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18 April 2012, Volume 32 Issue 2 Previous Issue    Next Issue
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1.综述
2.振动理论与数值解法
3.运载工具振动与噪声
4.环境振动与环境声学
5.建筑振动与建筑声学
6.信号处理与故障诊断
7.减振降噪设备和器材
9.振动噪声测试技术
10.工程实践


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1.综述

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Review of Vibro-acoustic Characteristics of Submarine and Advances in Acoustic Design CΗΕΝ Zhi-jian; XIA Qi-qiang; AI Hai-feng 2012, 32(2): 1-6.  DOI: 103969/j.issn.1006-1355-2012.02.001 Abstract ( )   The vibro-acoustic characteristic of submarines is always an important problem in acoustic stealth study. In this paper, the status and advance of vibro-acoustic research of the typical structure of submarines was reviewed. The research findings of acoustic design were also summarized. The significance and necessity of the structural-acoustic design was discussed. Then, a flow-chart and a method for submarine’s structure design were proposed from the viewpoint of acoustical properties of the structure, which provide a reference for further research in the area of acoustic stealth design. Related Articles | Metrics

2.振动理论与数值解法

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Analysis of Dynamic Characteristics of Rotor-bearing System of High Speed Spindle MENG De-hao; LONG Xin-hua; MENG Guang 2012, 32(2): 7-12.  DOI: 103969/j.issn.1006-1355-2012.02.002 Abstract ( )   Based on the quasi-static mechanics model of rolling bearing, a simplified method to solve the dynamics equation of the bearing was proposed by choosing the contact angle as the initial variable. The support stiffness of the bearing was derived, and the internal and external factors affecting the support stiffness were analyzed. A simplified model of the rotor-bearing system for a high speed spindle including the effects of the variable support stiffness was established. Finite element method was used for the solution of the model, and the first order and the second order natural frequencies of the high-speed spindle with different rotation speeds and axial preloads were obtained. Finally, a static hammering test of the spindle was conducted. The experimental results and the theoretical results were found to be in agreement essentially. This, the correctness of this analysis method was verified. Related Articles | Metrics

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Nonlinear Dynamic Analysis of Primary Resonance of Vibratory Pile Driving System ZHENG Hui-ping; WANG Wei 2012, 32(2): 13-17.  DOI: 103969/j.issn.1006-1355-2012.02.003 Abstract ( )   According to the mechanism of vibratory pile driving and non-linear stress-strain relation of soil, a nonlinear dynamic model for vibratory pile driving was established. In this model, the action of soil to the pile was represented by a soft nonlinear spring and a linear damper. The first approximate solution of the system in primary resonance case was obtained by using the method of multiple scales. Amplitude-frequency characteristic for steady primary resonance of the system was analyzed by selecting appropriate parameters. The initial displacement intervals in which the primary resonance had stable solutions in multi-solution frequency band were determined by using Matlab. Finally, the effects of construction parameters on amplitude-frequency characteristics for the primary resonance were discussed. The results of this research provide guidelines for vibratory pile driving construction. Related Articles | Metrics

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Influence of Structural Parameters of Bearingless Rotors on Its Aeroelastic Stability in Hover GAO Wen-jie 2012, 32(2): 18-22.  DOI: 103969/j.issn.1006-1355-2012.02.004 Abstract ( )   A new model of bearingless rotors for aeroelastic stability analysis was presented based on finite-state unsteady aerodynamics. Nonlinear strain-displacement relations were built using Green-Lagrange strain tensor. The blades were modeled as a multiple-load-path system and the finite element equations of dynamics for bearingless rotors were obtained from Hamilton’s principle. Finite-state induced flow model was used to evaluate unsteady aerodynamics effect. The nature of complex eigenvalues of flutter equations of blades was employed to judge the aeroelastic stability of the rotors. Effect of structural parameters on the aeroelastic stability of the bearingless rotors in hover was investigated. It is shown that the numerical results of the stability analysis using this model can more precisely agree with those of experiments using dynamic inflow model or uniform inflow model. Hub pre-conical angle, blade’s chordwise stiffness and flapwise stiffness have substantial influence on aeroelastic stability of bearingless rotors. Related Articles | Metrics

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Application of a Hybrid Method in the Analysis Acoustic-structure Coupled System WANG Yu;CHEN Xing-lin;LI guang-min;LIU Xiao-yi 2012, 32(2): 23-26.  DOI: 10.3969/j.issn.1006-1355-2012.02.005 Abstract ( )   To study the problem of noise radiation penetrating ship’s hull plate, a hybrid method for analyzing medium-frequency vibration of a model structure was established. Statistical energy analysis and finite element method based on wave propagation theory were applied. The reciprocity principle for diffusion field of multi-degree of freedom was subsequently employed to yield a new method which realized the coupling calculation between deterministic components and statistical components. Then the vibration-acoustic response of the model structure was obtained. Transmission loss of the plate structure was calculated. Through the comparison with the results from traditional SEA method and mass law curve, the effectiveness and accuracy of the current method was validated. Related Articles | Metrics

