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


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2.振动理论与数值解法

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Discussion on Acoustical Prediction Formulas of Road Sound Barrier WANG Zuo-min 2012, 32(3): 1-6.  DOI: 10.3969/j.issn.1006-1355.2012.03.001 Abstract ( )   There is some strict boundedness in acoustical prediction formulas of sound barrier recommended by some documents. The boundedness will limit applicable range of these formulas. Therefore some suggestion was proposed to improve acoustical prediction formulas of road sound barrier. The suggestion includes: (1) A universal method was introduced using the image source and image receiver when a reflect ground was considered; (2) Several corresponding prediction formulas were made when the source and receiver all are near a rigid ground, and for pulse point source, the attenuation formula was represented separately to express attenuation limiting value in an actual barrier when Fresnel number N>10; (3) The reflect sound reformation of a double barrier also can be calculated using the image source method. The examples discussed in this paper not only prove that the suggestion is reasonable, but also provide some interested conclusion, such as (1) The reflect ground will increase sound pressure at a receiver, and decrease attenuation of barrier. When the source and receiver all are near a rigid ground, sound pressure at a receiver will increase 3 dB without a barrier, and 6 dB with a barrier, the attenuation of barrier will decrease 3 dB; (2) The reflect sound reformation of a double barrier almost are same with or without the reflect ground, and the reformation will decrease with increase of the absorption of barrier surface toward source. Related Articles | Metrics

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A New Parametric Time-frequency Analysis Method for Instantaneous Frequency Estimation of Polynomial Phase Signal FANG Yang;PENG Zhi-ke;MENG Guang;YANG Yang 2012, 32(3): 7-11.  DOI: 10.3969/j.issn.1006-1355.2012.03.002 Abstract ( )   Nonlinear chirplet transform, a new parametric method for time-frequency analysis was proposed by replacing the linear chirp kernel by a nonlinear polynomial kernel. By choosing the proper kernel characteristic parameters, the nonlinear chirplet transform can render a time frequency distribution of excellent concentration for signals whose instantaneous frequency trajectory is an arbitrary function of time. In this paper, the polynomial chirplet transform was applied to estimate the polynomial phase signals with arbitrary order. As the performance of the nonlinear chirplet transform highly depends on the kernel characteristic parameters, an algorithm to evaluate these parameters was developed in order to estimate the instantaneous frequency and the phase parameters of the polynomial phase signal. The effectiveness of the algorithm was validated by analyzing the signals from numerical simulation. Related Articles | Metrics

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Interval Analysis for Intrinsic Frequency and Decoupling Ratio of Powertrain Mounting Systems WU Jie;; LIU Yu-bo 2012, 32(3): 12-15.  DOI: 10.3969/j.issn.1006-1355.2012.03.003 Abstract ( )   The mounting stiffness of powertrain mounting system (PMS) of vehicles has some uncertainty in the process of manufacturing, installation and vehicle operation, therefore the PMS frequency and decoupling ratio are also uncertain. To investigate the variation characteristics of the frequencies and decoupling ratios, an interval analysis method was proposed. In the case that the range of the mounting stiffness variation is known while its stochastic characteristics are unknown, the interval number in interval mathematics can be employed to describe the uncertainty of the mount stiffness variation. The variation range of the intrinsic frequencies and the decoupling ratios of the PMS were calculated accurately with the application of the combination method. The interval reliability formula was given to describe the robustness of the frequencies and decoupling ratios. The interval reliabilities of frequencies and decoupling ratios in the vertical and pitch directions were calculated. Computational results show that the mount stiffness parameters need to be optimized in order to increase the interval reliabilities of the frequencies and the decoupling ratios in vertical and pitch directions. Related Articles | Metrics

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Nonlinear Finite Element Analysis for Stiffness Characteristic, Contact and Friction of a Leaf Spring FAN Cui-lian; LI Shun-ming; ZHANG Yuan-yuan 2012, 32(3): 16-20.  DOI: 10.3969/j.issn.1006-1355.2012.03.004 Abstract ( )   It is difficult to establish a precise physical model for simulation of traditional leaf spring. In this paper the physical model of a leaf spring was built with some nonlinear effects, such as large deformation, interleaf friction and contact, considered simultaneously. The method for analyzing the distributions of contact pressure and friction in the contact interface between the adjacent leaves was put forward. The deformation, Von Mises equivalent stress, and contact and friction forces were determined for different friction coefficients and loads, and their influences on mechanics characteristics of the leaf spring were studied. The relation of contact pressures, friction stress and contact stress in the contact interfaces of the leaves was studied. The paper provides a reference for studying the nonlinear states between the adjacent leaves in the leaf spring. Related Articles | Metrics

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Optimal Control Analysis of Self-excited Oscillation of an Inclined Taut Cable under Wind Loading ZHANG Wei; YING Zu-guang; WANG Jian-wen 2012, 32(3): 21-24.  DOI: 10.3969/j.issn.1006-1355.2012.03.005 Abstract ( )   The optimal control of self-excited oscillation of an inclined taut cable with multi-modes under wind loading is studied. The nonlinear equations of motion are derived for the cable with control and wind forces. The partial differential equation for transverse cable vibration is obtained and converted into ordinary differential equations by using the Galerkin method, that describe the self-excited oscillation of the multi-mode system. Then based on the dynamical programming principle, the HJB equation is established and the optimal nonlinear control force is determined. The analytical solutions of the controlled system in self-excited oscillation are obtained by using the averaging method. The analytical and numerical results show that the proposed control can effectively suppress the self-excited oscillation of the cable. Related Articles | Metrics

