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  
2021 Vol. 40, No. 11
Published: 2021-06-15
 
1 Analysis of fractional order nonlinear system based on Adomian decomposition method and realization of Lyapunov exponent algorithm
LEI Tengfei1,2, HE Jinman3,4, WANG Yanling1, ZANG Hongyan1, HUANG Lili1, FU Haiyan1
Here, for a fractional order Lü hyperchaotic system, its nonlinear term was decomposed using Adomian decomposition method, and the system’s phase diagram was obtained with the software MATLAB.Then, abundant dynamic characteristics of a 0.90 order fractional order Lü hyperchaotic system were analyzed and studied with numerical simulation of the system’s bifurcation diagram, spectral entropy (SE) complexity, C0 complexity, etc.At the same time, QR decomposition was adopted to do expansion of Lyapunov exponent calculation.MATLAB was used to do simulation, it was shown that Lyapunov exponent spectrum is consistent with the complexity.
2021 Vol. 40 (11): 1-6 [Abstract] ( 325 ) HTML (1 KB)  PDF (1926 KB)  ( 138 )
7 Passive suction and blowing flow control of wind-induced vibration of tall buildings
LU Shanshan1,2, ZHANG Zhifu1,2, LIU Jinbo1,2, CHEN Wenli1,2, WANG Wei1,2
In order to suppress wind-induced vibration response of a high-rise building structure, a flow control method based on passive suction and blowing was proposed.The square cross-section high-rise building structure was combined with passive suction and blowing rings.A suction and blowing channel was set on the facade of the structure, and the unsteady vortex shedding was destroyed by the structure wake blowing to reduce average wind load and fluctuating wind load acting on the structure surface, and suppress wind-induced vibration.In wind tunnel tests, variation laws of wind load, wind-induced vibration response and tail flow field of the test model were studied when passive suction and blowing rings were installed at 3 different heights of the model.The test results showed that the passive suction and blowing ring control device can effectively suppress the overall wind load and wind-induced vibration response of the high-rise building structure; the closer to the structure top the ring installed position, the more significant the wind-induced vibration control effect.
2021 Vol. 40 (11): 7-16 [Abstract] ( 192 ) HTML (1 KB)  PDF (4253 KB)  ( 70 )
17

Global sensitivity analysis for peak response of a cantilevered rotor with single disc during start-up

Global sensitivity analysis for peak response of a cantilevered rotor with single disc during start-up[J]. JOURNAL OF VIBRATION AND SHOCK, 2021,40(11): 17-25')" href="#"> ZHOU Shengtong1, ZHANG Pei1, XIAO Qian1, LI Hongguang2, ZHOU Xinjian1, WANG Di1
The global sensitivity of peak response (such as, the maximum peak and its occurrence time) during start-up is an important basis for dynamic design and evaluation of flexible rotor systems.Here, based on Timoshenko beam rotor theory and the finite element method, and considering the randomness of input parameters, the deterministic and stochastic dynamic equations of a cantilevered rotor with a single disc during transient start-up were established.Then, with the limited number of test design samples, the calculation process of the asPC-Sobol sensitivity was given by combining adaptive sparse polynomial chaos (asPC) expansion and Sobol global sensitivity.Finally, based on the analysis of deterministic results of the mean operating condition and the verification of effectiveness of the asPC model, effect laws of start-up acceleration, parametric variability and response measurement point position on the maximum peak value and its time variance of the cantilevered rotor with a single disc passing through the first order positive whirl critical speed were discussed in detail.Example results showed that (1) under the condition of ± 3σ truncated Gaussian distribution, the maximum peak and its time distribution more accord with the lognormal normal distribution, disc diameter D, thickness T, material density ρ, elastic modulus E and unbalance f are the main contribution parameters of the peak response variance; (2) the starting acceleration can more obviously affect the total sensitivity of the maximum peak, but its influence on the total sensitivity of the maximum peak occurrence time is much smaller; (3) when the variability of some main contribution parameters (D, T and ρ) decreases individually or simultaneously, the total sensitivity of the other main contribution parameters can increase obviously, while the increase of the total sensitivity of  those non main contribution parameters is limited very much; (4) the influence of the position of response measuring point on the total sensitivity of the maximum peak value and its occurring time is very small, especially, at non-bearing positions.
2021 Vol. 40 (11): 17-25 [Abstract] ( 214 ) HTML (1 KB)  PDF (2746 KB)  ( 41 )
26 Effect of concentration gradient on explosion characteristic parameters of methane-air mixture
LI Zhe, CHEN Xianfeng, SUN Weikang
In order to study the influence of concentration gradient on combustion and explosion characteristics of methane-air premixed gas, pressure and temperature sensors were arranged in a square explosion experimental pipeline to perform explosion experiments of methane-air premixed gas under different methane concentration gradients.The results showed that with increase in concentration gradient, the average flame velocity and the maximum explosion pressure of methane-air premixed gas in the pipeline increase firstly and then decrease, and both reach the maximum when the concentration gradient is 1.0%; the rising rate of explosion pressure increases firstly and then decreases with increase in concentration gradient, and reaches the maximum when the concentration gradient is 1.5%; with increase in concentration gradient, the time to reach the maximum explosion pressure presents a reciprocating trend; with increase in concentration gradient, the explosion temperature of methane-air mixture firstly increases and then decreases.
2021 Vol. 40 (11): 26-32 [Abstract] ( 166 ) HTML (1 KB)  PDF (1892 KB)  ( 36 )
33 Topology optimization of constrained damping plate based on non-negative sound intensity
WU Zhenyun, ZHAO Wenchang, CHEN Haibo
Here, the acoustic radiation problem of constrained damping plate was analyzed and discussed based on the concept of non-negative intensity (NNI).The optimal distribution of damping material of constrained damping plate was studied.NNSI was applied to recognize the structure surface area with the main contribution to far-field sound radiation.Based on the solid isotropic material with penalization (SIMP) density interpolation scheme, an optimization model was established by taking the relative density of damping material as the design variable, the volume ratio of damping material as the constraint, and the surface area with the minimum contribution to sound radiation as the objective function.The moving asymptotic algorithm was used to solve the optimization model.Taking the plate with four fixed edges as an example, the vibration plate surface region with significant contribution to far-field was analyzed, and the distribution of damping material was designed optimally.The example results showed that the topology optimization algorithm based on NNI is effective in denoising optimization design, and has the potential to change the structural vibration radiation mode.
