 92 )
9 Model updating hybrid simulation test method based on uniform design
CHEN Zaixian, ZHONG Weipeng, LI Qinming
With increase in DOFs, substructure number and updating parameters in hybrid simulation tests, sample points and computational amount needed to search more optimal parameters for model updating hybrid simulation tests can obviously increase.Here, from the perspective of testing design, a model updating hybrid simulation test method based on uniform design was proposed.Based on tested substructures, the uniform design was used to construct a sample space of checking substructures.Taking restoring force as an objective, the most suitable numerical model of checking substructures for tested substructures was found as the source of updating constitutive parameters of the studied numerical structure to effectively improve the identification efficiency.Considering different constitutive models of steel products and bending moment processing situations at boundaries of tested substructures, a single-span two-story steel frame structure was taken as an example to do 4 types of numerical simulations.The model updating hybrid simulation tests adopted Matlab-OpenSees mixed programming, and the software data interaction adopted socket interface.The efficiency was improved effectively compared with the traditional text read-write interaction.Results showed that the proposed method is suitable for different boundary processing situations; the model updating calculation time is reduced greatly, and the accuracy of the proposed hybrid simulation tests is improved effectively.
2020 Vol. 39 (21): 9-16 [Abstract] ( 157 ) HTML (1 KB)  PDF (1835 KB)  ( 52 )
17 Recognition of leakage aperture of natural gas pipeline based on compression sensing and convolution network
WEN Jiangtao1, FU Lei1, SUN Jiedi2,3, WANG Tao1, ZHANG Guangyu1, ZHANG Pengcheng1
Aiming at problems of large redundancy of raw data, strong subjectivity dependence of feature selection and low recognition accuracy under complex environment for traditional natural gas pipeline leakage aperture recognition, a leakage aperture recognition method based on compression sensing and 1-D convolution network was proposed.Firstly, the random Gaussian matrix was used to do compression collection of original leakage signals, and the full leakage information was obtained with less compression sensing domain data.Then, a deep 1-D convolutional network was constructed, and the compression collection data were fed into the network to realize adaptive feature extraction and leakage aperture recognition with high accuracy.Finally, effects of the main parameters on recognition results were analyzed.Test results showed that the proposed method can quickly and accurately realize the leakage aperture identification of natural gas pipelines; it has better robustness under low SNR environment; its overall recognition effect is superior to that of the traditional classification method.
2020 Vol. 39 (21): 17-23 [Abstract] ( 196 ) HTML (1 KB)  PDF (1967 KB)  ( 158 )
24 Application of cage guided by combined action of outer race and balls in bearing vibration reduction
LIU Wentao1, ZHANG Xu1, WANG Shouren1, ZHANG Yun2, WANG Gaoqi1
Cage is a key component of a rolling bearing, and when a high-speed rolling bearing’s cage motion is guided by its outer race, contact and collision between cage and outer race can cause bearing’s larger vibration.Here, to reduce bearing vibration, a new cage guide mode was proposed, the cage motion was guided by the combination of outer race and balls.A cage with outer lock mouth pocket hole structure was designed to realize this guide mode.The cage’s pocket hole structure was composed of two parts, the part near the outside of the pocket hole was spherical, and the diameter of the outer port of the pocket hole was smaller than that of balls; the part near the inside of the pocket hole was cylindrical, and the diameter of the inner port of the pocket hole was larger than that of balls.Then, the mechanical model for motion of a cage with outer lock mouth pocket hole structure guided by combination of outer race and balls was established.Under conditions of different rotating speeds, offsets and contact states, magnitude and variation law of forces acting on a cage with outer lock mouth pocket hole structure and one with straight pocket hole structure, respectively in the opposite direction of their offsets were analyzed contrastively.The cage with outer lock mouth pocket hole structure was machined with the lathe cutting method, and its reducing bearing vibration effect was verified with tests.
2020 Vol. 39 (21): 24-33 [Abstract] ( 205 ) HTML (1 KB)  PDF (2499 KB)  ( 54 )
34 Dynamic response and trench development of deep-sea steel catenary riser touchdown section under floating bodies’ heave excitation
ZHENG Mengtian1,2, YUAN Yuchao1,2, XUE Hongxiang1,2, TANG Wenyong1,2
Based on Randolph-Quiggin nonlinear riser-soil interaction model, dynamic response characteristics of a steel catenary riser (SCR) touchdown section under its top floating bodies’ heave excitation were studied.Touchdown elements of the SCR were developed by using the user defined element extension module (UEL) in subroutine function of ABAQUS.The rationality and effectiveness of the developed numerical model were verified and its advantages over those of the traditional linear model were discussed by comparing to model test results.The effects of amplitude and frequency of top heave excitation on seabed trench shape, riser displacement and bending moment response were deeply explored with parametric sensitivity analysis.
2020 Vol. 39 (21): 34-41 [Abstract] ( 183 ) HTML (1 KB)  PDF (3340 KB)  ( 46 )
42 Tests for underwater radiated noise transmission characteristics caused by ship cabin air noise excitation
WU Guoqi， LIN Jin
Real ship tests were conducted to study transmission characteristics of underwater radiated noise caused by cabin air noise excitation.A real ship test method for underwater radiated noise caused by cabin air noise excitation was established with the simulated sound source excitation method.Based on a single input/output model and transfer function, the analysis method for transfer characteristics from air noise to underwater radiated noise was established.Real ship sound source excitation tests were conducted to acquire time histories of air noise and underwater radiated noise as well as the transfer function from air noise to underwater radiated noise, analyze feature laws and transmission characteristics of underwater radiated noise caused by air noise excitation, and verify the feasibility and validity of the real ship transfer characteristics test and analysis method.Results showed that there is a linear relationship between cabin air noise and underwater radiated noise; their transfer relationship presents characteristics of a linear system related to frequency; the overall change trend of the transfer function from air noise to underwater radiated noise within the frequency range of 50 Hz-5 kHz has a feature law of first increase and then decrease.
