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International Challenge of Noise Limit Values to Chinese Typical Light-duty Vehicles 2014, 34(1): 1-5.  DOI: 10.3969/j.issn.1006-1335.2014.01.001 Abstract ( )   PDF (885KB) ( )   UN ECE will reach a decision for the limit values of regulation ECE R51 / 03 series - noise emitted by accelerating motor vehicles in 2013, and the Chinese typical light-duty vehicles will meet serious challenge. And the main reason is that there are obvious differences of the light-duty vehicle type between China and Europe, and the Europe Union has not fully considered the Chinese typical light-duty vehicles when collecting data for the limit values. This paper amplifies the specific discrepancy on the noise emission level between Chinese typical light-duty vehicles and passenger cars, according to the verification test results, puts forward the sub-categories method which is more fit for the condition of China, and also suggests that the domestic manufacturers should take part in the amending of ECE regulations like Japanese companies and avoid the technical barriers. Related Articles | Metrics

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Review of Research and Development Status of Dynamic Load Identification in Time Domain 2014, 34(1): 6-11.  DOI: 10.3969/j.issn.1006-1335.2014.01.002 Abstract ( )   PDF (804KB) ( )   Compared with frequency domain load identification, time domain method is not only applicable to linear systems but also to nonlinear systems. Besides, time domain method can deal with transient impact force effectively. Consequently, more attention has been concentrated on time domain method in recent years. Development surveys of identification approaches widely utilized in time domain are summarized, such as deconvolution method, sum of weighted acceleration technique, function approximation technique, Kalman filter and recursive least square method, inverse system method and burgeoning intelligent algorithms. In addition, the merits and demerits of these approaches are analyzed respectively. With respect to research object, identification method and application area, the authors present that nonlinear system and linear time-variant system will be the focus of study objects, inverse system method combined with modern intelligent algorithm will be new research hotspot, and application of load identification to fault diagnose will be development trend. Related Articles | Metrics

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Prediction of Sound Transmission Loss for Sandwich Panel by  Using Beam Model 2014, 34(1): 12-15.  DOI: 10.3969/j.issn.1006-1335.2014.01.003 Abstract ( )   PDF (1041KB) ( )   An approach on the prediction of sound transmission loss for a finite sandwich panel with honeycomb core is described in the paper. The sand?wich panel is treated as orthotropic and the apparent bending stiffness in two principal directions is estimated by means of simple tests on beam elements cut from the sandwich panel. Utilizing orthotropic panel theory, together with the obtained bending stiffness in two directions, the sound transmission loss of simply-supported sandwich panel is predicted by modal expansion method. The predicted transmission loss is compared with measured data and the agreement is reasonable. Related Articles | Metrics

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Experimental Analysis of Virtual-force Computation Method 2014, 34(1): 16-18.  DOI: 10.3969/j.issn.1006-1335.2014.01.004 Abstract ( )   PDF (896KB) ( )   In the research of ship vibration transfer path analysis and structure response monitoring, the characteristics of machine force are always needed. As the inherent complexity of the machine and the structure onto which it is mounted, the real-time measurement becomes very difficult. On the basis of inherent connection between structural response and exciting force, the real exciting forces can be instead by pseudo-forces, which exactly reproduces the response caused by the noise generating mechanism inside the source. In this paper a regularization technique based on partial optimization is introduced into the pseudo-force model to solve the ill-conditioned problem. An experiment was carried out on a pump mounted on ship, and the results showed that the structural response reconstruction errors with partial regularization method was effectively reduced. Related Articles | Metrics

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Analysis of the Band Gap of a Layered Triple Periodic Structure 2014, 34(1): 19-22.  DOI: 10.3969/j.issn.1006-1335.2014.01.005 Abstract ( )   PDF (1169KB) ( )   Existing literature are mostly focused on band gap analysis of layered binary periodic structure, while researches on unidimensional layered triple periodic structure are still lacking. In this paper, layered triple periodic structure is simplified into a unidimensional phononic crystal structure based on phononic crystal theories, and effect of density and damping ratio of material on the first band gap is analyzed using lumped-mass method. The results indicate that effect of density of material on the first band gap is considerable, while effect of damping ratio of material is insignificant. This research provides theoretical basis for band gap design of layered triple periodic structure. Related Articles | Metrics

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Analysis of Far-filed Sound Pressure Level of Rectangular Plates 2014, 34(1): 23-27.  DOI: 10.3969/j.issn.1006-1335.2014.01.006 Abstract ( )   PDF (1517KB) ( )   The far-filed sound pressure level of rectangular plate is addressed, acoustic modes are established for the simply supported and guided supported rectangular plate in an infinite baffle. A far-filed approximation solution is derived in a closed form using Fourier method. Two kind of possible concentrated forces, a line force, a point force, are included in the analysis. Furthermore a parametric study is carried out to clarify the effect of the incentive loading position and the various physical characteristics parameters of the rectangular plate. Conclusion is drawn that, the far-filed pressure level decreased with incentive loading closed to the edge. Relative to the simply supported boundary is concerned, a guided boundary can enhance far-filed radiated sound pressure. when loss factor and thickness increased, far-filed sound pressure level decreased in all frequency range. When density changed, far-filed sound pressure level at low and high frequency range present different change rules. Through analysis on far-filed sound pressure level, that can give foundation of designing acoustical elements and active noise control. Related Articles | Metrics