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Steady-state Analysis of Forced Transverse Vibration for an Axially Moving Beam at High-speed SHAO Wen-yun; ZHANG Guo-ce; WANG Zhi-feng 2012, 32(3): 25-28.  DOI: 10.3969/j.issn.1006-1355.2012.03.006 Abstract ( )   The steady-state periodic response of transversely forced vibration of a simply supported viscoelastic beam moving axially at the supercritical speed was investigated. It was assumed that the external excitation is spatially uniform and temporally harmonic. Based on the coordinate transform, a nonlinear integro-partial-differential equation governing the small transverse vibration of the beam was constituted by the Kelvin model. The first two resonances were analyzed via the 8-term Galerkin truncation method. Based on the Galerkin truncation, the finite difference schemes were developed to compute the stable steady-state response. Numerical simulations display that the resonance occurs if the load frequency approaches any natural frequency in the supercritical speed range. Related Articles | Metrics

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Nonlinear Flutter Characteristic Analysis of the Hypersonic Wings LUO Qing;LI Dong-xu;NIE Hai-tao;ZHOU Yi;ZHANG Yi-ming 2012, 32(3): 29-33.  DOI: 10.3969/j.issn.1006-1355.2012.03.007 Abstract ( )   The dynamic equation of a 2-dimentional hypersonic wing was derived by using the modified third order nonlinear piston theory. Both linear and nonlinear flutter boundary conditions were obtained through Hopf-bifurcation theory and directive numerical method respectively. The simulation results show that the effects of nonlinearities can delay or precede the appearance of limit cycles oscillations according to the system parameters. Related Articles | Metrics

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Vibration Analysis of Rectangular Plates with Fractional Derivative Viscoelastic Model ZHANG Ya-peng;; GAO Feng; 2012, 32(3): 34-36.  DOI: 10.3969/j.issn.1006-1355.2012.03.008 Abstract ( )   Dynamic equations of rectangular thin plates based on fractional-order Kevin viscoelastic model were established. The analytical solution of the dynamic equations for a viscoelastic plate with four edges simply supported was obtained by using Laplace transform and inverter Laplace transform. The influences of the fractional order parameter, viscosity parameters and modulus parameters on the deflection of the fractional-order Kevin viscoelastic model with constant load were analyzed. The results show that the deflection of the viscoelastic plates decreases with the increasing of the viscosity parameters, while the deflection of the viscoelastic plates increases with the increasing of the modulus parameters. Related Articles | Metrics

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Modeling and Analysis for Reaction Wheel Model of Space Probe SHEN Hai-jun;DU Sheng;ZHOU Xu-bin;DU Dong; 2012, 32(3): 37-40.  DOI: 10.3969/j.issn.1006-1355.2012.03.009 Abstract ( )   Aiming at the static unbalance problem of reaction wheel equipped in space probe, a simple model was established to calculate the influence of the unbalance force on the flexible setting plate. Several existing simulation methods were introduced to simulate the static unbalance of the reaction wheel by using Adams and Patran. The result of the simulation was compared with the theoretical one to validate the veracity of this simulation method. Related Articles | Metrics

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Numerical Simulation and Analysis of Vibration Characteristics for Diesel Engine Exhaust System LU Hong-wei;JI Zhen-lin;MENG Rui-xue 2012, 32(3): 41-44.  DOI: 10.3969/j.issn.1006-1355.2012.03.010 Abstract ( )   The software Pro/E was employed to build the 3-D model of a diesel engine’s exhaust system. The software HyperMesh was used to create the FEM mesh, and then the FEM mesh data was input into the finite element software ANSYS for simulation to obtain the modal characteristics of the exhaust system. On this basis, the harmonic response analysis was performed for analyzing the diesel engine’s excitation force and the vibration of the exhaust system. Finally, the vibration isolation effect of metal bellows on the exhaust system was evaluated. Related Articles | Metrics

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Modeling and Parameters Optimization of n -Grade Tuned Mass Dampers DAI Lin;SHANGGUAN Wen-bin;ZHANG Shao-fei 2012, 32(3): 45-48.  DOI: 10.3969/j.issn.1006-1355.2012.03.011 Abstract ( )   A universal formula for optimal control performance of n-grade tuned mass dampers is established. At first, two optimization methods, including fixed point method and numerical method, were described. Then, a general-purpose optimization program was developed using MATLAB code. The optimized parameters of different type of tuned mass dampers were calculated using the program for a main system of single degree of freedom. The results indicate that the optimized tuned mass dampers can suppress the vibration of the main system effectively. The optimal methods and some conclusions presented in this paper are useful for tuned mass damper design. Related Articles | Metrics

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Application of Active Adaptive Vibration Absorbers in Floating Raft System SONG Gang;CHEN Wei-dong 2012, 32(3): 49-54.  DOI: 10.3969/j.issn.1006-1355.2012.03.012 Abstract ( )   The floating raft system with active-adaptive vibration absorbers (AAVAs) was studied. The dynamic models of the system with combined excitation were implemented by assembling the mobility matrices of the subsystems. Then the power flow expressions of this system with/without AAVAs were obtained. Considering the power flow transmitted into the foundation as the cost function, the effects of different control strategies under the single- frequency excitation were studied and compared. Numerical simulation results show that the total power-flow-minimization control strategy is much better than the others. It can achieve effective broad-band vibration absorption and reduce the power flow transmitted into the foundation significantly. The axial-force-minimization control strategy can produce good results at low frequencies, while the axial-velocity-minimization control strategy can produce good results at intermediate frequencies. Finally, adopting the total power-flow-minimization control strategy, the vibration reduction effect of AAVAs under multi-frequency excitation was verified. Related Articles | Metrics