2020 Vol. 39 (21): 42-46 [Abstract] ( 122 ) HTML (1 KB)  PDF (656 KB)  ( 37 )
47 Influences of far field measurement boundary on jet noise measurements
ZHANG Junlong1, LEI Hongsheng2, ZHAO Kun2, MA Ruixuan2, LI Jie1
Jet noise test is one of the most important means to study jet noise generation mechanism and denoising measures.In order to ensure the reliability of jet noise’s far field measurement data, a reasonable selection needs to be made between far field microphone layout condition and SNR of the final data.A strict design of jet noise simulation device and sophisticated acoustic measurement and correction method were used to systematically study influence laws of jet noise measuring angle and position, and jet speed, etc.factors on far field measurement results.The mechanism analysis was done for jet noise spectra variation features with increase in distance.Finally, the minimum far field boundary condition for far field measurement of jet noise was determined with tests, and an appropriate correction method was presented for far field jet noise measurements not satisfying far field boundary conditions.
2020 Vol. 39 (21): 47-54 [Abstract] ( 191 ) HTML (1 KB)  PDF (2735 KB)  ( 97 )
55 Seismic response analysis of local layered sea reef site
BAO Xin1, LIU Jingbo1, WANG Dongyang2, LI Shutao1, WANG Fei1
Here, comprehensively considering dynamic coupling action between reef and seawater, wave radiation effects at cutoff boundaries of solid and fluid media as well as seismic wave input, a 2-D seismic response analysis model for local layered reef-seawater system was established to study seismic field distribution laws of reef site by comparing with horizontal stratification site and slope platform site in land area.Results showed that seismic response amplitude of reef site is significantly amplified compared with that of horizontal layered site, the acceleration peak amplification coefficient near the middle point of reef top can reach 1-1.5, and that near the  corner point can reach 1.5-2; topographic factors, such as, seaward slope and reef flat width, and reef-seawater dynamic coupled effect have significant influences on seismic response of island reef site, seismic response analyses of a 1-D soil layer and slope platform site are difficult to fully describe real distribution characteristics of seismic field of island reef site; for important reef engineering sites, it is necessary to perform a reef-seawater coupled dynamic analysis for the purpose of reflecting their real mechanical characteristics.
2020 Vol. 39 (21): 55-64 [Abstract] ( 123 ) HTML (1 KB)  PDF (4614 KB)  ( 26 )
65 Numerical simulation for rotating motion of a natural super-cavitating vehicle
WANG Rui1, LIU Chuanlong2, ZHAO Sanfei2, QI Xiaobin1
Here, numerical simulation was performed for cavitation shape and hydrodynamic characteristics of a natural super-cavitating vehicle in its maneuver process.Based on Logvinovich’s principle of independent expansion, the theoretical model of its rotating motion under action of centrifugal force and the 3-D numerical calculation model for solving rotating motion of the super-cavitating vehicle were established.By comparing calculation results of these two models, the effectiveness of the numerical simulation method was verified.The numerical simulation method was used to study influence laws of centrifugal force’s “straightening” action on hydrodynamic characteristics of the vehicle in cavitation, and analyze pressure distribution characteristics on the surface of the vehicle at different rotating angular velocities.Results showed that with increase in rotating angular velocity, cavitation axis’s external displacement increases, the centrifugal force’s straightening cavitation action becomes stronger to have greater influence on development of cavitation on both sides of the vehicle’s rotation radius; lift coefficient and moment coefficient present a sinusoidal distribution; when rotating angular velocity is less than 1 rad /s, the generated pitching moment has a “head up” effect on the vehicle; when rotating angular velocity is larger than 1 rad /s, the generated pitching moment has a "head down" effect on the vehicle.
2020 Vol. 39 (21): 65-70 [Abstract] ( 175 ) HTML (1 KB)  PDF (2080 KB)  ( 49 )
71 Impact damage boundary of spacecraft plug-in components
XU Zijian1, NANGONG Zijun1,2, LI Bingwei1, ZHANG Zijun1, YU Muchun1, NIU Zhiling1
Spacecraft plug-in components can be damaged easily under serious shock environment to affect harmfully normal operation of aerospace electronic equipment, and even cause flight accidents.Impact dynamic response analysis was used to construct the impact damage boundary of plug-in components.Aiming at a frequently used plug-in component in spacecraft called Sub-Miniature-A (SMA) RF coaxial connector, numerical simulation and impact tests were conducted to verify its impact damage boundary.Results showed that when the dominant frequency of shock environment is lower than the first order natural frequency of SMA connector, its impact damage boundary is the absolute acceleration response asymptote of shock environment; when the dominant frequency of shock environment is higher than the first order natural frequency of SMA connector, its impact damage boundary is the relative displacement response asymptote of shock environment; the study results can provide an important base for the equivalent technique study of impact test conditions based on damage equivalent and the environmental adaptability design of spacecrafts.
2020 Vol. 39 (21): 71-78 [Abstract] ( 130 ) HTML (1 KB)  PDF (1931 KB)  ( 41 )
79 Numerical simulation for influence of line spacing on crossing pressure wave of high-speed trains in tunnel
HU Xiao1, KONG Fanbing2, LIANG Yongting2, YU Miao2, DUAN Xiuping1, MEI Yuangui1
Based on 3-D, unsteady and compressible flow Reynolds-averaged N-S equations and SST k-ω turbulence model, adopting the overlapping grid technique, effects of 3 line spacings of 4.6 m, 4.8 m and 5.0 m on crossing pressure wave during 2 high-speed trains meeting in a tunnel at speeds of 250 km/h, 350 km/h and 400 km/h were studied.In view of the harm of intersection pressure wave, the effects were presented from three aspects including the maximum pressure value of car body, the pressure difference on both sides of car body and the phenomenon of “head-tail wave”.Results showed that the time history curve shape of the pressure difference on both sides of car body is similar to that of crossing pressure wave in open line; when the head and tail of the met train passing the measurement points, the pressure difference produces firstly positive and then negative pulses and firstly negative and then positive pulses, respectively, the pressure difference generated by the train tail passing is obviously lower than that by the train head passing; the amplitude of the head wave is about two times of that of the tail wave; the maximum positive pressure, the maximum negative pressure, the maximum pressure peak value, the amplitude of pressure difference on both sides of car body and the amplitude of “head and tail wave” have a negative exponential relationship with line spacing.
