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2019 Vol. 38, No. 20
Published: 2019-10-15
1
A study on gas-liquid two-phase flow in a horizontal tube under heaving motion
ZHOU Yunlong，CHANG He，ZHAO Pan
According to the method of combining vibration apparatus with two-phase flow experiment loop, an experimental study on gas-liquid two-phase flow in a horizontal tube under heaving motion was conducted.At the same time, based on using the dynamic mesh technique, more about gas-liquid two-phase was simulated by the platform of FLUENT using UDF.The influences of vibration condition and fluid properties on mean pressure drop and flow regime transition line were analyzed.The results show that flow patterns of gas-liquid two-phase flow under heaving motion are different from those under steady condition, and main flow patterns are found as beaded flow, slug flow, shell flow, wave flow, and annular flow.Heaving motion has a great effect on mean pressure drop of fluid flow, but when flow rates or liquid viscosity of fluid are higher, it has a smaller influence on mean pressure drop and flow pattern transition lines.Similar to steady condition, there is little effect of viscosity on the flow pattern transition line.Flow regime shows that flow pattern zones were expanded with vibrate frequency and amplitude.Comparing to vibrate amplitude, vibrate frequency had a greater impact on the flow pattern transition line.
2019 Vol. 38 (20): 1-6 [
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313
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7
A study on electromagnetic-ring active balancing system for machine tool spindles with hollow rotors
PAN Xin1,2,HE Xiaotian2,WU Haiqi2,GAO Jinji1,2,JIANG Zhinong1,2
Mass imbalance is a typical cause to failure of machine tool spindles.Because the active balancing system can automatically reduce the unbalance vibration of spindle rotors, it is an essential component of intelligent machine tool spindles.A novel electromagnetic-ring balancing actuator was introduced in this study, which can be integrated into hollow rotors of spindles and compensate the initial mass imbalance through step rotation of two counterweight discs driven by magnetic field.The effectiveness of the balancing system was verified by an active balancing experiment.The experimental results show that the active balancing system could reduce the unbalance vibration of the machine tool spindle by 87.5% at 3 600 r/min.
2019 Vol. 38 (20): 7-11 [
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226
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12
Implementation of input shaping for the vibration control of flexible beams manipulated by industrial robot
LI Lin,HU Xiqin,ZOU Yanbiao
The residual vibration of a flexible object is inevitable in the operation of industrial robots, especially when the direction of motion coincides with the direction of deflection.A method for controlling the vibration of a flexible beam manipulated by a 6 degrees-of-freedom industrial robot was presented in this study.To achieve a precise and rapid rest-to-rest motion, the input shaping technique was applied to address the above mentioned problem.First, to design a reasonable input shaper, a vibration parameter identification algorithm combined with Fourier spectrum and time domain analyses was used to estimate the natural frequencies and damping ratios of a robot-beam system.Second, a shaping technique along the path direction in Cartesian space was proposed to avoid a contour error.Finally, experiments were conducted.Results show that the proposed approach effectively reduces vibration by approximately 90% and eliminates the contour error simultaneously.
2019 Vol. 38 (20): 12-17 [
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231
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18
Multi-scale noise tuning stochastic resonance analysis oftelemetry vibration signal based on double tree complex wavelet
LIU Xue，SUN Ao，LI Dong
Telemetry vibration signal contains a great deal of information that reflects the status of aircrafts during test, and has characteristics of non-linear, non-stationary, strong noise.How to extract the weak nonlinear features which reflect the operating status of the system is directly related to the accuracy of flight status monitoring and fault diagnosis.To solve this problem，a multi-scale noise tuning stochastic resonance analysis method based on double tree complex wavelets was proposed.The impact of multi-scale band limited noise on nonlinear stochastic resonance was fully considered, and a multi-scale noise tuning and salp-swarm-algorithm was used to optimize the iteration of nonlinear stochastic resonance，so the weak feature information of telemetry vibration signal was enhanced.Simulation and experimental results show the effectiveness of the method.
2019 Vol. 38 (20): 18-24 [
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201
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25
Rotor blades travelling-wave analysis based on non-contact vibration measurement
ZHANG Yansong, ZHANG Dongming, QIU Daming, LI Chenggang, LIU Yang
This paper describes application of a non-contact vibration measurement and analysis method, which is based on discrete Fourier transform analysis of the vibration frequency of engine all-blades in a stage.By comparing the stage vibration frequency of all-blades in the stationary reference frame with the vibrations frequency in the rotating reference frame, the travelling wave structures of the engine rotor were analyzed in detail.According to the measurement of blades vibration in the compressor experimental, the vibration frequency is 1752.7 Hz in the stationary reference frame and 926.4 Hz in the rotating reference frame respectively at the speed of 12343 r/min, forming a four-nodal-diameter forward travelling wave.The frequency and speed margin were obtained by further connecting the travelling wave with the Campbell diagram of compressor rotor vibration.