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Effects of Viscoelastic Dampers on Vibration Fatigue Behavior of Steel Trusses SUN Tian-fu;LIN Gao;LI Jian-bo;YU Ya-xin 2012, 32(3): 55-58.  DOI: 10.3969/j.issn.1006-1355.2012.03.013 Abstract ( )   In order to study the effects of viscoelastic dampers on fatigue behavior of steel trusses, the equivalent stiffness of viscoelastic dampers was derived. Based on random load, and according to load’s power spectral density（PSD）, structure’s frequency response and the structure’s modal, the fatigue behavior of the steel trusses were calculated and compared. These working conditions included that there was no viscoelastic damper added to the structure and that there were viscoelastic dampers with different damping coefficients respectively added to the structure. The result indicates that viscoelastic dampers can extend the structure’s fatigue lifespan efficiently. It is found that with the increase of the damping coefficient, the structure’s fatigue lifespan increases at first and decreases thereafter. Therefore structure’s fatigue resistant ability can be optimized through the best choice of the damping coefficients. Related Articles | Metrics

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Numerical-axis Method for Establishing the Mathematical Model of Mass-spring-damper System BAI Yan-yan;ZHANG Xiao-jun 2012, 32(3): 59-62.  DOI: 10.3969/j.issn.1006-1355.2012.03.014 Abstract ( )   A simple method called Numerical-Axis-Method for establishing the mathematical models of the common mass-spring-damper systems was put forward. In establishing the mathematical model, a numerical-axis parallel to the system was built, and the displacements of the spring or the damper were translated to the rational numbers which were marked on the numerical-axis. Then the magnitude and the direction of spring force or damping force applied to the corresponding mass was determined by comparing the two rational numbers mutually. The application of this method on establishing the mathematical models of mechanical vibration systems was expatiated through a single degree-of-freedom (DOF) system, a double DOF system and a multi-DOF system. The results show that this method was very efficient in establishing the kinematic differential equations of the mass-spring-damper systems. Related Articles | Metrics

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Shock Characteristics of Tilted Support Spring System with Critical Components under the Action of Semi-sinusoid Pulse CHEN An-jun; 2012, 32(3): 63-66.  DOI: 10.3969/j.issn.1006-1355.2012.03.015 Abstract ( )   The nonlinear dynamical equations of tilted support spring system with critical components were established under the action of semi-sinusoidal pulse, and the equations were solved using Runge-Kutta method. The shock response characteristics of the critical components were obtained and analyzed. To evaluate the shock, a new concept of shock response spectra was proposed. The ratio of the maximum shock response acceleration of the critical components to the peak pulse acceleration and the dimensionless pulse duration were employed as the basic parameters of the shock response spectra. Based on the numerical results, the effects of the peak pulse acceleration, the dimensionless pulse duration, the angle of the tilted support spring and the frequency ratio of the system on the shock response were discussed. It is shown that the effects of the angle of the tilted support spring and the frequency ratio of the system are particularly noticeable. By increasing frequency ratio of the system, the maximum shock response acceleration of the critical components can be obviously decreased, while the peak of the shock response of the critical components can be decreased by increasing mass ratio at low frequency ratio. Related Articles | Metrics

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Study on the Effects of Longitudinal Resonance on the Dynamic Instability of Beams by Quasi-wavelet Method SONG Zhi-wei;LI Wei;QU Hong-fei 2012, 32(3): 67-71.  DOI: 10.3969/j.issn.1006-1355.2012.03.016 Abstract ( )   The quasi-wavelet method to solve the dynamic response of beams was proposed. Then the method is used for studying the effects of longitudinal resonance on the dynamic stability with the damping effect taken into account. The study shows the longitudinal resonance can lead to a serious dynamic instability, while the damping can improve the stability effectively. These conclusions are coincident with the existing conclusions well. Hence, the feasibility and effectiveness of the quasi-wavelet method is verified. Related Articles | Metrics

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Application of Continuous Wavelet Transform in Intensive Operational Modal Parameter Identification DENG Xian-lai;JI Guo-yi 2012, 32(3): 72-77.  DOI: 10.3969/j.issn.1006-1355.2012.03.017 Abstract ( )   To study the effects of the wavelet transform in intensive operational modal parameter identification, a mode system with three degrees of freedom containing two intensive frequencies was established. Applying narrow-band white noise excitation and using the improved Morlet wavelet as the continuous wavelet transform base function, the modal parameter identification of this system was simulated. It was found that reducing bandwidth can improve the frequency resolution effect and decouple the dense modals when applying the continuous wavelet transform method to modal parameter identification. However, it also exacerbated the problem of edge effect which can reduce the accuracy for the dense modal recognition. In order to suppress the edge effect, the length of the useful part of the transformation signal was extended by using the SVM technique. Simulation results show that the better recognition accuracy can be obtained with this method. Finally, through identifying the first two modal parameters of a grinder mill, the feasibility and effectiveness of the method were verified. Related Articles | Metrics

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Experimental Study on Admittance Performance of Rails in Ballastless Railroad LIU Zhen;LIU Lin-ya 2012, 32(3): 78-81.  DOI: 10.3969/j.issn.1006-1355.2012.03.018 Abstract ( )   In order to study the vibration characteristics of rails in ballastless railroad, a P60 typical rail with unit length was tested with the impulse hammering excitation method. The force and acceleration responses of the rail were measured, and the frequency response was obtained by analyzing the rail admittance using DASP software. The frequency response graph of acceleration admittance was plotted. The vibration characteristics below 10000Hz frequency of the rail-top, the rail head side and the rail waist at the midpoint of the rail-specimen were given. The results show that the vibration response of the rail- waist at the midpoint of the rail specimen decreases gradually when the location of excitation translates from the midpoint to both ends of the rail. Since track admittance analysis is the basis of noise analysis, and is helpful for detecting the location and mechanism of noise sources, these results may provide the experimental data for theoretical analysis of the high-frequency admittance performance of the rail in ballastless railroads and the determination of the frequency-range for noise reduction and the location of the noise sources. Related Articles | Metrics