2021 Vol. 40 (11): 33-41 [Abstract] ( 177 ) HTML (1 KB)  PDF (2220 KB)  ( 42 )
42 Hydraulic characteristics of vibrational transport of a piped carriage within a pipeline
ZHANG Chunjin1， ZHANG Xueqin2， ZHANG Min1， LI Yongye3， SUN Xihuan3,4， JIA Xiaomeng3
In recent years, the problems of traffic congestion, energy crisis, and environmental pollution in the traditional transport modes have severely restricted the sustainable development of both economics and ecological environmental.The tube-contained raw material pipeline hydraulic transportation is a transport method with both energy saving and environmental protection, which overcomes the shortcomings of traditional transport modes.In order to analyze the hydraulic characteristics of vibrational transport of a piped carriage within a pipeline, the fluid-solid coupling solution between fluid domain of the flow field and the solid domain of the piped carriage within the pipeline was given, and simulated results were compared with experimental results.The results show that the instantaneous translational speed and instantaneous rotational angular speed of the piped carriage are in fluctuating state, and the motion of the piped carriage is regarded as vibrational transport.The increase in the placement angle of the guide vane causes both the translational speed and the rotational angular speed of the piped carriage to increase.The annular gap flow and the pipe fluid mixed with each other, causes the pressure at the downstream flow field of the piped carriage to first decrease and then increase.The velocity distributions of vibrational transport of the piped carriage are unified, while the pressure distributions shows a descending trend.The increase in the placement angle of the guide vane causes the average pressure drop coefficient to first decrease and then increase, and when the placement angle is set to 24°, the average pressure drop coefficient reaches the minimum.This paper provides a theoretical basis for practical application of the tube-contained raw material pipeline hydraulic transportation.
2021 Vol. 40 (11): 42-47 [Abstract] ( 111 ) HTML (1 KB)  PDF (2108 KB)  ( 17 )
48 Tests for vertical tension and horizontal hysteretic load of assembled steel
ZHOU Jing1,2, LI Peng1
Quasi-static tests of 6 assembled concrete-filled steel tube (CFST) composite shear wall specimens with shear span ratio of 1.62 were conducted to study effects of CFST core column content ratio, out of plane eccentricity and initial axial tension on the aseismic performance of assembled composite shear walls. Failure characteristics, hysteretic performance, deformation and ductility, load-bearing capacity, stiffness degradation and energy consumption of specimens were analyzed.The results showed that the overall failure mode of assembled composite shear wall specimens is bending-shear composite failure, they still have higher load-bearing capacity under the combined action of vertical tension and horizontal bending-shear hysteresis, the hysteretic curve is full, deformation and energy consumption are better, and their residual stiffness is large during failure; the shear deformation component is linearly related to the total deformation, it is about 21% of the total displacement; the average ultimate displacement angle of specimens is 1/42, their average ductility coefficient is 5.0, so the assembly integrity of composite shear walls is good; their shear-bearing capacity increases with increase in concrete-filled steel tube content ratio, while their deformation curvature decreases; their shear-bearing capacity decreases with increase in initial axial tension and out of plane eccentricity, the appropriate axial tension can increase the cross-section deformation capacity, but the out of plane eccentricity is unfavorable to deformation.
2021 Vol. 40 (11): 48-57 [Abstract] ( 132 ) HTML (1 KB)  PDF (3827 KB)  ( 37 )
58 Dynamic vertical interaction between man and bridge based on circular arc plantar inverted pendulum model
ZHU Qiankun, SHANG Xuqiang, ZHANG Qiong, DU Yongfeng
Here, based on a new circular arc plantar inverted pendulum model, vertical interaction between man and bridge was studied.The pedestrian was simplified as a concentrated mass and two supporting legs with arc sole.Lagrange equation was used to establish the dynamic equation of interaction between pedestrian and bridge.The fourth-fifth order Runge-Kutta algorithm with variable step size was used to numerically solve the equation.The variation causes of vertical walking force, dynamic load factor and mass center displacement were contrastively analyzed when pedestrian passing through rigid ground and vibrating bridge deck, and the relationship among pedestrian walking frequency, dynamic load factor and self-excited force was discussed.The study results showed that the bipedal model can accurately capture changes of pedestrian mass center and gait; the dynamic load factor increases with increase in pedestrian step frequency when pedestrian passing through a vibrating bridge; the vertical walking force has a certain self-excited force nature due to interaction between pedestrian and bridge, and self-excited forces are different under different pedestrian step frequencies.
2021 Vol. 40 (11): 58-64 [Abstract] ( 111 ) HTML (1 KB)  PDF (1290 KB)  ( 22 )
65 Dynamic characteristics of cylindrical eddy current damper under impact load
WANG Nannan, LIU Ning, SHEN Yanping, SUN Mingliang
Here, in order to study dynamic characteristics of cylindrical eddy current damper under impact load, the dynamic model of eddy current damper under impact load was established.The finite element model of cylindrical eddy current damper under impact load was established using the analysis software Maxwell, and the air gap magnetic field and eddy current distribution were analyzed.Relations of eddy current damping force and damping coefficient versus speed, respectively in braking deceleration stage were studied, and effects of working air gap, thickness of conductor cylinder and yoke thickness on braking performance of eddy current damper were analyzed.The impact loading test device of eddy current damper was developed, and test results agreed better with simulation ones.The study results showed that under the premise of ensuring motion accuracy of mover, working air gap should be as small as possible, yoke thickness should be 3/4 of permanent magnet thickness, and conductor cylinder thickness should be 1-2 mm, which are favorable to improve damping coefficient of eddy current damper; eddy current damper has good cushioning and braking performance under impact load, and has important application value in impact braking fields of weapon launching, train braking, etc.