2020 Vol. 39 (21): 79-88 [Abstract] ( 164 ) HTML (1 KB)  PDF (3182 KB)  ( 52 )
89 Coupled dynamic response of a cylindrical tunnel based on fractional order thermo-elasticity theory
WEN Minjie1,2, XU Jinming2, XIONG Houren2
Based on the generalized fractional order thermo-elasticity theory, coupled dynamic response of a cylindrical tunnel in an infinite soil under the action of heat/power source was investigated with the analytical method.The governing dynamic equations of the surrounding soil under time-varying thermal or force impact on inner wall surface of the circular tunnel were established.The analytical expressions for dimensionless temperature increment, radial displacement, radial stress and circumferential stress of soil body were obtained using Laplace transformation.Then, dynamic responses of soil body in time domain were obtained with Laplace Inverse Transformation and Crump numerical inversion method.Effects of fractional order parameters on soil body’s temperature, radial displacement, radial stress and circumferential stress under heat/power source were analysed numerically.It was shown that fractional order parameters have less influence on soil radial displacement, but have larger influence on soil temperature increment, radial stress and circumferential stress under action of heat source; fractional order parameters have significant influence on soil temperature increment, but have less influence on soil radial displacement, radial stress and circumferential stress under the joint action of heat and power sources; with increase in shear modulus, displacement peak values gradually decrease.
2020 Vol. 39 (21): 89-94 [Abstract] ( 156 ) HTML (1 KB)  PDF (1264 KB)  ( 46 )
95 Collapse characteristics of multi-cell square tube structure under oblique load
LI Zhichao1, KANG Yingzi1, ZHEN Ran2, LI Ruilong2, SHANGGUAN Wenbin1
The finite element model for calculating energy absorption characteristics of multi-cell square tube structure was established, and axial collapse tests of double-cell tubes were used to verify the correctness of the established model.The developed model was used to study collapse characteristics of multi-cell square tube structure under oblique load.Results showed that multi-cell square tube structure can have the global buckling deformation under oblique loads with angles of 20°and 30° to cause significant drop of its energy absorption capacity.Thus, a layered multi-cell square tube structure was proposed.It was shown that the layered multi-cell square tube structure has a larger energy absorption capacity and crushing force efficiency under oblique loading; under oblique loads with large angles, it can avoid the global buckling deformation.Using the complex proportion assessment method, oblique comprehensive impact performances of traditional square tubes, multi-cell ones and layered multi-cell ones were evaluated to determine the layered multi-cell square tube L5 having the optimal oblique impact performance.
2020 Vol. 39 (21): 95-100 [Abstract] ( 173 ) HTML (1 KB)  PDF (1655 KB)  ( 47 )
101 Influences of higher order wheel polygon on vibration of wheel-rail system
YANG Runzhi1, ZENG Jing2

Higher-order wheel polygon can have bad effects on vehicle dynamic performance, increase wheel-rail force, cause severe vibration of a vehicle-track system, cause fatigue damage to rail and wheel tread, produce fatigue cracks and uneven wear, and form a large noise pollution.Here, the rigid-flexible coupled dynamic model of a vehicle-rail system was constructed based on the rigid-flexible coupled system dynamics theory considering flexibility of track, wheel pair (including brake disc), bearing and axle box as well as rigid frame and car body.Effects of train speed, wheel polygon order and wave depth on vibration characteristics of wheel pairs, brake discs and axle boxeswere analyzed, and vibration transfer relations between axle and brake disc were studied.In addition, by adding emergency braking conditions, influences of braking conditions on lateral vibration of brake disc were analyzed, and vibration characteristics of brake discs at different positions were compared.Finally, the reliability of the proposed model was verified with tests.
2020 Vol. 39 (21): 101-110 [Abstract] ( 186 ) HTML (1 KB)  PDF (3065 KB)  ( 63 )
111 A solving method for impact response of a nonlinear dry friction system
YU Huijie, WANG Wenqian, CHANG Wei
Based on the dynamic model of a nonlinear dry friction system,combining with the strong geometric nonlinear mechanical charactristics of mental friction plates, the calculation formula for acceleration response of a dry friction isolator under larger impact load was derived by using the piecewise Duhame integral method.The theoretical calculation results were compared with test ones of pendulum to simulate large impact.It was shown that the proposed method can better reflect motion laws of a metal dry friction isolator under larger impact.
2020 Vol. 39 (21): 111-115 [Abstract] ( 193 ) HTML (1 KB)  PDF (1274 KB)  ( 40 )
116 A quasi-zero stiffness vibration isolation system based on bi-stable laminate
DENG Zehua, LI Hao, ZHOU Xubin
Here, according to the principle to decrease the overall stiffness of a system with a parallel negative stiffness mechanism, using negative stiffness feature of a bi-stable laminate and linear spring in series to form a new negative stiffness mechanism, a novel bi-stable laminate-based quasi-zero stiffness (QZS) vibration isolation system with tunable static stiffness was proposed.The mechanical principle of the proposed system was illustrated.Hamilton principle was used to derive the dynamic and static models of the system.The stiffness characteristics of the system were analyzed with theoretical and finite element methods.Results showed that the proposed vibration isolation system can realize different static stiffness characteristics and keep the QZS feature by matching stiffness of series and parallel linear springs.The verification tests of stiffness characteristics and vibration isolation performance were conducted for the manufactured principle prototypes.It was shown that the measured force-displacement curves agree well with the simulation results; the proposed quasi-zero stiffness vibration isolation system can effectively broaden the vibration isolation frequency band of a linear vibration isolation system with the same positive stiffness.Based on the test results, combining with the theoretical model, influence factors on vibration isolation performance were analyzed and discussed.