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Dynamic Test and Structural Modification for Bench Drilling Machine WANG Cheng-rong;LI Gong-yu;ZHAO Xiao-yun;RUAN Chong-sheng 2012, 32(3): 82-85.  DOI: 10.3969/j.issn.1006-1355.2012.03.019 Abstract ( )   The dynamic characteristic testing for Z4113 bench drilling machine was carried out with the LMS Test.lab acoustic vibration testing system. The structural weakening of the machine was recognized by using the Nyquist stability criterion in system analysis. Finally the dynamic modification of the machine was discussed. Related Articles | Metrics

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Analysis of Influence of the Moment of Inertia of the Roller on Coal Mining Machine’s Vibration Using Lab VIEW KANG Wen-long;LI Lin-lin 2012, 32(3): 86-89.  DOI: 10.3969/j.issn.1006-1355.2012.03.020 Abstract ( )   When the coal mining machine is working，the diameter of the roller is generally given, but its mass-moment of inertia is adjustable. By changing the thickness of the tube hub and the blade, the mass-moment of inertia of the roller will increase and the roller can store energy just like a flying wheel, maintain the stable rotation, and reduce the vibration of the machine. Using the LabVIEW platform and the data acquisition card, the change of the vibration amplitude was quantified with the known mass and the increment of the mass-moment of inertia of the roller. The influence of the mass-moment of inertia on the amplitude was tested. It was found that when the moment of inertia is increased by 11 %, the amplitude can be reduced by 9 %; and when the mass-moment of inertia is increased by 23 %, the amplitude can be reduced by 11 %. This finding may have practical significance in the roller’s design for maintaining the stability of coal mining machine’s operation. Related Articles | Metrics

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Low-noise Design for Engine Oil Pan WANG Qi-wen;HAO Zhi-yong 2012, 32(3): 90-93.  DOI: 10.3969/j.issn.1006-1355.2012.03.021 Abstract ( )   The FE model for a cast aluminum?oil pan was built. The modals of free vibration, the surface vibration and radiation noise if the pan were calculated using the combination of FEM and BEM method. The surface vibration velocity and the total sound power level were obtained. Then, the side face of the oil pan was reinforced and the shape of its bottom was improved, and the levels of structure vibration and radiation 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 free vibration is greatly increased, the vibration mode also changes obviously, the vibration amplitude is decreased, and the total sound power level is reduced by 3.1 dB. Related Articles | Metrics

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Quantitative Research for Gear Accuracy and the Control of Transmission Gear whine ZHOU Yi;ZENG Yi-fan;WANG Ze-gui 2012, 32(3): 94-98.  DOI: 10.3969/j.issn.1006-1355.2012.03.022 Abstract ( )   Gear’s accuracy has important impact on transmission gear whine. Hence, improving gear’s accuracy is an important approach to reduce the whine noise. In this paper, the final gear in 452AMT transmission was taken as a research object. The traditional shaving process was replaced by the grinding after heat treatment. Then, the gear accuracy was raised by 3 grades, and the RMS deviation of normal distribution for gear’s micro-geometry was raised by 1 time. The requirement of design was met. Finally, the comparative analysis of single-factor with orthogonal tests was done for the vibrations of 5 transmissions on EOL and the NVH performance testing of 2 transmissions of the vehicle. It was found that the amplitude of transmission housing’s vibration was decreased by 1/2 time, and the gear whine of final gear pair’s meshing order in compartment was decrease by 3 dB (A) and 6 dB (A) respectively at WOT and coast statues. This research reveals the mechanism for the impact of gear’s accuracy on the transmission gear’s whine. Related Articles | Metrics

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Control Spillover and Control Model of the decoupling of the Active Structural Acoustic Control based on the theory of Radiation Modes 2012, 32(3): 99-103.  Abstract ( )   In this paper, in the perspective of four kinds of symmetric forms of the acoustic radiation modes, the control characteristics of each group of actuators to adjoint coefficients of the acoustic radiation modes (1～8 order) are discussed based on the decoupling theories of Active Structural Acoustic Control and acoustic radiation modes. The analyses with control spillover of the decoupling of the Active Structural Acoustic Control based on the theory of radiation modes are conducted. Combining with the control characteristics of the four groups of actuators above, the sound power radiated from the first eight acoustic radiation modals is divided into four groups of modal acoustic power and a new model for the active control to restrain control spillover in the middle frequency effectively is presented. The simulation results demonstrate that a new control model not only maintain the good control effects at the low frequency range, but also avoid control spillover at the middle frequency range. Finally, the expected effect of the active control at 0 ～1000 Hz frequency range is realized. Related Articles | Metrics