2021 Vol. 40 (11): 65-69 [Abstract] ( 155 ) HTML (1 KB)  PDF (1198 KB)  ( 66 )
70 Dynamic energy absorption performance of arrow type honeycomb structure with negative Poisson’s ratio under impact load
BAI Linqi, SHI Xiaoquan, LIU Hongrui, SUN Yazhou
Here, taking an arrow type honeycomb structure with negative Poisson’s ratio as the study object, based on the existing theoretical stress model of honeycomb structure platform under impact load, its theoretical model of energy absorption under impact load was established considering platform area and platform stress enhancement area, and relations between the absorbed energy and the corresponding equivalent stress and geometric parameters in different stages under impact load were obtained.Based on the simulation software ANSYS, the energy absorption and stress of the arrow type honeycomb structure with negative Poisson’s ratio under impact load were simulated.The simulation results were compared with the theoretical model results to verify the theoretical model.The results showed that the proposed theoretical model can accurately describe the dynamic energy absorption performance of honeycomb structure under impact load, and provide a guidance for geometric parameter choosing and optimal design of honeycomb structure with negative Poisson’s ratio.
2021 Vol. 40 (11): 70-77 [Abstract] ( 167 ) HTML (1 KB)  PDF (2175 KB)  ( 71 )
78 Vibration control of cable stayed bridge with viscous damper under braking state of random traffic flow
LONG Guanxu1,2, HAN Wanshui3, XU Chuanchang1,2, HUANG Pingming3, WANG Yangchun1,2
Guide::null
Here, in order to study longitudinal response of cable-stayed bridge under braking state of random traffic flow and vibration control effect of viscous damper, firstly, combining the collected traffic load data and the key parameters statistics of traffic flow, random traffic flow models with 3 kinds of traffic flow density were established.Secondly, based on the vehicle-bridge system coupled relation, the improved half search method was used to determine the vehicle loading method of single girder model, and the vehicle-bridge coupled analysis module of the single girder model was compiled.Finally, longitudinal response of a cable-stayed bridge under braking condition, vibration control effect of longitudinal viscous damper and braking influencing factors were analyzed using the established random traffic flow braking model.The results showed that under braking state of random traffic flow, the braking response in opposite direction can be produced, and the bridge structure response is larger than that under normal random traffic flow; longitudinal viscous damper can effectively control the bridge’s longitudinal displacement, the smaller the speed index α, the larger the damping coefficient C and the more prominent the control effect, the maximum control efficiency can reach about 90%; the braking response and braking coefficient of the bridge’s second half are obviously larger than those of the first half; the more the braking lanes, the larger the braking response and braking coefficient; for the traffic flow density, the law of the braking response and braking coefficient is: dense flow > moderate flow > sparse flow.
2021 Vol. 40 (11): 78-85 [Abstract] ( 207 ) HTML (1 KB)  PDF (1885 KB)  ( 64 )
86 Horizontal vibration characteristics of monopile wind turbine in radial softening layered soil
WANG Teng1, WANG Chan2
Based on the multi-circle layer plane strain soil horizontal vibration model, the analytical solution to horizontal dynamic stiffness of radial softening soil around pile was obtained.Then, the horizontal vibration model of pile foundation in radial heterogeneous layered soil was established, and the dynamic stiffness matrix of pile top was obtained using the transfer matrix method.Furthermore, the equivalent fixed beam model was used to couple a pile-soil system into the wind turbine simulation software FAST 8 Effects of radial softening soil around pile on the horizontal dynamic response of monopile wind turbine under wind and wave loads were studied.The results showed that softening of soil around pile significantly affects dynamic stiffness of pile top; when the soil modulus attenuation coefficient is 0.25, horizontal stiffness of pile top decreases by 28.66% compared with that in case of homogeneous soil; with decrease in soil modulus attenuation coefficient, the first and second order natural frequencies of the wind turbine system decrease by 13.08% and 16.67%, respectively compared with those in case of homogeneous soil; when the soil modulus attenuation coefficient is 0.25, variances of wind turbine tower top’s displacement and rotation angle time histories have differences of 2.68% and 1.37%, respectively compared with those in case of homogeneous soil, while peak values of displacement and rotation angle response spectra are about 2.77 and 2.69 times, respectively of those in case of homogeneous soil.
2021 Vol. 40 (11): 86-93 [Abstract] ( 141 ) HTML (1 KB)  PDF (1454 KB)  ( 52 )
91 Vibration control of beam-TMDI system based on frequency domain analysis method
LI Jinhua1,2, CHAI Shizong2, ZHANG Yao2, YU Yong3
Here, tuned mass damper inerter (TMDI) was used to control vibration of beam structure.Analytical expressions for displacement response of beam structure under seismic acceleration excitation and that under moving force were derived.Optimal parameters of beam-TMDI system were given, and the sensitivity of parameters was analyzed.Then, the control effect of TMDI system was studied through numerical analysis, and the vibration reduction effect of TMDI system and that of tuned mass damper (TMD) system were compared.The results showed that the vibration displacement response spectrum of beam structure obtained with the frequency domain method can effectively reflect the displacement response of beam structure; using the augmented Lagrange parametric optimization method can accurately obtain parameters being able to minimize vibration response of beam structure; the sensitivity of TMDI system can be controlled with inertial device, and the latter obviously affects the former’s robustness; the vibration reduction performance of TMDI system is obviously better than that of TMD system.
2021 Vol. 40 (11): 91-100 [Abstract] ( 209 ) HTML (1 KB)  PDF (1623 KB)  ( 68 )
101 Weak fault feature extraction of rolling bearing based on autocorrelation and energy operator enhancement
PEI Di, YUE Jianhai, JIAO Jing
Aiming at weak impact components in rolling bearing’s early fault vibration signal and difficult fault feature extraction due to noise influencing, a method for rolling bearing weak fault feature extraction based on autocorrelation and Teager energy operator enhancement was proposed.Autocorrelation calculation and empirical mode decomposition (EMD) were used to suppress random noise and low-frequency noise in the whole frequency band of bearing vibration signal, respectively and highlight fault impact period.At the same time, cross-correlation coefficient-kurtosis index based on IMF energy ratio weighting was proposed to screen out the optimal IMF for signal reconstruction and enhancing fault information in the reconstructed signal.Teager energy operator (TEO) was used to act on the reconstructed signal to obtain the instantaneous energy sequence with enhanced fault impact characteristics, and the bearing fault characteristic frequency was extracted through power spectral analysis.The analysis of inner race fault’s simulated signal and rolling element fault’s measured signal showed that the proposed method can effectively suppress bearing vibration signal noise and significantly enhance weak characteristics of early faults.