2020 Vol. 39 (21): 116-125 [Abstract] ( 145 ) HTML (1 KB)  PDF (3334 KB)  ( 57 )
126 Structural vibration response prediction based on Blocked force method
LIU Niansi1, WENG Jiansheng1, ZHENG Zijian2
Vibration-noise source characteristics recognition is an important task in development of automobiles.Here, aiming at limitations of acquiring excitation in traditional transfer path analysis (TPA) method, a novel TPA method based on the Blocked force method was proposed to directly measure equivalent force and replace excitation source for structural vibration analysis.The Blocked force method was derived theoretically to verify the correctness of its theory.The method was used to study the structure-borne noise problem caused by working excitation of   an electronic brake booster(EBB).Results showed that vibration responses of its front panel predicted with this method agree well with measured values in tests; the engineering feasibility of the proposed method is verified;the study results provide a theoretical basis for the optimization of EBB structure-borne noise in vehicle development.
2020 Vol. 39 (21): 126-131 [Abstract] ( 137 ) HTML (1 KB)  PDF (1744 KB)  ( 101 )
132 Tests for collection of vibration and power generation characteristics with Fe-GA alloy material
LIU Huifang1,2, ZHAO Qiang1, GAO Shuang1, ZHANG Jing1
With more and more demandsfor technologies, such as, wireless sensor networks and remote health monitoring, vibration energy collectionis significantly developed.Here, a new type cantilevered vibration energy collection and power generation device based on magneto-strictive material Fe-Ga alloy was designed, developed and tested to harvest vibration energy in environment and convert it into electric energy.According to the dynamic model analysis of a Fe-Ga alloy cantilever beam, the mathematical model for the system’s maximum transfer efficiency was established, and the conditions to obtain the maximum transfer efficiency were clarified.The first five orders resonance frequencies of the system were determined with Lissajous graphic method.The influence law of frequency and amplitude of vibration excitation on the output voltage of the system was studied with comprehensive tests.A method to obtain the optimal energy conversion capability by adjusting the system with additional mass was proposed.With the aid of a signal interface circuit, the prototype successfully lighted up multiple LED light-emitting diodes and LED portable computer keyboard lights to further verify the sustainable power generation capability of the prototype.
2020 Vol. 39 (21): 132-139 [Abstract] ( 111 ) HTML (1 KB)  PDF (3176 KB)  ( 36 )
140 An improved deconvolution algorithm and its application in compound fault diagnosis of rolling bearing
QI Yongsheng1, FAN Ji1, LI Yongting1, GAO Xuejin2, LIU Liqiang1
Aiming at problems of compound fault signals of rolling bearing being non-stationary and nonlinear, and different types faults being coupled with each other to make it difficult to extract impact features of compound faults with the traditional method, a new fault diagnosis method was proposed based on the adaptive resonance-based signal sparse decomposition (ARSSD) and multipoint kurtosis optimal minimum entropy deconvolution adjusted (MKOMEDA).Firstly, ARSSD was adopted to analyze faulty signals, and a new composite index was defined as the objective function.Cuckoo search algorithm (CSA) was used to optimize high quality factors and low ones to obtain the optimal low resonance component containing transient impact components.Secondly, this low resonance component’s multipoint kurtosis spectrum was calculated to extract its fault impact periodic components.Thirdly, after a suitable period interval was set, different fault features were separated using the deconvolution calculation.Finally, using envelope demodulation, prominent fault feature frequencies in the spectrum were analyzed and then to identify fault types.A test platform was used to simulate composite cases of two and three faults of rolling bearing, and verify the proposed algorithm.Results showed that the proposed method can effectively extract various fault features in composite faults, and realize fault diagnosis.
2020 Vol. 39 (21): 140-150 [Abstract] ( 169 ) HTML (1 KB)  PDF (1565 KB)  ( 72 )
151 Vibration absorption effect of whole satellite system with series nonlinear energy sink
ZHANG Wenyong, NIU Muqing, CHEN Liqun
Here, in order to improve dynamic environment of a satellite in launching stage, a nonlinear energy sink device was introduced into the satellite adapter structure, it was coupled with the main structure of the satellite to realize the whole satellite system’s vibration suppression.For the equivalent lumped mass model of the whole satellite system after coupled, considering influences of the nonlinear energy sink’s gravity on nonlinear spring restoring force, using the 4th order Runge-Kutta method, vibration responses of the whole satellite system under harmonic excitation and impact excitation were solved.Results showed that vibration responses considering gravity are more accurate than those without considering gravity, their amplitudes are a bit smaller; to further lift the nonlinear energy sink device’s vibration suppression efficiency without changing original natural frequencies of the whole satellite system, a nonlinear energy sink device with the same mass and a two-stage series structure was adopted, and its nonlinear stiffness parameters were optimized based on the theory of target energy transfer.The analysis results showed that the nonlinear energy sink with 2-stage series structure can have better vibration reduction effect than the one with a single-stage structure can under impact excitation.
