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18 December 2011, Volume 31 Issue 6 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
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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Design and Simulation of Double-input Shaper for Suppressing Residual Vibration after Attitude Adjustment of Solar Array ZHU Chun-yan;SHAO Ji-ming;TANG Guo-an 2011, 31(6): 1-4.  DOI: 10.3969/j.issn.1006-1355-2011.06.001 Abstract ( )   The kinematic equations of a solar array are built in a non-inertia coordinate system and the double-input shapers based on continuous transfer function are designed and further applied to suppressing the residual vibration of the solar array in two rotation axes. Both rotation input signals are shaped respectively. Design parameters of the input shapers only depend on the natural vibration characteristic of the structural system including the natural frequencies, the damping ratio, the mass matrix and the modal vector. A finite element model is developed to simulate the dynamics response of the solar array in two rotation axes. Through the simulation, it is verified that the shaped rotation input signals to drive the attitude adjustment of the solar array can effectively suppress the residual vibration and the solar array has a good robust performance even if the parameters of the structure are not valued exactly. Related Articles | Metrics

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Analysis and Experiment on Vibration Isolation Characteristics of a Periodic Truss Raft System CHENG Shi-xiang;ZHANG Zhi-yi;HUA Hong-Xing 2011, 31(6): 5-9.  DOI: 10.3969/j.issn.1006-1355-2011.06.002 Abstract ( )   Utilizing the characteristics of periodic structures and waveform conversion function, a new floating raft with periodic truss structures is proposed. Frequency response functions of the new floating raft are calculated by the finite element method (FEM) and used in the FRF-based substructure method, which establishes a model of the assembled system involving the periodic truss raft as well as a base structure and equipment to evaluate the performance of the raft in an isolation system. Experiment is conducted to verify the simulation results. It is found that the floating raft with periodic truss structures has a better performance in suppressing vibration transmission than the traditional floating raft. When the new rafting system is composed of the floating raft and vibration isolators, the entire isolation system can reduce vibration transmission over a wider frequency band. Related Articles | Metrics

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Study on Propagation of Guided Waves in Thick Beam and the Selection of Excitation Frequency SUN Xue-wei;LI Fu-cai;SUN Kai;MENG Guang;CHEN Xue-dong 2011, 31(6): 10-14.  DOI: 10.3969/j.issn.1006-1355-2011.06.003 Abstract ( )   Mechanism of guided wave propagation in the thick beam is investigated in this study. Professional software for calculating and drawing the dispersion curves of Lamb waves in isotropic structures is developed by using the Rayleigh-Lamb equation. A number of influencing factors, such as selecting the guided wave modes, reducing dispersion effects, increasing amplitude of the wave signal, improving resolution in time domain, and suppressing the effects of local symmetry, are considered for the selection of excitation frequency. The parameters of the excitation wave are therefore optimized, and a standard process of selecting center excitation frequency in guided-wave based structural health monitoring technique is proposed. Related Articles | Metrics

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Experimental Study on Intermittent Characteristics of Wind Pressure on Long-span Spherical Shell’s Surface WANG Xu;HUANG Peng;GU Ming 2011, 31(6): 15-19.  DOI: 10.3969/j.issn.1006-1355-2011.06.004 Abstract ( )   The wind pressure measurement of a rigid model for long-span spherical shells was conducted in TJ-3 wind tunnel laboratory. In this paper, the continuous and discrete wavelet transform (CWT) are applied to the wind pressure signal to obtain intermittent events and wavelet coefficients of individual time series, respectively. Scale energy ratio, intermittent energy ratio and intermittent factor are studied by comparing them with the wind pressure from different location on the surface of the structure. Conclusions are drawn as follows: (1) At scale 11, the scale energies at circumferential measuring points have little changes with the position variation; but at scale 12, the scale energies at lateral measuring points 1-7 and 1-19 are significantly greater than those in other areas, about twice of those at points 1-1 and 1-13 in the windward and leeward areas, respectively. (2) Intermittent energies at points 1-7 and 1-19 mainly occur at scale 11, but the intermittent energies at point 1-1 and 1-13 are uniformly distributed with different scales. (3) Intermittent factors at points 1-1, 1-7, 1-13 and 1-19 have similar trend with different scales, which change slightly at low scales and increase rapidly at high scales. Therefore, we can see that the intermittent characteristics of wind pressure is different at different locations. These conclusions may be helpful for futher analysis of wind pressure characteristics. Related Articles | Metrics