2019 Vol. 38 (20): 25-30 [
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207
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31
Complementary ensemble adaptive sparsest narrow-band decomposition and its application
CHEN Junhang1,2,PENG Yanfeng1,2,LI Xuejun1,2,HAN Qingkai3,LI Hongguang1,4
Adaptive sparsest narrow-band decomposition (ASNBD) is the most sparse solution for searching signals in the over-complete dictionary library containing intrinsic mode functions (IMF), which transforms the signal Decomposition into an optimization problem, but the calculation accuracy still needs to be improved in the case of strong noise interference.Therefore, in combination with the algorithm of thecomplementary ensemble empirical mode decomposition (CEEMD), a new method of the complementary ensemble adaptive sparsest narrow-band decomposition (CE-ASNBD) was obtained.In this method, the white noise opposite to the paired symbol is added to the target signal to reduce the reconstruction error and realize the adaptive decomposition of the signal in the process of optimizing the filter parameters.The analysis results of simulation and experimental data show that this method is superior to CEEMD and ASNBD in inhibiting mode confusion, endpoint effect, performance, improving component orthogonality and accuracy, and can be effectively used in fault diagnosis of rolling bearing.
2019 Vol. 38 (20): 31-37 [
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187
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38
Saturation restraint of inputs backstepping control for a flexible hypersonic vehicle
LU Yao SUN You LU Kunfeng
According to the attitude tracking control problem of a flexible air-breathing hypersonic vehicle, a nonlinear control method with saturation restraint of inputs based on backstepping was proposed.Considering the influence of the deflection of the elevator on the lift, a new virtual control variable was introduced to control the state of angle of attack precisely.The effects brought by the elastic modes of the body were considered as a class of disturbance, which was estimated via the disturbance observer and compensated within the controller.A nonlinear gain function was introduced to improve the saturation restraint capability of the control input of the system, and the stability of the close-loop system was proved based on the Lyaponuv theory.The simulation analysis demonstrated the validity of the proposed method．
2019 Vol. 38 (20): 38-43 [
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144
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44
Analysis of characteristics of an ultrasonic motor in shock environment
SUN Dong1,TANG Yu-juan2,WANF Jiong1,WANG Xin-jie1
The influence of shock environment on an ultrasonic motor was studied.The dynamic response of the ultrasonic motor under different impact load was analyzed based on the finite element method.The material model of key components was bilinear isotropic hardening model during the analysis process.The influence of shock environment on mechanical characteristic of the ultrasonic motor and vibration characteristic of stator was analyzed via experiment.The analysis results show that the deformation of the rotor can be divided into two states, the sinkage of rotor’s center and twisting of rotor.Bsides the amplitude, the impact duration also has influence on the deformation of the structure.The vibration characteristic of stator will have distortion besides the reduction of mechanical characteristic of the ultrasonic motor in shock environment.Rubber can protect the ultrasonic motor in shock environment effectively.
2019 Vol. 38 (20): 44-50 [
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185
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51
A study on nonlinear vibration characteristics of gas storage well string based on the wavelet multi-scale transform
YAN Hang1, YAN Yifei2, YAN Xiangzhen
In order to explore the nonlinear vibration characteristics of the pipe string in a gas storage well injection process, the dynamic characteristics and frequency domain characteristics of the string in the wellbore were obtained.Firstly, according to the structural characteristics of the gas storage wellbore, a nonlinear vibration analysis method of the gas storage well string was established, and the mathematical equation of the nonlinearity of the tubular string was obtained by numerical solution.Secondly, an ANSYS simulation model was established according to the vibration model to simulate the inherentity of the r string.The characteristics were compared with the results of the mathematical model.Meanwhile, the transient dynamic response analysis of the gas storage well string was carried out to obtain the vibration effect of the column.Finally, the vibration of the gas string of the gas storage well was constructed in combination with the site conditions.An experimental device was designed as the vibration signal data acquisition terminal, and the vibration characteristic data were obtained through the nonlinear vibration experiment of the pipe string during the gas injection process.Taking the actual gas storage well J03-H1 as an example, the variation of vibration effect such as column pressure, wall speed and amplitude of gas injection process was analyzed.The results show that the model calculation results under the same production conditions are basically consistent with the ANSYS simulation results.With the increase of the column design, the annulus constraints have a great influence on the inherent characteristics of the column; low frequency pressure fluctuation is the important factor to induce the column vibration.Excitation source; with the increase of gas injection volume, the vibration effect of each column was obviously changed, which changes periodically.The near
gas injection section and the well inclined section are the high-incidence areas where the gas storage well string generatesvibration, and the column is safe.Corresponding safety measures should be taken during production design and operation.
2019 Vol. 38 (20): 51-60 [
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196
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61
A study on the performance of nonlinear viscous damper testing
SU Hexian1,2，PAN Wen1,2，LAN Xiang1,2，YANG Xiao-dong1,2，BAI Yu1,2，ZHANG Xingxian3
Performance test on non-linear viscous damper is an essential way to assess its performance.However, part of the technique provisions in the codes of practice associated with performance test on non-linear viscous damper has not been specified and detailed.There are still a few controversial issues of determining the performance parameters C and α, assessing the area of hysteresis loop, conducting low-velocity test, etc.In view of these, this study examined both the associated test technique and data processing approaches.Based on a series of test on the typical nonlinear viscous damper in engineering practice, a data processing scheme was determined for the performance parameters C and α.The technique provision about assessing the area of hysteresis loop and conducting low-velocity test was then specified.The results of this study will provide guidance for improving the technique provisions for assessing the performance of nonlinear viscous damper.
