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2019 Vol. 38, No. 23 Published: 2019-11-28 1 Vibration and crack propagation control for cracked asymmetric rotor based on 3-D finite element model LIU Jun1,2,HU Rong1,CHEN Jianen1,2,WANG Xiaofeng1,2 Aiming at vibration problems of a cracked asymmetric rotor, a 3-D finite element (FE) model for the rotor system was established using the nonlinear contact FE approach.The free interface modal synthesis method was used to reduce the model’s orders and computation time.Effects of related parameters on unstable zone of main resonance and those of different crack positions on the rotor’s vibration characteristics were analyzed through simulation analyses.The results showed that appearance of cracks can affect the rotor’s resonance frequency and unstable zone range; electromagnetic actuator (EMA) with fuzzy-PID control can be used to realize the active control of the rotor system’s vibration; based on the rotor dynamics theory and the crack open-close mapping method proposed here, effects of rotating speed, uneven mass and asymmetric rotor’s flatness on rotor crack’s open-close features were studied to propose the method effectively delaying crack propagation; test results reveal EMA can be used to suppress the cracked rotor’s vibration and crack breathing effect, and verify the effectiveness of the proposed control method. 2019 Vol. 38 (23): 1-9 [Abstract] ( 357 ) HTML (1 KB)  PDF (1992 KB)  ( 128 ) 10 Effects of parameter variation on a Pelton hydropower station system’s shafting vibration XU Beibei1,2, CHEN Diyi1,2, LI Huanhuan1,2, YAN Donglin1,2 To deeply study effects of structural parameters variation on shafting vibration of a Pelton hydropower station system, a nonlinear mathematical model with fractional order damping force was established for the system considering coupling among multi-subsystem including pressure penstock, governor, and hydro-turbine generator unit.Effects of excitation current, upper guide bearing stiffness, lower guide bearing one, water guide bearing one and its rotating speed on the system’s service performance parameters, such as, shaft offset, generator rotating speed, etc.were studied under damping force with different fractional orders.The results showed that nonlinear dynamic evolution processes revealed by the system’s service performance parameters have a unity under excitation current variation; the system dynamic instability modes are different under the variation of bearing stiffness parameters; the system shafting vibration amplitude has jump phenomenon with increase in rotating speed; the study results provides a theoretical basis for further revealing fault diagnosis mechanism of Pelton hydropower station systems.  2019 Vol. 38 (23): 10-18 [Abstract] ( 168 ) HTML (1 KB)  PDF (1681 KB)  ( 65 ) 19 Vertical resonance condition analysis for simply supported box girder with common span used in high speed railway MENG Xin1,2 Vertical resonance condition for a simply supported box girder with common span used in China high-speed railway under action of EMU train with different speeds was explored theoretically.Its actual measured vertical natural frequencies and dynamic response data were analyzed.The results showed that its vertical resonance mechanism is clarified, and the calculation formulas for its resonance speed, super-harmonic one and vibration isolation speed are derived; EMU train’s vertical loading frequency for bridge mainly depends on train speed and its length, when the loading frequency is equal to the bridge’s natural frequency or its 1/2, 1/3……, the bridge structure has resonance or super-harmonic resonance; our country’s simply supported box girder with common span can’t have vertical resonance within the operation speed range of less than 350 km/h.The actual measured data for high-speed railway’s simply supported box girders with a span of 40 m, 32 m and 24 m showed that there are 2nd, 3rd and 4th super-harmonic resonance phenomena within the operation speed range, the girders’ dynamic responses have peak value effect, these results are consistent to those of theoretical analysis; the simply supported box girder’s vibration isolation speed is related to bridge’s span and natural frequencies, when the vibration isolation condition is satisfied, the bridge’s dynamic response drops. 2019 Vol. 38 (23): 19-24 [Abstract] ( 196 ) HTML (1 KB)  PDF (953 KB)  ( 237 ) 25 Control for suspended structure’s swing vibration swing vibrationinduced by multi-hazard source excitation ZHANG Chunwei, WANG Hao In traditional structural disaster prevention design, effects of various disasters on a structure are usually considered separately, and effects of multi-hazard are less considered.Aiming at swing vibration control problems of suspension structures, tuned mass damper (TMD) and active mass damper (AMD) can’t effectively perform swing vibration control.On the other side, the tuned rotary inertia damper (TRID) has problems of being sensitive to tuning parameters, very poor robustness and difficult to control swing vibration induced by multi-hazard source.Here, the active rotary inertia driver（ARID）system was proposed, the small type scaled model’s shaking-table test was designed, and the numerical analysis was performed using the software Simulink.Firstly, the dynamic equation for in-plane swing vibration of a suspended structure attached with an ARID system was established and linearized.Its control algorithm was designed based on LQR.Secondly, under action of five loadings including free vibration, sinusoidal one, sinusoidal sweep one, simulated earthquake one and simulated ocean wave one, structural small type scaled model tests were performed using a single-axis shaking table.Finally, Simulink was used to solve the dynamic equation under simulated multi-hazard source excitation.The numerical results were compared with those of shaking table tests.The results showed that the ARID system can be used to better realize structural swing vibration control; it exihibits good stability and robustness under multi-hazard source excitation; its feasibility is verified by shaking table tests. 2019 Vol. 38 (23): 25-32 [Abstract] ( 189 ) HTML (1 KB)  PDF (3784 KB)  ( 69 ) 33 Performance degradation status identification and assessment for rolling bearing based on NAP and RMI XIA Junzhong， ZHENG Jianbo， BAI Yunchuan， L Qipeng， YANG Ganggang Extraction of degradation state features is the key for identification and evaluation of rolling bearing degradation status.Nuisance attribute projection (NAP) can be used to overcome shortcomings of traditional methods, and accurately extract characteristics of rolling bearing degraded status, but its monotonicity and sensitivity are poor in the whole life duration.Ranking mutual information (RMI) can be used for NAP’s optimization to accurately evaluate bearing degradation status.Here, the optimized orthogonal match pursuing (OOMP) was used to denoise vibration signals.The feature vector PE value calculated using NAP was compared with the reference PE value to identify bearing degradation status.RMI was used to enhance PE value’s sensitivity to subtle changes in signals and its monotonicity in the whole life duration to accurately assess bearing degradation status.The tests showed that after using NAP and RMI, the recognition rate of rolling bearing performance degradation status is high; if using NAP and RMI, bearing performance degradation status can be evaluated with high precision and in stages. 