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Study on the Influence of Suspender Damage on Mechanics Characteristics of Suspender Sestem in Through and Half-through Arch Bridges HE Wei;HE Rong;LI Ya-wei 2011, 31(6): 24-28.  DOI: 0.3969/j.issn.1006-1355-2011.06.006 Abstract ( )   Suspenders are important force-transmission components of through and half-through arch bridges. Their mechanical situation is closely related to the safety of the arch bridges. Since suspenders can only withstand tension, their tensile forces and the safety of the arch bridge will change when a suspender damages. In this paper, based on perturbation theory, the changing laws of the tensile forces and displacements of the suspenders due to the suspender damage are studied by means of a three-dimensional finite element model. Taking Liujiang Bridge in Beijing-Hong Kong-Macao expressway as an example, this model is verified. Results show that when a suspender damages, its internal force will reduce, but the reduction ratio is less than its damage extent. The forces of the other suspenders of the same arch rib with the damaged suspender increase, but the increasing reduces rapidly as the suspender getting far away from the damaged one. The forces of the suspenders of the opposite arch rib essentially keep unchanging. The displacements of suspender joints also change due to the suspender damage, but the change ratio is less than the damage extent and gradually reduces as the distance between the undamaged hanger and the damaged one increased. As the damage extent of suspender increases, the rates of changes of both forces and displacements of suspenders increase too. Related Articles | Metrics

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Supercritical Frequencies of Planar Vibration of Axially Moving Beams with Fixed Boundaries LUO Yi;DING Hu 2011, 31(6): 29-32.  DOI: 10.3969/j.issn.1006-1355-2011.06.007 Abstract ( )   The natural frequencies of nonlinear planar vibration of axially moving beams are numerically investigated in the supercritical speed range. The finite difference schemes are presented for the static equilibrium equation in the coupled plane of the beam in the supercritical range, and the non-trivial solutions are obtained. Based on the non-trivial statically equilibrium configuration, a typical governing equation of continuous gyroscopic systems is established in the supercritical range via introducing a coordinate transform. The natural frequencies are investigated for the planar vibration via the 8-term Galerkin method to truncate the corresponding governing equations of the beam in the supercritical state without nonlinear parts under the fixed boundary conditions. The effect of number of the terms of the Galerkin truncation method on the solution of the natural frequencies is also studied by analyzing the numerical results. Related Articles | Metrics

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Strategies for Dealing with Geometrical Continuity Conditions in the Interfances of Substructures and Their Application DENG Fei-yun;WANG Xu-eren 2011, 31(6): 33-37.  DOI: 10.3969/j.issn.1006-1355-2011.05.008 Abstract ( )   The geometrical continuity conditions in the interfaces of substructures have a significant influence on the accuracy of the solution of the substructure synthesis method. In this paper, some strategies for dealing with the problem using the reduction and non-reduction models in the system structure are investigated and applied to predict the vibration characteristics of a cylindrical shell structure. The feasibility of the strategies is discussed. Comparison between the vibration response predictions and the experimental results shows that the proposed method for dealing with the boundary conditions of the substructures is valid, and can be applied to study engineering problems. Related Articles | Metrics

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Piezoelectric Graded Optimal Control for Vibration Reduction of Non-linear Beam LIU Can-chang;LIU Lu;CHAI Shan;LI Hong-yan 2011, 31(6): 38-42.  DOI: 10.3969/j.issn.1006-1355-2011.05.009 Abstract ( )   A non-linear graded optimal control scheme is proposed and used in the piezoelectric vibration reduction control of non-linear beams. The dynamic model of a non-linear vibration reduction beam with piezoelectric damper is built. The non-linear dynamic differential equations of the vibration reduction system are deduced. The differential equation is linearized into a set of linear equations by means of perturbation. The state space equations are obtained by decoupling in the space coordinates. The vibration reduction system is controlled by the non-linear graded controllers. Related Articles | Metrics

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Study on Vibration of Multiple-deformable-body System JIN Jing;ZHANG Zhen-shan;XIONG Xin 2011, 31(6): 43-46.  DOI: 10.3969/j.issn.1006-1355-2011.06.010 Abstract ( )   On the base of vibration study of single-deformable-body system and the dynamic theory of multi- deformable-body system, vibration response of a mechanical system including multiple deformable bodies is analyzed. First of all, a crankshaft-piston mechanism is taken as a representation, and its dynamic model is created and analyzed by ANSYS and ADAMS codes. And then, the basic relations between the deformable-bodies and the system’s vibration response are obtained. These relations can provide a necessary reference for simplifying the vibration model of the large system and ensuring the precision of computation. Related Articles | Metrics

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A New Modal Strain Energy Method for Analyzing Dynamic Parameters of Viscoelastic Structures Shi-qi LI;Zhen-li ZHANG;Wen-ge ZHU;Yue WANG 2011, 31(6): 47-52.  DOI: 10.3969/j.issn.1006-1355-2011.06.011 Abstract ( )   Although viscoelastic structures have been widely used for vibration and noise reduction in the field of aerospace engineering, accurate calculation for dynamic parameters of viscoelastic structures remains difficult problem. Modal strain energy method and the corresponding modified methods have been always used for approximate calculations. On the basis of analysis of the priciples of existing modal strain energy methods and their correlations, a new modal strain energy method, whose correction factor varies with the amplitude of modal loss factor, is proposed for computing loss factor and natural frequency of viscoelastic structures. A four parameter prototype system, which is equivalent to beams and plates with constrained layer damping, and a new high damping spacecraft isolator are taken as example to verify accuracy of the proposed method by comparisons. Related Articles | Metrics