2019 Vol. 38 (20): 61-69 [
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193
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70
An improved collaborative optimization algorithm of ship structures’ static and dynamic subject based on the mixed and dynamic penalty function
GUO Tianqi 1,2，XIA Yimei3，WANG Fuhua3，WANG Deyu 1,2
Based on the standard collaborative optimization and aimed at the limitation of existing improved collaborative optimization like the relaxation factor method and the penalty function method, the collaborative optimization algorithm was improved by introducing the relaxation factor to construct the mixed dynamic penalty function.A hybrid algorithm based on the Non-dominated Sorting Genetic Algorithm and Adaptive Simulated Annealing was proposed for system-level optimization through the Isight software.The improved collaborative optimization algorithm was applied to the multi-objective optimization design of ship structures to optimize the static and dynamic characteristics of the marine engine room.The optimal solution was obtained and compared with the results of existing collaborative optimization algorithm based on the dynamic penalty function.It was shown that the improved algorithm has fewer iterations, better target value, and smaller interdisciplinary inconsistency information, which has certain value for multi-objective and multi-disciplinary structural optimization in actual ship engineering application.
2019 Vol. 38 (20): 70-76 [
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162
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77
A study on the shock stiffness of a titling-pad bearing in a turbo generator
LI Jia ZHANG Bo DING Wei ZHOU Xiangrong
The impact performance of a tilting-pad journal bearing in a turbo generator was studied by means of simulation and test.The shock stiffness of the bearing was considered as the only unknown quantity in a black box and it was identified through comparing the simulation result and the test result in various shock test cases.It shows that the shock characteristics of the tilting-pad journal bearing can be simplified as an equivalent non-intersecting stiffness parameter, and there is a simple formula relation between the shock stiffness and the shock velocity which is loaded to the bearing and represents the shock energy.
2019 Vol. 38 (20): 77-82 [
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174
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83
Structure design and output displacement modeling of a giant magnetostrictive actuator for a servo valve
ZHENG Jiawei，HE Zhongbo，ZHOU Jingtao，XUE Guangming，RONG Ce，BAI Guo
For the problem of poor homogeneity of axial bias magnetic field in traditional giant magnetostrictive actuators, a new one with distributed structure was designed.Then, under the condition of defining the radial and axial dimensions of this actuator, the distributed structure of bias magnetic field was simulated by changing the number of segments of the giant magnetostrictive rod, and the optimal distribution was determined.An output displacement model of the giant magnetostrictive actuator was established through the reluctivity theory, the J-A model, quadratic domain-transfer model and the knowledge of vibration theories.Based on this model, the step response and harmonic response of the actuator were obtained by the lsim function in Matlab.Finally, a test system for the actuator was established, and the step response test and harmonic response test were performed.The results show that the step response time of the actuator can reach 2.37 ms.and in the driving frequency range of 20 Hz to 200 Hz, the test results are basically consistent with the model calculation results, which proves the accuracy of the model.
2019 Vol. 38 (20): 83-89 [
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135
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90
Dynamic performance monitoring of high-speed automata based on phase-partitioned canonical variate dissimilarity analysis
WANG Baoxiang，PAN Hongxia
Aiming at monitoring the dynamic characteristics of high-speed automata with multi-stroke features, a phase-partitioned canonical variate dissimilarity analysis (PCVDA) method was proposed.The short-term transient shock signals were firstly partitioned into multiple phases through establishing the matching relationship between the whole strokes and the signals, the sinusoid-assisted empirical mode decomposition (SEMD) was then employed to transform each phase into high-frequency and low-frequency components, and by calculating the departure between the past-and future-projected canonical variables, the PCVDA models on those two components were built to monitor the dynamic characteristics of high-speed automata at different phases, respectively.Dynamic performance monitoring of a 12.7mm high-speed automata validates the efficiency of the proposed work.
2019 Vol. 38 (20): 90-96 [
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169
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97
A study on the kinematic behavior and crater shape of rhomboid particle impacting ductile material
DU Mingchao，LI Zengliang，DONG Xiangwei，SUN Zhaocheng，FAN Chunyong，CHE Jiaqi
A coupled numerical simulation model based on the Lagrange method was established for the erosion wear process of rhomboid particles, and the kinematic behavior and crater shape of rhomboid particle impact ductile materials at different impact velocity vi, impact angle αi and orientation angle θi were analyzed by the model.The results show that the impact angle and orientation angle are the key factors that determine the rotation of particles, but will be affected by the impact velocity.From the results, it is known that the impact velocity has little effect on the rotation direction and the kinematic behavior of the forward rotating particles, and the crater profile generated by the particles was almost unchanged.On the contrast, the impact velocity has great influence on the kinematic behavior of the backward particles; there is a cutting speed range from 55 m/s to 100 m/s.When vi is within this range, chip separation occurs on the ductile material surface.When vi is smaller or larger than this range, no chip separation occurs, but the material pile-up happens.The reasons for the material pile-up in the two cases are different.When the impact velocity is small, the initial kinetic energy is low, which is not enough to cut off the material, and the material accumulated on the surface of the crater; when the impact velocity is large, the normal insertion of the particles is deep, and the particles have the combined effects of “dig” and “micro-cutting”.Under the effect of “micro-cutting”, slender chips accumulated on the surface of the crater.The critical impact of low impact angle and large orientation angle generated particle kinematic behavior and crater profile under different impact velocity is consistent with the law of backward impact, and the critical impact of high impact angle and small orientation angle produced particle kinematic behavior and crater profile under different impact velocity is consistent with the law of forward impact.