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Arc-tangent Transformation Algorithm for Active Impulsive Noise Control SHAO Jun;ZHOU Ya-li;ZHANG Qi-zhi 2012, 32(2): 27-31.  DOI: 103969/j.issn.1006-1355-2012.02.006 Abstract ( )   In recent years, some effective algorithms for active impulsive noise control have been proposed. But these algorithms may not be stable due to the high-and-sharp peaks of the impulsive noise. To overcome the shortage of these algorithms, a new algorithm based on minimizing the squared arc-tangent transformation of the error signal was proposed. This algorithm doesn’t need to consider thresholds estimation and parameters selection based on priori knowledge of impulsive noise. Moreover, the algorithm is simple in structure, and easy to be realized. The simulation results show that the proposed algorithm can effectively eliminate the impulsive noise, and compared with the other algorithms, the performance of the proposed algorithm has a better convergence and stability. Related Articles | Metrics

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Vibration Mechanism Analysis and Design Improvement of Blade Pump ZHOU Pu;LIU Rui-feng;ZHANG Yi 2012, 32(2): 32-33.  DOI: 103969/j.issn.1006-1355-2012.02.007 Abstract ( )   The marine equipment includes seawater marine pump, drainage pump, screw pump, hydraulic pressure pump, air-conditioning chilled water pump etc. These pumps work with various forms including rotation, reciprocation, meshing etc., and vibrate with different frequency characteristics. In this paper，the vibration levels, characteristics and causes of different rotational marine pumps were analyzed. Some measures for vibration reduction were proposed and applied to the improvement design of some pumps. The results of testing showed that the vibration level of these pumps was reduced as the expected. Related Articles | Metrics

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Modeling and Simulation of Pendulum-type Automatic Balancer Wang Li-Jie;TAN Qing 2012, 32(2): 34-36.  DOI: 103969/j.issn.1006-1355-2012.02.008 Abstract ( )   A mathematical model of a pendulum-type automatic balancer were established using Lagrange equation．Using the test bench, the parameters in the model of the balancer were determined. The model was simulated by means of the Runge-Kutta method. The influence of the pendulum mass on the vibration-reduction performance of the balancer was analyzed. Related Articles | Metrics

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Dynamic Characteristics and Sensitivity Analysis of Gantry Crane WU Qian-yong; CHENG Wen-ming; ZHAO Nan; SU Jun-chao 2012, 32(2): 37-40.  DOI: 103969/j.issn.1006-1355-2012.02.009 Abstract ( )   The global and local vibration of gantry crane will occur when it is working. To assure the driver’s comfort and security as well as the duration of the crane, analysis of the dynamic rigidity of the crane is necessary. In this paper, the ANSYS software was utilized for modal analysis of the crane under practical restriction, and its inherent frequencies under fully loaded condition were obtained. Finally, the weakness of the crane structure was found by the sensitivity analysis of dynamic characteristics, and the improvement measures were put forward. This work provides a reference for dynamic analysis and optimization design for crane structures. Related Articles | Metrics

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Shock Characteristics Analysis of the System with Tilted Support under the Action of Half-sinusoidal Pulse KONG Fan-ling;CHEN An-jun; 2012, 32(2): 41-44.  DOI: 10.3969/j.issn.1006-1355-2012.02.010 Abstract ( )   The geometrically nonlinear impact dynamical equations of a structural system with tilted spring supports were established under the action of semi-sinusoidal impulse. To evaluate the shock characteristics of the tilted spring supports, a new concept of three-dimensional shock response spectra was proposed. The ratio of the maximum shock response acceleration of the system to the peak pulse acceleration, the angle of the tilted spring support and the dimensionless pulse duration were three basic parameters of the three-dimensional shock response spectra. The effects of the angle of tilted spring support, the dimensionless pulse duration, the dimensionless peak pulse acceleration and damping ratio on the shock response were analyzed using the fourth order Runge-Kutta method. It is shown that there is a sensitive area of the shock response to the dimensionless pulse duration, and this area can be avoided by controlling the stiffness of the tilted spring support. The effects of the angle of the tilted support of the system are noticeable. As the angle of the tilted support of the system is reduced, the sensitive area of the maximum shock response of the system will be expanded. As the peak pulse acceleration is increased, the maximum shock response of the system will fluctuate violently and the sensitive area will be expanded. Increasing the damping can obviously improve the anti-shock characteristics of the system. Related Articles | Metrics