2020 Vol. 39 (21): 151-155 [Abstract] ( 175 ) HTML (1 KB)  PDF (733 KB)  ( 57 )
156 A 2-DOF vibration energy capture device for magnetic levitation rail vehicle
KONG Lingqiang, YUAN Tianchen, YANG Jian, YANG Li
Here, a 2-DOF vibration energy capture devicefor magnetic levitation rail vehicle was proposed.This energy capture device was installed at the rail vehicle’s bogie, and its vibration energy collection efficiency was significantly improved compared with that of a single-DOF one.The dynamic model of the 2-DOF vibration energy capture device were established theoretically, and its dynamic characteristics were analyzed.Runge-Kutta method was used to calculate and obtain its dynamic characteristics and output power under simple harmonic vibration excitation and vertical vibration excitation of the rail vehicle.The calculated results were compared with those of the single-DOF energy capture device.Results showed that the 2-DOF energy capture system has two resonance peaks to widen its working frequency band range; changing its size parameters can lift its energy capture efficiency aiming at target frequency; the output power of the 2-DOF energy capture system is 1.5 times of that of the single-DOF one under simple harmonic vibration excitation and vertical vibration excitation of the rail vehicle to effectively capture vibration energy of the rail vehicle.
2020 Vol. 39 (21): 156-162 [Abstract] ( 119 ) HTML (1 KB)  PDF (2296 KB)  ( 98 )
163 Order reduction of geometrically nonlinear dynamic system based on POD in frequency domain
CHEN Bing1, GONG Chunlin1, QIU Likuan2, GU Liangxian1
In order to improve solving efficiency of a structural nonlinear dynamic system under large geometric deformation condition and study its dynamic behavior in a specified frequency range, the proper orthogonal decomposition (POD) method in frequency domain was used to study the dynamic order reduction problem of a geometrically nonlinear structure with a cantilevered plate taken as the study object.The geometrically nonlinear stiffness of the plate was solved using the cooperative rotation (CR) method.POD base vectors were generated with snapshots computed in a specified frequency domain, and Galerkin method was used to realize the order reduction of dynamic system.The nonlinear stiffness was added to the external force term in the form of increment, and the nonlinear behavior of the system was reflectedin the form of generalized external force.The POD order reduction analysis in frequency domain and comparison were done for the cantilevered plate.Results showed that (1) for a linear system, the POD order reduction analysis in frequency-domain has high precision, the error is less than 1%, and its solving time is far less than that for the full order system, the solving time for 1 order POD is less than 50% of that for the full order system; (2) for a nonlinear system, the error of 1 order POD analysis is less than 1.5%, and the error of 3 order POD analysis is less than 0.5%, the solving time for the two cases is less than 75% of that for the full order analysis under sine and step loads; (3) for a geometrically nonlinear dynamic system under multi-point random loads, if the first 6 orders POD base vectors are kept after order reduction in frequency domain, the reduced order system’s analysis error is less than 0.5% and its solving time is just 79% of that for the full order system.
2020 Vol. 39 (21): 163-172 [Abstract] ( 212 ) HTML (1 KB)  PDF (2945 KB)  ( 158 )
173 Active control system of vehicle interior road noise based on NFXLMS algorithm
ZHANG Lijun1,2, ZHANG Xiyu1,2, MENG Dejian1,2
Here, aiming at time-varying, broadband and random characteristics of vehicle interior structure-borne road noise, the road noise active control system was established based on the normalized filter-x least mean square (NFXLMS) algorithm.Firstly, through theoretical deriving,the multi-channel filter-x least mean square (FXLMS) algorithm and the multi-channel NFXLMS algorithm were established, respectively.The computation complexity analysis showed that the computational increment of NFXLMS algorithm can be negligible.Then, off-line simulation models for the vehicle interior road noise active control system were built with the two algorithmsin Simulink.The off-line simulation using data collected from damaged rough asphalt pavement showed that the road noise activecontrol system based on NFXLMS algorithm has better robustness and working condition adaptability.Finally, a MicroAutoBox was taken as the real-time controller, the hardware-in-loop test platform for the vehicle interior road noise active control system based on NFXLMS algorithm was built, and actual road tests were conducted to verify the effectiveness of the system.
2020 Vol. 39 (21): 173-178 [Abstract] ( 266 ) HTML (1 KB)  PDF (1682 KB)  ( 164 )
179 Dynamic analysis of pipe conveying fluid under impact load with spectral element method
LI Baohui, JING lina, WANG Zhengzhong
Here, a pipe axial flow-induced vibration model was built based on Timoshenko beam, and the spectral element method (SEM) was applied in dynamic response analysis of a pipe conveying fluid.By means of discrete Fourier transformation, the pipe’s dynamic equations in time domain were converted into those in frequency domain. Being similar to the finite element method (FEM), the spectral element matrix equation was obtained.Then, the computation method was developed for dynamic response of pipe conveying fluid under point impact loads.The natural frequencies and dynamic responses of the pipe conveying fluid were computed with SEM, and the results were compared with those published in literature to verify the effectiveness of SEM.Finally, the pipe’s dynamic responses were computed using SEM under different fluid flow velocities and transient impact loads.Results showed that the proposed SEM has a high accuracy; only two spectral elements are needed to analyze dynamic responses of a pipe conveying fluid under point impact loads.
2020 Vol. 39 (21): 179-185 [Abstract] ( 143 ) HTML (1 KB)  PDF (1109 KB)  ( 42 )
186 Non-linear dynamic characteristics of ejection transplanting mechanism with joint clearance
QIN Zhe, QIAN Mengbo, GONG Jianwei, LI Xibin
Rotary transplanting mechanism is a current research hotspot, and it is simple in structure, safe and reliable, and can complete the work of picking, transporting and planting seedlings at the same time.However, current research mainly focuses on function design, the problem of joint clearance caused by machining error, design precision, etc.is not considered.The clearance can cause collision and vibration of pair elements in joint and variation of constraint conditions, number of DOF and topological structure of the system.So, the influence of joint clearance has to be considered when studying dynamic characteristics of a transplanting mechanism.Here, based on dividing contact modes of pair elements, the contact force solving model of a clearance revolute jointwas established.A solving subroutine for contact force was compiled with Fortran language, it was embedded into the function solving library of ADAMS.An ejection transplanting mechanism considering revolute joint clearance was simulated based on this subroutine.Results showed that the joint clearance should not be too large or too small, otherwise it can cause severe collision between pair elements and their vibration; the study results provide a reference for improving control precision of transplanting mechanisms with joint clearance.