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Study on Radiation Acoustic Field due to Cavitation Bubble near Rigid Wall ZHANG Peng-li;LIN Shu-yu;ZHANG Hai-juan;ZHANG Tao 2012, 32(3): 104-107.  DOI: 10.3969/j.issn.1006-1355.2012.03.024 Abstract ( )   The radiation acoustic field due to cavitation bubbles collapse near the rigid wall was studied. And the sound pressure distribution of the radiation field due to a single bubble and double bubbles near the rigid wall was obtained. This study shows that due to the impact of rigid wall the acoustic radiation of cavitation bubbles becomes some directional. The distribution of radiation pressure by double bubbles depends on the bubbles’ collapse time, the distance between bubbles, and the initial radius of the cavitation bubbles. Considering the phase superposition of sound pressures, radiation pressure at the measurement points depends on sound pressure amplitude p of the bubbles, and the sound path difference of the two bubbles to the observation point, [Δ1=l12sinθ1] and [Δ2=l22sinθ2]. This computation process and result may provide some basis for the cavitation calculation near the rigid wall, and a theoretical basis for radiation sound field analysis of multi-bubble cavitation. It is also helpful for improvement of kinematic equations of cavitation bubbles. Related Articles | Metrics

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Suppression of Peak Noise Indueced by Time Delay of the Anti-noise Source YAO Jia-fei;LU Ping 2012, 32(3): 108-112.  DOI: 10.3969/j.issn.1006-1355.2012.03.025 Abstract ( )   Aiming at the peak noise induced by the time delay of the anti-noise source, the noise reduction effect and peak noise generation of periodic signals and random signals with different frequencies and different signal superimposed analog delay were analyzed. The peak noise induced by time-delay was processed. A kind of peak noise suppression strategy based on the fuzzy inhibit active noise control was proposed. Its effect for peak noise reduction was verified by the simulation result. Related Articles | Metrics

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Acoustic Characteristics of the Throat of the Low-frequency Airflow Modulator within Closed Space DONG Ming-rong;CHEN Ke-an;SUN De-yu;FANG Hou-lin 2012, 32(3): 113-117.  DOI: 10.3969/j.issn.1006-1355.2012.03.026 Abstract ( )   The gas chamber pressure, throat flow rate and the acoustic characteristics of an airflow modulator were analyzed by using the theory of fluid mechanics and aeroacoustics. The computation results are compared with the experimental results. The changes of the throat acoustic amplitude with gas supply pressure, gas supply flow rate and working frequencies were given. The results show that the computation results can agree with the experimental results, and the throat acoustic amplitude can be improved with the increase of the gas supply pressure and flow rate. Related Articles | Metrics

3.运载工具振动与噪声

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Noise Source Identification of Mining Vehicle's Cabin MA Yan;CHEN Jian;YUAN Zheng 2012, 32(3): 118-120.  DOI: 10.3969/j.issn.1006-1355.2012.03.027 Abstract ( )   The noise in cabin of a domestic mining vehicle was far beyond the industry standard. Thus, according to the standard, the noise and vibration testing of the cabin was conducted. Utilizing the spectrum analysis, order tracking technique and theoretical analysis, the main noise sources and their frequency characteristics were identified. Some effective improvement strategies were proposed. Through the comparative analysis of the testing data of the improvement strategies, the correctness of the noise source identification methods were verified. The result of analysis provides a reference for the noise control of mining vehicles. Related Articles | Metrics

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Optimization Method for Powertrain Mounting Systems Considering the Errors in Inertia Properties Testing HOU Wei-chun;WU Jie 2012, 32(3): 121-124.  DOI: 10.3969/j.issn.1006-1355.2012.03.028 Abstract ( )   Generally, the inertia properties of a powertrain mounting system (PMS) are determined by measuring, and the measurement error is less than 3 %. The PMS frequency and decoupling ratio are closely related to the inertia properties, mount stiffness, and mount position, thus the actual PMS frequency and decoupling ratio will not be consistent with their designed values. In this paper, the inertia properties were described with uniformly distributed random variables, the mount stiffness parameters were selected as design variables, and a robust optimization method was presented in order to desensitize the PMS frequency and decoupling ratio to the inertia properties. The optimization results of a transversely mounted PMS show that the robustness of the frequency, decoupling ratio, and frequency separation can be effectively improved compared with that of the traditional deterministic optimization method. Related Articles | Metrics

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Finite Element Analysis of the Control Arm beneath Vehicle’s Suspension HE Xiaojing;SHANGGUAN Wen-bin 2012, 32(3): 125-128.  DOI: 10.3969/j.issn.1006-1355.2012.03.029 Abstract ( )   The finite element model of lower control arm beneath vehicle’s suspension was established. In static analysis of the model, inertia relief principle was introduced to eliminate the stress concentration effect of the constraint reaction force on the structural strength of the control arm. In this method, the acceleration due to the unbalanced loads was calculated. The static stiffness properties of the control arm were analyzed. The breaking load and buckling load of the suspension control arm under the conditions of tension and compression were calculated respectively. The results demonstrate that the static stiffness and strength characteristics of the control arm can meet the design requirements. Related Articles | Metrics

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Noise Simulation and Optimization of Automotive’s Intake System SHI Yan;ZHANG Jian-ping;LIU Peng 2012, 32(3): 129-132.  DOI: 10.3969/j.issn.1006-1355.2012.03.030 Abstract ( )   Intake system of engine is one of the main noise sources of an automobile. In this paper, the acoustic transmission loss of the engine intake system was simulated by CAE, and the defects in its noise silencing were found. With the use of perforated muffler, the intake system was optimized. The defects in the noise silencing were removed and a favorite effect was reached. Related Articles | Metrics