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Identification of Modal Parameters Using Improved EMD and Random Decrement Method PENG Cheng;ZHANG Li-min;LI Yuan-Hui;QIU Fei-Li 2011, 31(6): 53-56.  DOI: 10.3969/j.issn.1006-1355-2011.05.012 Abstract ( )   In order to overcome the interference of environmental noise and improve the quality of EMD, the wavelet method is used to eliminate the noise signal. The correlation coefficients are applied to remove the pseudo components. And then, the random decrement method and ITD method are used to identify the natural frequency and damping ratio of train’s floor. Compared the identification results with those from LMS commercial software, it is found that the relative error of frequency is less than 5%, the relative error of damping ratio is less than 7%. This shows that the method has high precision of identification. Related Articles | Metrics

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Hybrid Simulation of Powertrain System Based on the Combination of Test Model and FE Analysis MA Bing-jie;FENG Hui-hua;SHEN Jian-ping 2011, 31(6): 57-61.  DOI: 10.3969/j.issn.1006-1355-2011.06.013 Abstract ( )   In order to realize high efficiency and high precision dynamic analysis for complex structures, the method of hybrid simulation with the combination of test mode analysis and finite element analysis is brought forward based on the idea of substructures. This method is realized in the Virtual Lab platform. Taking the vibration modes of a whole diesel engine resulted from experiments and the vibration modes of a gearbox resulted from the finite element analysis as examples, the hybrid simulation method is verified. With this method, a dynamic simulation of a powertrain system is done. It is found that the results of the hybrid simulation of the whole powertrain model are essentially the same as those from the finite element analysis, but this method consumes much less computer time. Thus, the hybrid simulation method is accurate and effective. Related Articles | Metrics

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Analysis of Energy Errors of CFD/CSD Coupled Algorithms in Time Domain DOU Yi-Bin;XU Min 2011, 31(6): 62-68.  DOI: 10.3969/j.issn.1006-1355-2011.06.014 Abstract ( )   Two kinds of computational methods, serial partitioned algorithm and parallel partitioned algorithm, coupled by computational fluid dynamics and computational structure dynamics (CFD/CSD) algorithms in time domain, are studied. Based on the energy conservation law in the coupled interface, the effects of these coupled algorithms on energy conservation error are analyzed. The non-collocated parallel partitioned algorithm is proposed based on the parallel partitioned algorithm and non-collocated algorithm. The two-dimensional aeroelasticity test case, Isogai Wing, is analyzed numerically with different coupled algorithms. The results show that reducing the energy conservation error at the coupled interface can effectively raise computation accuracy, and the non-collocated parallel partitioned algorithm is more efficient than the strongly-coupled algorithm. The non-collocated partitioned algorithm has less energy conservation error than that of collocated partitioned algorithm, and it can make the control equation to satisfy the continuous condition in the coupled interface. Non-collocated parallel partitioned algorithm has all the merits that non-collocated partitioned algorithm and parallel partitioned algorithm have. The flutter boundary is calculated using non-collocated parallel partitioned algorithm and the results agree with those provided in some references. Related Articles | Metrics

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Static Analysis and Experiment of a Nonlinear Vibration Isolator HU Guang-jun;ZHOU Sheng-tong;LI Hong-guang 2011, 31(6): 69-71.  DOI: 10.3969/j.issn.1006-1355-2011.06.015 Abstract ( )   The stiffness characteristic of a nonlinear vibration isolator is studied. Based on buckling theory, the force-displacement and stiffness-displacement relationships of an oblique thin-walled beam are analyzed, and the existence of negative stiffness is discussed. A prototype of the nonlinear vibration isolator is proposed. Its high-static and low-dynamic (HSLD) stiffness characteristics are validated by mutual comparison of the theoretical and experimental results. Related Articles | Metrics

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Affect of Displacement Restrictor on Shock Resistance Performance of Double-stage Vibration Isolation System MA Bing-jie;SHEN Jian-ping;WANG Zhi-gang 2011, 31(6): 72-75.  DOI: 10.3969/j.issn.1006-1355-2011.06.016 Abstract ( )   With the given shock actions, the displacement response of the equipment with vibration isolation mounting may exceed the deformation limits of outside pipelines, and even exceed the deformation limits of isolators themselves. Therefore, displacement restrictors should be used in order to limit the relatively large displacement without acceleration response increasing. In this thesis, the double-stage vibration isolation system is researched, displacement restrictors is simulated with nonlinear springs, the shock responses is analyzed using direct integral method, and the affects of parameters (stiffness and gap) on isolation mounting performance is discussed. Finally, a significant conclusion is summarized. Related Articles | Metrics

