Archive

18 February 2010, Volume 30 Issue 1 Previous Issue    Next Issue
---
目录
综述
振动理论与数值解法
运载工具振动与噪声
环境振动与环境噪声
信号处理与故障诊断
减振降噪设备和器材
标准规范与评价
振动噪声测试技术
工程实践


For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

目录

Select

《CONTENTS》 2010, 30(1): 0-1.  Abstract ( )   PDF (2965KB) ( )   Related Articles | Metrics

综述

Select

《Review of Structural Vibration Squeal of Drum Brakes 》 YANG Guo-jun 2010, 30(1): 1-6.  DOI: 10.3969/j.issn.1006-1355.2010.01.001 Abstract ( )   PDF (1655KB) ( )   Recently, brake squeal problem has become a hot research topic in automotive engineering. In this paper, research of structural vibration squeal of drum brakes in recent years is reviewed and summarized. The discussion is focused on the dynamic characteristics of systems and the measures for squeal elimination in order to provide some ideas to engineering technicians for solving practical problems. Related Articles | Metrics

振动理论与数值解法

Select

《Study on Mode Mechanical Impedance Synthesis Method with Damping Effect》 KONG Jing-zhi;LIU Yong-ming 2010, 30(1): 7-9.  DOI: 10.3969/j.issn.1006-1355.2010.01.007 Abstract ( )   PDF (596KB) ( )   In this paper, the comprehensive mechanical impedance problem of the complicated mechanical system is studied with the elastic deformation considered. The synthesis method of mode mechanical impedance with damping effect is presented. The process of system modeling by this method is similar to that of the modular processing. Finally, a floating raft system model is presented,and the natural frequency is computed and analyzed. Related Articles | Metrics

Select

《Modal Analysis of Compressor Frame’s Vibration》 SUI Xiao-dong;DAI Ting;GAO Feng 2010, 30(1): 10-14.  DOI: 10.3969/j.issn.1006-1355.2010.01.010 Abstract ( )   PDF (1137KB) ( )   The vibration mode and natural frequency of machines frame are closely related to its resonance phenomena. In order to improve the quality of sheet metal stamping, raise the lifespan of punch and die, and reduce vibration or avoid resonance, a vibration modal analysis for JG21compressors frame is made by using the finite element software ANSYS. The first five vibration modes, the corresponding natural frequencies, and the corresponding strain distribution diagrams are obtained. Some problems that should be noted in compressor frames design and analysis and in compressor’s operation are summarized through the analysis of the characteristics of the vibration modes. Related Articles | Metrics

Select

《Vibration Mode Analysis of Roots Blower’s Shell》 WANG Fu-mao;HE Jing-yu;ZHAO Li-fang;LI Zhi-min;DING Hong-chang 2010, 30(1): 15-17.  DOI: 10.3969/j.issn.1006-1355.2010.01.015 Abstract ( )   PDF (706KB) ( )   In this paper, the dynamic characteristic of Roots blower's shell is analyzed by the ANSYS code. The natural frequencies and the vibration modes of the shell are given. The output of computation shows that the natural frequency of the shell is higher than the fundamental frequency of the rotor system, and the vibration modes of the shell structure are mainly bending, twisting, and their combination. The dynamic analysis of the shell may predict the faults in structural design, and provide some scientific basis for reducing the structural vibration and the noise of the Roots blower. Related Articles | Metrics

Select

《Dynamic Properties of SingleParticle Vibration Isolating System Described by FractionalOrder Kelvin Model》 HUANG Xue-yu;LIU Lin-chao 2010, 30(1): 18-21.  DOI: 10.3969/j.issn.1006-1355.2010.01.018 Abstract ( )   PDF (889KB) ( )   Regarding the isolation layers as viscoelastic materials, the decay ratio of acceleration response and amplification ratio of displacement response of isolation structure for singleparticle vibrationisolation system described by fractional Kelvin model are obtained. The influences of the order of fractional derivative, damping ratio and frequency ratio on the amplification ratio of displacement response of the isolation structure are investigated. The result shows that the order of fractional derivative and damping ratio have a great influence on the amplification ratio of displacement response of the isolation structure. However, the influences of damping ratio on the amplification ratio of displacement response of the isolation structure described by, espectively, fractional Kelvin model and classical model are different. And the fractionalorder derivative model is more extensively applicable. Related Articles | Metrics

