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18 June 2010, Volume 30 Issue 3 Previous Issue    Next Issue
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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
振动噪声测试技术
工程实践


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振动理论与数值解法

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《Viscoelastic Damping Design for a Satellite Flywheel Bracket》 XU Chao;TIAN Wei 2010, 30(3): 1-4.  DOI: 10.3969/j.issn.1006-1355.2010.03.001 Abstract ( )   PDF (253KB) ( )   Constrained layer damping technique is applied as an effective passive vibration control method for aerospace structures. The approach of adding viscoelastic damping to a satellite flywheel bracket is investigated in this paper. Firstly, the finite element model of the bracket is built and the vibrationmode analysis is executed to obtain basic dynamic characteristics. Distribution of modal strain energy is analyzed to determine the locations where the constrained dampers are attached. Then, the thicknesses of the constrained layer and damping layer are taken as design parameters to examine the modal loss factors for different design schemes. The optimal values of the parameters are determined under the limitations of additional weight of the dampers and the cost for damping material processing. Finally, the acceleration frequency responses of the flywheel bracket with damping and without damping, respectively, are compared mutually. The results show that applying viscoelastic constrained layer damping for flywheel bracket is reasonable and effective. Related Articles | Metrics

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《Experimental Study on the Performance of MR Damper》 SHU Li-hong;WANG Yu-fei 2010, 30(3): 5-8.  DOI: 10.3969/j.issn.1006-1355.2010.03.002 Abstract ( )   PDF (239KB) ( )   Based on the working principle and the simplified model of MR damper, a series of experimental study on the damper force, energy dissipation and the response time under different excitation amplitude, frequency and control current is performed. The results indicate that the MR damper has a high effectiveness for energy dissipation, and the energy dissipation increases with the increasing of the excitation amplitude, frequency and control current. The response time of the MR damper does not change obviously with the control current changing, but decreases rapidly with the increase of vibration speed. Related Articles | Metrics

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《Experimental Study of Active Vibration Control Based on Modal Control Method》 DAI Xue-chang;ZHANG Yi;WANG Qiang 2010, 30(3): 9-12.  DOI: 10.3969/j.issn.1006-1355.2010.03.003 Abstract ( )   PDF (300KB) ( )   Based on modal control method, the vibration modes in an object test are directly controlled. The aim of the experiment is to reduce the vibration of the base of the object. The experiment result shows that the modal vibration shape can be controlled using this method, and the bases vibration can be reduced. Related Articles | Metrics

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《Restraint Modal Analysis of Threecylinder Diesel Engine Blocks》 BAO Lin-xiao;ZUO Yan-yan;ZHOU Hai-chao 2010, 30(3): 13-15.  DOI: 10.3969/j.issn.1006-1355.2010.03.004 Abstract ( )   PDF (189KB) ( )   The three dimensional model of a threecylinder diesel engine block is established by using UG 5.0 software, and the modal analysis of the engine block is carried out under four different constraint conditions using Lanczos method. Through the analysis, the inherent frequencies and the modal shapes of the first 10 order modes are obtained. The results are compared one another. Based on the comparisons, it is discovered that the inherent frequencies and the corresponding vibration modes are quite different for different constraint conditions. In addition, the weak portions of the engine block vibration are found by modal analysis, and the corresponding modifications are put forward, which may provide a reference for further structural design and dynamic response analysis of the diesel engine block. Related Articles | Metrics

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《Study on Active Noise Control Using Piezoelectric Material》 ZHU Cong-yun;NIE Jian-jun;HUANG Qi-bai 2010, 30(3): 16-20.  DOI: 10.3969/j.issn.1006-1355.2010.03.005 Abstract ( )   PDF (265KB) ( )   An active absorption method using piezoelectric material is proposed in this paper. In this method, a piezoelectric ceramic is used as the absorption material in the active absorption system. Two microphones are placed in the front of the piezoelectric ceramic with equal distance from it to measure the incidence plane wave and the reflecting wave. The voltage is applied on the surface of the piezoelectric ceramic in order to eliminate the reflection wave. Finally, simulation of the active absorption control is carried out by means of the MATLAB code for the incidence plane wave with different frequencies. Results show that the proposed method is effective and feasible. Related Articles | Metrics