2020 Vol. 39 (21): 186-194 [Abstract] ( 140 ) HTML (1 KB)  PDF (2494 KB)  ( 159 )
195 A method for rolling bearing fault feature extraction based on parametric optimization VMD
ZHENG Yuan, HU Jianzhong, JIA Minping, XU Feiyun, TONG Qingjun
Aiming at the problem of only using a single penalty factor in traditional variational mode decomposition (VMD) being difficult to extract fault features of rolling bearing in practical application, a method forrolling bearing fault feature extraction based on parametric optimization VMD was proposed.Firstly, the number of decomposition layers K was determined according to the maximum kurtosis criterion.Secondly, the penalty factor corresponding to each mode was optimized with the whale algorithm to realize adaptive selection of each mode’s optimal penalty factor, and obtain a vibration signal’s the optimal mode decomposition.Finally, the kurtosis criterion was used to screen the decomposed modal components, perform envelope demodulation, and extract bearing fault features.The improved VMD was used to analyze simulated signals and engineering actual data.Results showed that compared with the traditional VMD, EEMD and the fast speed spectral kurtosis method, the proposed method can effectively improve the sensitivity of fault feature extraction; it is valuable in engineering applicationto a certain extent.
2020 Vol. 39 (21): 195-202 [Abstract] ( 132 ) HTML (1 KB)  PDF (1288 KB)  ( 71 )
203 Modeling and simulation of composite vibration absorber for urban rail vehicle body
SUN Qian, WEN Yongpeng, JI Zhonghui, ZOU Yu
To reduce vibration of urban rail vehicle body, using modal orthogonality, car body was equivalent to a homogeneous Euler beam with uniform cross-section, the vertical dynamic model of an elastic body-track-composite absorber rigid-flexible coupled system was established, and the design method for composite absorber suitable for this model was proposed.According to operating conditions of urban rail vehicles, the functional relation among stiffness, mass parameters and target frequency of the composite absorber was solved analytically.By going through the mass value of two vibrators of the composite absorber, its matching stiffness parameters were obtained.Using the established evaluation index of the body vibration energy, the vibration reduction performance of the composite absorber designed with different parameters was evaluated to obtain the parametric design of the composite absorber with the minimum body vibration energy.Finally, the vibration reduction effect of the composite absorber was verified by combining with the vehicle stationarity index.The research results showed that there are two natural frequencies of the composite absorber; when designing its parameters, the two natural frequencies should be coordinated with the natural frequency of vehicle body floating and sinking and body first-order elastic frequency; the established body vibration energy evaluation index can be used to comprehensively evaluate vibration reduction performance of absorbers with different designs; the composite absorber installation has a better vibration reduction effect on the vehicle body vibration, and improves the vehicle’s operation quality; the study results provide a reference for the research using composite vibration absorbers to reduce   vehicle vertical vibration.
2020 Vol. 39 (21): 203-210 [Abstract] ( 70 ) HTML (1 KB)  PDF  (0 KB)  ( 20 )
211 Real-complex conversion parametric estimation algorithm based on subtraction strategy
CHEN Peng, TU Yaqing, LIU Yan, LI Ming, MOU Zelong
To suppress the influence of negative frequency component of a real signal on its parametric estimation, and improve the accuracy of parametric estimation, a real-complex conversion parametric estimation algorithm based on the subtraction strategy was proposed.Firstly, the sample signal was pre-processed with FFT algorithm to construct the reference signal only containing negative frequency components.Secondly, the subtraction strategy was used to subtract the reference signal from the sample one to realize the real-complex conversion.Then, the spectral interpolation analysis was done for the generated complex signal to obtain the estimated value of frequency offset.Finally, accurate estimated values of frequency, amplitude and initial phase were obtained with iterative calculation.Meanwhile, the estimated value for the signal to noise ratio (SNR) of the sample signal was solved through constructing the reference signal and using definitions of the subtraction strategy and SNR.The simulation test results indicated that the proposed algorithm can suppress the influence of negative frequency components, and have a good frequency estimation accuracy under conditions of different SNRs and frequencies, the mean square error of the frequency estimation value is closer to Cramer-Rao lower bound; it has good estimation performances for amplitude, initial phase and SNR of signals.
2020 Vol. 39 (21): 211-216 [Abstract] ( 94 ) HTML (1 KB)  PDF (1097 KB)  ( 37 )
217 Simulation of radial vibration characteristics of piezoelectric ceramic composite ultrasonic transducer
ZHANG Chao, DONG Shimin, LIU Tianming, ZHANG Jingxiang, JIA Hetong, LIU Qingyang
Being different from existing transducer equivalent circuit analysis methods, based on the mechanical system vibration theory, combined with the constitutive equation, radial vibration characteristics of a piezoelectric ceramic composite ultrasonic transducer were analyzed.It was simplified into the mechanical model of a combined thick-walled cylinder composed of a piezoelectric ceramic tube and a metal prestressed one.The radial vibration mathematical model of the transducer was established including radial vibration-wave coupled equation of a piezoelectric ceramic tube and a metal prestressed one, and the combined thick-walled cylinder’s radial vibration continuity condition and boundary conditions.The transducer’s natural frequency equation and mode shape function were derived.The calculation results of its natural frequencies have a higher coincidence rate with experimental measurement values published in references.Based on the analytical method and the difference method, numerical simulation models for the transducer’s radial vibration were established, and the amplitude-frequency characteristics and displacement responses of the transducer’s radial vibration were simulated.The simulation results showed that amplitude-frequency characteristics curves and displacement responses obtained using the two methods, respectively are the same to verify the correctness of the simulation results.Through simulation analysis, it was shown that the effect laws of structure size of the transducer on its radial vibration natural frequency are as follows: if the thickness of metal prestressed tube and piezoelectric ceramic one is constant, the transducer’s natural frequencies decrease with increase in inner diameter of piezoelectric ceramic tube; if the outer diameter of metal prestressed tube and the inner diameter of piezoelectric ceramic one are constant, the transducer’s natural frequencies decrease with increase in thickness ratio of piezoelectric ceramic tube to metal prestressed one.