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Study on Vibration Damping Characteristics of Triple Mass Flywheel Torsional Damper SHI Wen-ku;MIN De-lei 2011, 31(6): 76-80.  DOI: 10.3969/j.issn.1006-1355-2011.06.017 Abstract ( )   Inspired by the structure of curved-spring double-mass-flywheel (DMF-CS), a new type of torsional damper, triple mass flywheel (TMF) damper, is introduced. As to the powertrain torsional vibration problem of a truck, the matching method for TMF’s parameters, including damping coefficient, torsional stiffness and rotational inertia, is discussed. And these parameters of the truck are obtained using this method. Based on these parameters, the damping performance of the TMF is compared with that of DMF-CS of the truck. The impact of TMF on the safety of the shaft system is analyzed. The results verify the effectiveness of the parameter matching method and show that the TMF has obvious superiority over DMF-CS in the aspects of vibration damping and shaft-system safety. Finally, the feasibility of TMF is discussed. Related Articles | Metrics

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Influence of Thrust Bearing’s Oil Film Stiffness on the Coupled Vibration of the Shafting - ship Hull Structure LI Dong-liang;CHEN Yong;ZHANG Zhi-yi;HUA Hong-xing 2011, 31(6): 81-85.  DOI: 10.3969/j.issn.1006-1355-2011.06.018 Abstract ( )   Thrust bearing is one of the most important components which affect the coupled vibration of the shafting-hull coupled structure. Its impedance characteristics affect the transmission characteristics of the longitudinal oscillatory force from the propeller to the hull structure directly. So, the thrust bearing’s oil film stiffness in the ship propulsion system has a critical influence on the coupled vibration of the shafting-ship hull structure. The thrust bearing’s dynamic characteristics have been investigated in this paper and the thrust bearing’s oil film stiffness at different propulsion speeds is obtained, which is further applied to the dynamic model of the shafting-hull structure. The coupled vibration of the shafting-hull structure at different propulsion speeds is analyzed. The results show that the thrust bearing’s oil film stiffness at the low and medium propulsion speeds is the leading factor that affects the transmission of the longitudinal oscillatory force from the propeller to the hull structure, hence it must be considered in the prediction and control of the hull-structure’s vibration and acoustic radiation induced by the longitudinal oscillatory force. Related Articles | Metrics

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Dynamics Analysis of Power Transmission System of Diesel Engine MA Bing-jie;SHEN Jian-ping;ZHAO Da-peng;WANG Wen-jie 2011, 31(6): 86-90.  DOI: 10.3969/j.issn.1006-1355-2011.06.019 Abstract ( )   Vibration character analysis for the powertrain system of a diesel engine has been accomplished by means of the FEM based on multi-body dynamics model. The loading conditions applied to the diesel engine and the gear box are very similar to the practical situation, for example the connections between the engine and the gearbox are simulated by preload bolts and the headstock loads are simulated by the compressive elements without extension. The results show that the vibration level in the surface of the bottom shell of the engine is the highest. So, it is suggested that the ribbings be used in the side wall of the bottom shell. Since the vibration level of the engine surface increases gradually from the bottom to the top of the engine, it is suggested that composite material and high damping material be used to reduce the vibration level of the engine. Related Articles | Metrics

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Study of Balancing Method of Aero-engine Flexible Rotors WANG Si-ji;LIAO Ming-fu 2011, 31(6): 91-94.  DOI: 10.3969/j.issn.1006-1355-2011.06.020 Abstract ( )   A forward-and-backward orthogonal unified-balancing method of flexible rotors is established according to the in-situ balancing of aero-engine’s flexible rotors. Experimental investigations of the balancing effectiveness of this method are carried out. It is shown that the method is effective to balance the flexible rotors of the aero-engine, and have the advantages to improve the efficiency of the testing and reduce the number of the test weights. Related Articles | Metrics

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Study on the Computation Method of Roughness Based on Aures’ Model LIU Wei;JIAO Zhong-xing;HE Ling-song 2011, 31(6): 95-99.  DOI: 10.3969/j.issn.1006-1355-2011.06.021 Abstract ( )   The calculation procedure of Aures roughness model is discussed in detail. The basic principle and calculation skills of the algorithm are described. Some points that can easily lead to errors are pointed out and discussed in detail. Then the algorithm is implemented with MATLAB. And the roughness of typical signals is calculated.?The results are compared with the experimental data of Zwicker and S. Kemp and the numerical data from NI’s calculation modulus. The correctness of the algorithm is verified. Related Articles | Metrics

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Adaptive Synchronization of Noise-perturbed Chaotic Systems YANG Li-xin;HE Wan-sheng;LIU Xiao-jun 2011, 31(6): 100-103.  DOI: 10.3969/j.issn.1006-1355-2011.06.022 Abstract ( )   This paper investigates adaptive synchronization between two noise-perturbed chaotic systems with fully uncertain parameters. Based on Lyapunov stability theory and adaptive control theory, the general expression of suitable nonlinear controller is developed. At the same time, the noise-perturbed update laws of parameters are designed and the synchronization between different unknown chaotic systems is realized. Theoretical analysis and numerical simulation are presented, and the effectiveness and feasibility of the adaptive controllers are verified. Related Articles | Metrics