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Basic Theory of Operational Transfer Path Analysis and  Its Application 2014, 34(1): 28-31.  DOI: 10.3969/j.issn.1006-1335.2014.01.007 Abstract ( )   PDF (1378KB) ( )   Operational transfer path analysis is an effective in-situ method for measuring the vibration transmission path. OTPA requires only operational measurements of the path references and target response(s) to establish a transmissibility matrix between references and target(s) from operational data under different test conditions. There is no need to measure operational forces and transfer function comparing to traditional method. It is easier and can operate in-situ. This article analyzes the basic theory of the operational transfer path analysis and the cause of the error. A car’s vibration analysis is given as an analysis example. The implementation procedures of operational transfer path analysis are given in detail. The noise sources were found out, and reasonable noise and vibration reduction suggestion was given. Related Articles | Metrics

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Analysis of Cabin’s Vibro-acoustic Characteristics and Control of Bulkhead Vibration 2014, 34(1): 32-35.  DOI: 10.3969/j.issn.1006-1335.2013.04.008 Abstract ( )   PDF (1220KB) ( )   In order to depress effect of bulkhead vibration on cabin’s vibro-acoustic characteristics, structural-acoustic design of bulkhead was done. According to the theory of damping vibration attenuation, bulkhead was coated with viscoelastic layer for reducing vibration response. As to increase transmission loss, attached back-ring plate was layed between bulkhead and shell applying the principle of impedance mismatch. Vibro-acoustic characteristics of cabin were numerical calculated by FEM/BEM and analyzed the bulkhead’s vibration control effect. The results shows that bulkhead coated with viscoelastic layer and added with attached back-ring plate could not only reduce cabin’s vibration and sound radiation effectively, but also isolated the structure-borne sound to the adjacent cabin significantly. It was a better measure for bulkhead’s vibration damping and noise reduction. Related Articles | Metrics

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Updating and Optimization of Design Parameters in  Frame Structure Modeling 2014, 34(1): 36-40.  DOI: 10.3969/j.issn.1006-1335.2014.01.009 Abstract ( )   PDF (1126KB) ( )   In order to reduce the parameters setting error of the frame finite model, the modal frequency residual error vector has been founded based on the results of finite modal analysis and experimental modal analysis. Three elastic modulus and three density parameters are selected to be corrected from the twelve design parameters by sensitivity method. The objective function is constructed with modal frequency residual error vector and parameters correction value. And optimization method is introduced to solve the updating process. The modal result of the updated model is identical with the experiment modal result, which shows the updated finite model can reflect the structure characteristics correctly. The validity and feasibility of the design parameters updating method is also validated. Related Articles | Metrics

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Effect of Radial Offset of the Mass Centers of Wheelset on Its Longitudinal Vibration 2014, 34(1): 41-43.  DOI: 10.3969/j.issn.1006-1335.2014.01.010 Abstract ( )   PDF (1154KB) ( )   Abstract: When the wheel mass center exists radial offset,it will lead to cyclical changes in adhesion coefficient, causing severe self-excited torsional vibration, led directly to the wheel longitudinal vibration. The wheel longitudinal vibration and the wheel-rail sticky - slippery vibration coupled with each other, causing the destruction of the locomotive stable dynamics performance. Establish a new type of locomotive model.Through numerical simulation,analysis in different deviation and speed, the longitudinal vibration frequency of the frame and the wheel , vehicle body vertical resonance frequency. Calculate the variation of sticking coefficient.Analysis the principle of locomotive vertical stationarity deterioration.The conclusion shows that when the existence of radial eccentricity, the saturated wheel/rail creep force saturation produce dynamic coupling, causing wheel torsional and longitudinal vibration which will deteriorate the locomotive vertical stationarity through through framework and traction device.Stationarity through framework and traction device deterioration locomotive vertical. Related Articles | Metrics

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Optimal Control of Nonlinear Random Vibration of  an Inclined Taut Cable with Uncertainties 2014, 34(1): 44-46.  DOI: 10.3969/j.issn.1006-1335.2014.01.011 Abstract ( )   PDF (900KB) ( )   The optimal control of nonlinear random vibration of an inclined taut cable with uncertainty is studied. The nonlinear equation of transverse motion of the cable with control and excitation is derived, and converted into the vibration equations with multi-mode coupling by using the Galerkin method. Under considering uncertain parameters, the random optimal control problem on the uncertain system is formed. Then the HJI equation is determined and the minimax control law is obtained based on the random averaging method, differential game theory and dynamical programming principle. Numerical results show that the proposed control can achieve better effectiveness for the nonlinear random vibration of the cable. Related Articles | Metrics