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《Vibration Analysis and Control for Pipelines of Reciprocating Compressors》 HUANG Hong-jun;HUANG Tie-jun;CHEN Zhao-hui;LI Lian-chao;CHENG Jian 2010, 30(3): 21-22.  DOI: 10.3969/j.issn.1006-355.2010.03.006 Abstract ( )   PDF (102KB) ( )   The strong vibration problem of the outlet pipelines of the reciprocating compressor group of Yaha oil gathering station is investigated. Employing the PAP software developed by Xian Jiaotong University, a practical and effective model of the pipeline system is established. The natural frequencies of the outlet pipelines, the natural frequencies of the gas system in the pipes, and the pulsation of the gas flow are calculated, and the cause of vibration is found. According to the results of computation, a practical scheme is presented to control the system vibration. The vibration of the pipeline system is reduced significantly. Related Articles | Metrics

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《Resumption of Missingdata in Testing Based on Parameter Model》 GAO Shu-yuan;WU Ya-feng;ZHAI Wei-lei 2010, 30(3): 23-26.  DOI: 10.3969/j.issn.1006-1355.2010.03.007 Abstract ( )   PDF (199KB) ( )   Datamissing phenomena may happen in engineering testing due to the mismatch of component parts or breakdown of the testing system. In this paper, a parameter model is proposed to recover the missingdata. Through analyzing the correct data, the structure, the best order and the specific parameters of the model can be determined, and be further tested and optimized, so that the best model can be obtained. Finally, as an example, an AR model is applied to resume the missing data in the testing of an actual flight. The results show that the method is feasible and effective. Related Articles | Metrics

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《IFEM on Structural Exterior Acoustic Fields Analysis》 LI Li-jun;LI Hong-yan;CHAI Shan;GANG Xian-yue 2010, 30(3): 27-30.  DOI: 10.3969/j.issn.1006-1355.2010.03.008 Abstract ( )   PDF (223KB) ( )   Recently, the Infinite Element Method (IEM) is applied to the acoustic field analysis gradually. In this paper, basic theory of IEM is studied; the advantages and disadvantages of BEM (Boundary Element Method) and IEM are compared. The factors related to convergent precision of IEM are analyzed. Several important parameters and concepts of IEM, including the origin of coordinate system, the order of IEM, and vectors of coordinates, are introduced. The conclusions of IEM are presented for acoustic field analysis. Related Articles | Metrics

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《Forced Vibration Analysis of a Circular Arch by GDQ Spacetime Semianalytical Method》 ZHAO Hong-jin;LIU Chao;;DONG Ning-juan 2010, 30(3): 31-34.  DOI: 10.3969/j.issn.1006-1355.2010.03.009 Abstract ( )   PDF (178KB) ( )   Starting with the forced vibration governing equations for a uniform crosssection circular arch with the consideration of tangential inertia effect, the solution of displacement response of the arch is obtained. In this solution, the generalized differential quadrature method in space domain is adopted. Theresponse at each node is expressed as time series in time domain. Then, a set of sixthorder partial differential equations is obtained and solved by means of collocation method in the time domain. Finally, solution of the displacement response field is obtained. The inplane forced vibration problem of the circular arch with appropriately prescribed boundary constraint conditions is analyzed. A program is written in Matlab code for solving this problem. And some numerical examples are given. The results indicate that this method has the advantages of higher accuracy and efficiency for forced vibration analysis of circular arches. Related Articles | Metrics

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《Optimal Design of Powertrain Mounting System Based on the Theory of Energy Decoupling》 SHEN Zhi-hong;GUO Fu-xiang;FANG De-guang;LIANG Tian-ye;SHI Wen-ku 2010, 30(3): 35-37.  DOI: 10.3969/j.issn.1006-1355.2010.03.010 Abstract ( )   PDF (170KB) ( )   A sixfreedom dynamic model of the powertrain mounting system of an IVECO minibus is established. Some relevant formulas are derived based on the theory of energy decoupling. The optimal design of the parameters of the powertrain mounting system is carried out. The result indicates that a reasonable selection of the parameters of the powertrain mounting system is beneficial for reducing engine vibration and increasing vehicles comfort performance. Related Articles | Metrics

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《Analysis of Vibration Simulation of BoltsFlange Connection Structure》 GAO Xu;ZENG Guo-ying 2010, 30(3): 38-40.  DOI: 10.3969/j.issn.1006-1355.2010.03.011 Abstract ( )   PDF (174KB) ( )   Using ANSYS code, a 1/8cycle symmetric 3D nonlinear finite element model of boltsflange connection structure is established. Nonlinear transient dynamic analysis is done for the model with three different tightening torques under sinusoidal excitation. Using ANSYS postprocessing, the acceleration signals and signal differences of the pairs of nodes on the top and at the bottom of the flange near the bolt are obtained. The simulation data is compared with experimental data and the relationship between the tightening torques and the signals is acquired. The comparison result ensures the reliability of the finite element model. Related Articles | Metrics