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Analysis of Acoustic Radiation Modes Based on Discontinuous BEM SHEN Huo-ming;ZHANG Bo;ZHI Wei 2011, 31(6): 104-108.  DOI: 10.3969/j.issn.1006-1355-2011.06.023 Abstract ( )   In this paper, the discontinuous element is employed for separating the Helmholtz boundary integral equation. The polar coordinate transformation in discontinuous element is employed to eliminate the singularity in the integrals. Meanwhile, the CHIEF method in addition to the Lagrange multiplier is applied to deal with the non-uniqueness at the characteristic frequencyies. On this basis, the expressions for acoustic radiation power and radiation efficiency are derived by the discontinuous element. Taking the spherical radiation and cubical radiation as numerical examples, the radiation power, radiation efficiency, radiation modes and modal radiation efficiency are computed. The results are compared with those of the existing solutions based on linear continuous element. Both simulation results are in good consistency. Related Articles | Metrics

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Layout Optimizingation of Electro-acoustic Devices of Active Noise Control System for 110 kV Transformer MA Xi-yue;CHEN Ke-an;HU Han 2011, 31(6): 109-115.  DOI: 10.3969/j.issn.1006-1355-2011.06.024 Abstract ( )   The principle of active noise control using multiple secondary sources and error sensors in free special acoustic field is introduced. According to the measured sound pressure of 110kV transformer’s noise, a low-frequency noise-control strategy is proposed for the transformer with the use of multi-source arrays. The influence of different numbers of secondary sources and error sensors and their special layout on the control effect is analyzed through numerical simulation. Theoretically, the more the secondary sources and error sensors are, the better the control effect is. But excessive secondary sources and error sensors will lead to increasing of channels of the control system, so that the control system is unlikely to be implemented. Finally, considering the feasibility of the control system in physical point of view, an optimal control system which can yield good control effect with relatively less secondary sources and error sensors is made. Related Articles | Metrics

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Analysis of Sound Transmission Loss of Composite Structures Containing Foam Aluminum HAN Bao-kun;ZHENG Feng-min;BAO Huai-qian;LI Jun 2011, 31(6): 116-118.  DOI: 10.3969/j.issn.1006-1355-2011.06.025 Abstract ( )   As a new functional material, foam aluminum is of characteristics of sound absorption and vibration attenuation. A type of composite structure consisting of a foam aluminum layer and base plates is put forward. The sound insulation performance is investigated. The method for computation of sound transmission loss for normal wave incidence is developed. The influences of different thickness of the foam aluminum layer on the transmission loss of the structure are analyzed by numerical method. The results are in good agreement with those of experimental testing. It is found that the thickness of foam aluminum has a great impact on the sound transmission loss of the composite structure. Related Articles | Metrics

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Separation of Exploding Seismic Signal from Natural Seismic Signal by Empirical Period Based on Mode Cell Filtering Method HE Zhi-wen;QIAN Chang-song;DU Zhong-yong 2011, 31(6): 119-122.  DOI: 10.3969/j.issn.1006-1355-2011.05.026 Abstract ( )   Aiming at the problem of separating exploding seismic signal from natural seismic signal, an empirical-period based mode cell filtering (EP-MCF) method is introduced. A novel EP-MCF-based method for separating the exploding seismic signal is proposed. The experimental results show that this method can separate exploding seismic signal from nature seismic signal efficiently. This paper provides a novel method for seismic signal analysis. Related Articles | Metrics

3.运载工具振动与噪声

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Optimal Design of Automobile’s Vibration Absorber LI Yong;GU Yan;JIN Chun-mei 2011, 31(6): 123-126.  DOI: 10.3969/j.issn.1006-1355-2011.06.027 Abstract ( )   The purpose of this work is to formulate the analytical solution for the mathematical models of single and double vibration absorbers, and to establish the design procedure for developing the absorbers. Based on the mathematical models, the computer programs for tuning absorber mass, stiffness and damping are written. Finally, the absorber is made and applied to a vehicle. The test result shows that the structure-borne noise can be reduced obviously. The optimal design of the absorber’s parameters can be done very fast with this analytical solution, thereby large amount of computer time and engineer’s effort can be saved. Related Articles | Metrics

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Analysis of Dynamic Characteristics and Vibration Isolation Performance of Hydraulic Engine Mount JIAO Dong-ming;ZHENG Ming-jun;CHEN Jun-wei 2011, 31(6): 127-130.  DOI: 10.3969/j.issn.1006-1355-2011.06.028 Abstract ( )   A lumped parameter model of a hydraulic engine mount (HEM ) is built in order to analyze the low-frequency dynamic responses of the engine of a car. MATLAB code is used and the experiment is done for dynamic characteristics analysis. Both results are mutually in a good agreement. It shows that the HEM model can be used to analyze the dynamic response of the engine mount precisely. The full-vehicle dynamic model is built by ADAMS/CAR. Numerical simulations of the full-vehicle’s dynamic performance are carried out for the HEM and the rubber mount respectively. And their vibration isolation performances are compared mutually. The results show that the former have a better vibration isolation performance than the latter. Related Articles | Metrics