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Analysis of Vibration Fatigue Strength Coefficient Based on General Scaling Law 2014, 34(1): 47-51.  DOI: 10.3969/j.issn.1006-1335.2014.01.012 Abstract ( )   PDF (1161KB) ( )   Based on Dirlik model, this paper proposes a new model of the fatigue strength coefficient, which is applied to the stationary wide-band random vibration loading, combining with the general scaling law. General scaling law account that the spectral moment of the structure stress spectral under original loading and strength loading have a same proportional relationship,which is applied to Dirlik wide-band fatigue damage model, then the model of the fatigue strength coefficient can be deduced. Based on rainflow counting and Miner damage ruler, it predict the fatigue life time of cantilever under the original acceleration power spectral and strength acceleration power spectral by general scaling law, then calculate their fatigue strength coefficient and compare it with the result calculated by the model of fatigue strength coefficient. The result show that the accuracy rate of the model of fatigue strength coefficient proposed by this paper is 99.7%, which validates the model of fatigue strength coefficient proposed by this paper is effective. Related Articles | Metrics

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Test and Analysis of Vibration Environment of Helicopter’s Mast Mounted Sight 2014, 34(1): 52-56.  DOI: 10.3969/j.issn.1006-1335.2014.01.013 Abstract ( )   PDF (1418KB) ( )   The airborne vibration environment are the main cause of line-of-sight stable accuracy decline.In this paper, vibration environment of Helicopter Mast Mounted Sight(MMS)was tested, Test Equipment(IMU) and fake MMS that have same size and weight with real MMS were designed. 25m hovering flight and 160Km / h forward flight were implemented, The results show that the disturbance was smallest in 25m hovering flight; As forward speed increased, the disturbance intensified; The results also show that not only the line vibration, but also angle disturbances exist. The results support the preliminary design and ground test。. Related Articles | Metrics

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Active Control of High-frequency Vibration in Disc Brake System 2014, 34(1): 57-60.  DOI: 10.3969/j.issn.1006-1335.2014.01.014 Abstract ( )   PDF (1173KB) ( )   In order to reduce the high frequency vibration in the process of braking, through modeling the disc brake vibration dynamics, by using AFC (Active Force Control) control theory and PID control theory, it leads to the construction of the effective vibration control parameters and AFC controller. Take advantage of the MATLAB /Simulink to simulate the brake vibration under the AFC and PID joint controlling, and do the contrastive analysis with brake vibration under free state as well. According to the analysis, when α≤0.022, the brake disc tends to be stable in the scope of 2s’s amplitude under the PID and AFC mutual controlling, and the brake disc’s vibration amplitude will drop from 1e-3m to 1e-6m ; when α＞0.022, the brake disc’s vibration amplitude will enlarge under the joint controlling. Through the research of active control method, we can reduce the brake’s high frequency vibration to lower the noise arose from it. It provides the evidence to improve the performance of NVH in automobile. Related Articles | Metrics

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Analysis of Lateral-and-torsional Coupled Vibration of Drill String During Drilling Process 2014, 34(1): 61-66.  DOI: 10.3969/j.issn.1006-1335.2014.01.015 Abstract ( )   PDF (1001KB) ( )   Abstract: Coupled lateral and torsional vibration of the drill string is one of movement forms, which is inevitable during drilling. Because the force on the drill string is very complex in the process of drilling wells, a simplified assumption is provided and space drill stem element and gap element are analysed in the local-coordinate system. The dynamical matrices of coupled lateral and torsional vibration of the drill string are developed. It was obtained some correlation rules and revealed the basiccharateristic of coupled lateral and torsional vibration of the drill string during drilling. It reveals the basic characteristic of coupled lateral and torsional vibration of the drill string during drilling. Related Articles | Metrics

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Model Reduction and Active Vibration Suppression of  a Wind Tunnel Test Model by H∞ Control 2014, 34(1): 67-71.  DOI: 10.3969/j.issn.1006-1335.2014.01.016 Abstract ( )   PDF (1540KB) ( )   To measure the aerodynamic forces in wind tunnel, the test model is often mounted by a supporting beam axially inserted from backside. The test object and supporting, as a structure, is flexible with low natural frequencies. In transonic testing with a large angle of attack, fluctuation pressure by the airflow distributes in low frequency bandwidth, and high magnitude vibration with low frequency in vertical plane is easily generated for resonance of the flexible structure excited by the pressure. This vibration would contaminate the test data and even damage the instruments in a fatigue manner. For one test model with back supporting beam, the FEM model was generated and then reduced through balancing and modal truncation methods; An H∞ robust control method based on the flexible structure properties was applied to suppress the vibration. Simulations and analysis show this active vibration suppression solution is applicable and efficient, especially for large complex flexible structures. Related Articles | Metrics