2021 Vol. 40 (11): 101-108 [Abstract] ( 188 ) HTML (1 KB)  PDF (1072 KB)  ( 120 )
109 Dynamic response of asphalt bridge deck pavement under multi-vehicle load
ZHANG Xia, CHEN Enli, LI Lingyun
In order to analyze dynamic response characteristics of asphalt bridge deck pavement more accurately, a vehicle- road-bridge dynamic analysis method based on actual vehicle modeling was proposed to study dynamic behavior of asphalt bridge deck pavement under multi-vehicle load.Taking a steel-concrete I-shaped composite girder bridge as an example, considering effects of bridge vibration on deck pavement, the single vehicle-deck pavement coupled dynamic model was established through numerical simulation, and compared with the traditional model without considering coupling and moving load to verify the correctness of the coupling model and the necessity of considering coupling.Based on the single vehicle-deck pavement coupled model, dynamic response behavior of asphalt deck pavement under multi-vehicle load was studied.Stress and deflection responses of each layer of bridge deck pavement under double-vehicle in parallel and double- vehicle eccentric load conditions were analyzed, and compared with those under single vehicle conditions.The study results showed that eccentric load changes the direction of transverse stress of bridge deck pavement, tensile stress appears on top surface of asphalt layer and asphalt-concrete interface, so longitudinal cracks are easy to appear on top surface of asphalt pavement, and the maximum transverse tensile stress occurs on asphalt-concrete interface; the maximum longitudinal stress of bridge deck pavement occurs at asphalt-concrete interface; when two cars running in parallel, the longitudinal stress at asphalt-concrete interface increases by 52.7% compared with that during single vehicle running; shear stress is the maximum under eccentric load, it occurs at concrete-steel beam interface, and this interface is easy to separate, so anti-shear measures should be taken; largest deflections of different bridge deck pavements all occur under the condition of double-vehicle running in parallel, and their values can increase by 64% compared with those under single vehicle running condition; compared with action of single vehicle, considering coupling between multi-vehicle and bridge deck pavement should meet higher requirements for design and damage control of bridge deck pavement.
2021 Vol. 40 (11): 109-115 [Abstract] ( 163 ) HTML (1 KB)  PDF (1677 KB)  ( 41 )
116 Effects of tower crown on wind-induced response of super high-rise building
MA Wenyong1,2,3, HUANG Zhenghan1, ZHOU Jiahao1, ZHANG Lu1
Tower crown is the part with the most abundant appearance variation in super-high buildings.Because it is located at top of high-rise buildings, changes of its shape have a larger impact on base moment, top displacement and acceleration of high-rise buildings under strong wind.Here, wind tunnel tests of high-rise buildings with square cross section and 20 different tower crowns were conducted to do high frequency aerodynamic balance measuring in wind direction of atmospheric boundary layer.Based on the random vibration theory, displacement and acceleration at top of high-rise buildings with different tower crowns under wind load were analyzed.Wind-induced responses of structures with different tower crowns were compared, and the suggestion for selection of tower crowns was proposed to reduce wind-induced effect.The study showed that the performance of the closed tower crown with square opening is obviously superior to those of tower crowns with other shape openings; the cross-wind response of the smooth sloping tower crown is less than those of other kinds of sloping tower crown; the pyramid tower crown obviously reduces the downwind response at top of buildings; the stepped tower crown has no obvious effect on displacement and acceleration responses at top of buildings in most cases.
2021 Vol. 40 (11): 116-123 [Abstract] ( 183 ) HTML (1 KB)  PDF (2581 KB)  ( 58 )
124 Dynamic balance tests of large hydropower unit
ZHANG Haiku1,2, CHEN Qijuan1, GENG Qinghua2,3, ZHENG Yang1, WANG Weiyu1
Aiming at the vibration problem caused by rotor mass unbalance of large hydropower unit, a method for analysis and processing based on dynamic load balance to establish centrifugal force equation was proposed.Firstly, a large number of field test sample data and the regression analysis method were used to modify the traditional empirical trial counterweight formula, obtain the accurate regression coefficient and determine the trial counterweight’s mass.Then, the trial counterweight was added on the rotor, the varying rotating speed measuring results before and after adding the trial counterweight were compared to find balance points of the same vibration under different rotating speeds, and establish the centrifugal force equation.Finally, the centrifugal force equation was solved to obtain the total dynamic unbalance mass.Taking a certain hydropower unit as an example, the effectiveness of the proposed method was verified with tests.The results showed that compared with the traditional method, the proposed method can deal with the dynamic balance problem quickly and effectively.
2021 Vol. 40 (11): 124-127 [Abstract] ( 165 ) HTML (1 KB)  PDF (796 KB)  ( 52 )
128 Iterative frequency estimation algorithm for harmonic real signals based on spectrum shifting
MOU Zelong1, TU Yaqing1, CHEN Peng2, LIU Yan1
In order to suppress the influence of spectrum leakage of harmonic real signals, an iterative frequency estimation algorithm for harmonic real signals based on spectrum shifting was proposed.When estimating the frequency of a certain harmonic component, all other components with negative frequencies and positive ones were interference components to produce spectrum leakage.According to each interference component’s frequency, the spectrum shifting was done to suppress the interference component until a signal with a single component was obtained, its frequency was estimated with the parabolic interpolation algorithm.After frequencies of all harmonic components were obtained, suppressing interference components was performed again to update a single component signal for the purpose of estimating a more accurate frequency value.Simulation test results showed that the proposed algorithm can suppress interference components, and improve the frequency estimation accuracy of harmonic real signals; the mean square error of frequency estimation is closer to Cramer-Rao low bound (CRLB).