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Study on the Design Method of Subsystems for NVH Structure-borne Noise ZHANG Shou-yuan;ZHANG Yi-min 2011, 31(6): 131-134.  DOI: 10.3969/j.issn.1006-1355-2011.06.029 Abstract ( )   A method for vehicle interior structure noise design in the middle frequency range in early stage of development is proposed in this paper. The dominant cause of structure noise for main transfer path is determined according to the simulation result of the “Digital Mule” vehicle model and the reference vehicle model, and then NVH performance targets for corresponding subsystems are established. The overall target is finally reached by achieving subsystem targets. An example for powertrain induced noise confirms the efficiency of the proposed method. Related Articles | Metrics

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Optimization Design for Car-body Structure Based on the Frequency Response Sensitivity Analysis ZHANG Meng;CHEN Jian;CHEN Yong-gan 2011, 31(6): 135-138.  DOI: 10.3969/j.issn.1006-1355-2011.06.030 Abstract ( )   Aiming at the problem of car-body optimization, the frequency response sensitivity analysis is used to reduce the response displacement of the car-body structure. Based on the finite element model of the car-body，the frequency response is calculated，and the displacement response curve of driver’s seat bracket is obtained，from which the vibration peak for a given frequency is found. To reduce the vibration peak, an optimal design based on the frequency response sensitivity analysis is carried out by selecting the appropriate design parameters. After the optimization，the response displacement?at key frequencies of the car is obviously reduced，and the riding comfort of the car is improved. Related Articles | Metrics

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Measurement and Investigation of Loading Spectrum of the Left Side Wall of a Full-monocoque Coach CAI Jian-jin;SHAO Ming-liang 2011, 31(6): 139-142.  DOI: 10.3969/j.issn.1006-1355-2011.06.031 Abstract ( )   Because of the complexity of the structure and numerous members, the technology of the full-monocoque coach manufacture has not been sufficiently developed in our country. To expedite the research and development of the full-monocoque, a dynamic stress testing for the full-monocoque coach is carried out under different road conditions. The dynamic stress data in the left side wall of the coach is collected. The method of loading spectrum measurement of the full-monocoque frame is studied, and the stress frequency of the measured data is analyzed. The loading spectrum data for different road conditions is obtained. The dynamic stress level and its variation of the left-side wall of the full-monocoque frame under the conditions of bending, torsion, tension and compression are studied. This study may provide a technical base for the full-monocoque coach’s design, simulation and testing. Related Articles | Metrics

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Measurement and Analysis of Interior Noise of Car JIANG Jun;CHEN Jian 2011, 31(6): 143-146.  DOI: 10.3969/j.issn.1006-1355-2011.05.032 Abstract ( )   The interior noise of a car in different conditions is tested according to our national standards. Using Fourier transform, the spectrum analysis is done for the signals and the critical frequency is obtained. It is found that in rapidly accelerating conditions, Fourier transform can only yield overall trends of the interior noise variation, and the detailed information cannot be obtained. Then, the “adaptive changes” time-frequency window structure of wavelet transform is used to gain the details of the signals and more frequency information. Related Articles | Metrics

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Study on Application of Cadna/A Software in Evaluating Noisy Effects of Ground and Elevated Road Traffic on Residential Areas ZHENG Qing-feng;XU Wei-zhong;CHEN Chun-gen 2011, 31(6): 147-151.  DOI: 10.3969/j.issn.1006-1355-2011.06.033 Abstract ( )   With the use of Cadna/A software, 3D simulation models are built up for evaluating noise impacts of ground and elevated road traffic on adjacent residential buildings in different cases such as different road conditions, different driving speeds of vehicles, different clearance of the roads to the residential buildings etc. Furthermore, the noise-reduction effects of sound barriers with different clearance to the residential buildings are predicted and analyzed. Finally, a proper standard for sound barrier construction is put forward, which may provide an important technical basis for building layout and environment protection bureau. Related Articles | Metrics

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Application of Statistical Energy Analysis Method in Ship Noise and Vibration Control LI Feng;XU Qin-liang;TENG Yao;ZHANG Jing 2011, 31(6): 152-155.  DOI: 10.3969/j.issn.1006-1355-2011.06.034 Abstract ( )   The vibration and noise sources and their diffusing routes of ships are described and analyzed. The standard and method for control of noise and vibration of ships are introduced. The noise level of ship’s AFT is analyzed by VA ONE, and the result of noise and vibration are obtained by means of statistical energy analysis (SEA). It is found that the results are in good agreement with the measurement data in shake-down voyage. Related Articles | Metrics

6.信号处理与故障诊断

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Application of Wavelet Singular Entropy in Periodic Fault Detection of Sensors on Gas Turbines CHEN Jiao;WANG Yong-hong;WENG Shi-lie 2011, 31(6): 156-160.  DOI: 10.3969/j.issn.1006-1355-2011.05.035 Abstract ( )   Sensors are usually used to get the parameters for performance estimate of gas turbines in power plants. The measured values are immediately affected by sensors states. It is hard to detect periodic fault, which is one of common faults of sensors, since the periodic signal has small magnitude and can be easily covered by noise. In this paper, wavelet singular entropy (WSE) is used for periodic fault detection of sensors. Definition and calculation methods of the WSE are introduced. Through the simulation, the advantage of WSE in periodic fault detection is found in comparison with the traditional wavelet transform. It is proved that the WSE is independent of fault amplitude. The method is verified by experimental data from combustor’s outlet temperature sensors. Related Articles | Metrics