2019 Vol. 38 (23): 33-37 [Abstract] ( 169 ) HTML (1 KB)  PDF (1277 KB)  ( 77 ) 38 Vehicle-running test method for measuring wind pressure coefficient of buildings with wind generated by a moving vehicle LI Shengli1,WU Hao1, ZHENG Shunyun1, OU Jinping2, DING Jinquan3 Referring to test methods of wind tunnel test and field measurement, using wind generated by a moving vehicle, a vehicle-running test method to measure wind pressure coefficients of buildings under ideal road conditions was proposed.Based on theoretical derivation and tests on site, the basic theory of the proposed method was built, the physical test platform for vehicle-running tests was designed and assembled, and the software measurement system was also constructed.The test data processing method was studied and used to measure mean wind pressure coefficients of CAARC standard model’s typical measured points.Effects of different vehicle speeds and repeated tests at the same vehicle speed on mean wind pressure coefficient were analyzed.Results showed that the basic theory of the proposed method is correct; the built hardware and software systems are reasonable; mean wind pressure coefficients of the standard model’s measured points agree well with those of the previous wind tunnel tests published in literature; deviations of repeated test results at the same vehicle speed are small; different vehicle speeds affect mean wind pressure coefficient a little bit; the feasibility of the proposed method under ideal road conditions is verified. 2019 Vol. 38 (23): 38-45 [Abstract] ( 227 ) HTML (1 KB)  PDF (2142 KB)  ( 35 ) 46 Evolution behavior analysis for loading and unloading contact characteristics of fractal rough surface LIU Kaian, XU Yingqiang, WU Zhenghai, LI Wanzhong The evolution of loading and unloading contact characteristics of rough surfaces is of great importance to study on interface contact mechanical performance.Here, based on the rough surface fractal theory, according to the modified dual-parameter Weierstrass-Mandelbrot (W-M) fractal function, a 3-D fractal rough surface digital model was generated with the point cloud processing technique and Coons patch curved surface fitting method.According to Prandtl-Reuss constitutive relation and von Mises yield criterion, bilinear isotropic reinforced nonlinear materials were used to establish an accurate finite element model for a fractal rough surface contacting a rigid plane.Effects of fractal dimension and size parameters on contact load, contact area and deformation during loading and unloading were explored.The kernel density estimation method was used to analyze evolution laws of morphologic height parametric distribution of rough surface under different contact states, and reveal the mechanism of fractal rough surface contact characteristics from standpoints of fractal parameters and energy.The results provided a theoretical basis for further studying rough surface’s contact mechanical performance, interface load transfer efficiency and enhancement mechanism. 2019 Vol. 38 (23): 46-53 [Abstract] ( 188 ) HTML (1 KB)  PDF (2688 KB)  ( 57 ) 54 Vibration monitoring and fault pre-warning method for large axial compressor blades without OPR sensor WANG Weimin1,2, ZHANG Xulong1, CHEN Kang2, HU Dongfang1, LI Weibo2 During operation of a compressor, its blades bear complex alternating loads, they are easy to produce high-cycle fatigue faults.Here, in order to solve problem of the once per revolution (OPR) sensor being difficult to install using the blade tip timing (BTT) method in blade vibration monitoring process similar to aero-engine and other equipment without OPR one or the OPR’s reference is incorrect, a blade vibration monitoring method without OPR based on blade detuning characteristics was proposed.Then, its algorithm was improved to propose a monitoring method without OPR for tunable blades.The proposed method was verified through simulation.Tests were conducted on a large axial compressor, and test data were analyzed with the method with OPR and that without OPR, respectively to complete identification of blades’ synchronous vibration parameters.The analysis results showed that the proposed method can be used to identify blade synchronous vibration parameters correctly; the relative error of blade resonance frequency identification is less than 0.06%; the proposed method is effective and feasible in vibration monitoring and fault pre-warning for large axial compressor blades. 2019 Vol. 38 (23): 54-61 [Abstract] ( 304 ) HTML (1 KB)  PDF (2303 KB)  ( 95 ) 62 Flutter stability and main resonance of a milling system considering structural nonlinearity of cutter bar REN Yongsheng, MA Bole, MA Jingmin Here, flutter stability and main resonance of a milling system considering structural nonlinearity of cutter bar and structural damping were investigated.The cutter bar was simplified as a planar bending cantilevered beam model made of a viscoelastic material with effects of structural damping.Using the cutting force model containing regenerated time delay effect and periodic excitation, the nonlinear dynamic equations for the milling system were built with Hamilton principle.Galerkin method was employed to simplify the partial differential dynamic equations, and derive the ordinary differential ones expressed with principal coordinates.The milling system’s stability lobes figures were obtained through time domain integration.The multi-scale method and the perturbation one were used to solve ordinary differential dynamic equations, and obtain the closed-form approximation solution of the milling system’s main resonance response under periodic excitation.Effects of cutter bar sizes, structural damping, cutting force coefficient, cutting depth and cutting force amplitude, etc.on the system’s lobes figures and main resonance response curves were studied to get several interesting conclusions. 