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Study on Coupled Vibration Characteristics of Inclined Isolation System 2014, 34(1): 72-75.  DOI: 10.3969/j.issn.1006-1335.2014.01.017 Abstract ( )   PDF (1017KB) ( )   Abstract：To solve vibration isolation problems of powerplant in engineering, a dynamic model of inclined isolation system which is subjected to combined excitations and based on flexible foundation is proposed. A set of matrix formulations relating to dynamic parameters of vibration isolation system are derived, and the expression of power flow transmission is presented. Transverse-roll coupled vibration characteristics of the system are studied deeply, effects of vibration isolation under the decoupling conditions are explored, and the standing wave effect of isolators are analyzed. It is founded that the system could be decoupled and the system’s vibration transfer energy could be reduced significantly when the structure parameters of mounts are reasonable; the power flow in high frequency are increased significantly resulting from the standing wave effect of the isolators. Related Articles | Metrics

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Effect of Structural Parameters on Vibration Noise of   Rolling Bearings 2014, 34(1): 76-81.  DOI: 10.3969/j.issn.1006-1335.2014.01.018 Abstract ( )   PDF (974KB) ( )   A mathematic model of vibrational noise of rolling bearings is established based on the theory of the nonlinear dynamics and acoustics to analyze the effects of structural parameters on the vibrational noise. The research results show that radial clearance is the most significant factor affected the vibrational noise, effects of the channel curvature radius on the amplitude of vibration displacement and velocity are different, maximum sound pressure and the level of maximum sound pressure are gradually decreased with increasing the channel curvature radius. The bearing noise can be reduced by reducing the number of the steel balls. The noise in X direction is larger and more significant than that in Y direction. Comparing with the traditional method, the method by changing the structural parameters to reduce the noise is simple, feasible, effective and cost saving. A new research way of reducing noise of the bearing is obtained from the results in this paper and it is also laid the foundation to study the quantitative relationship between the vibration noise and various factors. Related Articles | Metrics

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Influence of Installation Eccentricity on Vibration Reduction Effect of Ball-type Automatic Balancers 2014, 34(1): 82-87.  DOI: 10.3969/j.issn.1006-1335.2014.01.019 Abstract ( )   PDF (1502KB) ( )   Running at the over critical speed，there are many factors influence the vibration reduction of ball-type automatic balancer. In this paper, through the establishment of the mathematical model of the exist installation eccentricity ball-type automatic balancer, and numerical simulation which simulation parameters determined by the existing experimental installation, get some information and analyze the effect of installation eccentricity on the vibration reduction of ball-type automatic balancer. The results show that the little the installation eccentricity exist the better effects of vibration reduction. Within a certain range, improving the machining accuracy and the installation accuracy of the rotor, reducing the installation, the vibration reduction effect of ball-type automatic balancer improving obviously. But improving the machining accuracy and the installation accuracy of the rotor excessively, the vibration reduction effect of ball-type automatic balancer improving slowly. Related Articles | Metrics

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Study on Dropping Damage Boundary of  Tilted Support Package System 2014, 34(1): 88-91.  DOI: 10.3969/j.issn.1006-1335.2014.01.020 Abstract ( )   PDF (1521KB) ( )   The dimensionless dropping shock dynamical equations of tilted support system were established. The system parameter，dimensionless dropping shock velocity and system support angle or damping ratio were selected as the basic evaluation quantities, the two-dimensional dropping damage boundary curves and the three-dimensional dropping damage boundary curved surfaces of the product are given by using the Runge-Kutta method. The effects of damping ratio, support angle and the system parameter on the dropping damage boundary were discussed. It is shown that the effects of the system parameter, dimensionless dropping shock velocity and damping ratio on the damage boundary is noticeable, and the system exists the best damping ratio, as system damping ratio is close to the best value, the system has good protection characteristic to the product. Decreasing the system parameter or reducing support angle can improve the protection characteristic to the product. The conclusion of the research can provide a reference for the design of tilted support system. Related Articles | Metrics

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Numerical Calculation for Sound Radiation of Thin Plate with Two-dimensional Periodically Distributed Bulk-damping 2014, 34(1): 92-94.  DOI: 10.3969/j.issn.1006-1335.2014.01.021 Abstract ( )   PDF (1022KB) ( )   By using FEM and BEM,this paper focused on the sound radiation characteristics of a specified size plate based on two-dimensional periodic damping.Numerical calculation results show that the sound radiation power of plate based on two-dimensional periodic damping is less than traditional free damping structure in specific frequency bands,and increase damping laying area、the periodicity appropriately can reduce the acoustic radiation characteristics of plate structure Related Articles | Metrics