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Application of Coupled Hidden Markov Models in Bearing Fault Diagnosis XIAO Wen-bin;CHEN Jin;ZHOU Yu 2011, 31(6): 161-164.  DOI: 10.3969/j.issn.1006-1355-2011.06.036 Abstract ( )   Due to the abundant information contained in multichannel data, a multichannel fusion method based on coupled hidden Markov models (CHMMs) is presented for rolling- element-bearing’s fault diagnosis. A double-chain CHMM is adopted to combine the horizontal and vertical vibration signals from bearings. An experiment was carried out to validate the proposed method. The experimental results show that the proposed method can improve the diagnostic accuracy when compared with the conventional hidden Markov model (HMM) based method. Related Articles | Metrics

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Modal Test and Vibration Analysis of the Optical Element with Different Boundary Constraint Conditions SHAO Jun;YE Jing-feng;HU Zhi-yun;ZHANG Zhen-rong 2011, 31(6): 165-168.  DOI: 10.3969/j.issn.1006-1355-2011.06.037 Abstract ( )   To analyze and evaluate anti-vibration performance of the optical element, a series of modal experiments about the L-shaped pad element with different boundary constraint conditions is carried on. Firstly, the deviation of the results from ANSYS simulation and measurement is limited in an allowable range, so that the definition of modal performance and the reliability of experiments of the model are validated. Secondly, anti-vibration performance of optical element is analyzed based on the experiments data, and the modal parameters of the element with different boundary conditions are obtained. Finally, the working stability of the element with different assembly situation is analyzed according to the different dynamic characteristics under different boundary constraint conditions. This work may provide a reference for improving the anti-vibration and working performances of optical elements in different environments. Related Articles | Metrics

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Method of Wavelet Denoising and Its Application to Analysis of Transient Evoked Otoacoustic Emissions XIE Bao-ling;WU Ke-qin;FAN Li-hua;ZHAO Lian-hua; ZHANG Lin-lin 2011, 31(6): 169-171.  DOI: 10.3969/j.issn.1006-1355-2011.06.038 Abstract ( )   Noises are artificially added to a real Transiently-Evoked Otoacoustic-Emission (TEOAE) signal to stimulate the collected TEOAEs signal. Then, the stimulated signal is denoised using traditional denoising method and wavelet transform method, and the results are analyzed. The suitable wavelet parameters for TEOAEs are found to improve the correlation ratio and the signal-to-noise ratio of the results, and to reduce the inspecting time. Related Articles | Metrics

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Study and Implementation of Health Monitoring Process for Half-through and Through Arch Bridges CHEN Huai;HE Rong;HE Wei;HU Feng 2011, 31(6): 172-175.  DOI: 10.3969/j.issn.1006-1355-2011.06.039 Abstract ( )   According to the structure characteristics of half-through and through arch bridges, the bridge health monitoring process and the concept of bridge health records are proposed. And the health indicators and characteristics of the bridge health records are analyzed. When monitoring the bridge health, the standard model and health records should be established firstly. Then, the inspection object and observation index can be determined, and the in-situ testing according to the monitoring process is carried out. Finally, comparing the measured data of each index with its reference value in the health records, the working condition of the bridge can be analyzed. Taking Liujiang Bridge on Beijing-Hong Kong-Macao expressway as an example, the implementation of health assessment is illustrated. The monitoring results show that the 4th span of the bridge was in good health at that time. Related Articles | Metrics

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Oil Membrane Oscillation Cause Analysis of a Centrifugal Compressor and Its Structural Improvement CHEN Hong-wei 2011, 31(6): 176-179.  DOI: 10.3969/j.issn.1006-1355-2011.05.040 Abstract ( )   The fault of oil membrane oscillation in a centrifugal compressor of a factory in Longyan of Fujian province is analyzed. It is found that this fault is a particular one of sliding bearings operating at high rotation speeds. It usually occurs in the vicinity of twice critical rotation speed of the bearings. The characteristics of oil membrane oscillation are summarized. It is found that the first-order critical frequency component of the rotor in the frequency spectrum is the main peak value, and the locus of the bearing’s shaft is irregular and diffusive. The influential factors of oil membrane oscillation are analyzed. It is concluded that the oil membrane oscillation depends on the load, the critical speed, the bearing’s eccentricity, lubrication state, and bearing’s load characteristic coefficient. Then, the HHT method for the fault detection is proposed. It is found that with this method, the fault of oil membrane oscillation can be identified very quickly and precisely. Finally, some structural improvement measures for the centrifugal compressor are proposed for reducing the oil membrane oscillation. It is verified after half-year use that this method is simple, convenient and practical. Related Articles | Metrics