2019 Vol. 38 (20): 97-105 [
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147
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106
Application of EDRS in blind source separation of rolling element bearing vibration signal
LIU Kunpeng，XIA Junzhong，BAI Yunchuan，L Qipeng，ZHENG Jianbo
Deterministic random separation (DRS) is a classic blind source separation method of bearing signal, but it is only fit to deal with the bearing signal in steady speed while fail at completing the signal separation under variable speed condition.Meanwhile, it has less robustness because the signal amplitude value fluctuations was not considered in DRS, a method named extended deterministic random separation (EDRS) was proposed to solve the above problems.The angular domain resampling technique was applied to transform the time-domain variable-speed signal into the steady-state signal in the angular domain to reduce the influence of the rotational speed variation; the Z-scoring model was used to normalize the steady-state signal in the angular domain to decrease the signal amplitude fluctuation.After the signal was normalized, the deterministic components were extracted and the random components of the vibration signal were obtained.Simulation analysis and bearing fault test show that blind source separation of bearing signals in variable speed can be completed by EDRS, and the fault features can be extracted effectively from the random components.
2019 Vol. 38 (20): 106-111 [
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170
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112
Experimental modeling of an integrated hydro-pneumatic strut
LIN Dezhao1，YANG Fan1，GONG Di1，ZHAO Feng1，LIANG Zhisheng2
In this paper, one type of integrated hydro-pneumatic strut(HPS), which integrates an internal gas chamber in the rod part and a floating piston used to separate gas from oil was investigated based on an experiment.The main purpose of this research is to invesitgate fundamental dynamic properties for this kind of HPS, and then provides theoretical basis for practical applications.Due to the high standard of seal, the friction characteristic is playing a main role in the dynamic property of this type HPS.It can be found from experiments that the friction properties of this type of HPS is the combination of multiple different friction phenomenon, which includes coulomb friction, viscous friction, Stribeck effect and hysteresis, affected by the system pressure and motion velocity.Considering the above, a novel friction model, which combines the hyperbolic tangent hysteresis model and the friction model for pure sliding and oscillating sliding contacts, has been proposed to describe the friction properties.The model parameters have been identified based on the experimental data.Finally, the effectiveness and accuracy of the friction and dynamic force models has been verified through comparison of the experimental data and the simulation result.
2019 Vol. 38 (20): 112-117 [
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157
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118
Effects of transverse shear and normal deformations on the vibration characteristics of laminated plates
YE Tiangui，JIN Guoyong，LIU Zhigang
A three-dimensional approach was proposed for solving vibration characteristics of laminated plates of arbitrary boundary conditions and lamination schemes, based on the generalized spectral method and the differential quadrature technique.Numerical verification shows that the proposed method converges rapidly and has high calculation precision.Effects of transverse shear and normal deformations on the vibration characteristics of laminated plates were systemically analyzed.The analysis shows that: ① transverse shear deformation has significant effects on the vibration frequencies of laminated plates and the effects are increased with thickness ratio; ② transverse normal deformation has significant effects on the vibration frequencies of laminated plates composed of layers of high hierarchy materials and the effects are increased with thickness ratio.
2019 Vol. 38 (20): 118-125 [
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163
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126
Influence on shock initiation of composite shell charges underthe impact of fragments
ZHAO Yu Feng, LU Zhi Chao, DONG Yong Xiang, AN Er Feng, FENG Shun Shan
The shock initiation of composite shell charges under the impact of fragments was studied.Simulations were compared with experimental results.The research on the pressure peak and energy change of the explosive in the protection of the different composite shell was carried out.By comparing different configurations, it was obtained that the pressure peak of the explosive in the protection of the composite shell with low wave impedance of the interlayer material reduce to 36% of that obtained from single steel shell.And the result also shows the higher strength and modulus of the interlayer material, the better performance of against penetration of fragments and energy absorption of the composite shell.By changing the arrangement of composite shell, placing the SPUA near the explosive, the pressure peak of explosive is 30% of the single steel shell, and the absorption of energy is a magnitude lower than that of the single steel shell.With a certain thickness of the composite shell, it is found that the pressure peak of the explosive of the steel-SPUA shell is 64% of the single steel shell, and the energy transmitted into explosive is half of the single steel shell.Therefore, the composite shell reduces pressure peak and the energy transmitted into composition B significantly, and improves the ability of explosives against shock initiation of fragments.