2019 Vol. 38 (23): 62-69 [Abstract] ( 185 ) HTML (1 KB)  PDF (1877 KB)  ( 52 ) 70 Dynamic modeling for a turbocharger and its vibration characteristics GU Cansong1,2, YUAN Zhaocheng1, LIU Jiaxin1, YANG Zhengrui2, LI Hongliang2 Using the multi-body dynamics theory and FEM, a multi-body system simulation model was established for a certain vehicle’s turbocharger with floating ring bearing.Based on the modal synthesis method, flexible body sub-structure models for turbocharger housing and rotor were built.Based on the generalized incompressible Reynolds equation, an elastic hydro-dynamic (EHD) lubrication model for the turbocharger’s floating ring bearing was established to calculateinner and outer oil films’ pressures, rotor vibration characteristics and turbocharger housing’s surface vibration velocity.The calculation results were verified with test ones.The results showed that the modeling method adopting the flexible multi-body dynamics and the EHD bearing lubrication model can be used to effectively analyze the turbocharger vibration characteristics; this method provides a theoretical basis for studying turbocharger’s synchronous vibration, sub-synchronous one and noise problem. 2019 Vol. 38 (23): 70-76 [Abstract] ( 226 ) HTML (1 KB)  PDF (2428 KB)  ( 67 ) 77 Nonlinear dynamic modelling and free vibration for a tapered cantilever beam based on hyper-geometric function and Meijer-G function BO Zhe,GE Gen Here, a tapered cantilever beam’s nonlinear vibration was studied theoretically.The beam’s modal function was based on the hyper-geometric function and Meijer-G one without needing perturbation and approximation.Kane’s equation was used to establish the beam’s vibration equation with geometric and inertial nonlinearities.The calculation results for various coefficients of this equation were the same as those obtained with other modeling methods in literature and their expressions were more concise.The beam’s fundamental natural frequency gained with the proposed method was compared with that obtained with the FE one, Rayleigh-Ritz one and other ones, and it has a very good accuracy.Under strong nonlinear vibration cases, the system’s amplitude-frequency response relation was obtained with the variational method and the energy balance one, the results calculated using this relation are more accurate than those gained with the multi-scale method under the condition of large amplitude.Furthermore, the energy balance method was improved, and the results obtained with the improved one are closer to numerical solution.Finally, the effective nonlinearity coefficients were calculated to judge the system characteristics becoming hard or soft. 2019 Vol. 38 (23): 77-83 [Abstract] ( 178 ) HTML (1 KB)  PDF (1353 KB)  ( 45 ) 84 Fault diagnosis for gear wear of planetary gearbox LI Haiping1,2， ZHAO Jianmin2, ZHANG Xin2, NI Xianglong3 To solve problems of planetary gearbox fault diagnosis method having higher professional requirements, complex calculation process and longer model training time, a new fault diagnosis method for planetary gearbox based on PCA-EDT-DBN was proposed.PCA was used to analyze vibration signals acquired with several sensors, select the first p principal components of each column of signals according to requirements, and arrange these p principal components into a one-dimensional (1-D) sequence.Euclidean distances between the first p principal components of each 2 columns data were computed to obtain a distance matrix.This matrix was sequentially expanded into a 1-D sequence.Two 1-D sequences obtained according to the mode mentioned above were synthesized into a 1-D one taken as a sample to be input into DBN for model training.Then, new samples were input into the trained model to output a classification result intelligently, and realize planetary gearbox’s fault diagnosis.Additionally, in order to improve the accuracy of model diagnosis, the orthogonal test method was used to optimize parameters of DBN.The preset fault test data for planetary gearbox teeth wear were used to verify the effectiveness of the proposed method.The results showed that the proposed method has advantages of higher diagnosis accuracy, shorter training time and simpler calculation process. 2019 Vol. 38 (23): 84-89 [Abstract] ( 186 ) HTML (1 KB)  PDF (1249 KB)  ( 103 ) 90 Circuit breaker mechanical fault vibration analysis based on improved variational mode decomposition and SVM TIAN Shu, KANG Zhihui Aiming at shortcomings of traditional signal decomposition causing circuit breaker’s incorrect mechanical fault vibration analysis feature extraction and lower fault diagnosis accuracy, a new method for circuit breaker fault diagnosis based on the improved variational mode decomposition (VMD) energy entropy combined with support vector machine (SVM) was proposed.The setting of VMD parameters was optimized by using the quantum-behaved particle swarm optimization (QPSO) method to obtain the optimal mode number and penalty factor.In order to verify this method’s advantages in suppressing mode aliasing and noise interference, it was applied to analyze a 10 kV high voltage circuit breaker 10kV high voltage circuit breaker ZN63A-12’s three kinds of vibration signals collected in cases of normal, transmission mechanism jamming and base screw loosing.The improved VMD energy entropy was used to extract vibration features of the circuit breaker ZN63A-12, and these features were input into a support vector machine to determine ZN63A-12’s fault state.Test results showed that the proposed method can be used to effectively extract fault vibration features of the circuit breaker, and classify faults under the condition of a few samples, so it has higher application value.  2019 Vol. 38 (23): 90-95 [Abstract] ( 173 ) HTML (1 KB)  PDF (833 KB)  ( 69 ) 96 Tests for impacts of turbulence on Reynolds number effect of stayed cables LIU Qingkuan1,2, ZHAO Guichen3, AN Miao3, JIA Yaya1,2, MA Wenyong1,2,LIU Xiaobing1,2 Cable-stayed cables of a long-span stayed cable bridge are typical wind sensitive structures under a complex turbulent environment.Incoming flow turbulence has a very significant influence on aerodynamic performance of stayed cables.Wind tunnel tests were conducted for stayed cable model under different turbulences to measure stayed cables’ surface pressure.Under the same turbulence, variation law of stayed cable’s aerodynamic coefficient with Reynolds number and variation law of that with turbulence under the same Reynolds number were analyzed contrastively.The results showed that turbulence makes Reynolds number effect in advance, the larger the turbulence, the earlier the Reynolds number effect; with increase in turbulence, fluctuating wind pressure coefficient on windward side increases; the smaller the Reynolds number, the larger the differences among stayed cable’s pressure coefficients under different turbulences, while the larger the Reynolds number, the smaller the differences. 