Select

《Modal Testing and Model Relativity Analysis of Raft Frame》 LIU Rui-feng;WANG Qiang;ZHOU Pu;FENG Hai-jun 2010, 30(1): 22-24.  DOI: 10.3969/j.issn.1006-1355.2010.01.022 Abstract ( )   PDF (703KB) ( )   The paper intends to analyze quantitatively the correlation between the NASTRAN finite element (FE) model and a testing model for a middle raft frame of a floatingraft isolation system. The first five vibration modes of the raft frame are estimated by finite element method (FEM) and measured by testing. The modal assurance criterion (MAC) matrix is established in LMS virtual lab for relativity analysis between the FE model and the testing model. The MAC estimated by LMS virtual lab shows that the modal computed by FEM is basically correct and the method can be used for dynamic esponse analysis of the structure. Related Articles | Metrics

运载工具振动与噪声

Select

《Experimental Study on Noise Reduction for Valve Controlled Hydraulic Systems》 HU Jun-hua;CAO Shu-ping;LUO Xiao-hui;NIU Zi-hua 2010, 30(1): 25-28.  DOI: 10.3969/j.issn.1006-1355.2010.01.025 Abstract ( )   PDF (846KB) ( )   To reduce the fluidbone noise of the pressure pulsation and hydraulic impact in valvecontrolled actuator systems, the accumulator, holestyle muffler and active pressure feedbackequipment were adopted. The test results indicate that the active pressure feedbackequipment can reduce the pressure pulsation efficiently. With the accumulator installed at the inlet and outlet of the controlling valve, the pressure pulsation and hydraulic impact can be absorbed effectively. The holestyle muffler can only absorb the high frequency pressure pulsation, and has less effect for eliminating the impact noise. Related Articles | Metrics

Select

《Prediction and Control of Contribution of Modal Vibration to Noise》 ZHAO Yang-dong;LIU Geng;WU Li-yan;Ma Shang-jun 2010, 30(1): 29-32.  DOI: 10.3969/j.issn.1006-1355.2010.01.029 Abstract ( )   PDF (846KB) ( )   The structural finite element model and soundstructure coupling boundary element model of a transmission box are established in this paper. The modal analysis of the structural finite element model is done. The soundstructure coupling boundary element model is solved by boundary element method (BEM). The distribution of noise in a particular frequency domain is analyzed. Based on modal acoustic contribution analysis (MACA), the identification and effective control of the main noise source of the transmission box are carried out. This work has a practical significance for research and development of this product. Related Articles | Metrics

Select

《Study on the Concept of Interior Noise Design of EMU》 SHEN Yan-xiang;SONG Lei-ming 2010, 30(1): 33-36.  DOI: 10.3969/j.issn.1006-1355.2010.01.033 Abstract ( )   PDF (1196KB) ( )   This paper elaborates the significance of introducing the concept of sound quality evaluation for interior noise of EMU. It is suggested that full-frequency acoustic analysis software should be applied for the noise design of the corresponding psychoacoustic indicators as the guidance of engineering application. Related Articles | Metrics

Select

《Experimental Study on Vibration of Dashboard in Braking for a Small Passenger Car》 WANG Yong;MAO Zhi-qiang;LI Zhi-yin;ZHAO Da-wei 2010, 30(1): 37-39.  DOI: 10.3969/j.issn.1006-1355.2010.01.037 Abstract ( )   PDF (768KB) ( )   The strong vibration situation of the dashboard in braking process of a small passenger car traveling at a high speed is studied. The modal testing and frequencyspectrum methods are used to analyze the possible factors of the dashboard vibration. The abnormal vibration source of the dashboard in the braking process and the vibration level of the component parts in the vibration transmission channel are determined. The theoretical basis is then provided for distinguishing vibration source and the cause of abnormal vibration of the dashboard. Related Articles | Metrics

Select

《Experimental Study on Noise Sources Identification of Vehicle》 SI Chun-di;CHEN En-li;YANG Shao-pu;WANG Cui-yan 2010, 30(1): 40-43.  DOI: 10.3969/j.issn.1006-1355.2010.01.040 Abstract ( )   PDF (842KB) ( )   The sound intensity method is an effective method in noise source identification and acoustic field analysis. According to the principle of sound intensity measurement, the major sources of the exterior radiation noise of the vehicle are surveyed, and the noise source identification in vehicle is presented. The results show that the research could provide the reliable basis for the engineering practice to reduce vehicle noise leve1. Related Articles | Metrics