2019 Vol. 38 (20): 126-130 [
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173
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131
Effects of Küssner-function-based aerodynamic admittance models on the buffeting responses of a long-span bridge
ZHANG Zhitian，CHEN Tianle，WU Changqing
The Küssner-type function was adopted to simulate the buffeting forces and aerodynamic admittances (AAs) in the time domain.Wind tunnel tests were conducted with the elementary scheme of a long-span bridge to obtain the AAs of its main girder.Based on the experimentally obtained AAs and the Sears function, which was derived from thin airfoil theories, the corresponding Küssner functions were obtained via parametric identification.Finally, the buffeting responses of the concerned bridge were computed in the time domain with the Küssner functions identified from the Sears AAs, experimentally obtained AAs, and without consideration of any, respectively.The analytical results show that the Küssner function method is able to transfer frequency-domain-based AAs to time-domain flexibly, and therefore benefits inclusion of various nonlinearities in dynamic FEM simulations.Results based on the numerical example indicate that exclusion of the AAs results in extraordinarily large buffeting responses.When AAs are included, the buffeting results based on the Sears function are significantly greater than those based on experiments.Therefore, it is appropriate to employ experimentally-based AAs to replace the extensively used the Sears function for buffeting analyses of long-span bridges, even for those stiffened with flat box-girders.
2019 Vol. 38 (20): 131-139 [
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190
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140
Theoretical and experimental study on the static stability of labyrinth seals
MA Kai1 ZHANG Wanfu1 ZHANG Yao1 GU Qianlei1 CHEN Luqi1 LI Chun1 YANG Jiangang2
The static stability of labyrinth seals directly affects the safe and stable operation of a rotor system.This paper proposed an experimental method to identify the fluid-induced force and static stiffness coefficients.A three-dimensional fluid model of the labyrinth seals was established.And the static characteristics under different eccentricities and inlet pressure were studied.Theoretical results show a good agreement with the experiment results.The labyrinth seal with different eccentricities produces a fluid-induced force and a negative direct stiffness, which causes the rotor deviating from the geometric center of the stator.Both the fluid-induced force and negative direct stiffness increase with eccentricity and inlet pressure.The static instability is mainly due to the fact that the fluid velocity in the small clearance increases more rapidly along the seal leakage path.The mass inertial force is increased significantly and the pressure decreases.This results in greater pressure distribution in the larger clearance.The fluid-induced force and negative stiffness that tend to push the rotor away from the stator center are produced, and eventually lead to the static instability of labyrinth seals.
2019 Vol. 38 (20): 140-147 [
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135
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148
A fault diagnosis method for gearbox based on neutrosophic K-Nearest Neighbor
WANG dongcui1 DING yunfei1 ZHU chenxuan1
It is valuable to study the fault diagnosis method for the gearbox as gearboxes are widely used in rotating machinery.In order to improve the accuracy of diagnosis, a neutrosophic K-nearest-neighbor-based fault diagnosis method was presented for gearbox.Firstly, the method uses the wavelet packet to extract the signal features and constructs a fault sample set.Then, with the help of the neutrosophic theory, the feature weights of the samples are redistributed, and finally the fault diagnosis model based on the KNN decision rules was established, and the concept of the neutrosophic partition was proposed.Experiments show that the proposed method can improve the accuracy of classification and robustness effectively, and make up the shortcomings of the weight distribution.
2019 Vol. 38 (20): 148-153 [
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222
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154
A study on a base isolation RC frame structure with specially shaped columns designed for seismic fortification intensity 8 zone
SU Hexian1,2, PAN Wen1,2, ZHANG Xingxian3, BAI Yu1,2, GAO Yonglin1,2, YU Mingkun4
The isolation performance of a base seismic isolated RC frame structure with specially shaped columns designed for seismic fortification intensity 8 (0.2 g) zone were investigated through numerical analyses and shaking table test.The base isolation design of RC frame structure with specially shaped columns was compared with that of a RC frame structure with common rectangular columns.A shaking table test was conducted on the model of base seismic isolated RC frame structure with specially shaped columns that satisfied the objective of base isolation design.Results show that the RC frame structure with specially shaped columns tends to have considerable lateral stiffness, which makes it have smaller horizontal seismic decrease coefficient than the RC frame structure with rectangular columns.In addition, the shaking table test shows that the acceleration and displacement responses of base seismic isolated RC frame structure with specially shaped columns are significantly reduced.That is to say, the seismic fortification objective, i.e., buildings are neither damaged when subjected to frequently earthquake influence nor collapsed when subjected to rarely earthquake, has been achieved.Furthermore, the base isolation has been validated to be one of effective ways to enhance the seismic performance of the RC frame structure with specially shaped columns.It should be noted, however, that the weakness of the upper structure should be carefully considered in seismic isolation design, and the development of the plastic state should be constrained to a certain level.In sum, the seismic isolation technique can improve the seismic performance of the RC frame structure with specially shaped columns in seismic fortification intensity 8 (0.2 g) zone, indicating the promising application in high intensity area.
2019 Vol. 38 (20): 154-163 [
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189
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164
An analysis on parametrically excited nonlinear vertical vibration of a roller system in corrugated rolling mills
HE Dongping, WANG Tao, XIE Jiaquan, REN Zhongkai，LIU Yuanming
Considering the nonlinear damping and nonlinear stiffness within corrugated interface of corrugated rolling mills, a model of parametrically excited nonlinear vertical vibration of the roller system was established.The stability of theroller autonomous system of corrugated rolling mills was discussed by using the singular value theory.The approximate analytical solution and amplitude-frequency characteristic equations of principal resonance and sub-resonance of roller system excited by corrugated interface were carried out by using the multiple-scale method.The influences of nonlinear stiffness coefficient, nonlinear damping coefficient, system damping coefficient and rolling force amplitude on vibration were analyzed.The correctness of the analysis results was verified by numerical simulation.