2019 Vol. 38 (23): 96-102 [Abstract] ( 154 ) HTML (1 KB)  PDF (3018 KB)  ( 40 ) 103 Simulation for transmission error and mesh-in impact excitation of high speed gears and their tooth surface optimal modification JIA Chao1, FANG Zongde2 Aiming at cases of influence of contact ratio being not considered in traditional tooth modification methods, and noise and vibration reduction effect being not significant only considering reduction of amplitude of loaded transmission error (ALTE) for high speed gears, a new tooth surface modification method considering contact ratio or overlap ratio, and an approach for calculating mesh-in impact force based on the tooth contact analysis (TCA) and the loaded tooth contact analysis (LTCA) were proposed.Ultimately, based on the intelligent optimization algorithm and the proposed tooth surface modification method, an optimization model was established to minimize ALTE and mesh-in impact force, and the optimal tooth surface modification values were determined through the multi-objective optimization.The actual example calculation results showed that compared with the traditional tooth surface modification, the proposed new method can be used to effectively reduce fluctuation of loaded transmission error and mesh-in impact force. 2019 Vol. 38 (23): 103-109 [Abstract] ( 224 ) HTML (1 KB)  PDF (1513 KB)  ( 75 ) 110 Aerostatic instability mechanism of a cable-stayed bridge with double main spans of 1 500 m HU Chuanxin1, ZHOU Zhiyong1, YAN Kangjian2 Aerostatic instability is one of main assessments for wind-resistant performance of a ultra-long span cable-stayed bridge.Here, taking a cable-stayed bridge with double main spans of 1 500 m as the study object, the whole bridge’s aero-elastic model wind tunnel test combined with numerical computation method was used to track displacement responses and the bridge’s synchronous cable forces in its instability process, and deeply reveal the structure’s static wind instability mechanism with evolutionary characteristics of structural stiffness in its instability process.Wind tunnel test results showed that there are obvious omens of aerostatic instability at the initial wind attack angle of + 3 ° and 0 °, aerostatic instability happens before flutter instability.Based on the nonlinear FEM, evolutionary characteristics of the bridge’s displacement responses in instability process were studied and then compared with the wind tunnel test results, it was shown that they agree better with each other; the critical wind speed of aerostatic instability at the initial attack angle of -3 ° is much higher than those at the initial attack angles of + 3 ° and 0 °, respectively.In order to reveal the inherent mechanism of the above mentioned critical wind speed phenomenon, cable forces synchronous with displacement responses were extracted to analyze evolutionary characteristics of structural stiffness in instability process.The results showed that the structural aerostatic stability depends upon evolutionary characteristics of structural stiffness, and the latter is related to structural responses; the vertical downward displacement of the main girder at the initial wind attack angle of -3 ° enhances the stable triangular relationship among cable, main girder and bridge tower, this is the essential reason to cause the aerostatic stability at the initial wind attack angle of -3 ° being far superior to those at the initial attack angles of + 3 ° and 0°; the structure instability pattern at initial attack angle of -3° is characterized by obvious main girder’s first order symmetric torsional-first order asymmetric torsional coupled modal shape, this pattern is significantly different from that of a single-main span cable-stayed bridge; the study results for the first time reproduce the aerostatic instability phenomenon of a long-span cable-stayed bridge with double main spans in wind tunnel tests, reveal the inherent mechanism of aerostatic instability of long-span cable-stayed bridges, and provide a reference for further wind-resistant design of our country’s super-long span cable-stayed bridges. 2019 Vol. 38 (23): 110-118 [Abstract] ( 125 ) HTML (1 KB)  PDF (2776 KB)  ( 42 ) 119 Bearing life prediction method based on phase space reconstruction of state tracking features BO Lin,YAN Kang,LIU Xiaofeng Aiming at feature selection and model optimization problems in residual life prediction of rolling bearing, a bearing life prediction method based on phase space reconstruction of state tracking feature was proposed.Based on monotonicity and sensitivity assessment of bearing features, quantitative evaluation was done for tracking capability of bearing running state to screen the optimal feature set of bearing performance degradation.In order to uniformly describe each feature’s representation information for bearing degradation state, the adaptive chaos particle swarm optimization (ACPSO) algorithm was used to optimize support vector data description (SVDD), and construct the bearing health index.This index was used to accurately divide bearing operation states.Finally, based on the phase space reconstruction index of bearing recession, ACPSO-GRNN was used to predict bearing residual life.Test results showed that the proposed method can be used not only to find the decline time point of bearing operation as soon as possible, but also have higher prediction accuracy than those of SVR and BP neural networks. 2019 Vol. 38 (23): 119-125 [Abstract] ( 202 ) HTML (1 KB)  PDF (1437 KB)  ( 88 ) 126 Electromagnetic type vibration energy harvester based on bi-stable cantilever beam LIU Zhonglin, LENG Yonggang, LIU Jinjun, FAN Shengbo The bi-stable cantilever beam-based electromagnetic type vibration energy harvester built with dual-magnet structure was taken as the study object, the shape correction function method and the magnetizing current theory were adopted to analyze the bi-stable cantilever beam’s vibration response features.According to the electromagnetic induction principle, the accurate simulation method for electromagnetic induction electromotive force under moving coordinate system was explored.The results of numerical simulation and test verification showed that the established nonlinear magnetic force, magnetic field analysis and simulation computation for cantilever beam’s vibration response and induced electromotive force are reasonable and correct; the proposed method can be used to effectively evaluate the bi-stable cantilever beam-based electromagnetic type vibration energy harvester’s induced electromotive force and output power. 2019 Vol. 38 (23): 126-133 [Abstract] ( 164 ) HTML (1 KB)  PDF (2227 KB)  ( 79 ) 134 Optimizing of commercial vehicle cab suspension paraments by means of experiments LI Bin1, CAO Yang2, YUN Weiguo3 Aiming at the comfort problem of commercial vehicle cabs, the dynamic model of cab and its mounting system of a typical commercial vehicle was established by using ADAMS software,based on the rigid-flexible coupling multi-body dynamics theory.The accuracy of the model was verified.The DOE optimization test was designed, the stiffness and damping of the cab mount are optimized by simulation analysis, and the test vehicle was improved according to the optimization parameters.Finally, the road test shows that the ride comfort of the optimized commercial vehicle is 9.6% higher than that before optimization, and the vibration isolation performance of the cab is improved. 