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Experimental study on track vibration control using a tuned damper floating rail fastening system on Chengdu Metro 2014, 34(1): 95-100.  Abstract ( )   PDF (1498KB) ( )   　　　In order to reduce the track vibration of rail subway system, a high stiffness of the tuned damper floating rail fastening system has been developed. It makes full use of the dynamic isolator and absorber to effectively reduce the vibrations of rail and slab. This paper introduces the testing method of rail deformation and vibration measurement, slab and tunnel wall vibration measurements on Chengdu Metro Line one where the DTVI2 fasteners and tuned damper floating rail fasteners were installed respectively. Comparison of the tests show that the tuned damper floating rail fastener has the better damping effect to reduce the rail vibration, and has achieved a good vibration insertion loss of 8-9dB on the slab and the tunnel wall. Track deformation with tuned damper floating rail fastening system has also met the design requirements on safe issue. Related Articles | Metrics

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Application of 6-DOF Wheel Center Forces to the Analysis of Interior Road Noise 2014, 34(1): 101-103.  DOI: 10.3969/j.issn.1006-1335.2014.01.023 Abstract ( )   PDF (1184KB) ( )   Related Articles | Metrics

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Comparison and Analysis of Vehicle’s Speed Selection Methods in Noise Prediction Models 2014, 34(1): 104-108.  DOI: 10.3969/j.issn.1006-1335.2014.01.024 Abstract ( )   PDF (1141KB) ( )   Taking several Shenzhen High-speed road, Expressway road and Main road traffic noise as the research object, use three different speed selection methods including the predictive speed, actual speed and design speed to comparison research with measured result and prediction result by the road traffic noise prediction model recommended “technical guidelines for environmental impact assessment of environmental noise”( HJ2.4-2009 ),in order to validate noise prediction model accuracy under different speed value methods. The research results can provide reference for the application of HJ2.4-2009 guideline noise prediction model. Related Articles | Metrics

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Simulation of Vibration of an Automobile Transmission Shaft  and Its Optimization 2014, 34(1): 109-112.  DOI: 10.3969/j.issn.1006-1335.2014.01.025 Abstract ( )   PDF (1308KB) ( )   During the design of Propeller Shaft, CAE method is used to simulate the mode and check the vibration. There is a Propeller Shaft that the first mode has met the target, but having resonance problem on full vehicle when test. In this paper, the CAE method was improved, and the structure was optimized to remove the problem mode. According to the test result and subject evaluation, a favorite effect was reached. Related Articles | Metrics

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Analysis of Three-dimensional Sound Field of  Automobile’s Exhaust Mufflers 2014, 34(1): 113-117.  Abstract ( )   PDF (1613KB) ( )   Three-dimensional finite element method is used to optimize the design for a vehicle exhaust muffler. Based on the transfer admittance theory, muffler perforated pipe and the perforated plate are processed. The numerical model is established and three-dimensional acoustic field of the primary and secondary mufflers are simulated and analyzed, then got their transmission loss; The Transmission loss of the primary and secondary mufflers are measured with the method of double load based on four microphone, the experiment results show that the Three-dimensional finite element method have high accuracy to predict the mufflers acoustic performance. According to the simulation results and principle of the muffler design, the primary muffler is optimized, which can improve the exhaust system acoustic performance, and make it meet the requirements of vehicle noise emission regulations. Related Articles | Metrics

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Evaluation of Noise Performance of Automobile’s Water Pumps 2014, 34(1): 118-122.  DOI: 10.3969/j.issn.1006-1335.2014.01.027 Abstract ( )   PDF (1343KB) ( )   Related Articles | Metrics

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Radiation Noise Analysis and Structure Optimization for an     Engine Oil Pan 2014, 34(1): 123-127.  DOI: 10.3969/j.issn.1006-1335.2014.01.028 Abstract ( )   PDF (2008KB) ( )   The radiated noise from oil pan surface was accounted for about 24% in the total engine, has become an important restrictive factor to reduce engine noise. In order to reduce radiated noise of the oil pan, the finite element model was established, the constraint mode was calculated, and unsubstantial place of oil pan was found; and then, the surface vibratory acceleration of oil pan was obtained by the excitation load from test, and on that basis, the total sound power level was calculated using the BEM method. According to the results, the structural optimization was done, and the levels of structure radiated noise of the oil pan were predicted. The results were compared with those of the original pan. It is found that after the improvement, the frequency of constraint mode was greatly increased, the modal shape also changes obviously, and the total sound power level was reduced by 1.83dB (A). Related Articles | Metrics

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Analysis of Vibration Characteristics of Linear Motor Suspension of Metro Vehicles 2014, 34(1): 128-131.  DOI: 10.3969/j.issn.1006-1335.2014.01.029 Abstract ( )   PDF (1853KB) ( )   Due to the linear motor vehicle motor suspension system has a special motor suspension structure, so it's vibration characteristics are different from the traditional motor suspension vehicle. In order to study the vibration characteristics of linear motor vehicle, we analyzed the positioning method from it's structure and it's vibration characteristics, then we studied the influence of it's structure to the bogie vibration characteristics and wheel/rail interaction, finally we introduced an innovative idea—underground linear motor initially. The result show that, the vertical and the horizontal vibration of the linear motor exist a certain degree of coupling, and the linear motor positioning structure has a great impact on the bogie vibration and wheel/rail interaction. Related Articles | Metrics