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《Study on Application of Magnetic Shape Memory Alloys to Vibration Control of Structures》 WANG She-liang;DAI Jian-bo;ZHAO Xiang;JI Qing-bo 2010, 30(3): 41-45.  DOI: 10.3969/j.issn.1006-1355.2010.03.012 Abstract ( )   PDF (332KB) ( )   Magnetic shape memory alloy (MSMA) is a new intelligent material that can produce large stain in magnetic field, and meanwhile has the shape memory function. Using these characteristics of MSMA, one can fabricate intelligent actuators for vibration control of structures. At first, the mechanism of deformation of MSMA in magnetic field and its characteristics of magnetic control are introduced in this paper. On this base, two new MSMA actuators, which may be applied to vibration control of structures, are proposed. Their working principle is analyzed and the design method is given. Finally, the reciprocal characteristics of MSMA, key technology and its solution method of the MSMA selfsensing actuators are described. This study may set a foundation for MSMAs application in civil engineering. Related Articles | Metrics

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《Parameter Optimization of Transmission Gear Clusters and Squeak Noise Control》 SHI Quan;LONG Yue-quan;SHI Xiao-hui;GUO Dong 2010, 30(3): 46-49.  DOI: 10.3969/j.issn.1006-1355.2010.03.013 Abstract ( )   PDF (341KB) ( )   In order to reduce the transmission’s squeak, the main noise source of the transmission is recognized by the NVH testing. By analyzing the dynamic actuation of gear clusters, it is confirmed that the mesh impact among gears is the main actuation source of the squeak. Then, by reducing backlash and increasing contact radio, the optimization of the gear clusters is carried out. This method is proved useful in reducing the transmissions squeak induced by the gear meshing. Related Articles | Metrics

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《ODS & Low-frequency Noise Analysis on the Tilt Open Drum Washing Machine》 LIU Bin;FENG Tao;WU Xue;HUANG Zhi-gang;ZHU Teng-fei 2010, 30(3): 50-54.  DOI: 10.3969/j.issn.1006-1355.2010.03.014 Abstract ( )   PDF (268KB) ( )   By using operational deflection shapes (ODS) technology, the vibration of a tilt open drum washing machine （7-600Hz）during dehydration was investigated. Combining with the noise measurement results, the correlation between vibration and noise during dehydration was preliminary discussed. It showed that, the vibration of the machine excited by the unbalance force of the running parts and the electromagnetic force of the electromotor, and the lowfrequency noise was closely related to the vibration. The noise level of both left and right sides were higher than front and back sides. To decrease the noise level, it can modify the frequencyresponse of the machine. Related Articles | Metrics

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《Influence of Transducer Array on Directivity of Acoustic Fields》 LIN Jian;MA Jian-min;ZHUANG Zi-ting 2010, 30(3): 55-59.  DOI: 10.3969/j.issn.1006-1355.2010.03.015 Abstract ( )   PDF (253KB) ( )   Based on the point source directivity function, the directivity functions of a finite area ultrasonic transducer and rectangular arrays of these transducers are obtained. Then, the directivity of the single transducer and the transducer arrays are studied. The influences of array element area, interelement spacing and the number of elements on the ultrasonic transducer array directivity are calculated and analyzed, which may be helpful for the control of high directivity noise and the countermeasure of acoustic weapon. Related Articles | Metrics

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《Sound Intensity Analysis of Shell Structures Subjected to Dynamic Loading》 ZENG Guo-ying;ZHAO Deng-feng 2010, 30(3): 60-63.  DOI: 10.3969/j.issn.1006-1355.2010.03.016 Abstract ( )   PDF (229KB) ( )   Structural sound intensity vector diagrams present directly and visually the energy distribution and propagation of the points on shells surface. First of all, the formula for calculating structural sound intensity in local coordinate systems is deduced. By using coordinate transformation, the expression of the structural sound intensity in the global coordinate system is obtained. The sound intensity of a composite shell structure is calculated using FEM, and the sound intensity diagrams are obtained. The results show that the FEM used in this paper is very effective for analysis of the sound intensities of shell structures. Related Articles | Metrics