Select

《Study on Automotive Interior Structural Noise Excited by Engines》 ZHANG Guang-rong;YU De-jie;YAO Lin-yun;ZANG Xian-guo 2010, 30(1): 44-47.  DOI: 10.3969/j.issn.1006-1355.2010.01.044 Abstract ( )   PDF (1041KB) ( )   The rigid body model of the minibus power-train system is established in MSC.Nastran and connected to the finite element model of the flexible vehicle’s frame. Considering the influence of frame flexibility on natural frequency and vibration mode of the rigid power-train system, the internal structural noise induced by the second order inertia excitation of the engine due to revolution speed change is calculated. The panels which have outstanding contribution to the sound pressure at driver's right ear are evaluated and confirmed. According to the results of analysis, the corresponding modification measures for reducing the internal noise are proposed. Related Articles | Metrics

Select

《Modal Analysis of a SemiTrailer》 ZHU Yi;ZHANG Dai-sheng;LU Chang-nian 2010, 30(1): 48-50.  DOI: 10.3969/j.issn.1006-1355.2010.01.048 Abstract ( )   PDF (756KB) ( )   Modal analysis of the structure of a semitrailer is carried out. At first, the model of the semitrailer is built by using UG. Then, the model is meshed by using HyperWorks for finite element analysis. Finally, the vibration mode analysis is done by means of the finite element method. The modal parameters of the frame of the semitrailer are obtained and analyzed. The results of the modal analysis show that the natural frequencies of the semitrailer are quite different from the frequencies of all the excitation sources, so that the resonance phenomena can be avoided. Related Articles | Metrics

Select

《Study on Simulation of Acoustics Characteristics of Tractor’s Cab》 PENG Xue-jun;LI Li-jun;SHEN Yu-feng;GANG Xian-yue 2010, 30(1): 51-54.  DOI: 10.3969/j.issn.1006-1355.2010.01.051 Abstract ( )   PDF (985KB) ( )   The finite element model of FT80 tractor’s cab is established by using FEM software ANSYS. Then, using the acoustics software SYSNOISE, the soundsolid coupling analysis with the combination of FEM and intermediate BEM is carried out. By means of the intermediate BEM, the acoustic characteristics of the cab are computed and analyzed. The sound pressures of neartheear sound fields of three cases—empty cab, cab with a chair in it, and cab with a chair and a driver in it—are computed and compared. The acoustic contribution of the chair and the driver in the cab is calculated and analyzed. It is proved that the chair and the driver have some influences on the internal noise of the cab. These influences should be considered in the modeling. Related Articles | Metrics

环境振动与环境噪声

Select

《Comparative Study on Speech Intensification Algorithms in Strong Noise Background》 CAO Bin-fang;LI Jian-qi;LI Ting 2010, 30(1): 55-58.  DOI: 10.3969/j.issn.1006-1355.2010.01.055 Abstract ( )   PDF (1046KB) ( )   The principle of speech enhancement and the method of extracting speech signals from strong noise background are introduced. Three kinds of speech intensifying algorithms based on spectrum subtraction algorithm, wiener filtering and wavelet transform, respectively, are comparatively studied. However, the two purposes of the speech enhancement algorithms, to enhance articulation and to enhance the understandability, are not related each other, and even in contradiction sometimes. Therefore, a good speech enhancement algorithm is in fact a compromise between the two purposes according to the requirement of application. In this paper, results of numerical experiment of the three algorithms are compared and studied. The results demonstrate that the speech enhancement algorithm using wavelet ransform is more efficient than the others. Related Articles | Metrics

Select

《Study on Radiating Sound Roughness of AcousticStructure Coupling Field in Sealed Cavity》 YUAN Ji-xuan;HUANG Qi-bai;WANG Jian-liang 2010, 30(1): 59-62.  DOI: 10.3969/j.issn.1006-1355.2010.01.059 Abstract ( )   PDF (946KB) ( )   Based on the finite element model of acousticstructure coupling field in a sealed cavity and the improved Senthares nonharmonic psychoacoustics model, the sound pressure level of the internal radiating sound due to the excitation of the harmonic force exerted on the shell of the cavity is calculated. The acousticstructure coupling effect is considered. The sound roughness caused by the rapid modulation at the evaluation point is analyzed. Moreover, the effects of the sound pressure level of the modulated sound, the frequency of the modulated sound and the stiffness of the shell on the radiating sound roughness are studied. This work provides the data and method for determination of the internal radiating sound roughness in the cavity caused by the rapid modulation of the other sound sources. Related Articles | Metrics