2019 Vol. 38 (20): 164-171 [
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Analysis of Damping damping Characteristics characteristics of Magnetorheological magnetorheological Damper dampers for the Aartillery Recoil recoil during Bore bore Period period
ZHANG Guang, WANG Huixing, WANG Jiong
MR Gel (MRG) has a certain anti settlement and long stability compared with MRF.Therefore, MRG is very suitable for recoil applications of a class of weapons, such as artillery, which can still meet the operation requirements after long time storage in peacetime.In order to study the influence of the mechanism of the micro magneto-mechanical properties of MRG on the damping mechanics of the macro-scopical output of the dampers, a parallel plate model for the mixed flow pattern of Couette shear flow and Poiseuille pressure flow was established.The theoretical analysis of the damper output damping was carried out.Finally, the controllability of the damper was analyzed by MRG-70 mechanical parameters.The results of the analysis shows that: the damping coefficient of the damper increases with dynamic viscosity, the effective working area of the piston, the length of the magnetic pole and the Bingham coefficient; in contrast, it decreases with the square of the width of the damped channel and the dimensionless width of the pre-yield plunger.MR damper was controllable to recoil at the beginning of the process of bore period, and the very small energy input (0-131 mT) can achieve a wide controllable range.
2019 Vol. 38 (20): 172-180 [
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181
Modeling the elastic contact angle of preloaded ball screw pair with non-ideal double-arc raceway considering radial clearance
JIANG Hongkui 1 SONG Xianchun 1 XU Xiangrong 1 LI Yanfeng 1 WANG Leyuan 1 DU Wei 2 RONG Bo-song 2
Double-arc raceway (Gothic raceway) is widely adopted in precision ball screw mechanism because it can made the ball screw’s mechanical properties such as bearing capacity, stiffness and transmission accuracy more stable.However, it is more difficult to manufacture and measure the double-arc raceway, and non-ideal raceway are often obtained in practical production.The geometric errors of raceway and radial clearance seriously affect the overall performance of the precision ball screw.In order to improve the assembling quality of ball screw pair, a mathematical model of elastic contact angle of double nut ball screw mechanism with non-ideal profile under pretention load was established based on the Hertz elastic contact theory and the deformation compatibility principle, considering initial radial clearance.The proposed model was verified by applying the model into the calculation of contact angle of split inner-ring ball bearing.Taking the example of double nut ball screw mechanism 3210, the influences of tolerance of raceway and ball diameter on elastic contact angle were analyzed.This method can provide a theoretical reference for optimization design of ball screw, and the intelligent optimization of assembly.
2019 Vol. 38 (20): 181-187 [
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188
Seismic behavior and damage evolution of RAC filled steel tube column versus RAC short beam frame
MENG Ercong1,YU Yalin1, ZHANG Xu1, SU Yisheng2, CHEN Zongping2
To study the seismic performance and damage evolution of recycled aggregate concrete (RAC) filled steel tube column versus RAC short beam frame, three frame specimens with different replacement rates were designed and tested under cyclic reversed loading, and the damage evolution of specimens was analyzed based on a Park-Ang double parameter damage assessment model.The results mainly show that the failure form of RAC filled steel tube column versus RAC short beam frame with different replacement rate presents brittle shear failure.The hysteretic curves of specimens present plump shuttle shape, and all the he of specimens exceed 0.3 when the experiment ends, which shows the structure having good energy dissipation ability.With the increase of replacement rate, the descending section of specimen skeleton curve presents the trend of being steeper.Compared with the specimen with 0% replacement rate, the average yield and peak load change amplitude of the specimens with 50% and 100% replacement rate are both within 5%, and the ductility coefficient decreases 9.70% and 20%, respectively.The inter-story displacement angle of specimens is within 1/107~1/95 when yielded, and it can satisfy the comfortable requirement in normal service stage of the structure.The inter-story displacement angle of specimens is within 1/39~1/36 when destroyed, which shows good collapse resistance ability.Replacement rate has little effect on the specimen stiffness degradation, and the stiffness degradation curves of the specimens with different replacement rate are almost coinciding together.At the beginning of loading, replacement rate has little effect on the damage evolution of specimens, but with the increase of loading displacement, the damage degree of specimens gradually increases with replacement rate.
2019 Vol. 38 (20): 188-195 [
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A non-intrusive vibration measurement method of an axial piston pump based on fiber Bragg grating sensing
HE Zhenxin1,ZHANG Zhengyi2,LI Hongcai1,LIU Chuntong1,FENG Yongbao1
Vibration signal is an important source of information for mechanical equipment fault diagnosis.In order to overcome the system demolition problem of traditional detection methods, this paper innovatively uses the fiber grating sensing method to perform non-intrusive vibration measurement on the hydraulic pump, and fully utilizes the advantages of the optical fiber sensing with strong anti-electromagnetic interference, corrosion resistance, good stability, and high sensitivity measurement.The original fiber Bragg grating vibration sensor was analyzed, and a double equal strength cantilever beam fiber Bragg grating (FBG) vibration sensor was designed and simulated.Based on this, a fiber Bragg grating demodulation system and a vibration test table for the sensor were used.The performance was verified by experiments, and the sensitivity of the sensor was 0.024 nm/(m?s-2), the natural frequency was 185 Hz, and the linearity was good.The modal analysis of the axial piston pump was optimized to arrange the sensing sampling point.Actually the vibration signal of the pump was measured.The research results can provide reliable data support for non-intrusive condition monitoring and fault diagnosis of hydraulic pumps.