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Simulation of Influence of Road Roughness on Vehicle’s Ride Comfort Based on Inverse Discrete Fourier Transform 2014, 34(1): 132-136.  DOI: 10.3969/j.issn.1006-1335.2014.01.030 Abstract ( )   PDF (1337KB) ( )   By simulating the various levels of random road excitation and building a two-degree-freedom vehicle model, chassis vibration response can be used to evaluate ride comfort of tracked vehicle. The inverse discrete Fourier transform (IDFT) method is analyzed and designed to generate different road roughness based on road spectrum and has contrast research on this method’s feasibility. Tracked vehicle suspension model with two degree of freedom is constructed and system simulation model is built by Simulink software. After inputting different kinds of vehicle velocity and road roughness at the same time, the road stochastic excitation will have an influence on ride comfort of tracked vehicle. The results indicate that the improvement of the road roughness level and the speed will reduce the vehicle ride comfort. Related Articles | Metrics

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Simulation of the Impact of Different Precisions of Road Segmentation on Traffic Noise 2014, 34(1): 137-139.  DOI: 10.3969/j.issn.1006-1335.2014.01.031 Abstract ( )   PDF (1326KB) ( )   The standard ISO 9613-2 computational model of noise attenuation is used to simulate the noise distribution with different precisions of road segmentation. The simulation subject is Zhujiang New Town in Guangzhou. The traffic data of seven roads is monitored in Zhujiang New Town. For each road segmented precision, eight points are selected to measure the noise level for the error analysis. Both the noise level error and the calculation time are considered in the analysis. The results show that the center scanning angle, between 10 degree and 15 degree, for every receiver is appropriate for traffic noise simulation. Related Articles | Metrics

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Fast Modeling Method for Analyzing the Intensity of Road Traffic Noise Sources 2014, 34(1): 140-145.  DOI: 10.3969/j.issn.1006-1335.2014.01.032 Abstract ( )   PDF (1162KB) ( )   Abstract: Prediction of road traffic noise source is the key to road traffic noise prediction. Because the vehicle conditions and road conditions in China are different from those in foreign countries, the direct application of the foreign models in China will reduce its accuracy. It is very difficult to obtain local model because of the demanding experimental site and the huge demand of the number of samples. Besides, the model based on standard experiment may not be suitable to the complex urban traffic flow. This paper proposed a simple and rapid method to establish a model accords with the characteristics of the local urban transport, which calculates the noise of the observation points, and then determines the optimal model parameters by optimizing algorithm. This method inversed the equivalent sound level to obtain the single-car sound power level model, which not only contained a wealth of samples, but also saved the measuring time. In this paper, a model was established and validated based on actual measured traffic data in Beijing, and the results showed that this method was fast, easy and with high accuracy. Related Articles | Metrics

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Optimal Control of Structure-borne Noise Transmission of Residential Buildings 2014, 34(1): 146-149.  DOI: 10.3969/j.issn.1006-1335.2014.01.033 Abstract ( )   PDF (941KB) ( )   At present, the structure sound transmission problem caused by water pump room , distribution room and central air conditioning facilities , more and more attention is acquired by people. For the problem, this paper take distribution room as an example , the sound power of the three transmission way which are source structure sound, air transmission of sound, the sound hole diffraction is forecasted, and puts forward the design scheme of active vibration isolation for the nstructure sound management. To choose and optimization the design of the isolation system parameters and material, can make the structure sound transmission part of the noise reduce 14 ~ 20 dB. Related Articles | Metrics

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Intrinsic Structure Modeling and Target Recognition  for Impact Sounds 2014, 34(1): 150-154.  DOI: 10.3969/j.issn.1006-1335.2014.01.034 Abstract ( )   PDF (954KB) ( )   The statistical data-driven method is used to model the intrinsic structures of impact sounds. The essential features of single impact sound as well as ensembles of similar impact sounds are studied based on the temporal and spectral basis functions, respectively. The temporal and spectral features of sounds from the impacted cylinder hull and road vacancy examination are extracted and then used by a RBF-based classifier. It is shown from the experimental results that such feature extraction methods can achieve good classification performances for both types of sounds. Related Articles | Metrics

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Identification of steady sound source via moving microphone array 2014, 34(1): 155-159.  Abstract ( )   PDF (1809KB) ( )   The main disadvantages of beamforming technique are a poor spatial resolution at low frequency, and the spatial aliasing problem at high frequency, leading to the identification of false sources. For steady sound source, this paper introduces two kinds of microphone array moving methods, which include changing the position of the microphone array center and adjust the measurement distance to improve the resolution in low-frequency sound source identification, and rotating the array for multiple measurements to reducing the spatial aliasing problem in high-frequency sound source identification so as to achieve the goal of using less microphone to enhance the performance of sound source identification. The effectiveness of this method is verified by simulation and experiment. Related Articles | Metrics