Select

《Study on Influence of Sound Barrier Structure on Its Noise Reduction Performance with Numerical Simulation》 CHEN Ji-hao;JI Zhi-jiang;ZHANG Zhong-lun;WANG Jing;SUI Tong-bo 2010, 30(1): 63-66.  DOI: 10.3969/j.issn.1006-1355.2010.01.063 Abstract ( )   PDF (1002KB) ( )   The acoustic performances of Yshaped, multiwedgeshaped, and Tshaped structures of noise barrier are simulated by using acoustic softwareRAYNOISE. In the region of 30m height and 50m width behind the sound barrier, the simulation result of noise reduction effect is obtained. The result indicates that the multiwedgeshaped structure is the best for noise reduction. Its insertion loss can reach 14.5dB in the region of 2m height and 50m width behind the noise barrier. The noise barrier of the Tshaped structure has good acoustic performance in the region of lower height behind the noise barrier. The insertion loss of the Yshaped structure decreases slightly when the height of the measurement point increases. The influence of sound absorption material on noise reduction is studied. The result indicates that the distribution of sound absorptionmaterial has no influence on the noise reduction effect in the region just behind the barrier. The possible reason is that the reflection between the barrier and the vehicle is not considered in the simulation. Related Articles | Metrics

Select

《Numerical Analysis of Railway Vibration Isolation of New Style Trenches》 LUO Kun;LEI Xiao-yan 2010, 30(1): 67-71.  DOI: 10.3969/j.issn.1006-1355.2010.01.067 Abstract ( )   PDF (1041KB) ( )   Operation of BeijingTianjin intercity railway indicates that the “highspeed era” of Chinas railroad started. However, with the increase of the train speed the environmental vibration control along the railways has been becoming a serious problem. Therefore, the project on the groundborne vibration due to railway traffic is becoming a special concern in civil and environmental engineering. In this paper, the numerical model is set up, which consists of the vehicletrackroadbedground coupling system and the groundbarrierbuilding coupling system. The universal finiteelement software ANSYS is used to analyze the reduction effect of vibration isolation of a new style trench. The style includes trapezoid, upsidedown trapezoid, triangle, upsidedown triangle and so on. The vibration isolation effect of the new style trench is compared with that of the traditional trench. It is shown that the effect of the new style trench is better than that of the traditional trench, and the style of the trench can be properly changed to improve the effect of vibration isolation. Related Articles | Metrics

信号处理与故障诊断

Select

《Analysis of Vibration Signals of Engines Based on Sub-Band Energy Method》 LIANG Hong-bo;SI Jing-ping;GAO Zhi-ying;ZHAO yong;REN Qing-shuang 2010, 30(1): 72-77.  DOI: 10.3969/j.issn.1006-1355.2010.01.072 Abstract ( )   PDF (1198KB) ( )   Taking the vibration signals on the surface of cylinders of DA462 engine as an example, the diagnosis mechanism of the engine vibration is studied. The measured signals are calculated and analyzed by means of subband energy method. It is verified that the subband energy method can be applied for vibration signal analysis of engines, and the engine fault can be diagnosed accurately. Related Articles | Metrics

Select

《NonSteadyState Noise Signal Analysis of Fans》 GUO Wei;ZUO Shu-guang;CEHN Rui-feng;HE Rong 2010, 30(1): 78-81.  DOI: 10.3969/j.issn.1006-1355.2010.01.078 Abstract ( )   PDF (990KB) ( )   Based on wavelet package transform technology, this paper proposes a method for analyzing the frequency characteristics of nonsteadystate signals in an energyratio and frequencyband coordinate system. Result of this method is compared with that of common frequency spectrum method. The correctness and feasibility of this method is verified. Meanwhile, taking the fan's noise signal of a fuel cell vehicle as an example with a lowfrequency sinusoidal interference signal chosen as the representation of periodic signals, the periodic signals hidden in the nonsteadystate signals are identified. Finally, the fan's noise signals are analyzed. The noise due to low and medium frequency vibration and the noise due to high frequency vibration in the signals are separated. Their information is extracted in timedomain. The measures for further noise reduction are proposed. Related Articles | Metrics

Select

《Blind Separation of Fault Sources Based on Variational Bayesian Independent Component Analysis》 FAN Tao;LI Zhi-nong;LU Ji-fu;YUAN Xian-feng 2010, 30(1): 82-85.  DOI: 10.3969/j.issn.1006-1355.2010.01.082 Abstract ( )   PDF (999KB) ( )   A blind separation method of rotor’s fault sources based on variational Bayesian independent component analysis (VBICA) is proposed. This method can directly separate the signals of mechanical sources in noisy environment. In this method, the unknown noise need not to be regarded as an independent source, and the denoising preprocessing is not necessary either. Then, this method is compared with the traditional blind source separation method for machine faults. Finally, this method is applied for the fault sources separation of rotor system. Experiment results show that this method is very effective. Related Articles | Metrics