2019 Vol. 38 (23): 134-138 [Abstract] ( 212 ) HTML (1 KB)  PDF (1065 KB)  ( 45 ) 139 Fast analysis of blade aerodynamic force under wake excitation LUO Xiao1, LI Lizhou1, ZHANG Xinyan1, ZHANG Jun2, YANG Minglei1, YUAN Meini1 To quickly solve blade aerodynamic force under wake excitation, the blade aerodynamic force reduced order model (ROM) method based on the harmonic balance method was proposed here.Through further studying this method, it was found that under small turbulence, proportional coefficients between aerodynamic force’s harmonic amplitudes and wake harmonic amplitudes are only related to wake frequencies.Based on this finding, the fast analysis method of blade aerodynamic force was proposed.Firstly, proportional coefficients between aerodynamic force’s harmonic amplitudes caused by wake harmonics and wake harmonic amplitudes were obtained, and then the relation curves between these proportional coefficients and wake harmonic frequencies were fitted.For any wake, proportional coefficients corresponding to its various harmonics were acquired through these curves interpolation, further blade aerodynamic force harmonic amplitudes were gained.Finally, the blade aerodynamic force ROM was used to solve blade aerodynamic force under wake excitation.The example calculation results showed that the proposed fast analysis method can be used to rapidly and accurately estimate blade aerodynamic force under any wake excitation without needing to do repeatedly CFD aerodynamic force computation for wakes of different frequencies. 2019 Vol. 38 (23): 139-145 [Abstract] ( 204 ) HTML (1 KB)  PDF (1229 KB)  ( 79 ) 146 Damage mode and mechanism for membrane of discharge hole of high pressure vessel under high energy gas impact load ZHANG Hongyan1, CAI Xuanming1, MA Tiehua2, ZHANG Yu2, FAN Zhiqiang1, GAO Yubo1 Aiming at problems of damage mode of discharge hole membrane structure caused by high energy blast gas of high pressure vessel being unable to predict accurately and effectively and existing dangerous cases of membrane early breaking and non-membrane breaking, the macro and micro damage characteristics of Q235 steel structure membranes with pre-fabricated damage hole under blast impact load were studied.Based on high-pressure blast device, a series of tests were conducted for the anti-blast damage effect of membranes above mentioned.Combining with test results, quantitative relations among seven-hole gunpowder blast impact load energy release behavior and relevant parameters were explored to provide the theoretical basis for studying membrane damage mechanism, and establish the relation between membrane damaged hole size and peak pressure of blast impact load.Finally, based on the dynamic constitutive relation and failure criterion of J-C model, the membrane failure mode was simulated numerically.The results showed that with increase in blast impact load pressure, membranes with prefabricated hole mainly reveal macro-damage modes, such as, uniform damage holes, edge stress concentration tearing and shear plug; the built energy release relations and the inner correlation between damaged hole size and peak pressure of blast impact load provide a quantitative basis for studying multi-scale damage mechanism; membrane failure forms and damaged hole size obtained with numerical simulation agree well with test results. 2019 Vol. 38 (23): 146-151 [Abstract] ( 143 ) HTML (1 KB)  PDF (1698 KB)  ( 41 ) 152 Fault diagnosis method based on sample quantile permutation entropy DAI Hongde1, CHEN Qiangqiang2, DAI Shaowu2, ZHU Min2 Aiming at problems of rolling bearings’ obscure fault features and difficult to extract features, a new method to measure the complexity of time series, i.e., the sample quantile permutation entropy (SQPE) method was proposed and applied in feature extraction of rolling bearing fault vibration signals.By calculating sample quantile permutation entropies of fault vibration signals, fault features of different vibration signals were effectively separated.Then, the obtained entropy values were formed into feature vectors to construct a classifier, and realize fault diagnosis of rolling bearings.The proposed method was applied to analyze test data.The results showed that SQPE method can be used to effectively extract fault features of rolling bearings; the process of calculating entropy values avoids the selecting process of embedded dimension to effectively improve the self-adaptability of entropy value calculation, and expand its application range. 2019 Vol. 38 (23): 152-156 [Abstract] ( 155 ) HTML (1 KB)  PDF (724 KB)  ( 107 ) 157 A SFEM-based algorithm for computing SEA parameters of laminated plates YUAN Jinlong1,CHEN Haibo1,WANG Kun2,CAO Xiaolong2 Aiming at the problem of difficult to acquire common laminated plates’ SEA parameters, an effective algorithm based on the spectral finite element method (SFEM) for SEA parameters computation was proposed.The 3-node quadratic spectral finite element was used to divide grids in thickness direction of a laminated plate, and the characteristic equation of wave number was established by using the plate’s stiffness and mass matrices.According to the modal similarity criterion, Pearson correlation coefficient was used to classify various modes’ wave numbers to gain the laminated plate’s SEA parameters, such as, modal densities and radiation efficiencies.Numerical simulation was performed for single-layer thin plates and sandwich ones.The computation results were compared with other theoretical values or test ones to verify the effectiveness of the proposed method.A five-layer C-C orthotropic laminated plate was taken as an example to investigate analysis deviations of the classical laminate plate theory and the first-order shear theory.Finally, the internal loss factor of automobile glass laminated plate was calculated to verify the effectiveness of calculating laminated plate’s internal loss factor based on SFEM.  2019 Vol. 38 (23): 157-164 [Abstract] ( 134 ) HTML (1 KB)  PDF (1054 KB)  ( 49 ) 165 Effects of double-layer cylindrical shell side to side sound channel on whole shell’s vibro-acoustic performance LOU Jingjun1,QU Duo2,TANG Yuhang3,ZHANG Zhenhai1 Aiming at the present situation of larger underwater vehicle shell radiation noise, the vehicle shell was simplified into a ribbed double-layer cylindrical shell.Considering coupling between double shell layers and inter-board/outboard fluids, the automatic matching acoustic radiation boundary condition technique AML was employed to establish a double-layer cylindrical shell model containing inter-board fluid to study the difference between the finite element vibro-acoustic coupled method and the additional mass method.Effects of inter-board/outboard fluid load, inter-board medium and pallet on the whole shell’s vibro-acoustic performance were analyzed.The results showed that the vibro-acoustic coupled method based on AML technique is more effective to study the vibro-acoustic performance of underwater double-layer cylindrical shell; inter-board/outboard different fluid loads have greater effect on the shell’s vibro-acoustic performance; water’s load effect is obviously higher than air’s, water load has effects to suppress vibration and reduce resonance peaks in lower frequency range, while it increases vibro-acoustic coupled effect to raise structural vibration response and radiation efficiency in higher frequency range; when inter-board fluid is air, pallet has larger influence on the shell’s vibration and acoustic radiation. 