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Magnification Effect of the Action of Seismic Wave at the Head of a Single Pile in FDV Soil Foundation YU Huan-xin 2012, 32(2): 45-48.  DOI: 10.3969/j.issn.1006-1355-2012.02.011 Abstract ( )   A model for analyzing the magnification effect of the action of seismic wave at the head of a single pile in soil foundation was established. The soil foundation on bedrock was regarded as a viscoelastic medium with the constitutive relation of fractional derivative viscoelasticity (FDV). The horizontal displacements of the FDV soil foundation under the action of SH harmonic seismic wave were obtained by employing the orthogonality of trigonometric functions and the boundary conditions of the soil foundation. Considering a single pile of circular sections with its end supported on the bedrock, the interaction between the pile and the soil foundations was represented by a series of equivalent dynamic Winkler spring-damper elements. On the basis of Novak plane assumptions, the radial and circumferential displacements of the FDV soil were determined, and then the coefficients of stiffness and damping of the Winkler spring-damper elements were obtained. Furthermore, the lateral vibration of the single pile in FDV soil under SH harmonic seismic wave was solved, and the magnification factor at the head of the single pile in the FDV soil was obtained. The results indicate that the order of fractional derivative and model parameters of the soil foundation has a great effect on the resonance of single pile in FDV soil under the action of the SH harmonic seismic wave, while the density ratio and modulus ratio of pile to soil have very small influence on the magnification factor at lower frequencies, and have some effect at higher frequencies. Related Articles | Metrics

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Torsional Dynamic Impedance of Single Pile in Layered and Saturated Soil Based on Transfer Matrix Method YANG Wen-ling;YU lie;LIN Bin-bin 2012, 32(2): 49-53.  DOI: 10.3969/j.issn.1006-1355-2012.02.012 Abstract ( )   The torsional vibration of a single pile in layered and saturated soil foundation was taken as the research object. The soil around the pile was regarded as a medium with the constitutive relation of fractional-derivative viscoelasticity. The dynamic differential equations of the soil for torsional vibration analysis were established in virtue of the dynamic equilibrium equation, viscoelastic constitutive relation and the stress-displacement relation of the soil. With a double-layered viscoelastic saturated soil foundation as an example, the influence of main mechanical parameters of the pile and the soil on torsional dynamic impedance was investigated. It is shown that the order ratio of the viscoelastic constitutive relations of lower soil layer to upper soil layer has great influence on the torsional dynamic impedance of the pile, and the influence of the ratio of shear wave velocities and the ratio of thicknesses between the two soil layers, and the influence of the ratio of moduli of the pile to the soil on the torsional dynamic impedance depends on the frequency of torsional vibration. However, the influence of these ratios is very small when the solid-liquid coupling coefficients of both soil layers are small. Related Articles | Metrics

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Analysis of Vibro-acoustic Coupling Sound Field and Structure Vibration and Noise Isolation FEI Chao-yang;CHEN Chang-zheng;ZHOU Bo;WANG Zhong 2012, 32(2): 54-58.  DOI: 103969/j.issn.1006-1355-2012.02.013 Abstract ( )   Taking measured loads spectrum generated by blower unit pipeline as excitation source, the room sound field and its vibro-acoustic coupling condition at different frequency are simulated using ANSYS and Virtual Lab sound field simulating software. Simulation results show that vibro-acoustic coupling could be negligible below 400Hz, but the strong vibro-acoustic coupling is existed above 400Hz. The simulation results are consistent with actual measuring results. Through analyzing frequency bandwidth characteristics of loads spectrum and noise spectrum, the double-layer vibration isolation system with general damping vibration isolator and small middle mass is established and its vibration transmission coefficient is calculated. Vibration insulation and noise reduction effects are satisfactory. Related Articles | Metrics

3.运载工具振动与噪声

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Road Testing for Vibration Isolation System Between Ark and Vehicle JIANG Mei-hua;ZHOU Shao-liang;CHEN Xin;LIU Jing-qiang 2012, 32(2): 59-61.  DOI: 103969/j.issn.1006-1355-2012.02.014 Abstract ( )   The wire rope isolators were installed between the ark and the vehicle. Its effect of vertical vibration isolation of the cargo was tested in three different road conditions. Though analyzing the testing data, it was found that the wire rope isolators have obvious isolation effect in the road transportation for the ark on the vehicle. Related Articles | Metrics

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Simulation and Analysis of the Effects of Vibration Acceleration on Visual Identification WANG Bo;LI Yong-jian;SONG Zhe-ming;GUO Zi-zheng 2012, 32(2): 62-66.  DOI: 10.3969/j.issn.1006-1355-2012.02.015 Abstract ( )   The effects of vibration acceleration on visual identification were researched through simulation experiment. A function model for the relation of acceleration to the visual identification efficiency (the response time of correct identification) was established. The results show that vibration acceleration has a significant influence on visual identification efficiency, and their relation can be described by an exponential function. The results offered experimental parameters for vibration reduction design of visual display equipment in vibration environment, and put forward a new idea for vibration reduction. Related Articles | Metrics