Select

《Mechanical Breakdown Diagnosis of CNC Machine Using Neural Network Expert System》 CHEN Hui-lian;GU Ming-yue;CHI Dan-dan;QIAO Yan-ping 2010, 30(1): 86-88.  DOI: 10.3969/j.issn.1006-1355.2010.01.086 Abstract ( )   PDF (679KB) ( )   Because of the limitations of a singleexpert system or neural network system in fault diagnosis, a new integrative fault diagnosis expert system which combines neural network technique with expert system is proposed. This system is applied in the mechanical breakdown diagnosis of CNC machine. The structure, characteristics and diagnostic methods of the neural network expert system are introduced. The system is verified based on the knowledge of machine failure and sampling data of faults. The result shows that this system has friendly interface and is easy to handle. It raises the level and efficiency of mechanical fault diagnosis of CNC machines. Related Articles | Metrics

Select

《Analysis of Welding Seam Split of Safety Hangers Based on Experimental Modal Analysis》 DUANG He-peng;ZHANG Li-min;HE Yuan-xin;ZHENG De-qing 2010, 30(1): 89-92.  DOI: 10.3969/j.issn.1006-1355.2010.01.089 Abstract ( )   PDF (852KB) ( )   The welding seam of the upper tensilerods safety hangers of GQ70 light oiltank truck may split easily during the operation. But the safety hangers usually bear small load, and its failure is not a material strength problem. The modal test with hammering method is carried out at some key portions of the safety hangers. Using experimental modal analysis method, the modal frequencies of the hangers are found. Through comparative analysis, the cause of splitting of the hangers is found, and some suggestions for repairing are proposed. Related Articles | Metrics

Select

《Characteristic Analysis of Crack Growth in Fan’s Blades Based on Wavelet Transform of Fluid-Induced Vibration Signals》 LI Shao-hui;;LI Yi-min 2010, 30(1): 93-95.  DOI: 10.3969/j.issn.1006-1355.2010.01.093 Abstract ( )   PDF (757KB) ( )   Crack in fan’s blades is one of the serious hidden dangers. It is important to find the cracks in the blades as early as possible. In this paper, the method of wavelet decomposition is applied to process the fluidinduced vibration signals of cracked blades and crackfree blades respectively. The energy of each frequency band is calculated and normalized as the characteristic vectors. Results show that the frequency range of the vibration signals extends further with the crack expansion, low frequency reduces and high frequency rises. This phenomenon provides scientific basis for fault diagnosis of cracked fan’s blades. Related Articles | Metrics

Select

《Realization of Dual Adaptive Noise Cancellation Algorithm》 LIU Wei-dong;DING En-jie 2010, 30(1): 96-98.  DOI: 10.3969/j.issn.1006-1355.2010.01.096 Abstract ( )   PDF (707KB) ( )   Extraction of the signals, which can represent sound source information and meanwhile include noise signals, from acoustic sensors is the key technique for sound emission monitoring. To eliminate the noise efficiently and raise the signaltonoise ratio, this paper brings up a dualadaptive noisecancellation algorithm, which includes adaptive subband decomposition algorithm and adaptive noise cancellation algorithm. First of all, to reduce the complexity in computation and realize parallel algorithm, the method of the subband decomposition, which matches the noise powerspectrum density, is adopted for nonuniform signal subband decomposition. Then, to save the computer time, the effective filtering is performed according to the distribution of noise in the subband. The subbands with lownoise or essentially without noise do not need filtering, while the adaptive filtering algorithm is used for the other subbands. The simulation shows that this method can greatly save computer time in comparison with the traditional adaptive noise cancellation method with uniform subbands, and the effect of filtering has been improved. Related Articles | Metrics

减振降噪设备和器材

Select

《Experimental Research of a New SiliconBased Elastomer Damper》 JIA Jiu-hong;HUA Hong-xing 2010, 30(1): 99-101.  DOI: 10.3969/j.issn.1006-1355.2010.01.099 Abstract ( )   PDF (693KB) ( )   A new siliconbased elastomer damper designed especially for the antiimpact requirements of ship piping systems is studied. In order to test the effect of the damper in practical application, the new damper was attached to a main engine lubricating oil pipe of a ship. An explosion experiment was done to test the antiimpact ability of the damper. In this experiment, the main engine lubricating oil pipe near the explosion spot was protected by two new siliconbased elastomer dampers. However, the other main engine lubricating oil pipe did not have the new dampers. Comparing the responses of acceleration of the two pipes, the good antiimpact ability of the new siliconbased damper is confirmed. Related Articles | Metrics