2019 Vol. 38 (23): 165-170 [Abstract] ( 155 ) HTML (1 KB)  PDF (2269 KB)  ( 48 ) 171 Performance of track vehicle suspension system based on inerters CHEN Wentao2,3, FENG Zhouquan1,2, CHEN Zhengqing1,2, FAN Youquan3, NIU Huawei1,2 In order to study effects of inerter on vibration response and vibration isolation performance of a track vehicle inerter-spring-damper (ISD) suspension structure, its vertical dynamic model was established.The forced vibration theory was used to analyse the system’s vibration response characteristics and vibration isolation performance.The results showed that there are minimum value points on curves of amplitude, amplitude amplification factor, speed one and acceleration one of ISD structure versus its mass ratio, and these optimal mass ratios are functions of frequency ratio and damping one; the suggested ranges of damping ratio and mass one are ξ<0.2 and 0.1<μ<0.3, within these ranges, the system’s vibration isolation performance can be lifted to the maximum extent; the larger the mass ratio, the smaller the phase difference; relations of critical frequency ratio and resonance point frequency ratio versus mass ratio are derived, the larger the mass ratio, the smaller the critical frequency ratio and resonance point one, and amplitude amplification ratio at resonance point and width of resonance region obviously decrease; the study results provide a new way for track vehicle ISD suspension structure’s vibration isolation performance analysis and lightweight study, and a reference for choosing key parameters in ISD structure design.  2019 Vol. 38 (23): 171-177 [Abstract] ( 164 ) HTML (1 KB)  PDF (1704 KB)  ( 150 ) 178 A road condition recognition method for leg amputees with intelligent prostheses based on blind identification model and extreme learning machine LIU Lei1,YANG Peng2,LIU Zuojun2,SONG Yinmao1, WU Qinge2 In order to solve the problem of lower road condition recognition rate of leg amputees with intelligent prostheses, a road condition recognition method based on blind recognition theory combined with extreme learning machine was proposed.Firstly, surface electro-myographic (sEMG）signal was selected as the road condition identification information source, and blind identification model coefficients of sEMG signal were extracted as the signal features.In order to fully reflect the road condition features, different feature values were compared to analyze the reasonability of choosing blind identification model coefficients as road condition recognition features.In order to overcome the disadvantage of only a few input weights generated randomly by ELM classifier being superior, a firework ELM was used to classify 6 road conditions including walking on flat ground, going upstairs, going downstairs, going uphill, going downhill and running.Finally, the results using the proposed method were compared with those using ELM algorithm and BP neural network, respectively.It was shown that using the blind identification model and the ELM with firework evolution algorithm, the average recognition rate of 6 road conditions is increased to 92.51%, it is superior to those using ELM algorithm and BP neural network, respectively. 2019 Vol. 38 (23): 178-185 [Abstract] ( 154 ) HTML (1 KB)  PDF (1151 KB)  ( 135 ) 186 Expanding law of cracks formed by slotted cartridge blast under unidirectional confining pressure YUE Zhongwen1,2, TIAN Shiying1, ZHANG Shichun1, ZONG Liangliang1,XU Shengnan1 In order to study dynamic mechanical behavior of main cracks formed by slotted cartridge blast under unidirectional confining pressure, a new digital-laser dynamic caustic line test system was used to perform multi-set blast light-measurement tests.At the same time, the FE software ANSYS/LS-DYNA was used to analyze effects of initial pressure on the blast stress field.The results showed that crack propagation direction and expanding length are controlled by combined action of slit angle and confining pressure; when pressure is vertical or parallel to direction of slit, combined action can suppress or boost initiation and evolution of main cracks formed by blast, and reduce or raise crack expanding speed and dynamic stress intensity factor; when pressure is at a certain angle with slit, main cracks tend to expand in pressure direction and dynamic mechanical parameters decrease; when unidirectional pressure is vertical or parallel to direction of slit, initial confining pressure static loading produces compression or tension stress in circumferential direction to reduce or raise tensile action of blast impact in circumferential direction, and reduce or raise blast load’s impact and crack-forming ability. 2019 Vol. 38 (23): 186-195 [Abstract] ( 149 ) HTML (1 KB)  PDF (3260 KB)  ( 57 ) 196 Weak fault feature extraction of bearing based on sparse decomposition and frequency domain correlation kurtosis ZHAO Le1,2, YANG Shaopu1,2, LIU Yongqiang2, GU Xiaohui1,2, WANG Jiujian2 Under interference of strong background noise and complex excitation, early weak fault features of rolling bearing are often difficult to extract.The sparse representation method is an effective way to analyze non-stationary signals, and adopting K-SVD algorithm to construct an adaptive dictionary and OMP algorithm to sparsely decompose the acquired data is a common method in bearing fault diagnosis.Here, a method combining sparse decomposition and frequency domain correlation kurtosis was proposed to extract bearings’ early weak fault features.The frequency domain correlation kurtosis with the advantage to be able to accurately recognize bearing, etc.rotating machineries’ cyclic impact sequence features was used to construct the adaptive dictionary.Firstly, the frequency domain correlation kurtosis of the signal approached by each iteration was solved when performing sparse decomposition.Secondly, the position for the maximum frequency domain correlation kurtosis value was found.Finally, the signal corresponding to this position was used to reconstruct the original signal, calculate its envelope and envelope spectrum, and analyze bearing fault types.The analysis results of simulated signals and ones obtained in tests showed that the proposed method can be used to accurately identify bearing faults, and verify the effectiveness and superiority of this method in identifying cyclic impact sequences. 