2021 Vol. 40 (11): 128-133 [Abstract] ( 153 ) HTML (1 KB)  PDF (992 KB)  ( 43 )
134 Optimization design of drum brake stability based on Kriging surrogate model
WANG Wenzhu1,2, LI Jie2, LIU Gang1, WEI Jun3, ZHANG Zhenwei2, CHENG Mianhong1
Aiming at the brake noise problem of drum brake, Kriging surrogate model was introduced to do optimization design for the stability of drum brake.The optimal Latin hypercube design (Opt LHD) was used to generate sample point data, they were substituted into the finite element model of drum brake to generate the surrogate model, and the model accuracy test was done.Taking Young moduli of friction lining, brake drum and brake shoe as design variables and weighted instability tendency coefficient as the objective function, the mathematical model for drum brake stability optimization design was established.The multi-island genetic algorithm (MIGA) was adopted to do optimization design.The results showed that introducing surrogate model can greatly improve the solving efficiency of drum brake stability optimization; optimization design can improve the stability of drum brake and suppress braking noise.
2021 Vol. 40 (11): 134-138 [Abstract] ( 165 ) HTML (1 KB)  PDF (1235 KB)  ( 48 )
139 Model denoising based on absolute node coordinate method
ZHANG Zhigang1,2, ZHOU Xiang1,2, MAO Hongsheng1,2, WANG Shengyong1, SONG Huitao3
Absolute nodal coordinate formulation (ANCF) is successfully applied in dynamic problems’ modeling and simulation of large deformation flexible multibody system.However, due to many node parameters and containing complex high-order modes, the system dynamic equation’s stiff problem is prominent.The core step of the existing widely used implicit algorithm is to filter high-frequency response with numerical damping, but the solving efficiency is not satisfactory.Here, based on the idea to filter high frequency components in modeling, the instantaneous stress in virtual power of elastic force was replaced by the average stress in a short time period to derive the absolute nodal coordinate element model denoising formulation containing additional inertia term and additional damping term.Through adjusting time interval length parameter of the average stress, high frequency components in the system equation could be eliminated, and the conventional explicit algorithm could be applied in simulation solving of traditional stiff problems.Numerical examples showed that the proposed absolute nodal coordinate element model denoising formulation can greatly reduce solving difficulty of numerical simulation, ensure calculation accuracy and improve calculation efficiency.
2021 Vol. 40 (11): 139-146 [Abstract] ( 118 ) HTML (1 KB)  PDF (1878 KB)  ( 34 )
147 Fault diagnosis of planetary gearbox based on multi-Agent deep Q-learning and fuzzy integral
CHEN Renxiang1, ZHOU Jun1, HU Xiaolin2, ZENG Li1, CHEN Cai3, HU Chaochao1
Aiming at the problem of low recognition rate of single-agent in deep Q-learning for fault diagnosis of planetary gearbox, using multi-agent for strategy learning and fuzzy integral for fusing decision results of multiple-agent, a planetary gearbox fault diagnosis method based on multi-agent deep Q-learning and fuzzy integral was proposed.Firstly, the continuous wavelet transform (CWT) and S transform (ST) were performed for vibration signals to obtain the corresponding time-frequency feature matrix, and then using the original time domain data and the obtained time-frequency feature matrix, a multi-domain environmental state space was constructed to interact with multi-agent.Secondly, the original time-domain features, CWT time-frequency features and ST features returned by the environment space were taken as the corresponding agent state in interaction process.The Q function value of each agent was maximized with the deep Q-learning algorithm to obtain the optimal strategy.Finally, fuzzy integral was used to fuse the decision results of multi-agent, and obtain the final diagnosis results.The fault data of planetary gearbox were used to do verification and analysis.It was shown that the proposed planetary gearbox fault diagnosis method based on multi-agent deep Q-learning and fuzzy integral can effectively improve the diagnosis accuracy; its diagnosis results are better than those of the method based on single-agent deep Q-learning.
2021 Vol. 40 (11): 147-153 [Abstract] ( 224 ) HTML (1 KB)  PDF (1457 KB)  ( 33 )
154 Fine numerical simulation of row-hole blasting in tunnel excavation
GUAN Zhenchang1, ZHU Lingfeng1, YU Bolin2
Here, aiming at common surrounding rock conditions and blast hole types in tunnel blasting excavation, five kinds of blast hole fine models were established on LS-DYNA numerical platform, and the fluid-structure interaction algorithm was used to simulate the transient process of row-hole blasting.Firstly, the pressure crushing zone was formed instantly around blast hole, and the initial crack was continuously expanded due to action of air wedge to form the surrounding rock fracture zone.Then the detonation pressure wave was reflected at free face, and its reflected tensile wave made a large range of parallel cracks appear on surrounding rock near free face.Finally, radii of the crushing zone and fracture zone were about 3-4 times and 22-24 times of blast hole radius, respectively.The pressure time history curve on the boundary of blast hole crushing zone received attention, it was shown that obvious multi-peak form including the first peak, the second one and negative one appear; the main peak value and the axial decoupling coefficient have a power exponential decay relationship; if averaging peak pressures on blasting contours, the simplified triangle shape load on each blasting contour can be obtained, it can be applied in the following work, such as, far-field vibration effect evaluation.
2021 Vol. 40 (11): 154-162 [Abstract] ( 215 ) HTML (1 KB)  PDF (3687 KB)  ( 55 )
163 Shape coefficient of insulator under vertical and inclined conditions
SHEN Guohui1, BAO Yunan2, XING Yuelong2, WANG Yiwen2, SONG Gang2
In order to study shape coefficient of vertical and inclined insulators, the model force measurement and free wind deflection method were used in wind tunnel tests.The variation of shape coefficient of vertical insulators with wind speed and turbulence degree varying was obtained.The method of measuring shape coefficient of inclined insulators using free wind deflection was proposed, and fluctuating wind deflection characteristics and shape coefficient of composite insulators under free wind deflection were studied.Finally, the recommended values of shape coefficients for disc and composite insulators were given.The results showed that the shape coefficient of vertical insulator decreases with increase in wind speed; shape coefficients of insulator under different turbulence degrees are closer to each other; the suspended insulator has significant sinusoidal fluctuation under turbulence, but its fluctuation is not significant under uniform flow; the average wind deflection angle of suspended insulator under turbulence is larger than that under uniform flow, and the larger the wind speed, the more significant the difference; the recommended shape coefficient value for vertical disc insulator is 0.89, those for vertical composite insulator and inclined one are 0.93 and 1.00, respectively; these recommended values are closer to those in Chinese code and smaller than those in IEC, EN and JEC codes.