7.减振降噪设备和器材

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Research of Relief Annealing Technology for 304 Metal Rubber ZHAO Cheng;LUO Kun;LI Xiang 2011, 31(6): 180-182.  DOI: 10.3969/j.issn.1006-1355-2011.06.041 Abstract ( )   Relief annealing technique of 304 Metal Rubber is researched. Test results show that relief annealing can significantly change the static loss factor and the dynamic loss factor of 304 Metal Rubber. It is found that the influences of annealing temperature, annealing time, Metal Rubber density and cooling manner on the static loss factor and the dynamic loss factor are obviously different. The optimal combination of the relief annealing parameters of 304 Metal Rubber is: annealing temperature 270 ℃, annealing time 25 minutes, Metal Rubber density 1.6 g/cm3, and oil cooling manner. Related Articles | Metrics

9.振动噪声测试技术

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Online Monitoring of Cylinder-to-cylinder Uniformity in Diesel Engine Based on Instantaneous Rotational Speed CHENG Li-Jun;yingtang Zhang;zhi-ning Li;guoquan Ren;jianwei Li 2011, 31(6): 183-187.  DOI: 10.3969/j.issn.1006-1355-2011.06.042 Abstract ( )   Considering the situation of rotational speed changing and space limitation, a smart online monitoring system for diesel engine is designed. After sampling the signal of magnetoelectricity speed sensor, the instantaneous speed signal of the diesel engine is analyzed. Corresponding parameters are computed to estimate the fault of the diesel engine. After analyzing the parameters of 120 swatch samples in normal condition, one cylinder misfire and two cylinder misfire working conditions when the engine operates at low speed, middle speed, accelerating and high speed, it is shown that these working conditions can be distinguished effectively using these parameters. Corresponding thresholds of the parameters are also indicated to estimate the cylinder-to-cylinder uniformity. Related Articles | Metrics

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Sound Identification using Phase Conjugation by Introducing the Acoustic Sink LIU Song;LI Sheng;ZHAO De-you 2011, 31(6): 188-192.  DOI: 10.3969/j.issn.1006-1355-2011.06.043 Abstract ( )   Two methods for calculating the amplitude of the acoustic sink, by introducing the concept of the sink in time reversal method, are proposed. The first method is to derive the amplitude of the phase conjugation array in the focusing location of the acoustic sources directly, which is employed as the amplitude of the acoustic sink. The second method is to calculate the amplitude of the acoustic sink by introducing the measurement spherical surface. The effect of the spherical radius on focusing properties is also discussed. The numerical results show that the diffraction limit can be broken through at a certain distance by introducing the acoustic sink for the two methods. The best reconstruction can be obtained by considering the spherical measurement surface, that can yield more accurate results which agree well with the theoretical solution of the point source. The radius of the spherical measurement surface must be less than the wavelength according to the properties of the evanescent waves. Related Articles | Metrics

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Analysis of Southeast Alaska Acoustic Measurement Facility LIU Xing-zhang;CHEN Tao 2011, 31(6): 193-195.  DOI: 10.3969/j.issn.1006-1355-2011.05.044 Abstract ( )   The Southeast Alaska Acoustic Measurement Facility (SEAFAC) is currently the most advanced acoustic testing field for submarines. It is also the most important acoustic testing area of the United States in Pacific Ocean. It provides the capability to perform noise monitoring, measurement and evaluation for ships, to determine the sources of radiation noise, to assess vulnerability, and to develop quieting measures. SEAFAC is also capable of supporting submarine target strength measurements. In this paper, the history, main facility and fuction of SEAFAC are introduced and studied. It may be helpful for building acoustic testing field in China. Related Articles | Metrics

10.工程实践

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Design and Achievement of Double-stage Vibration Isolation System of Scroll Compressor WANG Yue;CHEN Chang-zheng;ZHAO Xin-guang;LIU Xin-hong 2011, 31(6): 196-198.  DOI: 10.3969/j.issn.1006-1355-2011.06.045 Abstract ( )   Vibration and noise of scroll compressors of air conditioning units at the top floor of an office building in an Economic and Technological Development Zone are excessively high. The noise and vibration of the units have severe impact on the downstairs offices. Through the testing of these units, it is found that the central air conditioning unit and its pipes have no vibration isolators at all, which form an acoustic bridge between the equipment and the building and cause the spread of solid sound. Therefore, vibration isolation must be considered according to the characteristic of the solid sound spread to effectively reduce the pollution of low frequency noise. Due to the actual situation of the top floor, a double-stage vibration isolation system is considered. With the calculation, the vibration isolation system is designed, and then it is made and installed to the equipment. Finally, a good isolation effect is obtained. The average value of the noise level is reduced by 20 dB. Related Articles | Metrics

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Study and Application of Noise Control Technology in Air Compressor Room GUO Zhao-xuan;GUO Jun;LUO Xiao-Wei 2011, 31(6): 199-202.  DOI: 10.3969/j.issn.1006-1355-2011.05.046 Abstract ( )   The main noise source and the frequency spectrum characteristics of a piston-reciprocating air-compressor are analyzed. And an effective synthetic management method is introduced. With this method, a strategy of noise control is designed and implemented for a practical engineering project, which has been checked and accepted by government and yielded good economic and social benefits. Related Articles | Metrics