2019 Vol. 38 (20): 196-202 [
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155
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Coupled vibration of functionally graded pipes conveying fluid based on a multi-layered model
ZHU Hongzhen1,WANG Weibo2,YIN Xuewen2,GAO Cunfa1
The coupled vibration of fluid conveying pipes with gradient material property along the thickness was investigated based on the Timoshenko beam theory.A multi-layered homogeneous model was employed to discretize the functionally graded material(FGM).With the consideration of axial compressibility of fluid and its friction with pipe wall, the coupled equations were established through the Hamilton’s principle, as well as the fluid momentum and continuum equations.The dynamic stiffness method was used to solve the governing equations of the pipe element.Afterwards, the effects of gradient index of FGM on the dynamic characteristics of pipes were discussed.
2019 Vol. 38 (20): 203-209 [
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177
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A rail profile matching method based on dynamic time warping
LU Yingjie, ZHU Hongtao
Precise matching of rail profiles is an important prerequisite for studying changes in their geometric shapes.Due to random vibration is generated when the track inspection trolley travels, the vibration of the sensor is caused, the acquired data are distorted.In the measurement process, there is some difference in the vibration of each sensor because the absolute symmetry of the sensor cannot be guaranteed.The traditional feature point algorithm can only rigidly compensate for vibration-induced noise, and sometimes feature points cannot be extracted.Based on this, a dynamic time warping algorithm was proposed.From the preliminary matching data, the data of the standard rail profile and the lumbar profile of the measurement rail were selected as two time series, and the distance matrix was established.The recursive idea was used to calculate the cumulative cost matrix with twisting the time axis.The optimal regulatory path was obtained.The correspondence was found between each point in the two time series so as to achieve the exact match of the track profile.Experimental results show that compared with the feature point algorithm, the matching accuracy of the dynamic time warping algorithm is improved by nearly 7 times, the matching effect is good, and the stability is high.
2019 Vol. 38 (20): 210-215 [
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197
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Modal parameter identification of a quayside container crane based on monitoring data
QIN Xianrong, YU Chuanqiang, SUN Yuantao, ZONG Rui, ZHANG Qing
Aiming at modal parameter identification of a quayside container crane (QCC), based on monitoring data, the modal parameters of the QCC were identified by a covariance-driven stochastic subspace identification method (CSSI) in this paper.The main theory of this method and its algorithm were summarized, then, the parameters of the QCC were identified by the CSSI method with the stabilization diagram.The results reveal that this method can effectively identify the five modes of QCC within 1 Hz, the identified damping ratios are less than 3%, and the trolley (loading) has negligible effects on the modal results of the monitored QCC under different working states in an unworking plane, but has certain effects on the modal results in the working plane, i.e.lifting plane.
2019 Vol. 38 (20): 216-221 [
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189
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A study on the resilience model of a reinforced concrete shear wall with concealed bracings
WANG Yijun, CAO Bing,ZHANG Jinlun
A reinforced concrete shear wall with concealed bracings has a series of advantages such as convenient construction, high bearing capacity, and ductility.Based on experimental study on six one-font reinforced concrete shear wall with concealed bracings under low-cycle load, the hysteretic loop curves were simulated and given the formula of key points by using the resilience mode.The resilience model has good simulation result, and it can show the seismic performance of the component pretty well, which lay a theoretical foundation for the elastoplastic seismic response analysis of the reinforced concrete shear wall with concealed bracings.Then, a regression model quantifying the stiffness degradation was proposed based on the stiffness degradation data using the MATLAB.The result shows that the horizontal displacement of shear wall is the result of its stiffness degradation, and the horizontal displacement of shear wall is mainly related to the shear span ratio and the axial compression ratio.
2019 Vol. 38 (20): 222-228 [
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118
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229
Study on wave loads and slamming loads of a ship by large-scale model hydroelastic experiment
JIAO Jialong 1 ZHAO Yulin 1 ZHANG Hao 2 REN Huilong 2
The predictions of wave-induced hull girder hydroelastic vibrations and bow flare slamming loads are important for structural strength and load response issues during ship design and construction.The classical small-scale ship model wave load tests in the towing tank are associated with limitations such as pronounced scale effects, artificially generated waves, and limited model navigational range.The self-propelled large-scale model wave loads testing technique was proposed in this paper.The experimental setup and data analysis method were described in details.The design of backbone for the segmented model and vibration modal results were reported at first.Then wave-induced hull hydroelastic vibrations and impact loads were analyzed based on the large-scale model sea trial measurement data.The bow slamming loads and global whipping responses of hull in three-dimensional waves were finally analyzed.