2021 Vol. 40 (11): 163-169 [Abstract] ( 140 ) HTML (1 KB)  PDF (2180 KB)  ( 20 )
170 Amplitude-frequency response characteristics of non-smooth pure nonlinear vibration absorber with increasing stiffness
CHEN Jianen1,2, ZHANG Weixing1,2, HU Wenhua1,2, SUN Min3
When the amplitude of simple harmonic excitation increases to a certain extent, smooth pure nonlinear vibration absorber can make its main oscillator produce higher branch response, and cause sudden failure.Here, in order to avoid failure, a scheme of non-smooth vibration absorber was proposed.It was shown that it has lower stiffness coefficient during its amplitude being smaller; when its amplitude is larger than the critical value, its stiffness coefficient can increase significantly.The complex variable average method was used to derive the slowly-varying dynamic equation of the system, and amplitude-frequency responses of the main oscillator connected with smooth and non-smooth absorbers were obtained, respectively using the least square method.The study showed that the non-smooth absorber can effectively suppress the occurrence of higher branch response through reasonably controlling spring gap; when the excitation amplitude is smaller, performances of the two kinds of absorbers are very close to each other; when the system is under medium excitation, the smooth absorber has better vibration absorption performance; when the excitation amplitude further increases, the non- smooth absorber has a significant superiority.
2021 Vol. 40 (11): 170-175 [Abstract] ( 116 ) HTML (1 KB)  PDF (1467 KB)  ( 31 )
176 Effects of cross stiffness on dynamic characteristics of rubbing rotor
LIU Xiaofeng, ZHANG Chi, BO Lin, LUO Hongling
Aiming at the problem of the simplified spring model and nonlinear dynamic oil film force model being not conducive to analyzing effects of cross stiffness on rubbing rotor dynamics, a Jeffcott rotor dynamic model based on asymmetric direct stiffness and cross stiffness was established.Combining the shooting method and Floquet theory was used to study influence laws of rotor cross coupled stiffness on rotor system motion stability.A new parameter “rubbing energy” was introduced to characterize quantitatively the rotor rubbing fault, and analyze effects of rotor-stator clearance on rubbing degree of rotor with different cross stiffnesses.The results showed that in cases of different rubbing energy, the change of cross stiffness of rotor system can induce period-1 motion, and then through side-wiping bifurcation suddenly transit to chaos or through Neimark-Sacker bifurcation gradually transit to chaos; the forward whirl through trans-critical bifurcation evolves to reverse whirl; when the cross stiffness is larger, increasing rotor-stator clearance can aggravate the rubbing degree between rotor and stator.
2021 Vol. 40 (11): 176-181 [Abstract] ( 256 ) HTML (1 KB)  PDF (2871 KB)  ( 62 )
182 Dynamic characteristics study and tests of bistable piezoelectric cantilever beam energy harvester under raindrop impact
LIU Lilan, ZHONG Sheng, WU Ziying
Bistable piezoelectric cantilever beam energy harvester can be used to convert raindrop kinetic energy into electrical energy.Here, the mechanical model and control equation of bistable piezoelectric cantilever beam energy harvester were established.The mathematical model of single raindrop impact force was obtained through simplification.The lognormal distribution function was used to simulate the random distribution of raindrop diameter under different rainfall intensities.Effects of raindrop diameter and rainfall intensity on dynamic characteristics and power generation performance of the energy harvester system were studied using numerical simulation.The test device for raindrop impact to generate electric energy was built, and effects of raindrop falling height on the system output voltage were actually measured.The study results could provide a reference for study on exploring new energy sources by adopting raindrop impact to generate electric energy.
2021 Vol. 40 (11): 182-189 [Abstract] ( 123 ) HTML (1 KB)  PDF (4267 KB)  ( 48 )
190 Loosening mechanism and stress-resistance mapping relationship of electrical connector under triaxial random vibration
LIU Shaojie1, QIU Yuanying1, BAI Jin1, DU Jiangong1, LI Jing1, WANG Haidong2, 
Under multi-axis complex vibration environment, an electrical connector structure may be loose to affect electrical contact performance of its electrical appliances and cause failure of equipment function.Here, in order to explore mechanical characteristics of electrical connector in loosening process under multi-axis random vibration environment, a model of electrical connector in missile electronic cabin was established.The change time history of contact pressure in pin’s withdrawing process during it being loose relative to pinhole was simulated under random vibration environment, and the stress evolution mechanism in loosening process of electrical connector was revealed.Through comparing stress varying trend under triaxial random vibration and that under uniaxial random vibration, according to differences of three intervals, looseness characteristics of electrical connector under triaxial vibration were compared with those under uniaxial vibration, and a triaxial vibration stress screening method for connector looseness was provided.The mapping relationship between stress and resistance of electrical connector was derived by using R.Holm expression for relation between contact resistance and contact pressure, and the monitoring of contact stress between pin and pinhole was converted into monitoring of contact resistance to solve the technical problem of dynamic stress inside pinhole being difficult to measure.
2021 Vol. 40 (11): 190-195 [Abstract] ( 110 ) HTML (1 KB)  PDF (1594 KB)  ( 91 )
196 Structure of giant magnetostrictive ultrasonic transducer
LI Pengyang, LIU Qiang, LI Wei, ZHOU Xuan, WANG Limeng, WANG Quandai, YUAN Qilong
Here, in order to realize high-power and large amplitude ultrasonic vibration output, a new type of giant magneto-strictive ultrasonic transducer was designed.The shape of the transducer was a window structure.The dynamic analysis of the designed giant magneto-strictive transducer was performed with the finite element software ANSYS to verify the effectiveness of the design method.The software ansoft Maxwell was used to do magnetic analysis for window transducer and bar transducer, respectively.It was found that the magnetic circuit of window transducer is a closed one with less magnetic leakage.The impedance and amplitude of window transducer and bar transducer were measured, respectively.The results showed that resonant frequencies of the two transducers are basically the same, and the impedance of window transducer is much smaller than that of bar transducer; under the same driving voltage, the average amplitude of window transducer is about 1.5 times of that of bar transducer; window transducer has advantages of small impedance, compact structure and large output amplitude, it is a new development direction of giant magneto-strictive transducer in future.