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《Study on Control of the Sound Radiation for Thin Plates with Additive Mass Loading》 LIU Cong-guang;YU De-jie;YAO Ling-yun;ZANG Xian-guo 2010, 30(3): 64-66.  DOI: 10.3969/j.issn.1006-1355.2010.03.017 Abstract ( )   PDF (160KB) ( )   To control acoustic radiation of the thin plate with the additive mass loading, the optimized finite element model for structural acoustic radiation analysis is built. The structural acoustic radiation power is computed by means of the finite element method and Rayleigh integral. The distributed mass loading is imposed by the plate mass elements with stiffness free. Taking the thicknesses of the mass elements as design parameters, the acoustic radiation optimizing problem of the thin plate under harmonic excitation is studied. Numerical results show that the acoustic radiation power of the plate is effectively reduced by the optimized additive mass loading. This method has an important significance in engineering practice. Related Articles | Metrics

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《Experimental Modal Analysis of a Refrigeration Compressor’s Shell》 GUO Wei;LIU Bin;FENG Tao;ZHANG Yi 2010, 30(3): 67-70.  DOI: 10.3969/j.issn.1006-1355.2010.03.018 Abstract ( )   PDF (242KB) ( )   By using hammering pulseinspirit method, the experimental modal analysis of a refrigeration compressors shell is carried out. The fundamental modal parameters, including natural frequencies (1kHz 4kHz), damping and mode shapes, are estimated and identified. The intrinsic vibration characteristic of the compressors shell is obtained. Based on the experimental modal analysis, the dynamic characteristic of the shell structure is investigated. The results show that the main modal shapes of the compressors shell are essentially the outwardexpanding and inwardcontracting vibrations. The main cause of noise radiation is the intrinsic vibration of the shell. The results of the experimental modal analysis can provide a useful reference for vibration and noise reduction of the compressors. Related Articles | Metrics

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《Optimized Design of the Double Drive Embroidery Machine Beam》 BAI Qiao;ZHAO Fu;LIN Jian-long;GONG Yan-jue 2010, 30(3): 71-73.  DOI: 10.3969/j.issn.1006-1355.2010.03.019 Abstract ( )   PDF (165KB) ( )   Vibration experiment and FEA simulation are applied to GY902A computerized embroidery machines beam, and the results of beams inherent frequency are given. With the optimized design the structure of beam was modified to increase its inherent frequency and reduce the ratio of breaking thread. Related Articles | Metrics

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《Flexible Multibody Dynamic Simulation of the Valve Train》 LI Xing-ran;ZHANG Bao-cheng;XU Yan-fang;ZHAO Yan-tao 2010, 30(3): 74-77.  DOI: 10.3969/j.issn.1006-1355.2010.03.020 Abstract ( )   PDF (210KB) ( )   Focusing on the deficiency of dynamic simulation for dynamic analysis of valve train of internal combustion engine , flexible multibody dynamic simulation for dynamic analysis of valve train of internal combustion engine is applied. First of all, the rigid body model is built through the software Pro/E,the multiflexible body dynamics model is built through the software ANSYS, which mesh and yield flexible body, such as flexible bodypushrod, flexiblebodyrocker and flexiblebodyvalve. And then, the valve trains flexible multibody simulation analysis is established by ADAMS/Engine. In the end, the valve trains flexible multibody dynamics analysis is carried out. The simulation results at different speed are given. The noise mechanical of valve train is analyzed. The method can describe dynamic characteristics of valve train more precisely and the simulation results are given as a more accurate boundary condition to analyze and predict the vibration and noise characteristics of the diesel engine in the future. Related Articles | Metrics

运载工具振动与噪声

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《Study on the Method of Railway Noise Prediction》 FANG Jian;LEI Xiaoyan;LIAN Songliang;CHENG Xiaoping 2010, 30(3): 78-80.  DOI: 10.3969/j.issn.1006-1355.2010.03.021 Abstract ( )   PDF (145KB) ( )   Railway noise prediction study is the base of vibration and noise mitigation technology. The railway noise prediction models provided by U.S. Department of Transportation Federal Transportation Administration and French are more mature and more effective in European and American countries. This paper has discussed the feasibility of the two methods. Referring to the above models and using the measurement data on site, this paper has produced a model of LA,max. By comparing the results of computation with those of field testing, the feasibilities of the two models can be verified. Related Articles | Metrics

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《Finite Element Analysis of Noise Decreasing with Damping Treatment for Vehicle’s Body 》 WU Zhen;ZUO Yanyan;GE Wei 2010, 30(3): 81-84.  DOI: 10.3969/j.issn.1006-1355.2010.03.022 Abstract ( )   PDF (212KB) ( )   The finite element model of a vehicle’s body, whose roof has been treated with damping, is established. The modal analysis, vibration response analysis, and acousticstructural coupling analysis are carried out. Comparing the sound pressure levels before and after the damping treatment, it is proved that the surface damping treatment of the body can reduce the noise in the vehicles cavity effectively. The result provides guidance for the application of the technology of surface damping treatment to reducing the vibration radiating noise from the vehicle’s body. Related Articles | Metrics