2020 Vol. 39 (21): 217-225 [Abstract] ( 215 ) HTML (1 KB)  PDF (1178 KB)  ( 62 )
226 Elasto-hydrodynamic lubrication of gears under coupling of vibration and contact impact
JIAN Guangxiao, WANG Youqiang, YU Xiao, LUO Heng, LI Yunkai
In order to explore elasto-hydrodynamic (EHL) characteristics of gears under coupling of vibration and contact impact, considering effects of time-varying meshing stiffness on gear dynamic behavior, a 6-DOF friction dynamic model of involute spur gears was established based on the theory of dynamics.Then, the contact impact phenomenon caused by velocity difference at meshing point of gears was studied.Effects of dynamic load and steady load, impact position and impact rotating speed on gears’ time-varying EHL were analyzed contrastively.Results showed that compared with steady load, the EHL study based on dynamic load can more accurately reflect gears’ transient lubrication characteristics; the velocity difference at meshing point can cause contact impact phenomenon of two gears’ teeth; the impact rotating speed and position have larger influence on impact resultant force and further affect gears’ lubrication; the closer to meshing point the impact position, the higher the impact rotating speed, the more obvious the "surge" effect of gear lubrication; too high impact rotating speed or too small gear equivalent mass can cause "de-meshing" in gear transmission process.
2020 Vol. 39 (21): 226-232 [Abstract] ( 228 ) HTML (1 KB)  PDF (863 KB)  ( 49 )
233 Low-frequency vibration suppressor applied in suppressing vibration and acoustic radiation of underwater thin plate
WANG Yujie, TAO Meng, FU Lei, ZHAO Xuefeng
In order to study vibration and noise reduction performance of a low-frequency vibration suppressor to an underwater plate structure, an acoustic-vibration simulation model of an underwater plate structure considering fluid-structure interaction was established.By comparing its FE results with the theoretical solution, the feasibility of the FEM was verified.Effects of material and structural parameters of the low-frequency vibration suppressor on vibration and sound radiation of an underwater simply supported plate were analyzed.Results showed that low-frequency vibration suppressor has a wider vibration suppression frequency range and characteristics to suppress bending wave propagation in plate structure; viscoelastic material plays an important role in vibration and noise reduction performance of low-frequency vibration suppressor; increasing loss factor is beneficial to the effect of low-frequency vibration suppressor; increasing material Young’s modulus can reduce peak values of high frequency vibration and sound radiation in plate structure, but it is not true that the larger the Young’s modulus, the better the overall effect; increasing  low-frequency vibration suppressor’s mass and height is beneficial to improving its performance within a lower frequency range; changing its cavity diameter can simultaneously change its mass, stiffness and damping, so choosing its cavity diameter should comprehensively consider effects brought by variation of these parameters.
2020 Vol. 39 (21): 233-240 [Abstract] ( 144 ) HTML (1 KB)  PDF (1591 KB)  ( 66 )
241 Multi-objective parameter optimization for ultrasonic milling of titanium alloy in longitudinal and torsional directions based on NSGA-II
NIU Ying, JIAO Feng, ZHAO Bo, Wang Xiaobo
Aiming at problems of high cost, low efficiency and poor quality appearing in processing titanium alloy, etc.aeronautical materials, the longitudinal-torsional ultrasonic vibration was combined with milling, and the nondominated sorting genetic algorithm II (NSGA-II) was proposed to do multi-objective optimization for processing and ultrasonic parameters.Firstly, based on orthogonal tests, the prediction models for machining induced residual stress, surface roughness (SR), surface hardness (SH) and tool life were established and validated, respectively.Then, to get larger residual compressive stress (RCS) and higher processing efficiency, the multi-objective optimization model I was built.To get larger RCS and SH, the model II was built.To get lower SR and larger surface RCS, the model III was built.To get smaller SR and higher processing efficiency, the model IV was built.To get lower SR and higher tool life, the model V was built.To get lower SR and SH, the model VI was built.Finally,tests were conducted to verify these optimization models and their results.Results showed that the established optimization models based on NSGA-II can provide various parameter optimization schemes with higher accuracy for different engineering applications.
2020 Vol. 39 (21): 241-249 [Abstract] ( 135 ) HTML (1 KB)  PDF (2408 KB)  ( 64 )
250 Anti-explosion performance of stay cable under near field blast load
SHEN Dajia, HU Zhijian, LI Yang
In order to study dynamic response of a stay cable of cable-stayed bridges under blast loading, based on the basic blast theory, the anti-explosion performance of the cable under near field blast loading was analyzed.Stress and damage of the cable were analyzed, and further the parametric analyses for different scaled distances were performed.Results showed that under near field blast load, fracture does not appear on the cable, and its failure mode presents a failure caused by its stress exceeding yield one;its weakest position is the cable-girder anchorage zone where the stress of the cable is larger than that of the cable near explosion point due to reflection of blast wave; the safe scaled distance to keep the cable from failure is 0.287 m/kg1/3,if the scaled distance is larger than this critical scaled distance, the cable can’t fail.