2021 Vol. 40 (11): 196-201 [Abstract] ( 128 ) HTML (1 KB)  PDF (1376 KB)  ( 65 )
202 Numerical simulation of hypervelocity impact characteristics of energetic active material protective structure
WU Qiang1, GONG Zizheng1, ZHANG Qingming2, REN Siyuan2
The numerical simulation for hypervelocity impact of energetic active material is of great significance for the exploration study on new type space debris protection mechanism.Here, adopting the improved Lee-Tarver ignition growth model and the dynamic simulation program AUTODYN, after verifying the effectiveness of the computing model, the numerical simulation for spherical projectile with hypervelocity to impact energetic active material protective structure was performed to analyze critical crushing velocity, debris cloud morphology features and back wall damage.The critical crushing velocity formula for aluminum alloy projectile with hypervelocity impacting PTFE / Al energetic active material protective shield was deduced.Influence laws of projectile diameter, impact velocity and thickness of energetic active material protective shield on characteristic parameters of debris cloud were obtained to further reveal the new type protection mechanism of energetic active material structure under condition of hypervelocity impact.
2021 Vol. 40 (11): 202-210 [Abstract] ( 95 ) HTML (1 KB)  PDF (2505 KB)  ( 55 )
211 Dynamic load identification correction algorithm based on polynomial fitting initial value
ZHAO Fengyao1, ZHANG Jiancheng1, GE Wei1, JIANG Jinhui2, LI Hanyu1
Aiming at the problem of load identification results being not ideal due to initial value sensitivity of Wilson-θ inverse analysis method, the polynomial fitting method was introduced to correct initial value based on the idea of error correction to improve Wilson-θ inverse analysis method.Through deducing the error transfer formula of Wilson-θ inverse analysis method, the influencing principle of initial error on identification results was summarized, and the polynomial fitting method was used to calculate the displacement trend term to correct the initial value of the system.The results showed that the polynomial fitting method can effectively solve the initial value sensitivity problem of Wilson-θ inverse analysis method, and has a certain anti-noise performance and higher accuracy.
2021 Vol. 40 (11): 211-219 [Abstract] ( 193 ) HTML (1 KB)  PDF (2077 KB)  ( 57 )
220 Design and research of QZS vibration isolator with double link-spring-curved surface mechanism
WANG Zhicheng, WANG Shenlong, YU Huijie
Based on the parallel connection principle of positive and negative stiffnesses, taking double link-spring-curved surface mechanism as negative stiffness mechanism and a vertical spring as positive stiffness mechanism, a new configuration of quasi-zero stiffness (QZS) vibration isolator was proposed.According to the above configuration, through static analysis, the displacement-stiffness characteristics and displacement-restoring force characteristics of QZS system were studied to obtain QZS condition under the system’s static equilibrium.Nonlinear dynamic equations of QZS system were established and solved with the harmonic balance method and Runge-Kutta method.Aiming at different excitation amplitudes, damping coefficients and QZS parameters, dynamic response and transmissibility characteristics of the system were studied.The theoretical study showed that the proposed QZS configuration can effectively reduce the system model’s resonance frequency and the maximum transmissivity amplitude.Finally, based on the 3-D model of QZS isolator, numerical simulation and test study showed that the proposed QZS configuration has better low-frequency vibration isolation performance, and has the same high-frequency vibration isolation performance as linear system.
2021 Vol. 40 (11): 220-229 [Abstract] ( 193 ) HTML (1 KB)  PDF (3337 KB)  ( 58 )
230 Wind turbine gearbox fault diagnosis based on sound signal and improved MS-LMD
LIU Shaokang1, WU Yingjie1,2, AN Weilun1, XIN Hongwei1,2, YANG Yanjun1, WANG Jianguo1,2
Machinery’s fault diagnosis based on sound signal is feasible, but sound signal sensors of wind turbine gearbox can pick up multiple vibration source signals and interference noise in its engine room to affect accurate locating of faults.Here, an improved local mean decomposition (LMD) method was proposed to realize gearbox composite fault diagnosis through separating frequency modulation (FM) and amplitude modulation components of a sound signal.According to the feature of masking signal (MS) being able to suppress mode aliasing, the dichotomy method was used to search MS frequency in the range of 1.0-1.5 times of amplitude weighted average frequency.A cyclic iterative method to combine repeatedly MS and LMD was proposed to judge and suppress multi-group mode aliasing in turn.The effectiveness of the proposed method was verified using two kinds of simulated signals being easy to have modal aliasing.The proposed method was applied in sound signal analysis of an actual wind turbine gearbox to successfully diagnose its composite faults.
2021 Vol. 40 (11): 230-239 [Abstract] ( 240 ) HTML (1 KB)  PDF (2170 KB)  ( 50 )
240 Sensitivity analysis of influencing factors of JPC forming and penetration performance based on orthogonal test method
YANG Shiquan1, BAI Yunshan1, GUO Feng2, WANG Hongbo1, FENG Gaopeng1
Aiming at a certain ball-lacking shaped charge liner structure with equal wall thickness, 3D numerical simulation for jetting projectile charge (JPC) forming and concrete-penetrating process was performed by using the software LS-DYNA 3D.Based on the analysis of influencing factors of rod jet forming and penetration performance, 3 influencing factors of shaped charge liner wall thickness, charge height and initiation diameter, and 5 evaluation indexes of jet head and tail velocities, head and tail velocity difference, jet length and penetration depth were determined using the orthogonal test method, and the sensitivity of each influencing factor to evaluation indexes was analyzed.The results showed that the shaped charge liner wall thickness is the main factor affecting jet head and tail velocities, the relation  curve increases monotonously; its initiation diameter has a smaller effect on jet tail velocity, it is the main factor affecting jet head velocity, head and tail velocity difference and jet length, the relation curve increases monotonously; the charge height has the least effect on jet head and tail velocity difference; the jet penetration ability increases monotonously with increase in each factor level, but its increase gradually weakens.