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《Numerical Simulation of Vibration and Sound Radiation of Tires》 CHAN LiangG;XIAO Wang-xin;XIE Wei-ping 2010, 30(3): 85-90.  DOI: 10.3969/j.issn.1006-1355.2010.03.023 Abstract ( )   PDF (302KB) ( )   Numerical simulations of vibration and sound radiation of the 225/50R17 smoothing tire and longitudinally grooved tire excited by surface load are carried out by using the FEM software ANSYS and the BEM software SYSNOISE. The displacement frequency responses of the tires excited by, respectively, radial contact force, tangential contact force and lateral contact force are calculated using FEM. Then, the result of nodal displacement responses is used as the boundary condition for the BEM model. The radiation sound power, radiation efficiency, and the directivity of sound in far field in three working cases are computed by means of BEM technique. Related Articles | Metrics

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《Comparative Study on Near Field Noise Radiation for Automobiles and Warships》 XIONG Ji-shi;WU Chong-jian;Zeng Ge-wei;Xu Zhi-yun 2010, 30(3): 91-93.  DOI: 10.3969/j.issn.1006-1355.2010.03.024 Abstract ( )   PDF (182KB) ( )   In order to raise detecting distance and precision, it is necessary to study the near field noise radiation in warships systemically. This paper analyzes and compares the similarities and differences of the near field noise radiation between automobiles and warships in order to provide the methods and theories for the near field noise radiation study for warships. Related Articles | Metrics

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《Comprehensive Evaluation of Vehicles Engine Vibration Based on PCA》 JIA Ji-de 2010, 30(3): 94-96.  DOI: 10.3969/j.issn.1006-1355.2010.03.025 Abstract ( )   PDF (145KB) ( )   Large sample data analysis for vehicles engine vibration is a difficult issue. An approach of extracting the characteristic information from the large sample data is proposed using the principal component analysis (PCA) method. In this method, the mutually related highdimensional characteristic parameters are reduced to several independent lowdimensional characteristic parameters, so as to constitute a model for comprehensive evaluation of a vehicles engine vibration. Using this method, the vibration state of the vehicles engine is analyzed. The result shows that using this method, the vibration state of vehicles engine can be quantitatively evaluated with a smaller information loss. Related Articles | Metrics

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《Analysis of Sound Quality of Lowfrequency Noise for Fuel Cell Vehicles》 HE Rong;ZUO Shu-guang;SHEN Xiu-min;ZHANG Jiang-fen 2010, 30(3): 97-99.  DOI: 10.3969/j.issn.1006-355.2010.03.026 Abstract ( )   PDF (163KB) ( )   The internal and external noises of a fuel cell vehicle (FCV) are collected. Considering that low frequency noise occupies a large amount of energy, the noise signals in the range from 20Hz to 150Hz are extracted through the lowpass filter. Then, based on Zwicker model, the objective evaluation index is calculated. The score of subjective evaluation of the noise sample is given by means of the paired comparison method. Finally, the multiple linear regression model for lowfrequency sound quality analysis is established according to the linear correlation between subjective score and objective index, in order to get more accurate evaluation of sound quality of FCV noise in low frequency range. Related Articles | Metrics

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《Study on Powertrain Mounting System of Passenger Cars Using Energy Decoupling Method》 WANG Hai-xia;WU Yi-min;ZHANG Yue;DU Peng 2010, 30(3): 100-103.  DOI: 10.3969/j.issn.1006-1355.2010.03.027 Abstract ( )   PDF (218KB) ( )   The commonly used domestic and foreign decoupling methods are introduced. A model of powertrain mounting system with six degrees of freedom is established. Aiming at the vibration problem of some passenger cars, a test and a vibrationisolation performance analysis of the original mounting system are carried out. Taking the stiffness and installangle of the mounts as variables, improvement of design is done based on the energy decoupling theories to improve vibrationisolation performance of the mounting system. The vibration test of the entire vehicles mounting system is done, and the testing data before and after the improvement of the system is compared. It is proved that the improved design is effective and rational. Related Articles | Metrics

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《Some Considerations of Parameter Inspection for Vehicle’s Suspension Systems by Using QuasiImpulse Excitation 》 ZHANG Yu; 2010, 30(3): 104-107.  DOI: 10.3969/j.issn.1006-1355.2010.03.028 Abstract ( )   PDF (257KB) ( )   In this paper, some measures for ensuring the effect of inspecting vehicle suspension parameters by the quasiimpulse excitation are proposed. They are the excitation with press bodywork; the plate inspecting; the calculation of suspension parameters; adopting the criterion of the correlated dimension D2; recognizing the periodicity of samples with maximal Lyapunov index λmax; and selecting the maximum/submaximum values in the samples to compute the dampingratio ξ. With these measures, the parameters of the suspension systems of two testing automobiles are inspected. And the results show that the measures introduced in this paper are feasible. Related Articles | Metrics