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Line Modal Test of High-speed Train Body Using Test. Lab QIU Fei-li;ZHANG Li-min;WANG Xue-liang 2012, 32(2): 67-70.  DOI: 10.3969/j.issn.1006-1355-2012.02.016 Abstract ( )   The line modal testing was carried out for analyzing the modal parameters of the body structure of high speed train. The LMS test.lab, a famous noise and vibration test system, was used for data collection and processing. Based on the theory of modal parameter identification and the modal testing method under environmental excitation, the PolyMax modal extraction method was used and the elastic modal parameters and the corresponding vibration modes of the first three orders of the train’s body were obtained. This work may provide a reference for body structure optimization. Related Articles | Metrics

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Analysis of Dynamic Characteristics of Aluminum Alloy Metro Car-body Using Dynamic Substructure Method CHEN Dong-dong;ZUO Yan-yan 2012, 32(2): 71-74.  DOI: 10.3969/j.issn.1006-1355-2012.02.0.17 Abstract ( )   Because of the large and complex structure of the metro car-body, its local modification will lead to a large number of rework in finite element modeling and analysis. Taking into account the modular manufacturing characteristics of the aluminum-alloy metro car-body, modal analysis of this model was performed based on the dynamic substructure method. Results of computation were compared with those from the conventional finite element method. It is shown that the finite element model can be quickly established and the accuracy of the solution can also be guaranteed with the use of dynamic substructure method. Related Articles | Metrics

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Influence of Assembly State of Powertrain Mounting System on Vehicle’s Vibration HUANG Zun-guo;FU Ji-hong;LI Hai-xiong;ZENG Ling-xian;SHANGGUAN Wen-Bin 2012, 32(2): 75-78.  DOI: 10.3969/j.issn.1006-1355-2012.02.018 Abstract ( )   The influence of assembly state of powertrain mounting system on the vehicle vibration was studied. Especially, the affect of the local stiffness of the frame in the mounting system was analyzed and discussed. Analysis of an example indicated that this influence could be greatly reduced through reasonable design. Related Articles | Metrics

4.环境振动与环境声学

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Evaluation and Control of Underwater Noise of Geophysical Vessel TONG Zong-peng;YE Lin-chang;NI Ming-jie;SHEN Jian-ping 2012, 32(2): 79-82.  DOI: 103969/j.issn.1006-1355-2012.019 Abstract ( )   With a 12-cable geophysical vessel as an example, the underwater noise evaluation technology of ships were studied by means of the combination of the FEM and BEM according to the frequency band features of the vessel. The evaluation methods were verified. Some measures for noise control of ships were proposed and verified by a real-ship testing. The evaluation methods of underwater noise and measures for noise control proposed in this work provide a reference for underwater noise control of the deep-water geophisical vessels. Related Articles | Metrics

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Analysis of Characteristics of Wind Power Noise and Its Environmental Influence WANG Wen-tuan;SHI Jing-hua;JIA Kun;SONG Feng 2012, 32(2): 83-87.  DOI: 10.3969/j.issn.1006-1355-2012.02.020 Abstract ( )   Applying the measurement data in environment protection monitoring, the variation law, characteristics and environmental influence of the noise caused by wind power were analyzed. The result may provide a reference for wind power noise control and the management of wind power stations. Related Articles | Metrics

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Subjective Evaluation of Environment Noise in Classrooms YANG Qing-lei 2012, 32(2): 88-90.  DOI: 10.3969/j.issn.1006-1355-2012.02.021 Abstract ( )   With the development of collegiate ecosystem campus, quality of acoustic environment in teaching area is extensively concerned. Taking a campus of a university in Qingdao as an example, the noise characters in the teaching area were analyzed, and some representative teaching areas were selected according to the characteristics of noise source distribution. Through the noise monitoring in the teaching areas, student’s questionnaire investigation of noises in classrooms, and the analysis of the information of student’s subjective response by means of fuzzy mathematics, the noise threshold based on comfort sense in the teaching areas were determined. Finally, according to the characteristics of noise source distribution and the noise threshold, some measures for improving acoustic environment in the teaching areas of campus were proposed. Related Articles | Metrics

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Prediction of Flight Noise Level by Using Far Field Noise Data of the Eengine in Static Testing LIU Jin-hu;YAN Guo-hua;XIE Fu 2012, 32(2): 91-94.  DOI: 103969/j.issn.1006-1355-2012.02.022 Abstract ( )   （ Aviation Engineering College of Civil Aviation University of China, Tianjin 300300， China ） Abstract : Before an aircraft with the advanced engine putting into the market, its airworthiness noise recertification is necessary. Using the static test data of the engine to predict the flight noise level of the aircraft can reduce the cost of the recertification. In this article, the far field noise data of the testing engine was modified according to the flight condition and then used to predict the flight noise level of the aircraft. The feasibility of this method was verified by comparing the results with those in the real flight test. Related Articles | Metrics