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Modeling and Analysis of Inner Noise of Vehicle’s Cab QIU Tao;JIANG Wei;LI Xiao-ping 2012, 32(3): 133-138.  DOI: 10.3969/j.issn.1006-1355.2012.03.031 Abstract ( )   The internal noise in vehicle’s cab is one of the important criteria for riding comfort. Considering the outside noise and the suspension vibration, the acoustic-vibration coupled finite element model of the cab of a cement mixer was built. With the finite element analysis, the noise sensitivities to the excitation sources and the sound absorption parameters of the cab panels were researched. Some improvements were proposed to reduce the noise inside the cab based on the simulation results. After the improvements, the model was simulated again, and the simulation results were found to be in good agreement with those by experiments. The noise abatement is noticeably reduced about 3dBA, and the low frequency noise is also suppressed. These results indicate that the finite element model is accurate, and the improvements for noise reduction are effective. Related Articles | Metrics

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Analysis of Interior Noise in a Cab and Noise Reduction with Damping BAI Song;XU Xin-xi;REN Xu-dong;TAN Shu-lin 2012, 32(3): 139-142.  DOI: 10.3969/j.issn.1006-1355.2012.03.032 Abstract ( )   The sound-structure coupled finite element model and the acoustic boundary element model of a cab were presented by applying ANSYS and SYSNOISE codes respectively. Vibration of panels under the specified condition and sound pressure level at driver’s right ear was computed. According to the results, panel’s acoustic contribution was analyzed and the panels which have important contribution to the sound pressure at the driver’s right ear were confirmed. Applying the asphalt damping materials to the panels, the noise at driver’s right ear was effectively reduced. Related Articles | Metrics

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Experimental Verification for the Properties of Fiber Glass Applied in Automotive’s Exhaust Silencer ZHU Lian-jie;ZHANG Hong-bo;ZHANG Liang;HAO Yu-cai;HOU Jian-zhang;QIU Qun-lin 2012, 32(3): 143-146.  DOI: 10.3969/j.issn.1006-1355.2012.03.033 Abstract ( )   Fiber glass has been widely used for automotive exhaust muffler to achieve good performance of noise reduction from the middle to the high frequency range. In this paper, the classification of the raw material and component of domestic fiber glass was studied experimentally. The results indicated that the domestic fiber glass can completely meet the requirements of acoustic attenuation performance. Related Articles | Metrics

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Design and Appraisal of Acoustics Laboratory for NVH Performance Test of Vehicle’s Alternators XIN Yang;DONG Da-wei;YAN Bing;ZHANG Sheng-jie 2012, 32(3): 147-151.  DOI: 10.3969/j.issn.1006-1355.2012.03.034 Abstract ( )   Aiming at the requirement of NVH performance test of vehicle alternators, a special acoustics laboratory was built. This laboratory was divided into test room and control room by an acoustic wall. It was designed in the light of GB/T 3767-1996 “Acoustics-Determination of sound power levels of noise sources using sound pressure-Engineering method in an essentially free field over a reflecting plane” and the test requirements of relevant enterprises. After the completion of the laboratory, it passed the appraisal of National Institute of Measurement and Testing Technology, and its respective indicators met the design requirements. Related Articles | Metrics

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Test and Analysis of Environmental Vibration of Weinan North Elevated Station of Zhengzhou-Xi’an High-speed Railway HE Yu-long;XIANG Yi 2012, 32(3): 152-154.  DOI: 10.3969/j.issn.1006-1355.2012.03.035 Abstract ( )   Vibration is one of main forms of the environmental pollutions of elevated station for high-speed railway. In order to investigate the environmental vibration level of elevated station of high-speed train at 300 km/h in operation, the environmental vibration were tested and preliminarily analyzed in four different positions in and near Weinan north elevated station of Zhengzhou-Xi’an high-speed railway, which is the first elevated station in operation for high-speed railway in China. The result shows that the vibration level in the vertical direction is much higher than the vibration level in the horizontal direction, and the vibration level in the station hall is much lower than that of viaduct bridge outside the station. The vibration reduction measures of Weinan north elevated station are very effective. Related Articles | Metrics

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Analysis of Vibration and Acoustic Radiation of Submarine Hull Induced by Longitudinal Vibration of Propulsion Shafting ZHANG Gan-bo;ZHAO Yao 2012, 32(3): 155-158.  DOI: 10.3969/j.issn.1006-1355.2012.03.036 Abstract ( )   The pulsatile thrust of propeller induced by asymmetrical wake field can cause longitudinal vibration of the propulsion shafting. The vibration will transmit through the shafting, thrust bearing and foundation to the submarine hull, and induce the low frequency underwater acoustic radiation of the hull. Considering the coupled effect of shafting, foundation and the hull, the structural model of the propulsion shafting was established. The propulsion shafting – submarine hull coupled vibration was analyzed, and the acoustic radiation field of the hull was calculated by FEM/BEM based on the mode superposition method. The results show that the longitudinal vibration mode is one of main modes which participates the acoustic radiation. By instilling a dynamic vibration absorber between the thrust bearing and its foundation, the transmission of longitudinal vibration to the hull can be decreased. The acoustic radiation of hull induced by longitudinal vibration of propulsion shafting can be controlled. Related Articles | Metrics

4.环境振动与环境声学

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Prediction and Assessment of Traffic Noise for New Campus RUAN Xue-yun;; LI Zhi-yuan; WEI Hao-zheng 2012, 32(3): 159-162.  DOI: 10.3969/j.issn.1006-1355.2012.03.037 Abstract ( )   Traffic noise is the main noise factors of university campuses, especially for the new campuses which have internal roads beneath the ground. In this paper, the method of noise prediction was used to predict and assess the noise level of the new campus of Anhui University of Science and Technology so as to provide the corresponding database and technical support for the environment planning. By measuring the traffic flow and traffic noise of different types of motor vehicles in the old campus, the traffic noise prediction model of the new campus was built through the noise prediction software Cadna/A. Then the noise distribution diagram was drawn and the corresponding noise control measures were proposed. The result shows that the noise level of the campus can meet the noise standards of domestic first-grade area by constructing enclosing wall around the campus and setting the noise barrier around the internal north-south road beneath the ground. Related Articles | Metrics