2019 Vol. 38 (20): 229-236 [
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199
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Characteristic analysis of ground motions of a canyon topography under obliquely incident SV waves
SUN Weiyu1,2，WANG Jinghe1,2，YAN Songhong1,3，OU Erfeng1,2，LIANG Qingguo1,2
Based on the input method of the visco-elastic artificial boundary combined with the equivalent load, the ground motion input of the obliquely incident SV waves was realized.The effects of the incident angles of the SV waves and the canyon slope angles on the ground motion amplification coefficient distribution characteristics were studied.It shows that: with the incident angle and slope angle increase, the ground motion amplification coefficient of the slope surface and a certain range of slope crest are increased, and the impact width of the slope top is also larger; when the seismic wave is incident at left, the ground motion amplification coefficient distribution is asymmetry on both sides of the canyon, x component of canyon left bank and z component of canyon right are greater with the incident angle, the greater of incident angle, the more obvious of asymmetry; the ground motion amplification coefficient of slope top and impact width of the slope top are increased linearly with the slope angle in different incident angles; the more incident angle and slope angle, the greater of slope top acceleration response spectrum of x component and the peak has a tendency shift to the right.
2019 Vol. 38 (20): 237-243 [
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220
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A study on the effect of an abnormal worn rail on the lateral acceleration of a bogie frame
WANG Chen1，WU Pingbo1，LUO Shihui1，XU Ziqiang2，MA Weihua1，DONG Xiaoqing2
For exploring the causes of altered bogie lateral accelerations of certain high speed trains, this paper aims at analyzing the relationship between the profile of worn rails and the dynamic behaviors of such high speed trains.A dynamic model was developed with actual measured wheel and rail profiles.The effect of the worn wheel/rail relationship on transverse vibration of the bogie frame was investigated.Simulation results indicated that the lateral acceleration of wheelsets and the bogie frame running on long-term unpolished rails was remarkably higher than those on rails with once and twice polishment.During the testing process, the equivalent conicity would increase with running distance for unpolished rails.The main reason for poor contact between wheel and rail was found to be gauge angle worn and the camber worn rail has not been polished for a long time.
2019 Vol. 38 (20): 244-251 [
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151
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Transient response of a circular cavity under the radial inhomogeneous load
GENG Daxin，TAO Biao，HU Wentao
Based on the theory of elastic medium dynamics, the dynamic response of a circular cavity under transient radial inhomogeneous load was studied.Considering the circular cavity inner surface stress boundary conditions of uneven, the numerical solution of stress and displacement of sourrounding rock was obtained in the time domain under unit impulse load by an expansion method for wave function and the Laplace transform method.The factors, such as wave characteristics of radial nonuniform transient loads and shear modulus, produce effects on the distribution of stress and displacement in radial and annular direction.The effects were analyzed through an example.The dynamic response of tangential stress and displacement were asynchronous with time, and the position of peak value changes from 0 to π over time.When the dimensionless parameter of time was greater than 2, radial stress damped obviously.When the dimensionless parameter of time was greater than 8, radial displacement and tangential response damped to 0 gradually.The vibration period of radial stress is minimal.Shear modulus has significant influence on the amplitude of cavity inner surface displacement.Under non-uniform load, the response amplitude of non-uniform location is obviously greater than that of other positions, and the response of radial stress and displacement is greater than that of ring direction, and the attenuation speed is faster.
2019 Vol. 38 (20): 252-259 [
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136
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Multi-scale entropy analysis of two-phase flow in a horizontal pipe under heaving motion
ZHOU Yunlong, CHANG He, ZHAO Pan
According to the method of combining vibration apparatus with two-phase flow experiment loop, an experimental study on the gas-liquid two-phase flow in a horizontal tube under heaving motion was conducted.Flow regime and pressure fluctuation signal were recognized.Meanwhile, pressure fluctuation signal was analyzed by the method of multi-scale entropy under 102 different flow conditions.The results show that the main flow patterns are found as beaded flow, slug flow, shell flow, wave flow, and annular flow.The changing rate of sample entropy at small scales can be used to classify typical flow regime, and the fluctuation of entropy of large scales reflects the dynamic characteristics of different flow regimes.
2019 Vol. 38 (20): 260-265 [
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A test study on the influence of geometric parameters of annular trench on vibration isolation area
LIU Jinglei1,2, YU Chuanqing1,2, LIU Jie1,2
In order to study influences of geometric parameters such as depth, width, and distance of an annular trench on a vibration isolation area, an outdoor test of the annular trench was carried out, and the contour map of the amplitude reduction ratio was drawn.The area with the amplitude reduction ratio of not more than 0.35 was used as the evaluation index of the effective vibration isolation area, and the influence of the above geometric parameters on the effective vibration isolation area was analyzed.The results show that the depth of the trench, width of the trench, the distance from trench to the vibration source and center angle of the trench have different effects on the effective vibration isolation area.When the ratio of the trench depth to Rayleigh wave length is 0.54-0.77, the ratio of trench width to Rayleigh wave length is 0.23-0.33, and the ratio of the distance from the trench to the vibration source to Rayleigh wave length is 1.18-1.52, a good effective vibration isolation area of annular trench can be obtained.Under the conditions of this test, continuously increasing the ratio of each parameter is not beneficial to enlarge the effective vibration isolation area.The central angle of the annular trench is an important factor affecting the effective vibration isolation area.Increasing the angle can obviously enlarge the area of the effective vibration isolation area.When the angle is 90, a discontinuous effective isolation area will be formed in the isolation area.The selection of the angle is related to the frequency, when the effective isolation area of the same size is achieved, and the angle increases with the decrease of the frequency.
2019 Vol. 38 (20): 266-274 [
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