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Influence of Exhaust Pipe on Noise Radiation of Range Hoods HUANG Wei-xi;HOU Hong;ZHU Yong-ding;FANG Xian-liang;LI Bin 2012, 32(2): 95-98.  DOI: 103969/j.issn.1006-1355-2012.02.023 Abstract ( )   The A-grade sound level and spectrum characteristics of the range hood’s noise with and without exhaust pipes were measured and analyzed respectively, and the acoustic impedance of the pipeline and volute system was studied using the impedance transfer and equivalent impedance model. Theoretical and experimental results showed that the rotation speed of the fan was raised obviously and the A-grade sound level increased as well after installing the exhaust pipe. Meanwhile, sound quality was impaired by the low-frequency sound resonance due to the change of the acoustic radiation impedance of sound source. The resonance frequency depended on the length of the pipe and the volume of the range hood’s cavity. Study of effects of the exhaust pipe on the range hood’s noise radiation is of practical significance for assessment and control of the range hood noise. Related Articles | Metrics

5.建筑振动与建筑声学

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Response Analysis of Underground Structure Under Multi-direction Seismic Loads ZHANG Yu-xu 2012, 32(2): 99-101.  DOI: 10.3969/j.issn.1006-1355-2012.02.024 Abstract ( )   Currently, only lateral-horizontal seismic load is considered in seismic response analysis of underground structure, and the seismic loads in longitudinal-horizontal direction and vertical direction are usually neglected. In this paper, an underground structure, whose length was much larger than the width, was considered. The three-dimensional model for finite element analysis was established and its dynamic responses under lateral, longitudinal and vertical seismic loads were analyzed respectively. The results show that it is not enough to consider lateral horizontal seismic load only for this type of underground structure. The results provide a reference for anti-seismic design of underground structures. Related Articles | Metrics

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Physical Mechanisms of Active Acoustical Control for Double-panel Structure ZHANG Xian-ying;CHEN Ke-an;HU Han;MA Xi-yue 2012, 32(2): 102-107.  DOI: 103969/j.issn.1006-1355-2012.02.025 Abstract ( )   The theoretical model of a double-layer panel for active control of sound radiation was established based on the vibro-acoustic coupling equations. Then, the optimal secondary control force was obtained by minimizing the sound power of the panel. Next, the sound intensity distribution on the observed surface was calculated. Finally, the simulation results were analyzed in terms of the sound intensity in the near-field, and a preliminary conclusion for the mechanism of active control of this structure were obtained. Related Articles | Metrics

6.信号处理与故障诊断

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An Endpoint Extension Algorithm of EMD and Its Application in Gear Fault Diagnosis LI Yue-xian;HAN Zhen-nan;GAO Jian-xin;YANG Hao-lin 2012, 32(2): 108-111.  DOI: 103969/j.issn.1006-1355-2012.02.026 Abstract ( )   EMD is an effective method for non-stable signal analysis, but the endpoint effect exists in the decomposition process. In this article, the GM (1, 1) model was used to predict and modify the extension values at the endpoints, which made the cubic interpolation envelope more effective in sifting process. In this way, the endpoint effect was effectively suppressed. The result of gear fault signal analysis shows that this method is correct and effective. Related Articles | Metrics

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Research on Shear Elastic Property of Viscous Liquid by Signal Processing Method CAO Han-jie;NOIREZ Laurence;MENG Guang 2012, 32(2): 112-114.  DOI: 10.3969/j.issn.1006-1355-2012.02.027 Abstract ( )   By changing the connection condition in the interface between the substrates and viscous liquid in the experiments, the shear elastic property of the liquid with several-ten-micron thickness can be observed under the condition of low shear-strain rate. To confirm the property, the strain-stress signals in the experiments were collected and processed by the discrete Fourier transformation (DFT). From the viewpoint of phase difference of strain and stress in rheology theory, it was proved that liquid has shear elastic properties under some small-scale dimension conditions. Related Articles | Metrics

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A New Denoising Method Based on DT-CWT and Improved Thresholding unction for Mechanical Fault Diagnosis QIU Ai-zhong 2012, 32(2): 115-118.  DOI: 10.3969/j.issn.1006-1355-2012.02.028 Abstract ( )   In order to reduce the noise, a denoising method based on DT-CWT (Dual-tree complex wavelet transform) and improved threshold function is proposed to extract the weak failure information in machinery vibration signals to diagnose mechanical faults. The improved threshold function and the design principles of the DT-CWT filter are described in this paper. Because of the advantage of the shift invariance of DT-CWT, the presented method can not only avoid Gibbs phenomenon, but also can obtain higher signal-to-noise ratio (SNR) than conventional methods. Moreover, the improved threshold function can overcome the shortcomings in soft and hard threshold algorithms. The experiments indicate that this method can extract the fault feature submerged in heavy noises, and provide a theoretical basis for early fault diagnosis. Related Articles | Metrics