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《Computation of Shock Response of a Warship’s Transformer》 JIANG Guo-he;XUE Bin;FENG Wei;WU Guang-ming 2010, 30(3): 108-112.  DOI: 10.3969/j.issn.1006-1355.2010.03.029 Abstract ( )   PDF (386KB) ( )   Transformer is an important equipment of warship’s electrical system. In this paper, the finite element model of a warships transformer is established by means of the ANSYS code. The structural vibration modes of the transformer are obtained through the modal analysis. The rationality of the model is verified. Then, transformers shock load is studied and shock load resistance is analyzed. The time and location for the maximum stress are determined through the transient response analysis. This work is beneficial for further study on antishock property of warships transformers. Related Articles | Metrics

环境振动与环境噪声

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《Study on Design Method for Acoustical Environment and Noise Control in Hospitals》 LI Ying;WANG Xiou 2010, 30(3): 113-117.  DOI: 10.3969/j.issn.1006-1355.2010.03.030 Abstract ( )   PDF (290KB) ( )   Hospital’s environment needs to be quiet. Noise pollution in the hospital’s environment not only affects the patient’s physical and mental health directly or indirectly, but also impacts the quality of doctors work. Currently, noise pollution becomes a serious problem in some hospitals. However, the design and research of acoustics environment in hospitals have not attracted sufficient attentions. In this paper, the acoustical environment of a hospital in Beijing is tested and evaluated. Some problems in noise pollution and acoustical environment design are analyzed and studied. The design method for noise control in hospitals is discussed. Related Articles | Metrics

信号处理与故障诊断

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《Processing of Mechanical Noise Date Using PCA》 LIANG Sheng-jie;ZHANG Zhi-hua;CUI Li-lin 2010, 30(3): 118-122.  DOI: 10.3969/j.issn.1006-1355.2010.03.031 Abstract ( )   PDF (256KB) ( )   Ribbed doublelayer cylindrical shells have many mechanical noise sources, and the noise date is very intricate. In this paper, the noise date of the cylindrical shell is studied using the relativity analysis method. And the dimensionreduction processing of the noise date is also carried out using the PCA method. After summarizing some specific steps of dimension reduction, the relation between the mechanical noise sources and the principal components (PCs) in different sensors is analyzed. Results show that it is reasonable to select these mechanical noises, which accumulated contribution ratios are larger than 0.85, as a standard for determination of the number of principal components. Related Articles | Metrics

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《Application of Wavelet Packet Transform in Metal Magnetic Memory Signal Processing 》 ZHANG Xi-yong;ZHANG Yong-xiang;MING Ting-tao 2010, 30(3): 123-125.  DOI: 10.3969/j.issn.1006-1355.2010.03.032 Abstract ( )   PDF (152KB) ( )   The metal magnetic memory technique is very effective in early damage detection for metal parts. However, information of disturbing magnetic fields also exists in the magnetic memory signals so that the characteristic signals in the stress concentration area can not be recognized easily. This paper puts forward a new filtering method based on wavelet packet decomposition and reconstruction. Wavelet packet decomposes signals according to different frequency ranges. The goal to filter the disturbing signals can be achieved through intercepting the interested frequency ranges and reconstructing signals. Simulation analysis verifies the feasibility of this method. Then, this method is used to decompose and reconstruct actual magnetic memory signals and a preferable effect is gained. It makes the signal characters in stress concentration area more clear and depresses the probability of damage misjudgment. Related Articles | Metrics

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《Fast AE Signal Recognition》 DAI Wei;JI Chang-peng 2010, 30(3): 126-128.  DOI: 10.3969/j.issn.1006-1355.2010.03.033 Abstract ( )   PDF (203KB) ( )   Based on the technology of using acoustic emission (AE) signal to extrapolate the AE source, an approach to fast recognize the coal mine AE signal is presented by using nearfield MUSIC algorithm. This approach can be used to estimate the position of the AE signal source by comparison of the estimation result with roadway shape and working face of the coal mine. The simulation results show that the proposed approach is effective in estimating the position of the AE signal source. Related Articles | Metrics