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Fault Diagnosis of an Automobile’s Transmission Shaft Based on Second Order Cyclic Spectrum and Support Vector Machine 2014, 34(1): 160-163.  DOI: 10.3969/j.issn.1006-1335.2014.01.036 Abstract ( )   PDF (1084KB) ( )   According to the cyclic stationarity characteristics of the vibration signals from automobile transmission shaft with fault and the situation that it is hard to obtain enough fault samples, fault diagnosis method of transmission shaft based on second-order cyclic spectrum and support vector machine (SVM) was proposed. Firstly, the vibration signals of transmission shaft with imbalance fault were collected from the stimulant fault experiment of vehicle, and then modulation source was separated by calculating the second-order cyclic spectrum and scanning cyclic frequency. It turned up the value of cyclic spectrum in the half shaft frequency obviously increased along with the growing imbalance fault. Therefore, these amplitudes were selected as eigenvectors. Finally, with the help of SVM, the fault patterns were exactly identified. The results show that this method has high accuracy in fault diagnosis of transmission shaft in the case of a small quantity of samples. Related Articles | Metrics

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Feature Extraction Method of Seismic Signals Based on1(1/2) Dimensional Spectrum and Wavelet Packet Energy 2014, 34(1): 164-168.  DOI: 10.3969/j.issn.1006-1335.2014.01.037 Abstract ( )   PDF (1132KB) ( )   The features of vibration signals generated by ground moving targets are studied. Focusing on the actual situation of the overlapping of non-Stationary and non-Gaussian characteristics in vibration signals generated by vehicles (wheeled vehicles, tracked vehicles), the 1(1/2)-dimensional spectrum is studied and theoretically proved to be able to eliminate Gaussian white noise or colored noise in vehicle induced ground motion signals, and a feature extraction method combining the 1(1/2)-dimensional spectrum analysis and wavelet packet energy spectrum is proposed to distinguish different vehicle targets. The joint eigenvectors of 1(1/2)-dimensional spectrum and wavelet packet energy spectrum are first constructed in the time-frequency domain, and then an error training BP neural network pattern classifier is established to identify the two types of vehicle signal. The results of field experiments show that this method can effectively and accurately identify ground vibration signals. Related Articles | Metrics

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Application of Order Analysis Method to Diagnosis of Abnormal Noise of Starters 2014, 34(1): 169-172.  DOI: 10.3969/j.issn.1006-1335.2014.01.038 Abstract ( )   PDF (1353KB) ( )   The automobile starter stop process was observed, and the driving gear’s rotational speed as well as starter noise was experimentally analyzed. Measurement results were processed based on order analysis method, so that the characteristics of abnormal noise and the corresponding order were thus obtained. Furthermore, the measured starter’s structure was studied, and the conclusion was achieved that abnormal noise and armature slot number is closely related. Analysis indicates that the characteristics order that equals the product of slot number and reduction ratio contributes to the abnormal noise most obviously. Paper has offered theoretical foundation and operation method for reducing or eliminating starter abnormal noise and laid theoretical basis for improving the starter quality. Related Articles | Metrics

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Judging of the bearing weak fault signal based on the method of improved Duffing 2014, 34(1): 173-177.  Abstract ( )   PDF (1537KB) ( )   This paper analyse the lack of fundamental theory about traditional Duffing oscillator chaotic system in weak signal detection, and gives a new way based on improved Duffing oscillator in testing weak signal. The improved method can make up the limitation on the natural frequency in the teaditional way , it can test the weak signal with bigger natural frequency. This paper mainly use the traditional and improved way respectively to test the fault of the outer ring of bearing, the results show that the improved method can better find out the weak fault signal. The results from simulation signal analysis and bearing fault diagnosis experiments showed that the method purposed in the paper is effective. Related Articles | Metrics

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Application of EMD-Robust ICA to Noise Sources Identification of Diesel Engines 2014, 34(1): 178-182.  DOI: 10.3969/j.issn.1006-1335.2014.01.040 Abstract ( )   PDF (1252KB) ( )   The combination of empirical mode decomposition (EMD) and robust independent component analysis (RobustICA) is proposed to identify diesel engine noise sources from single-channel noise signal. Instinct mode functions (IMF) after correlation analysis integrated with original noise signal are used as virtual channels of RobustICA. With the advantages of RobustICA, single-channel observed noise signal can be separated into several original independent components without filtering processing. Separation result of simulated signals identified the effectiveness of the method proposed above. Applied to a four-cylinder-diesel-engine noise signal analysis, combustion noise and piston slap noise can be identified combined with Fast Fourier Transform (FFT), continuous wavelet transform (CWT) and priori knowledge of diesel engine. Related Articles | Metrics

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Identification of Inertia Parameters of a Commercial Vehicle’s Cab 2014, 34(1): 183-187.  DOI: 10.3969/j.issn.1006-1335.2014.01.041 Abstract ( )   PDF (982KB) ( )   Related Articles | Metrics