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Extraction of Transmission Bearing Fault Characters Based on EMD Fractal Technology XIA Jun-zhong;LIU Yuan-hong; DAN Jia-bi;YANG Gang;XIAO Yun-kui 2012, 32(2): 119-122.  DOI: 103969/j.issn.1006-1355-2012.02.29 Abstract ( )   Since the vibration signal of faulty bearing has fractal characteristics, the fault modes of a transmission bearing can be effectively identified by using fractal dimensions. However, the noise in the signal has a serious influence on the fractal dimension calculation, so empirical mode decomposition (EMD) method is necessary for solving the problem. In this article, the vibration signal of the transmission bearing was decomposed into intrinsic mode function (IMF) components by EMD, and then the fractal dimensions of these components were calculated to extract the fault characters of the transmission bearing in different conditions. The results show that EMD method is able to separate signals in different frequency bands effectively, and the fractal dimensions of specific IMF components are able to reflect the working state of the transmission bearing sensitively, which can be selected as the characteristic parameters to diagnose the transmission bearing’s fault. The combination of EMD and fractal dimension is an effective method of transmission bearing’s fault character extraction. Related Articles | Metrics

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Signal Processing of Rubbing Trouble Between Rotor and Stator of Aeroengines in Flight-test Using Hilbert-Huang Transform FU Rao;ZHANG Qun-yan;ZHAO Shu-yuan 2012, 32(2): 123-127.  DOI: 103969/j.issn.1006-1355-2012.02.030 Abstract ( )   A new method of time-varying signal processing based on empirical mode decomposition (EMD) and Hilbert transformation (HT) was proposed. At first, the time series data was separated into components with different time scales, say, intrinsic mode functions (IMF) using EMD. Then the Hilbert transformation was applied to each IMFs. The result of the method was a spectrum of the HT. In the paper, this method and the corresponding algorithm were explained in detail, and the program written by MATLAB was verified by comparing its output with the result of a vibration signal simulation. Then, this method was applied to the vibration signal processing of rotor-stator rubbing trouble of the aeroengine in the real flight testing. The result shows that the EMD and HT-based time-frequency analysis method is valid in vibration signal processing of rotor-stator rubbing trouble of aeroengines. Related Articles | Metrics

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Vibration Source Identification of Typical Equipment FENG Hai-jun;WANG Qiang 2012, 32(2): 128-131.  DOI: 103969/j.issn.1006-1355-2012.02.031 Abstract ( )   Different component parts of equipment have different vibration causes, so the methods of their vibration source identifications are also different. Based on the measurement data and the signal processing, some methods of vibration source identification, including time-domain analysis, frequency domain analysis, self-correlation, cross-correlation, envelope analysis etc., of rotational machinery and their engineering applications were studied. This work provides a help for handling different methods of vibration source identification. Related Articles | Metrics

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Modal Analysis Method of Combination Structure for Marine Diesel Engine WEI Li-dui;DUAN Shu-lin;WU Ji;WU Qi-li;YU Hong-liang 2012, 32(2): 132-136.  DOI: 103969/j.issn.1006-1355-2012.02.032 Abstract ( )   The simplified finite element models of base, frame, cylinder’s body, scavenge box, and air cooler of a diesel engine were established and validated by numerical simulation respectively. Treatment method of bolt-connection in the finite element analysis (FEA) was verified by the results modal testing of bolted plates. Based on these, the finite element model of the combination structure of a 6-cylinder diesel engine was built. Weak parts and the modals of whole engine were found through modal analysis. A simple approach for prediction and reduction of engine structure’s vibration was proposed. Related Articles | Metrics

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Modal Parameters Identification of Diesel Engine’s Body Using LSCE Stabilization Diagram CUI Yan-hong 2012, 32(2): 137-139.  DOI: 10.3969/j.issn.1006-1355-2012.02.033 Abstract ( )   With the use of hammering excitation method, the modal test of a diesel engine’s body was made using LMS Test.Lab modal test and analysis system. The pole and the residue of each mode were calculated using least square complex exponential(LSCE) method. Then the stabilization diagram was built and the modal parameters of some low orders of the engine’s body were provided. Related Articles | Metrics