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Design of Sound Absorber of Urban Rail way Station and Its Performance Testing XU Wen-jun;LI Shuang 2012, 32(3): 163-165.  DOI: 10.3969/j.issn.1006-1355.2012.03.038 Abstract ( )   Based on the structural and noise characteristics of urban railway stations, a sound absorber with wooden cavity structure was designed and 1/4 wavelength sound tube was installed in the absorber to increase its absorption capacity for the noises of middle and low frequencies. The Impulse Response Method (IRM) with single microphone was used to test the sound absorber’s absorption coefficient. The result shows that absorption capacity of the absorber for the noise of low and middle frequencies is greatly enhanced after the cavity and sound tube have been placed in. The sound fields of an urban rail transit station before and after sound absorber installation was calculated respectively by means of the software ANSYS and SYSNOISE. The results show that sound pressure of waiting point on the platform can be reduced by 2 -5 dB. Related Articles | Metrics

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Locating of Airport Noise Monitoring Points Based on Minimum Vertex Cover Model of Single Aircraft Noise Event DING Wen-ting;XU Tao;;YANG Guo-qing 2012, 32(3): 166-170.  DOI: 10.3969/j.issn.1006-1355.2012.03.039 Abstract ( )   In order to monitor and analyze the noise pollution around a small and medium scale airport, a locating method of airport noise monitoring points based on minimum vertex cover model of single aircraft noise event was proposed. First of all, a large number of grid points constituting the vertex set were assumed as candidate monitoring points. The INM noise prediction software was used to calculate the noise values of these vertices when each event happened. According to the noise threshold of single event, one could determine whether a vertex monitors the event or not. Then the minimum vertex cover model could be established. After that, the minimum number of vertices which cover all noise events could be obtained by employing the improved greedy algorithm. Experimental results show that the improved greedy algorithm is better than traditional greedy algorithm. It needs less monitoring points for covering all noise events. Related Articles | Metrics

6.信号处理与故障诊断

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Fault Diagnosis of Rotor System Based on EMD-Fuzzy Entropy and SVM WANG Lei;JI Guo-yi 2012, 32(3): 171-176.  DOI: 10.3969/j.issn.1006-1355.2012.03.040 Abstract ( )   A comprehensive fault diagnosis method combining Empirical Mode Decomposition (EMD) with Fuzzy Entropy and Support Vector Machine (SVM) for rotor system was proposed. Firstly, the fault signal of the rotor system was decomposed with EMD method into a number of intrinsic mode functions (IMFs), and a method for canceling pseudo mode function in EMD was presented based on energy conservation law. Then as the fact that Fuzzy Entropy can express the complexity of signal and has relative stability, the fuzzy entropies of the first four IMFs were taken as eigenvectors of fault signals. Finally, the eigenvectors were put into SVM to distinguish the faults of the rotor system. The result indicates that this method can effectively extract fault characteristics and diagnose the fault of the rotor system. Related Articles | Metrics

7.减振降噪设备和器材

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Analysis and Design Optimization of Porous Materials for Sound Absorption CHEN Wen-jiong;LIU Shu-tian 2012, 32(3): 177-182.  DOI: 10.3969/j.issn.1006-1355.2012.03.041 Abstract ( )   Sound absorption performance of porous materials is closely related to materials properties, size and shape of the hole and pore-distribution mode. It is significant to research and design porous materials for high sound-absorbing performance. In this paper, the relations between sound energy absorption rate and size and porosity of the materials were presented by studying sound propagation characteristics of porous metallic materials and structures based on surface impedance method and transfer matrix method. Then, an optimization problem was proposed and solved. In the optimization, sound energy absorption rate of the porous structure under a specific frequency was taken as an objective function, and the change rule of the size of cylindrical holes across material thickness was taken as the design parameter. Finally, a gradient porous structure with higher sound energy absorption rate was given through the optimizing design. Related Articles | Metrics

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Numerical Simulation and Analysis of Temperature Field in Exhaust Silencers LIU Chen;JI Zhen-lin;CAO Min-xia 2012, 32(3): 183-187.  DOI: 10.3969/j.issn.1006-1355.2012.03.042 Abstract ( )   A coupled heat transfer model was constructed for silencer and external atmosphere environment, and the Fluent code was used to calculate the temperature field of a simple expansion chamber silencer. The reasons for internal and external temperature distribution of the silencer and the effect of internal flow on the temperature field were analyzed. Based on the above study, the temperature field of dual-inlet silencer was calculated under a given work condition. Related Articles | Metrics

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Acoustic Performance Measurement of Perforated Plate Using Impulse Method in the Condition of Grazing Flow YAN Li-jun;HOU Hong;HUANG Wei-xi 2012, 32(3): 188-190.  DOI: 10.3969/j.issn.1006-1355.2012.03.043 Abstract ( )   A broadband method was proposed by using impulse method. The acoustic performance of a perforated plate in the condition of grazing flow was measured by generating a pulse in the pipe with controllable waveform. The measurement results show that the acoustic resistance ratio of perforated plate increases gradually with the flow-rate increasing for the Mach number below 1 500 Hz, while in the frequency range from 1 500 Hz to 4 000 Hz, the acoustic resistance ratio tends to decrease with the flow-rate increasing, and the resonance peak moves to the high frequency side under the grazing flow and the frequency band of the perforated plate for sound-absorption becomes winder. Related Articles | Metrics