2019 Vol. 38 (23): 196-202 [Abstract] ( 192 ) HTML (1 KB)  PDF (1370 KB)  ( 203 ) 203 Anti-collapse performance of RC frames with external pre-stressed tendons after failure of middle column FAN Yunlei,PENG Yifan,WANG Jie In order to study anti-collapse performance of a RC frame with external pre-stressed tendons after failure of middle column, five 1/3 scale single-story two-span RC frames with external pre-stressed tendons were designed and fabricated.Tests for these RC frame’s mechanical performance, mechanism transformation, ultimate load-bearing capacity and catenary effect were conducted through changing boundary conditions and layout forms of external pre-stressed tendons after failure of middle column.Their loads, displacements, strains, and cracks’ initiation and expansion were measured.On the basis of test results, the finite element analysis model was established.The finite element computation results and test ones were compared.The results showed that external pre-stressed reinforcement can obviously improve anti-cracks performance of RC frames; on the premise of beam ends having reliable horizontal constraints, RC frames’ ultimate anti-collapse ability under frame beam mechanism can increase up to 70%, while their ultimate anti-collapse ability under catenary mechanism depends on yield strength and ultimate strength of external cable; compared with horizontal reinforcement form, fold line reinforcement one can provide larger vertical anti-collapse ability, and speed up mechanism transformation; increasing beam height and tensile stress value can improve the ultimate anti-collapse ability under frame beam mechanism; reasonable finite element model can be used to more accurately predict peak resistance under frame beam mechanism, and those under catenary mechanism and mechanism transformation node, respectively. 2019 Vol. 38 (23): 203-212 [Abstract] ( 153 ) HTML (1 KB)  PDF (1812 KB)  ( 51 ) 213 Linear vibration characteristics of a thin ring with rotary acceleration based on wave method LIN Jie,HUANG Dishan Using Hamilton’s principle, the in-plane linear partial differential dynamic equations of a thin ring with rotary acceleration were established on the basis of Euler-Bernoulli beam theory considering effects of Coriolis force and centrifugal one.The wave method was used to solve the differential equations, and natural frequencies of the ring under its rotating state were computed and compared with those published in literature to verify the correctness of these dynamic equations.Effects of rotating angular acceleration and angular velocity on mode characteristics of the thin ring were analyzed.The study results provided the wave method for calculating linear vibration characteristics of a thin ring with rotary acceleration, and widened the scope of dynamic calculation with the wave method. 2019 Vol. 38 (23): 213-218 [Abstract] ( 171 ) HTML (1 KB)  PDF (836 KB)  ( 30 ) 219 Feature extraction for rolling bearing incipient faults based on adaptive MOMEDA and VMD LIU Yan,WU Xing,LIU Tao,CHEN Qing Due to bearing incipient fault size being smaller and susceptible to environmental noise and signal degradation, fault impact signals are often very weak.Variational mode decomposition (VMD) has a certain application in bearing fault feature extraction, but bearing weak fault extraction is not ideal under stronger background noise.Here, aiming at this problem, the multipoint optimal minimum entropy deconvolution adjusted (MOMEDA) and VMD were proposed to do bearing early fault diagnosis.Influences of filter length on MOMEDA effect were studied.An adaptive MOMEDA method based on the forward and backward one was proposed to determine the optimal filter length.The adaptive MOMEDA was used to de-noise signals and avoid false peal values after traditional MED iteration and filtering.The de-noised signals were decomposed with VMD to do signal reconstruction based on spectral kurtosis.Fault features were extracted from the reconstructed signals to gain the better effect.Finally, the feasibility and effectiveness of the proposed method were verified with tests. 2019 Vol. 38 (23): 219-229 [Abstract] ( 221 ) HTML (1 KB)  PDF (1501 KB)  ( 288 ) 230 Wind pressure characteristics of large-span terminal roof under mesoscale typhoon ZHU Rongkuan,KE Shitang Roof partial damage is the most typical form of wind-induced damage of long-span terminals, especially, in China southeast coastal areas where strong typhoons frequently occur.Here, aiming at the problem of excessive simple typhoon model in the existing civil engineering theory system, the weather forecast model WRF based on the non-static equilibrium Euler equation model was introduced to simulate the typhoon Catfish with higher space-time resolution.Xiamen international airport terminal was taken as an example.Firstly, the triple nested mesoscale WRF technique was used to analyze the typhoon Catfish near-ground 3-D wind field characteristics, and the boundary layer wind speed profile was obtained based on nonlinear least squares fitting.Then, the user-defined function was used to determine the inflow wind field of small scale CFD numerical simulation, the standard k-ε turbulence model was used to simulate the typhoon wind field and wind field distribution of large-span terminal structure in good state class A wind field environment, respectively.The most unfavorable incoming flow’s wind direction angle was determined based on the pressure difference analysis between upper and lower ends of suspended eaves.Finally, the extreme value wind pressure characteristics of the terminal roof under the most unfavorable working conditions were deeply explored based on the large eddy simulation technique, and the flow field and wind pressure forming mechanisms of the roof under typhoon and class A wind field were presented contrastively.The results showed that WRF model can be used to effectively simulate the near-ground typhoon wind field, and the fitted typhoon profile index is 0.091; considering effects of mesoscale typhoon can increase the roof’s average wind pressure and extreme value one, the latter can be increased up to 31%; the study results can provide a scientific basis for typhoon load choosing and anti-typhoon design of such long-span terminal roofs.  2019 Vol. 38 (23): 230-238 [Abstract] ( 167 ) HTML (1 KB)  PDF (5465 KB)  ( 50 ) 239 Vibration reduction performance of metal rubber coated pipeline damping structure XIAO Kun,BAI Hongbai,XUE Xin,WU Yiwan Based on the bi-fold line hysteresis model, the mechanical analysis and reasonable simplification of a coated pipeline damping structure were done to establish its appropriate mechanical model.The mechanical model of a single-DOF hysteretic system was linearized equivalently using the equivalent linearization method to analyze the variation law of metal rubber’s stiffness and damping with variation of excitation force, and conduct test verification.Meanwhile, the characteristic quantity was proposed to characterize damping performance of a coated pipeline damping structure.Variation laws of a metal rubber coated pipeline damping structure’s damping characteristics with variation of its forming density, number of coated layers and magnitude of excitation were studied with tests to provide theoretical and test bases for vibration reduction engineering application of pipeline systems. 