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Research on Fault Feature Extraction of the Submersible Pump Units TAO Feng-yang;LIU Guang-fu;LI Xin-guang 2012, 32(2): 140-142.  DOI: 10.3969/j.issn.1006-1355-2012.02.034 Abstract ( )   Currently, electric submersible pump (ESP) unit is the main device for oil extraction in oil fields. Impeller’s eccentric wear, impeller’s tip screenout and bearing’s eccentric wear are the ordinary faults. In this article, the typical frequency features of the three main faults were extracted by acquiring the vibration signals at the wellhead caused by the submersible pump units and analyzing them with wavelet analysis. According to these features, the in-situ fault diagnosis can be completed effectively. Practical application showed that this method can identify these ordinary faults effectively. Related Articles | Metrics

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Audio Signal Analysis for Detection of the Raw Material Level in Ball Mill FANG Tao;CHEN Le-geng 2012, 32(2): 143-146.  DOI: 103969/j.issn.1006-1355-2012.02.035 Abstract ( )   A method for detecting the raw material level in ball-mills based on audio signal processing was presented. By using multi-scale wavelet transform and the multi-channel decomposition technique based on wavelet packet in audio signal processing, the feature frequency bands which can reflect the height and changes of the level of the raw material in ball-mills were identified and extracted. Then the audio signal energy in above-mentioned frequency bands was treated as a characteristic quantity which can reflect the changes of the material level. According to the audio signal energy of lower feature frequency of different material levels, the curve-fitting was done and the curve of characteristic quantity of the audio signal related to the material level was obtained. Thus, the non-linear mapping between the characteristic quantity of the audio signal and the material level was realized. Related Articles | Metrics

7.减振降噪设备和器材

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Mechanical Model for Creep Performance Testing and Analysis of Polyurethane Isolator SHU Li-hong;HE Lin; 2012, 32(2): 147-150.  DOI: 10.3969/j.issn.1006-1355-2012.02.036 Abstract ( )   A generalized mechanical model for polyurethane and rubber isolators analysis based on Zener components was presented. The parameters related to the creep characteristics of the isolators could be extracted readily with genetic algorithm from the step-loading process as well as from the non-ideal loading process. Seven polyurethane and rubber isolator specimens were tested and their model parameters were obtained through the analysis of the testing data. Results from the computation and testing show that the presented model can predict the creep characteristics of the polyurethane and rubber vibration isolators with high accuracy. Related Articles | Metrics

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Acoustic Simulation of Mufflers with Multiple Perforated Tubes HE Yan-song;LI Jing;LU Hui-chao 2012, 32(2): 151-154.  DOI: 10.3969/j.issn.1006-1355-2012.02.037 Abstract ( )   Based on acoustic FEM, the transmission losses of three mufflers with different combinations of perforated tubes were computed. The influences of the perforation porosities of the tubes on the transmission losses of the mufflers were discussed. Then, the acoustic performance of a complicated muffler with multiple perforated tubes was stimulated. The result shows that the transmission loss of the muffler is low when the noise frequency is below 1 000 Hz. This work provides a reference for further improvement of the muffler. Related Articles | Metrics

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Optimization Study of the Air Passage of the House-hold Dehumidifier LI Kong-qing;SHU Le-hua;CHENG Ying-ying 2012, 32(2): 155-158.  DOI: 103969/j.issn.1006-1355-2012.02.038 Abstract ( )   The outflow air passage of the house-hold dehumidifier was studied using CFD and experiment setup. The influences of radius of stabilizer and expansion angle of outlet on flow rate and noise were presented. The results show that an appropriate larger radius of the stabilizer can reduce the collision loss of airflow in the stabilizer, and a proper expansion angle of the outlet is helpful to reduce the separation loss at the outlet. Meanwhile, airproof enhancement in the inlet and fan is beneficial for reducing the noise and increasing the flow rate. The results can be applied to the practical design of dehumidifier. Related Articles | Metrics

9.振动噪声测试技术

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Creditability Assessment of Ship’s Radiated Noise Model Based on Characteristic Similarity SHEN Zhi-wei;LI Rong;LI Zhi-hua 2012, 32(2): 159-162.  DOI: 10.3969/j.issn.1006-1355-2011.04.039 Abstract ( )   Ship’s radiation noise modeling is the key technique for the research of underwater noise processing and sonar systems. In this paper, the model was established based on the time-frequency characteristic of the ship’s radiation noise. A method of model creditability assessment based on characteristic similarity was proposed and used to analyze the creditability of the ship’s radiation noise model. Related Articles | Metrics

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Measurement and Analysis of Transfer Performance of Noise and Vibration for Civil Aircraft with Tail Mounting Engine Based on LMS Test. Lab HAN Feng;WANG Chun-mei;HU Xi-zhi 2012, 32(2): 163-167.  DOI: 10.3969/j.issn.1006-1355-2011.04.040 Abstract ( )   Internal noise control of the cabin of commercial aircrafts is an important issue in aircraft design. Analysis of transfer performance of noise and vibration of the full aircraft is the key technology. In this article, a method of measurement and analysis of transfer performance of noise and vibration for civil aircrafts based on the reciprocity principle was introduced. The LMS Test. Lab, the low-volume sound source, sound pressure and acceleration sensors were used to acquire the frequency response function, amplitude and phase transfer functions and the coherence function. The performances of noise and vibration transfer among the pylon, fuselage structure, interior trim and cabin cavity were analyzed. The feasibility of engineering application of this method for civil aircrafts was verified. Related Articles | Metrics