Select

《Analysis of Influence of Parameters of NonLinearly Elastic Dual Mass Flywheel on Vibration Reduction Effect》 TANG Ming-xiang;TANG Xin-long;DONG Gui-jun 2010, 30(1): 102-105.  DOI: 10.3969/j.issn.1006-1355.2010.01.102 Abstract ( )   PDF (915KB) ( )   In virtue of the dual mass flywheel (DMF), the torsional vibration and noise of vehicle power train can be controlled effectively. And the vehicle power train can be well protected from impact loading. Taking an indigenous vehicle as an example, a kind of torsional dampers, the two-grade elastic characteristic DMF, is investigated. The influence of DMFs dynamic parameters (mass, stiffness and damping) on the function of the power train are analyzed theoretically. A three-dimensional model is built and the numerical simulation is carried out. The optimal parameters of the DMF are gained. Related Articles | Metrics

Select

《Study on Fatigue Behavior of 65Mn MR Made of Thin Wires》 ZHAO Cheng;LUO Kun;LIU Chang-hong 2010, 30(1): 106-108.  DOI: 10.3969/j.issn.1006-1355.2010.01.106 Abstract ( )   PDF (743KB) ( )   The fatigue behavior of 65Mn metallic rubber (MR) made of thin wires is studied. The results show that with the increasing of the density of the MR, the stiffness of soft characteristic range increases, static and dynamic loss factors, and fatigue life expectancy decrease. Related Articles | Metrics

Select

《Analysis of Impedance Chip Muffler with Elbow Portions》 LIN Jia-xiang 2010, 30(1): 109-111.  DOI: 10.3969/j.issn.1006-1355.2010.01.109 Abstract ( )   PDF (784KB) ( )   In engineering application, the impedance muffler has the problem of failure in highfrequencies and poor effect of silencing for low frequencies. This paper provides an approach for solving the problem. Using the characteristics of the silencing elbow, the function of the muffler can be improved by adding elbow portions to the impedance chip muffler. This kind of mufflers has both the functions to absorb the high frequency noise due to the impedance chip silencer and to absorb lowfrequency noise due to the elbow structure. The spacing, number and thickness of the chips and the type of soundabsorption body can be determined according to the crosssectional area, wind flow flux and wind speed of the muffler. And the size, length and the elbow structure can also be adjusted according to engineering requirements. Related Articles | Metrics

标准规范与评价

Select

《Generic Criterion for Random MicroVibration of HighTech Precision Facilities》 ZHANG Wei;YING Zu-guang 2010, 30(1): 112-113.  DOI: 10.3969/j.issn.1006-1355.2010.01.112 Abstract ( )   PDF (529KB) ( )   The generic criterion for random microvibrations has a significant application in hightech field, such as vibrationsensitive precision facilities. First of all,the meansquareroot velocity of random micro vibration is introduced as a criterion. Different from the usual displacement and acceleration of vibration, this criterion describes both the statistical characteristics and centrefrequency effects of random disturbances. Then five microvibration levels are defined for disturbing environment according to various vibration sensitivities and requirements. And the corresponding uplimits and frequency spectrums of the meansquareroot velocities are given. Finally, application of the criterion, the meansquareroot velocity, is illustrated through an example of disturbing environment. Related Articles | Metrics

Select

《Small Sample Approach for Reliability Evaluation of Commercial Aircrafts》 GUO Qiang 2010, 30(1): 114-117.  DOI: 10.3969/j.issn.1006-1355.2010.01.114 Abstract ( )   PDF (928KB) ( )   The reliability evaluation of commercial aircrafts and their subsystems, especially of the novel commercial aircrafts and their subsystems, is a small sample statistics problem, which is an interesting and important research focus today. In this paper, the fault characteristics of the commercial aircrafts are analyzed. The small sample approach for reliability evaluation is developed based on threeparameter Weibull . The parameters are obtained by the grey theory. Finally, an example is employed to verify the accuracy and applicability of this approach. Related Articles | Metrics