2020 Vol. 39 (21): 250-257 [Abstract] ( 77 ) HTML (1 KB)  PDF  (0 KB)  ( 24 )
258 Improved model of seismic power spectrum and its application in artificial ground motion synthesis
DING Jiawei1, HE Haoxiang1, YAN Xiaoyu2
Ground motions have significant time-frequency non-stationarity and randomness.The precision of the current intensity envelope function and power spectrum model to characterize ground motions’ time-frequency features should be verified with statistical analysis.Here, to overcome the limitation of the method for direct alignment of peak values of time-domain signals and other ones being not able to verify statistical characteristics of intensity envelope function, a method to establish statistical model of seismic intensity based on energy duration was proposed to verify the accuracy of traditional statistical model of intensity envelope under different site types.Statistical analysis
showed that the current power spectrum model based on random response with exceeding probability has insufficient precision in high frequency range.So,a high-frequency suppression term was proposed to be added to the original formula, and do modification.Results showed that the corrected formula can improve the precision obviously.Aiming at the traditional smooth power spectrum model being not able to fully characterize the non-stationarity of actual ground motions in frequency domain, a smooth-noise power spectrum model was proposed to realize fine description of ground motion power spectrum.Finally, an artificial ground motion synthesis method with time-frequency domain dual-control was proposed.It was shown that the proposed method can simultaneously meet the accuracy requirements of response spectrum and power spectrum, and realize higher accuracy ground motion generation.
2020 Vol. 39 (21): 258-266 [Abstract] ( 136 ) HTML (1 KB)  PDF (4559 KB)  ( 46 )
267 Physical parametric identification of time-varying system based onchirp wavelet integration
ZHANG Jie, SHI Zhiyu, ZHAO Zongshuang
A method of chirp wavelet integration was derived based on the short-time linear change assumption.Applying this method, velocity and displacement response signals of a time-varying structure were reconstructed only with its acceleration response signal.Then, time-varying stiffness and damping of the structure were identified by constructing a least squares algorithm when the structure’s mass parameters were known in advance.It was shown that due to introducing frequency modulation slope parameter to characterize the short-term frequency modulation characteristics of a signal, compared with the traditional identification method, this method can better track fast time-varying parameters and greatly improve computational efficiency.In a simulation example, a 3-DOF time-varying structure model was constructed, and its physical parameters were identified under various time-varying conditions to verify the correctness, applicability and anti-noise ability of the proposed method.
2020 Vol. 39 (21): 267-273 [Abstract] ( 168 ) HTML (1 KB)  PDF (2304 KB)  ( 17 )
274 Mis-operation mechanism and suppressing method for pipeline explosion-proof valve
GAO Xuezhong1，3, LIU Xiaoping1，2, QIANG Hongbin1，2, ZHANG Lijie1，2
Aiming at the practical difficult problem of pipeline explosion-proof valves being easy to be mis-operated in engineering application,a simulation model for flow rate of a pipeline explosion-proof valve system and the software Amesim was established.Through theoretical analysis, it was shown that the fundamental reason of mis-operation is the influence of the system flow rate and working temperature on flow rate characteristics of pipeline explosion-proof valve.Modeling and simulation were performed under the software Amesim environment, and test verification was conducted with a harbor equipment.Results showed that the method to adjust system’s valve parts and control working temperature can effectively avoid the mis-operation of pipeline explosion-proof valves;this method can provide a reference for the application and site debugging of pipeline explosion-proof valves.
2020 Vol. 39 (21): 274-278 [Abstract] ( 154 ) HTML (1 KB)  PDF (1267 KB)  ( 27 )
279 Ultrasonic non-linear detection tests for 45 steel thermal damage
MAO Hanying1, QIN Guoli1, LI Qingzhu2, YI Xiaoxu2, MAO Hanling2
45 steel is a common material for parts manufacturing, and it is important to study its thermal damage detection for parts failure assessment.Here, in order to study ultrasonic nonlinear effects of 45 steel with different degrees of thermal damage, specimens with different degrees of thermal damage were made.Ultrasonic nonlinear detection tests were conducted for specimens using the RAM-5000 system made by RITEC company to obtain relation curves between ultrasonic nonlinear coefficients and heating temperature.These curves were deeply analyzed combining with the material’s metallographic microstructure evolution laws.Results showed that the ultrasonic nonlinear coefficient of 45 steel firstly increases, then decreases and increases again with increase in heating temperature;when heating temperature reaches 600 ℃, the ultrasonic nonlinear coefficient begins to increase; when temperature reaches 800 ℃, itreaches the peak value;thenit drops sharply, this is consistent with the coherent strain state of 45 steel between 700-800 ℃; finally, it at 1 300 ℃ rebounds slightly;the correlation between variation of ultrasonic nonlinear coefficient of 45 steel and its metallographic microstructure varying provides atest basis for the ultrasonic nonlinear detection of 45 steel thermal damage and the evaluation of its metallographic microstructure change.
2020 Vol. 39 (21): 279-283 [Abstract] ( 52 ) HTML (1 KB)  PDF  (0 KB)  ( 20 )
284 Tests for effect of track vibration reduction measures in a depot on vibration and noise reduction of a superstructure
WANG Yigan1, LIU Penghui1, LI Teng2, ZHOU Zheng1

9 kinds of track structures were tested at the original position of the 20th track in a depot of Beijing Metro.The vibration reduction effect of 8 kinds of track structures and the denoising effect of secondary structure noise indepot’s superstructure were analyzed contrastively.According to the test data of structural vibration and structural noise, the relationship between structural vibration and secondary structure noise was analyzed, and the prediction formulafor secondary structure noise based on structural vibration was verified.The research indicated that structural vibration and secondary structure noise caused by train passingin superstructure of subway depot have high consistency in frequency domain; secondary structure noise can be predicted according to vibration speed of floor; due to differences of weight calculation methods and frequency calculation ones, there are differences in numerical expression of vibration reduction value and structural noise reduction one;in practical engineering, reasonable track vibration reduction measures should be selected according to the actual vibration and noise spectral characteristics.
2020 Vol. 39 (21): 284-291 [Abstract] ( 211 ) HTML (1 KB)  PDF (3127 KB)  ( 69 )
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