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Noise Test and Analysis of Two-phase Flow in Pipelines YUAN Jin-ning;HAO Dian;WANG Jia 2012, 32(2): 168-170.  DOI: 10.3969/j.issn.1006-1355-2012.02.041 Abstract ( )   Gas-and-liquid double-phased flow in pipelines generates noises. In this work, the double-channel data collector and spectrum analysis instrument were applied for data collection and processing of the noise of the pipelines. By changing the experiment conditions, the noises of the pipelines with different gas and liquid ratios were measured, and the corresponding frequency spectra of the noise were obtained. Through statistical analysis of the noise frequency spectra, the noise characters were summarized. It is concluded that noise testing is an effective method to confirm that whether the gas pipeline contains liquid and whether the liquid plug appears. Related Articles | Metrics

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Methods of Noise Analysis for Offshore Platforms ZHANG Yan-chun;HUI Ning;SHEN Zhi-heng 2012, 32(2): 171-174.  DOI: 103969/j.issn.1006-1355-2012.02.42 Abstract ( )   Vibro-acoustic analysis methods and related software for noise analysis of offshore platforms, FPSO structures, etc. were summarized and discussed. It was elaborated that there are two paths in transmission-airborne transmission and structural borne transmission, and both of them should be considered in the analysis. Moreover, it was indicated that the fast multi-pole boundary element method would play an important role in vibro-acoustic analysis in the future. Related Articles | Metrics

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Simulation of Radiation Noise of a Tire GUO Yan-ru;CHEN Jian;SUN Xue-qian 2012, 32(2): 175-178.  DOI: 103969/j.issn.1006-1355-2012.02.43 Abstract ( )   The finite element model of a tire was established by means of ABAQUS. The modal of the tire was computed and also measured in testing. The results were compared each other and the correctness of the finite element model was verified. Then, the rolling process of the tire on the road was simulated, and output of the reaction force of the road was obtained. Based on the concept of acoustic transfer vector, the MATV technology was used to compute the radiation noise response of the tire under the random excitation, and the results were analyzed and discussed. Related Articles | Metrics

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Vibration Monitoring of Desalination Plant WU Zheng-guang;LIU Bo 2012, 32(2): 179-181.  DOI: 103969/j.issn.1006-1355-2012.02.044 Abstract ( )   Through?vibration measurement?and spectrum?analysis, the state monitoring and fault?diagnosis of?a sea-water desalination plant were carried out. Its technical state?was controlled, and its fault was identified and analyzed. This work provides some database for preventive maintenance of the desalination plant. Related Articles | Metrics

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Standardized Algorithm of Cumulative Absolute Velocity and Its Effect on Seismic Monitoring ZHU Yi-zhou 2012, 32(2): 182-184.  DOI: 103969/j.issn.1006-1355-2012.02.045 Abstract ( )   Earthquake is fatal to the nuclear power plants. It can directly lead to plant shutdown. Currently, the Cumulative Absolute Concept (CAV) has been employed in both RG code and AP1000 code for anti-seismic design in order to exclude the non-destructive earthquake. In this article, the background and concept of the CAV were introduced, and its standardized algorithm was elaborated. A computation example with the standardized CAV algorithm was provided using the time-historical data of an earthquake. The result of computation was employed to illustrate that the CAV is helpful to evaluate the destructive effect of the earthquake on the nuclear power plants. Related Articles | Metrics

10.工程实践

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Characteristics of a Focusing-type Thermo-acoustic Transducer WAN Guang-tong;DONG Wei;WANG Hong-xing;WU Zhong-wu;YAO Li 2012, 32(2): 185-190.  DOI: 10.3969/j.issn.1006-1355-2012.02.046 Abstract ( )   A new type of focusing thermo-acoustic transducer, which is composed of a heating surface, an insulation layer and a thermal storage substrate, was designed. When alternative voltage signal is input to the heating surface, due to the Joule heating effect and thermodynamic characteristic of material in each layer, the pressure of the air near the heating surface will oscillate, and the radiation sound will be focused in a small region by the concave spherically heating surface. Through numerical simulation and experimental study of the device, the variations of the focusing area and the sound pressure at the focusing point with acoustic frequency were given. The device can be used as a new type of acoustic-focusing and energy-exchanging device. It can radiate sound in the audible and ultrasonic regions without resonances and moving components. This study has a practical significance and an application prospect. Related Articles | Metrics