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《Research of the Application of Acoustical Signals in Fault Diagnosis of Diesel Engines》 HUANG Zhi-qiang 2010, 30(3): 129-132.  DOI: 10.3969/j.issn.1006-355.2010.03.034 Abstract ( )   PDF (274KB) ( )   This paper mainly introduces how to recognize the acoustical signals of the diesel engines using wavelet packet analysis and pattern identification. The fault diagnosis of the diesel engines is also introduced. Using the updated data base of experts, the fault of small diesel engines can be recognized. This technique is evaluated and applied for the fault diagnosis of the KM178F diesel engine, and good results are obtained. Related Articles | Metrics

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《Design of Engine Fault Diagnosis System Based on Exhaust Noise VQ Analysis》 DING Zhe;XU Yong 2010, 30(3): 133-137.  DOI: 10.3969/j.issn.1006-1355.2010.03.035 Abstract ( )   PDF (250KB) ( )   By collecting exhaust noise with PC sound card and LabVIEW, and using vector quantization (VQ) approach to analyze exhaust noise under different engine conditions, a new system for engine fault diagnosis of whole vehicles without disintegration has been designed. The experimental results indicate that this method is simple, effective, economic and feasible. It also has excellent performance of noncontact testing and high diagnosis accuracy. Related Articles | Metrics

减振降噪设备和器材

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《Development and Application of Sound Absorption Casting Board》 NI Rong;SUN Xiuping;SUN Zhaoxing 2010, 30(3): 138-140.  DOI: 10.3969/j.issn.1006-1355.2010.03.036 Abstract ( )   PDF (185KB) ( )   Acoustical casting board is made of a new composite material for sound absorption purpose. In the manufacture of this board, a polyurethane board is taken as a carrier. Then, it is coated by mixed cream including some basic components such as casting powder, additives, water and gelatin. After vibration consolidation process, this board is solicited in the natural environment. The acoustical casting board has the merits of high stiffness, porosity and open pores. In this paper, the influence of board thickness and pore dimensions on the sound absorption coefficient of the board is studied. It is shown that increasing the board thickness with the pore dimension unchanging can raise the sound absorption coefficient for medium and low frequencies, but has small influence on the sound absorption coefficient for high frequency. The NRC of the board of 50mm thickness can reach 0.6, and the property of sound absorption can reach grade Ⅱ. Related Articles | Metrics

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《Optimal Design of Mufflers Based on Multiobjective Genetic Algorithm》 ZHANG Cui-cui;WU Wei-wei;CHEN Hao 2010, 30(3): 141-143.  DOI: 10.3969/j.issn.1006-1355.2010.03.037 Abstract ( )   PDF (134KB) ( )   A methodology, which combines fourterminal network method with genetic algorithm method, for mufflers shape design is proposed. The main goal is to obtain the optimal dimensions of the acoustic mufflers with their transmission loss (TL), insert loss (IL) and noise reduction (NR) being maximized in the frequency range of interest. The improved fourparameter method is used for TL, IL and NR evaluations. The mufflers are optimized by means of the MultiObjective Genetic Algorithm. The result shows that the performance of the mufflers has been improved significantly. Related Articles | Metrics

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《Analysis of Acoustic Characteristics for Expansion chamber Muffler Using Finite Element Method》 LIU Fei;LU Sen-lin;LIU Hong-guang;Wang Jing 2010, 30(3): 144-147.  DOI: 10.3969/j.issn.1006-1355.2010.03.038 Abstract ( )   PDF (397KB) ( )   The finite element method is used to analyze the acoustic characteristics of an expansionchamber muffler with its inlet and outlet pipes being coaxial. Its transmission loss (TL) is calculated. The result is compared with that of the onedimensional solutions based on planar wave theory. The limitation of onedimensional planar wave theory is discussed. The acoustic characteristics of eccentric outlet muffler, doubleoutlet muffler and doublecavity muffler are analyzed. The result indicates that the position and the number of outlet can affect the acoustic characteristic of a muffler for higher and medium frequencies; while the doublecavity muffler has high noiseelimination efficiency for lower and medium frequencies. Related Articles | Metrics

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《Design of Acoustic Enclosure for Outside Boxswitchboard Transformer with Natural Ventilation》 MAO Wan-hong;SHENG Lu-gang;XU Li;WEI Jun-qi 2010, 30(3): 148-152.  DOI: 10.3969/j.issn.1006-1355.2010.03.039 Abstract ( )   PDF (275KB) ( )   The complaints for the noises of the outside boxswitchboard transformer and the cooling fans increase recently. Based on the complaint cases, an acoustic enclosure for noisedecreasing is designed through the theoretical and experimental analysis. The acoustic enclosure is ventilated mainly through natural ventilation with the auxiliary mechanical aiding. The results of measurement show that the acoustic enclosure with natural ventilation has fine effects in both ventilation and noise reduction. Related Articles | Metrics