2019 Vol. 38 (23): 239-245 [Abstract] ( 189 ) HTML (1 KB)  PDF (1390 KB)  ( 176 ) 246 Gear system modeling considering sliding bearings’ time-varying dynamic parameters WEI Wei,GUO Wenyong,WU Xinyue,WU Qihao In order to study a gear system more deeply, considering its bearings’ time-varying dynamic parameters and effects of its dynamic gear backlash, its dynamic model was established to analyze its vibration responses.A cylindrical spur gear system was taken as the study object.A dynamic pressure lubricated bearing model was combined with a gears’ meshing one, considering effects of dynamic gear backlash, the gear system’s dynamic equations were established.Here, a method to solve a gear-sliding bearing coupled system was proposed.Effects of bearing clearance, backlash and rotating speed on the system’s vibration responses were studied.The results showed that sliding bearing dynamic parameters’ time-varying characteristics are helpful to improve the system’s vibration responses; increasing bearing clearance and gear backlash within a certain range can reduce gears’ dynamic meshing force and radial vibration; with increase in gear rotating frequency, the system’s vibration response amplitudes decrease and its motion tends to be stable. 2019 Vol. 38 (23): 246-252 [Abstract] ( 170 ) HTML (1 KB)  PDF (763 KB)  ( 67 ) 253 Application of interference suppression gate in line spectrum extraction NIU Fang1, 2, 3, HUI Juan1, 2, 3, ZHAO Anbang1, 2, 3, 4 Due to complexity of ship radiated noise and marine environment noise, it is difficult to directly extract line spectra from demodulated signals of ship radiated noise.Here, an interference suppression gate was designed to suppress broadband noise interference in line spectrum extraction.Simulations for single-frequency input signal and harmonic input one verified the effectiveness of the suppression algorithm.Moreover, statistical analysis was performed for the output signal to noise ratio (SNR) gain of the interference suppression gate.The processing results of actual ship radiated noise data showed that application of interference suppression gate can effectively reduce broadband noise interference, and provide convenience for line spectrum extraction; the extracted propeller shaft frequency can be taken as a feature quantity for ship target classification and recognition; the interference suppression gate algorithm can also be applied in line spectrum detection. 2019 Vol. 38 (23): 253-258 [Abstract] ( 136 ) HTML (1 KB)  PDF (2080 KB)  ( 29 ) 259 Dynamic characteristics analysis for an in-pipe robot driven by pressure difference based on CEL approach JIANG Xudong1, SUN Qihai1, TENG Xiaoyan2 Aiming at the problem of fluid-structure interaction between flexible multi-body system of an in-pipe robot driven by pressure difference and pipe’s internal flowing fluid, the robot system’s fluid-structure interaction dynamic model was established based on the coupled Euler-Lagrange (CEL) approach to obtain structural dynamic responses of the robot operating in the complicated pipe.Stress field of sealing cup, friction between pipe and robot, and driving pressure difference exerted on robot by fluid under different pipe internal radius and robot segment length, respectively were analyzed contrastively.The numerical results indicated that peak driving pressure difference appears during robot initially entering pipe and reappears with fluctuation of robot motion velocity and change in pipeline topology; when robot is at pipe’s small curvature radius bend, sealing cup experiences strong localized squeeze to form peak equivalent stress, but friction drops to vale value due to clearance between sealing cup and bend; with decrease in pipe’s inner radius, equivalent stress of sealing cup, average friction and average driving pressure difference increase; with increase in robot segment length, equivalent stress of sealing cup, average friction and average driving pressure difference increase. 2019 Vol. 38 (23): 259-264 [Abstract] ( 206 ) HTML (1 KB)  PDF (2332 KB)  ( 42 ) 265 Effects of elastic tube bundle’s wet modal frequency variation on its heat transfer characteristics YU Yijie,SONG Jiwei,CHAI Xiaoming,HOU Lanya,CHENG Lin In order to study effects of an elastic tube bundle’s wet modal frequency change on its heat transfer characteristics, here, the elastic tube bundle was taken as the study object to do modeling under actual operating conditions and numerical simulation of wet modal analysis.The added mass coefficient was used to characterize variation of the elastic tube bundle’s wet modal frequency, considering effects of fluid’s flow velocity and viscosity, the added mass coefficient corresponding to wet modal frequency was calculated.Elastic element’s heat transfer performance was analyzed with change of wet modal frequency.The results showed that the higher the fluid viscosity, the larger the added mass coefficient for the elastic tube bundle, the more the drop of elastic element’s wet modal frequency; with increase in incoming flow’s velocity, wet modal frequency of elastic element in a flow field increases; external flow field’s fluid velocity and viscosity affect elastic elements, the higher the wet modal frequency, the smaller the added mass coefficient, and the better the surface heat transfer effect.  2019 Vol. 38 (23): 265-270 [Abstract] ( 128 ) HTML (1 KB)  PDF (1533 KB)  ( 40 ) 271 Multi-fault diagnosis for gearboxes based on multi-task deep learning ZHAO Xiaoping1,WU Jiaxin1,QIAN Chengshan1,ZHANG Yonghong2, WANG Lihua2 The field of mechanical fault diagnosis enters a "big data" era, and the deep learning achieves fruitful results in mechanical big data processing with its powerful adaptive feature extraction and classification capabilities.However, this method is used in a single-label system to diagnose a single target fault.Under the background of big data, the single-label system not only cuts apart connections among different target faults of mechanical equipment, but also is difficult to fully describe lots of equipment fault state information, such as, fault location, type, and degree, etc.Here, a diagnosis method based on the multi-task deep learning model was proposed to simultaneously diagnose faults of bearing and gear in gearbox.It was shown that with this method, features of different targets can adaptively be extracted from the same signal, and then these features are used to perform fault diagnosis through a separate task layer.The test results showed that the proposed method realizes simultaneous correct diagnosis of bearing and gear different faults in gearbox under multiple working conditions and a large number of samples. 2019 Vol. 38 (23): 271-278 [Abstract] ( 241 ) HTML (1 KB)  PDF (2415 KB)  ( 152 )

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