2021 Vol. 40 (11): 240-247 [Abstract] ( 141 ) HTML (1 KB)  PDF (1743 KB)  ( 61 )
248 Approximate analytical solution to a class of membrane vibration equations with time fractional derivatives
GE Zhixin1, CHEN Xianjiang2
Here, a class of membrane vibration equation with time fractional derivative was studied.The equation boundary varied with sinusoidal perturbation.Taylor series was applied to expand the boundary independent variable, and then multi-scale were introduced to the original equation and boundary.By using the definition and properties of Riemann-Liouville fractional derivative, the approximate solution of the equation for the zero-order small parameter was obtained.Furthermore, the consistent effectiveness of the solution was proved by using the theory of differential inequalities.Finally, the influence of each parameter on the solution was analyzed using graphs.
2021 Vol. 40 (11): 248-251 [Abstract] ( 76 ) HTML (1 KB)  PDF (998 KB)  ( 48 )
252 Parameter design of movable teeth of two-tooth difference pendulum based on dynamic characteristics
YI Yali1, GUO Zhenghui1, WEI Rui1, GAO Yunfei1, JIN Herong1,2
Here, in order to reduce steady-state response amplitude of movable teeth of a two-tooth difference pendulum bar, and reduce dynamic load of meshing pair and improve running stability of transmission system, a parameter design method for movable teeth of the two-tooth difference pendulum bar was proposed based on dynamic characteristics analysis of movable teeth transmission system.The dynamic model for movable teeth transmission was established to solve and obtain time-varying meshing stiffness of meshing pair, and derive the equivalent meshing stiffness.Combining with the system dynamic analysis model, the steady-state vibration response of each sub-component of the system was calculated.The evaluation function of component dynamic performance was established based on the system transmission stability and dynamic load coefficient of meshing pair.The objective function of system dynamic performance evaluation was established according to weights of sub-components in the system.Through evaluating the objective function, design parameters with good dynamic performance were obtained.The harmonic response simulation analysis for the virtual prototype with 3 groups of design parameters was performed.The simulation results showed that the sweep amplitude of the virtual prototype with the design parameters determined based on dynamic characteristics analysis is the minimum; the study results can provide a technical reference for improving dynamic performance of movable teeth transmission system.
2021 Vol. 40 (11): 252-261 [Abstract] ( 104 ) HTML (1 KB)  PDF (1772 KB)  ( 17 )
262 Optimization design and performance of vehicle ISD suspension based on ADD positive real network
LIU Yanling, YAN Long, YANG Xiaofeng, SHEN Yujie, LIU Changning
The ISD （inerter spring damper) suspension system of passive vehicle can effectively suppress low-frequency vibration of vehicle body, combined with the classical acceleration driven damping (ADD) control able to suppress medium-high vibration of vehicle body, the comprehensive optimization design method of vehicle ISD suspension based on ADD positive real network was proposed to convert the problem of broad frequency field vibration suppression of vehicle ISD suspension into the problem of positive real optimization control based on ADD network synthesis.The suspension dynamic models of first-order and second-order positive real networks were constructed, respectively.The suspension’s structural parameters were optimized based on the fish swarm algorithm.The coupling action mechanism of ADD control and positive real network and the influence of positive real network order on suspension performance were simulated and analyzed.The results showed that the vibration isolation performance of suspension is improved with increase in order of positive real network; the ADD network synthesis method can effectively realize vibration suppression of vehicle ISD suspension in broad frequency field, and further expand the idea of active control of vehicle ISD suspension.
2021 Vol. 40 (11): 262-268 [Abstract] ( 160 ) HTML (1 KB)  PDF (2084 KB)  ( 28 )
269 Dynamic response characteristics of blasting strata in silt-rock stratum under different working conditions
YIN Tao1, ZHOU Chuanbo2, ZHENG Changqing3, JIANG Nan2, CHEN Zhengjin4
The environment of blasting broken rock in silt-rock stratum is complex, boreholes are full of groundwater, and rock is subjected to silt pressure.Here, based on the study method of field tests combined with dynamic finite element numerical simulation, dynamic response characteristics of rock stratum under 3 working conditions of water coupling charge plus silt pressure, water coupling charge plus no silt pressure, air coupling charge plus silt pressure were studied.The study results showed that linear relations exist between peak value of rock stratum node’s vibration velocity vectors’ superposition and hole depth and between peak value of element pressure and hole depth, respectively under two working conditions of water coupling charge plus silt pressure and water coupling charge plus no silt pressure; the dynamic response of rock stratum is not affected by variation of hole depth under the working condition of air coupling charge plus silt pressure; the silt pressure has smaller effect on dynamic response of rock stratum.
2021 Vol. 40 (11): 269-276 [Abstract] ( 180 ) HTML (1 KB)  PDF (1288 KB)  ( 49 )
277 Leakage source locating of safety valve based on improved KDE algorithm
LI Shuxun1,2, HOU Jianjun1,2, KANG Yunxing1,2, WANG Zhihui1,2
Aiming at the problem of it being difficult to accurately locate tiny leakage holes of safety valve, a leakage source locating method based on improved approximate kernel density estimation (KDE) algorithm was proposed.With this algorithm, firstly, the combination of signal-to-noise ratio (SNR) tracking and  coherence test (CT) was introduced to extract the time-frequency support domain less affected by environmental noise and with dominant leakage sound source energy so that the KDE algorithm could be applied in the safety valve leakage source locating.Then, the high frequency aliasing was suppressed by using the frequency division fusion processing, the approximate kernel density function was calculated, and 3-D spectrogram bases of the approximate kernel density function were reduced.Through simulation computing with the software MATLAB, according to the peak value of the improved KDE spectrogram, locating coordinates of safety valve’s leakage source were obtained.The results showed that relative errors of safety valve leakage locating results under working pressures of 0.72 MPa, 0.75 MPa and 0.77 MPa, respectively are all less than 10%; the method of combining acoustic emission testing and improved KDE algorithm can more accurately locate leakage source of safety valve; with increase in working pressure of safety valve, the locating accuracy increases accordingly.
2021 Vol. 40 (11): 277-284 [Abstract] ( 226 ) HTML (1 KB)  PDF (2072 KB)  ( 46 )
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