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《Threedimensional Acoustical Analysis for a Resistance Muffler in the Case of Different Arrangements of Crosssections》 CAO Yu-huang;LUO Ma-ji;LIU Zhi-en 2010, 30(3): 153-155.  DOI: 10.3969/j.issn.1006-1355.2010.03.040 Abstract ( )   PDF (148KB) ( )   Since onedimensional and twodimensional commercial codes may not be used to accurately analyze the acoustical performance for resistance mufflers in the case of different arrangement of crosssections, threedimensional software is employed to analyze this problem. It is found that different arrangements of crosssections can induce different transmission loss in a large frequency range. According to the exhaust noise spectrum and the computation results, the design of the mufflers can be optimized further. Related Articles | Metrics

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《Optimal Design of Motor Vibration Isolator for Control of Mower Exterior Noise》 YAO Hao-ping;ZHANG Jian-run 2010, 30(3): 156-159.  DOI: 10.3969/j.issn.1006-1355.2010.03.041 Abstract ( )   PDF (228KB) ( )   Dynamic and acoustic characteristic of a certain mower were tested and analyzed in this paper ,and the corresponding model of mower were made by usingthe finite element and boundary element methods. Vibration isolator to connect motor with mower to reduce radiation noise was adopted . In the optimization design ofvibration isolator,stiffiness and damping were used as variablesand average displacement of mower was used as object function.And the result shows that thenoise is reduced effectively. Related Articles | Metrics

振动噪声测试技术

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《Study on Characteristics of a New Type of ElectroThermoAcoustic Transducer》 WUXiao-jun;DONG Wei;CHEN Yan;WEI Xian 2010, 30(3): 160-163.  DOI: 10.3969/j.issn.1006-1355.2010.03.042 Abstract ( )   PDF (233KB) ( )   A new type of high frequency electrothermoacoustic transducer was designed and fabricated. This transducer consists of an electric heating surface layer, an insulation layer and a thermal conduction substrate. When an alternate voltage signal is input to the electric heating surface layer, a thermal signal will be generated. This thermal signal will cause the pressure of the air near the electric heating surface to oscillate, forming the acoustic wave correspondingly. This transducer can produce a high frequency thermoacoustic effect in the measurable frequency range from 3kHz to 25kHz. It also has the advantage of the wide frequency bandwidth, flat frequency response and no moving parts. Related Articles | Metrics

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《Noise Testing and Analysis of a Reciprocating Compressor》 QIAN Xiao-ping;HAO Dian;CHEN Lan-ying 2010, 30(3): 164-167.  DOI: 10.3969/j.issn.1006-1355.2010.03.043 Abstract ( )   PDF (201KB) ( )   The noise of an onsite reciprocating compressor is measured and analyzed. Sound level testing and spectrum testing are carried out by using sound level meter and twochannel dataacquisitionandanalysis instrument. The sound level is evaluated according to the Industrial Enterprise Noise Standards (Grade A). Through the frequency spectrum analysis, the main noise source and its main feature are found. Finally, some measures for noise reduction and control are proposed. Related Articles | Metrics

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《Study on the Method of Noise Testing of the Microdosage Xray Security Inspection Equipment》 LIANG Shi-lei;BAO Jun-yao;QU Jun-jian 2010, 30(3): 168-171.  DOI: 10.3969/j.issn.1006-1355.2010.03.044 Abstract ( )   PDF (280KB) ( )   Testing and evaluation of noise are important work for the quality controlling of security inspection equipment. In this paper, some indexes for noise evaluation are analyzed and compared one another. As an example, the characteristic of the noise radiation distribution in the EI10080 security inspection equipment is analyzed experimentally. The method for testing and evaluation of noise of security inspection equipment is proposed by analyzing the sound pressure levels of noise at two prescribed points. Results of testing show that this method is easy to handle and has a high precision. Related Articles | Metrics

工程实践

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《Analysis and Control of Noise in Water Supply Systems of Buildings 》 ZHANG Qin;HAO Guang 2010, 30(3): 172-175.  DOI: 10.3969/j.issn.1006-1355.2010.03.045 Abstract ( )   PDF (227KB) ( )   In this paper, the reasons of noise of the water supply systems of buildings is analyzed in three aspects: the pumping unit，water supply piping system, and water utilization equipment. The corresponding measures in both design and construction for noise control of the building water supply systems are discussed. Related Articles | Metrics