Select

《Evaluation Research of Diesel Engine Noise Annoyance》 LIANG Jie;LU Peng-yu;SUN Qiang;LU Bing-wu;JIANG Wen-jun;ZHAO Tong-hang 2010, 30(1): 118-121.  DOI: 10.3969/j.issn.1006-1355.2010.01.118 Abstract ( )   PDF (940KB) ( )   The noise sampled in 1m position beside four types of diesel engines at different operation conditions were selected for evaluation. The subjective evaluation test of diesel engine noise annoyance was carried out with grading estimation. Several primary objective psychoacoustical parameters of these samples were analyzed and calculated. Through correlation and multidimensional regression analysis, a mathematical model for noise annoyance evaluation was established. The research results indicate that the diesel engine noise annoyance under the steady operation conditions is affected by two psychoacoustical parameters: loudness and sharpness. Related Articles | Metrics

振动噪声测试技术

Select

《Noise and Vibration Measurement and Simulation of Large Scale Compressor’s Piping System》 CHEN Bing;YUE Heng-chang;YIN Zhong-jun;WANG Wen-rui;ZHAO Ai-min 2010, 30(1): 122-126.  DOI: 10.3969/j.issn.1006-1355.2010.01.122 Abstract ( )   PDF (1240KB) ( )   The noise and vibration of a centrifugal compressor’s piping system in an oxygen company are measured for its abnormal noise studying. The distribution of noise and vibration are obtained and analyzed. The model of piping system is built and simulated by using the statistical energy analysis (SEA) method. The cause of the overnoisy of the piping system is detected. Results of the simulation are essentially in accordance with the measurement data. Therefore, the SEA method is proved to be significant for optimal design and noise monitoring and control of the compressors pipeline system. Related Articles | Metrics

Select

《Numerical Prediction of Sound Intensity and Pressure Fluctuation of Aerodynamic Noise of a CounterRotating Axial Flow Fan》 ZHANG Yong-chao;WANG Wei-bin;BEI Guang-xia;ZHANG Yong-jian;CHEN Qing-guang 2010, 30(1): 127-131.  DOI: 10.3969/j.issn.1006-1355.2010.01.127 Abstract ( )   PDF (1253KB) ( )   Numerical simulation of a threedimensional steady turbulent flow in the overall flow field, from the inlet of the collector to the outlet of the diffuser, of a counterrotating axialflow fan is performed. Unstructured grid is used to discrete the domain for computation. Pressure boundary conditions are specified to the inlet and the outlet. The SIMPLE algorithm in conjunction with the RNG kε turbulence model is used to solve the threedimensional NavierStokes equations. The moving reference frame is adopted to transfer data across the interface between the rotating field and the stationary field. The broadband noise source model based on the Lighthill noise analogy theory is introduced to simulate the aerodynamic noise field of the fan. The sound intensity distribution inside the fan, on the impellers, the blades and the shell of the fan are predicted. The pressure fluctuation of three interfaces around impellers caused by the rotating impellers and blades vibration is studied by the Fast Fourier Transform (FFT) method. The simulation results are of important significance to the optimal design and noise control of the fan. Related Articles | Metrics

Select

《Analysis of Vibration Testing Data of Flange Connection Structures》 LI Ting-ting;ZHAO Deng-feng;MA Guo-lu 2010, 30(1): 132-134.  DOI: 10.3969/j.issn.1006-1355.2010.01.132 Abstract ( )   PDF (668KB) ( )   An analysis system, including the functions of signal generation, data acquisition, spectrum analysis etc, is developed using the virtual instrument LabVIEW software,for analyzing the vibration testing data of flange connection structures. With the use of the analysis system, analysis of the vibration testing data for the flange and bolt connection structure is completed for various prestressed bold forces. The spectrum analysis and difference analysis show that the dynamic response of the structure is significantly affected by the nonlinear behavior of the flangebolt connection structure. The nonlinear vibration effect and signal asymmetry can be obviously observed, and strongly depend upon the prestress state of the bolts. In virtue of the frequencyspectrum signals, the looseness of the bolts can be identified and some information can be provided for diagnosis of the connection structures. Related Articles | Metrics

Select

《Analysis of Factors Influencing Wave Velocity in Hydraulic Media》 AN Ji;ZHANG Hong-peng;ZHANG Yin-dong;SUN Yu-qing 2010, 30(1): 135-138.  DOI: 10.3969/j.issn.1006-1355.2010.01.135 Abstract ( )   PDF (1049KB) ( )   The factors which influence the wave velocity in hydraulic media are analyzed and computed. It is presented that in the high pressure system and oilgas doublephased state the previous assumptions for compressive wave velocity formula in hydraulic media are not true any more. Thus, a new estimation method is necessary. In this paper, a new nonintrusive measurement method is proposed. In this method, the pressure gauges are installed at two different positions on the pipeline to measure the time difference when the compressive wave reaches. Therefore, the wave velocity can be determined. The randomness of elastic modulus under the condition of oilgas doublephased flow is studied in highpressure fluid system. The results provide references for simulation, design and management of hydraulic systems. Related Articles | Metrics