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Experimental Investigation on Influence Factors of Active Noise Attenuation of Sound-insulation Ventilation Window YU Hao-xin;CHEN Ke-an;HU Han;MA Xi-yue 2012, 32(3): 191-197.  DOI: 10.3969/j.issn.1006-1355.2012.03.044 Abstract ( )   The factors influencing the active noise attenuation of a sound-insulation ventilation window were investigated experimentally. The window system was constructed by staggering the opening sashes of a spaced double glazing window to allow ventilation. Transparent microperforated absorbers (MPA) and sound-absorbing material were used along the ventilation path to attenuate external noise. The performances of the four-input and four-output active control system for the window with different secondary source locations and secondary-path modeling length were compared mutually. It is found that to achieve the considerable attenuation effect in the surface of the window, locations of the secondary sources should be so arranged that the effective scope of the secondary sound field can cover the inner space of the window and the noise energy can be reduced, or the sound field is directed to the internal window glass to directly control the radiation noise. If the optimal length of the secondary-path modeling cannot be achieved in actual application, a longer modeling length should be chosen appropriately to avoid degenerating the noise attenuation or leading the system instability. Related Articles | Metrics

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Study on the Effective Region of Excitation Force of Magnetic Rubber Layer Damping Treatment LI Ming 2012, 32(3): 198-200.  DOI: 10.3969/j.issn.1006-1355.2012.03.045 Abstract ( )   The reason that the damping performance of magnetic rubber layer damping treatment (MRLD) depends on the force excitation has been analyzed. Analyzing the different dissipation energy mechanisms between MRLD and the passive constrained layer damping treatment (PCLD), the ratio of dissipation energy of MRLD to dissipation energy of PCLD was obtained. And the effective range of exciting force, in which MRLD achieves better damping than PCLD, was estimated. The results show that the material loss factor has a decisive influence not only on the effective range, but also on the best damping improvement of MRLD. Related Articles | Metrics

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Analysis of Stiffness of Rectangular Air Spring Isolator Used in Ship TANG Zhao;WENG Xue-tao;ZHU Shi-jian;LOU Jing-jun 2012, 32(3): 201-205.  DOI: 10.3969/j.issn.1006-1355.2012.03.046 Abstract ( )   By changing the structure and parameters, the rectangular air spring can have an ideal ratio of vertical stiffness to lateral stiffness, which can satisfy the engineering requirements. Considering the nonlinearity of the rubber-cord composite material, the geometric nonlinear process caused by large deformation and the contact between the rigid base plate and the flexible capsule, a finite element model for the rectangular air spring was established, its vertical stiffness and lateral stiffness were calculated and their characteristic curves with different initial gas pressures, gas volumes, cord angles and number of cord layers were plotted. The influence of these factors on the air spring’s stiffness was analyzed. Finally, the reliability of the results of the finite element analysis was proved by the experimental testing. Related Articles | Metrics

9.振动噪声测试技术

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Research and Development and Related Experimental Study of Standing Wave Tude System for Sound Absorbing Wedge YAO Lei;TONG Xian;QIU Jian-min;LUO Feng;WANG Huan 2012, 32(3): 206-211.  DOI: 10.3969/j.issn.1006-1355.2012.03.047 Abstract ( )   Research and development and related experimental study of a standing wave tube system applied in sound absorbing wedge measurement were discussed in this article. Based on standing wave ratio principle, the tube system with 0.6 m×0.6 m rectangular cross-section and 7.2 m length was constituted. Sound pressure along the axial distance in the tube was measured through the microphone driven by an automatic driving system which has a distance resolution of 0.3 mm at 5 mm/s velocity. The acoustical parameters, such as sound absorbing coefficient, acoustic impedance, reflection factor and acoustic admittance can be obtained through the system within frequency band 40~280 Hz. The system overcame the shortcomings of traditional standing-wave measurement methods, which are the low measurement efficiency and low measurement precision. A new efficient and precise method was then provided for sound absorbing test. No similar system has been found in our country so far. The system was calibrated by a superior metrology institute and the technical data can meet the demands. Furthermore, the experiment related to the system was done and some referential conclusions for sound absorption measurement were obtained. Related Articles | Metrics

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Design of Testing Method for Performance Measurement of Gear Oil Pump MA Fu-yin;HUANG Xin-liang;WU Wei-wei;LIJin-guo 2012, 32(3): 212-216.  DOI: 10.3969/j.issn.1006-1355.2012.03.048 Abstract ( )   The testing and analysis methods of the performance parameters of the oil pump of a vehicle’s engine, such as the flow-rate, outlet pressure, volumetric efficiency, pressure fluctuations, vibration-noise, durable, cavitation etc was introduced. The physical meaning of each parameter and its influence on the performance of the product was evaluated. According to the actual requirements, the testing case and the corresponding load-condition were determined, and a reasonable scheme for performance testing of the oil pump was proposed. Some noticeable problems in testing were put forward and the methods for collecting and analyzing the testing data were suggested. Related Articles | Metrics

10.工程实践

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Analysis of Noise and Vibration Pollution and Its Control Measures of a Stamping Workshop LIANG Chang-de;AN Xue-li;OU Yan 2012, 32(3): 217-222.  DOI: 10.3969/j.issn.1006-1355.2012.03.049 Abstract ( )   The noise and vibration of a stamping workshop were tested and analyzed. The contribution of the punch noise to the factory boundary and the sensitive point (residential building) was calculated. The overall amount of noise reduction was determined. According to the noise and vibration analysis, noise reduction results and the actual engineering situation, the overall control scheme and measures were put forward, and the control effect was expected. The engineering case can be as a reference for similar engineering projects. Related Articles | Metrics