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Structure Optimization for a High-speed Rotating Scribing Knife Based on Noise Analysis and Evaluation 2014, 34(1): 188-190.  DOI: 10.3969/j.issn.1006-1335.2014.01.042 Abstract ( )   PDF (1052KB) ( )   For ultra high speed rotating scribing knife actual work problems of cutting noise problem, through the use INV3018G type vibration and control analysis instrument on the cutting wafer scribing knife structure experiment analysis, use change scribing knife process groove Angle α value, it is concluded that different angles corresponding speed spectrum diagram, and the application of statistical data chart through the analysis method for Angle and frequency spectrum peak for the corresponding axes draw the corresponding change to map, determine the process groove Angle α of the structure, it is concluded that the influence of the corresponding peak minimum that produces small noise results show that different process groove Angle α of high speed rotating scribing knife structure design has a certain significance. Related Articles | Metrics

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Experiment of Audition Compensation Performance of an Incus Driving Piezoelectric Vibrator in Human Temporal Bone 2014, 34(1): 191-195.  DOI: 10.3969/j.issn.1006-1335.2014.01.043 Abstract ( )   PDF (1613KB) ( )   Related Articles | Metrics

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Design of Testing System for Measurement of Sound Absorbing Properties of Porous Metallic Materials 2014, 34(1): 196-200.  DOI: 10.3969/j.issn.1006-1335.2014.01.044 Abstract ( )   PDF (1669KB) ( )   To study thoroughly acoustic properties of porous metal material, an impedance tube test system was developed for the measurement of sound absorbing properties of porous metals on the basis of two-microphone transfer function method. The designing process of the whole system was described in detail in this work and the detailed designing parameters are put forward. Further, a real measurement system is established based on the above-mentioned mechanism and its feasibility and stability are validated by means of the experimental comparison testing for a standard porous metallic sample. Finally, the source of error existing in this test system and corresponding correcting methods were analyzed and discussed also. The results in this work will lay an experimental foundation for future investigation of porous metal under extreme conditions. Related Articles | Metrics

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In-situ Measurement of Average Sound Absorption Coefficients in Cars Based on Sabin Principle 2014, 34(1): 201-204.  DOI: 10.3969/j.issn.1006-1335.2014.01.045 Abstract ( )   PDF (1527KB) ( )   In order to measure the average sound absorption coefficient of the interior trim materials in practical car effectively, further to evaluate and analyze the acoustical performance in car accurately, the in-suit measurement method of the average sound absorption coefficient in car based on Sabin principle was proposed and the corresponding process for measurement and calculation was given out in detail. On that basis, an experiment was conducted. Results show that this method is effective and practical and the average sound absorption coefficient in the car holds steady above 1250Hz, approximating to 0.33. Research results provide an effective method for the in-suit measurement of the average sound absorption coefficient in car and underlie the evaluation and analysis of the acoustical performance of the interior trim materials. Related Articles | Metrics

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Analytical Calculation of Sound Radiation for Underwater Laminated Composite Rectangular Plates 2014, 34(1): 205-210.  DOI: 10.3969/j.issn.1006-1335.2014.01.046 Abstract ( )   PDF (1073KB) ( )   Related Articles | Metrics

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Noise and Vibration Test of a Medical Oxygen Generator and Its Noise Reduction Design 2014, 34(1): 209-213.  DOI: 10.3969/j.issn.1006-1335.2014.01.047 Abstract ( )   PDF (1772KB) ( )   To reduce the operating noise of a medical oxygen generator, the shell’s vibration and the radiation noise are tested and analyzed in an experiment. The result show that shell’s vibration and air compression pump noise is the main source of the operating noise. In accordance with the transmission path of the oxygen generator structural vibration, the spring anti-vibration devices are installed between air pump and bottom plate, meanwhile, sound insulation materials are pasted on the internal surface of shell. After the implementation of the above measures, the operating noise of oxygen generator is reduced from 51.9dB(A) to 44.3dB(A). Related Articles | Metrics

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Noise Control at the Vents of Heat Pump Units of Bars 2014, 34(1): 213-218.  DOI: 10.3969/j.issn.1006-1335.2014.01.048 Abstract ( )   PDF (1113KB) ( )   The fans of heat pump units in the bars have big-air quantity. Strong noise with high dB value and wide frequency band is generated while the units are running. Except that, there are lots of sensitive points around the bars, so it’s difficult to achieve a good effect of noise reduction in a limited space. At present, most of projects make use of dissipative or single resistance - dissipative muffler to control the air-outlet noise in our country, but the results are not ideal. Combining with the engineering example, spectrum analysis and expansion muffler theory, putting three expansion chambers with different length and different expansion ratio in series (instead of single expansion chamber), and also using the dissipative muffler, a new type of dissipative - resistance muffler was designed in a limited space, which makes the air-outlet noise of heat pump units be reduced by about 18dB (A). This muffler is not only simple, economical, reliable and advanced, but also save space, so it has high practical value. Related Articles | Metrics