工程实践

Select

《Comparative Analysis of Vibration Source of FourCylinder Engine Using Two Commercial Codes》 LI Shuang-hu;FAN Wen-xin;ZHAO Yan-tao;MA Yan-yan 2010, 30(1): 139-142.  DOI: 10.3969/j.issn.1006-1355.2010.01.139 Abstract ( )   PDF (977KB) ( )   The vibration sources of a fourcylinder engine are analyzed using MATLAB and ADAMS codes. Firstly，the main vibration excitation sources of this engine, the second order reciprocating inertia force and the overturning moment, are gained through theoretical analysis. The characteristics of the excitation sources are investigated in both time domain and frequency domain using MATLAB code. Afterwards, the finite element model of the engine is built and the dynamic simulation is performed using ADAMS code. Then, in the postprocessing, using the measured signals in the properly selected positions，types of the main vibration excitation sources and their characteristics in both time domain and frequency domain are gained. The results from the two codes are found to be in good accordance with each other. Thus, the validity of the two methods is verified. The results gained in this paper provide some necessary data for vibration control of engines. Related Articles | Metrics

Select

《Extraction of Exhaust Noise for SingleCylinder Diesel Engines Using Singular Value Decomposition Technique》 SHAO Ying-li;;WU Pei;WU Xu 2010, 30(1): 143-145.  DOI: 10.3969/j.issn.1006-1355.2010.01.143 Abstract ( )   PDF (661KB) ( )   Singular value is one of the main characteristic of matrix. In this paper, a method to separate periodic signals is elaborated through the theoretical analysis of matrix singular value decomposition. Aiming to the characteristic that the exhausting noise of singlecylinder diesel engine is mainly a periodic noise with sparking frequency being the basic frequency, the exhausting noise signals acquired by sound sensor are resolved and then reconstructed, and the periodic signals are extracted. Based on short time Fourier transform, the character of signal is extracted from the frequency domain. Related Articles | Metrics

Select

《Noise Reduction of MultiStep Planetary Gear System》 Cheng Chuan-hai 2010, 30(1): 146-148.  DOI: 10.3969/j.issn.1006-1355.2010.01.146 Abstract ( )   PDF (700KB) ( )   Planetary gearsystem is widely used in mechanical equipment which transmits motion and power. But its fault diagnosis is somewhat difficult. In this paper，by means of the traditional edgefrequencysignal recognition technique，the fault of a threestep planetary gearsystem is measured and analyzed. The analysis shows that the axis of the solargear of the first step deviates the theoretical axis, thus the axes of the planetary gears of the first step deviate their theoretical axes also. The eccentricity of these axes leads to large vibration and noise. In addition, modal analysis shows that the resonance of the planet gears happens due to the excitation of the large meshingimpulsion. Finally, the structure of the planetary gear system is improved, and a 2.5dB(A) noise decreasing is obtained. Related Articles | Metrics

Select

《Discussion of Noise Reduction Design of Cooling Circulating Water Treatment Plant》 JIN Ya-biao 2010, 30(1): 149-152.  DOI: 10.3969/j.issn.1006-1355.2010.01.149 Abstract ( )   PDF (1136KB) ( )   Many facilities in cooling circulating water plants are the large noise sources. When the plant is near the resident area, the noise reduction measures should be given more attentions. In this paper, some noise reduction design methods are discussed. They can be used as references in engineering design. Related Articles | Metrics

Select

《Vibration Isolation Transformation for the Roof Building Equipment》 LIU Xiang-hua;WAN Hai-ying;JIA Xia-nan 2010, 30(1): 153-155.  DOI: 10.3969/j.issn.1006-1355.2010.01.153 Abstract ( )   PDF (660KB) ( )   The paper proposed new vibration isolation technology called “steel frame floating building vibration isolation”(SFFBVI). The equipment is supported on the beam and column of structure. It could avoid the deficiencies of traditional vibration isolation in which the equipment is supported on the plate directly. The actual operation and the measument results show that this technology could reduce noise effectively. Related Articles | Metrics