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Analysis of Vibration and Stability of Structures Using Edge-based Smoothed Finite Element Method 2014, 34(2): 1-4.  DOI: 10.3969/j.issn.1006-1335.2014.02.001 Abstract ( )   PDF (1031KB) ( )   A novel numerical method—edge-based smoothed finite element method(ES-FEM) was used to analysis the vibration and stability of the beam and plate structure. In the ES-FEM, the system global stiffness matrix is computed using strains smoothed over the smoothing domains associated with edges of the element. As a result, the smoothing operation reduces the over-stiff behavior of the finite element method. Numerical examples of beam and plate under special boundary conditions were presented to demonstrate that ES-FEM achieves higher accuracy and convergence as compared with FEM for structures. Related Articles | Metrics

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Experimental Research of Nonlinear Chaotic Vibration Responses 2014, 34(2): 5-7.  DOI: 10.3969/j.issn.1006-1335.2014.02.002 Abstract ( )   PDF (1289KB) ( )   The nonlinear vibration isolation system worked in a chaotic vibration state when the parameters were in a certain range. Then chaotic responses with wide spectral characteristic were produced under line spectrum excitation, and the line spectrum of radiation noisy in submarine could be reduced. The piecewise vibration isolation system was designed and experiment research carried out. Then the measured signals were filtered and identified based on the improved wavelet transform and space grid method. Complex dynamics behaviors which provided useful guide for chaotic engineering applications were observed through the experiment. Related Articles | Metrics

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Resonance Analysis of a Forced Fluid-conveying Pipe with 2:1 Internal Resonances under Supercritical Fluid Velocity 2014, 34(2): 8-11.  DOI: 10.3969/j.issn.1006-1335.2014.02.003 Abstract ( )   PDF (1153KB) ( )   In this paper, the behavior of the pipes conveying fluid in the supercritical fluid velocity regime is investigated by taking into the two-to-one internal resonance account. The equilibrium configuration bifurcates into multiple equilibrium positions. The partial differential equation is discretized via the Galerkin’s method. The resulting equations are numerically solved by the multi-scale method. Attention is concentrated on the possible response of the system with a different govern dimensionless parameters. Finally, the cumulative effect of frequency on the internal resonance is studied and the Hopf bifurcation is briefly discussed. Dynamic response of the system in the vicinity of Hopf bifurcation is presented in the form of time histories and phase plane trajectories via the Runge–Kutta numerical method. Related Articles | Metrics

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Analysis of Jump Avoidance and Vibration Reduction Performances of a Piecewise Linear Single DOF System 2014, 34(2): 12-16.  DOI: 10.3969/j.issn.1006-1335.2014.02.004 Abstract ( )   PDF (1301KB) ( )   This paper studied the vibration performance of a single-degree-of-freedom systems with piecewise linear terms under primary resonance excitation. By employing an averaging method it was possible to obtain an implicit function of Amplitude-Frequency response equation under primary resonance excitation. The transition boundary could be calculated from this function on the basis of constraint bifurcation theory. Critical parameter boundary to avoid jumping was calculated by qualitatively analyzing the Amplitude-Frequency response equation in the sub-regions of the transition sets. Numerical calculation verified the feasibility of theoretical study. In addition, the influence of damping ratio and external excitation amplitude within the no-jumping region was considered on the global force transmissibility and the force transmissibility at the peak point of Amplitude-Frequency response curve. The results showed that under small excitation, large damping ratio would enhance the vibration resistance of the system. Related Articles | Metrics

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Experimental Study on Active Control of Sound Radiation from a Submerged Cylindrical Shell with Finite Length 2014, 34(2): 17-21.  DOI: 10.3969/j.issn.1006-1335.2014.02.005 Abstract ( )   PDF (1443KB) ( )   Experimental study on active control of a submerged finite cylindrical shell using secondary force sources was performed. Through the experiment, both position and number of secondary exciters and errors sensors and excitation frequency were varied during the test to determine the influence on control effects. The results show that the underwater sound radiation of the cylindrical shell subjected to force excitation can be effectively attenuated by method of active noise control, the area of noise reduction would be enlarged with increasing the number of secondary exciter and error sensor; the active noise control of the cylindrical shell at 3000Hz is still valid；at the same time, the sound radiated from the submerged cylindrical shell subjected to multiple lines spectrum excitation can also be suppressed by introduced secondary force excitation. Related Articles | Metrics

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Decoupling Characteristic of Viscoelastic Damping Layer and Its Influence on Sound Radiation Field of Underwater Cylindrical Shell 2014, 34(2): 22-27.  DOI: 10.3969/j.issn.1006-1335.2014.02.006 Abstract ( )   PDF (1562KB) ( )   Based on the modal superposition method, a model of vibration and sound radiation from underwater cylindrical shell with viscoelastic damping layer was established, in which the motion of damping layer was described with Navier equation. The model was proved by comparing with numerical results. The decoupling characteristic of viscoelastic damping layer on sound field radiated from underwater cylindrical shell was investigated by analyzing the mean radial quadratic velocity and sound radiated power from cylindrical shell. The results show that the mean radial quadratic velocity frequency response curve of viscoelastic damping layer can be divided into three frequency bands, and the sound radiated power can be reduced better only at high enough frequency. Compared with the shell thickness, the damping layer thickness affects the decoupling characteristic of damping layer more greatly. Related Articles | Metrics

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Simplification of Fourier Expansion in the High-order Harmonic Balance Method for Nonlinear Ordinary Differential Equations 2014, 34(2): 28-33.  DOI: 10.3969/j.issn.1006-1335.2014.02.007 Abstract ( )   PDF (975KB) ( )   A simplification computation method of the high-order harmonic solution of nonlinear ordinary differential equation was discussed. The Fourier coefficient expansion procedure of nonlinear ordinary differential equation with quadratic or cube term is improved and simplified. The procedure is composed of two steps of matrix operation with the same computation process so that the algorithm is easier to program than previous. Results for the Duffing equation show high-order harmonic solution in line with numerical solution but more efficient. Related Articles | Metrics

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Analysis for Natural Frequencies and Mode Shapes of Laminated Composite Plates Using Layerwise Theory 2014, 34(2): 34-40.  DOI: 10.3969/j.issn.1006-1335.2014.02.008 Abstract ( )   PDF (1440KB) ( )   A detailed simulation an experimental analysis of natural frequencies and mode shape of laminated composite plates using the layerwise theory method is presented. The present formulation is based on layerwise finite element models to obtain the displacement of laminated composite plates. A preliminary study is conducted for the natural frequency of the laminated composite plates. Numerical examples with different mesh size are presented and achieved results are composed with reference solution available in the literature. Several aspects of the model involving relevant parameters, fiber orientations, lay-up numbers, length-to-length, etc. affected on frequency are analyzed numerically in details, and then achieve the first several mode shapes. Finally, the simulation result has been verified by experiment. As a consequence, the applicability of the effectiveness of the present method for accurately computing natural frequencies of laminates is demonstrated. Related Articles | Metrics

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Sliding Mode Control for Weak Chattering of Building Structures with Compensators Based on Hybrid Reaching Law 2014, 34(2): 41-45.  DOI: 10.3969/j.issn.1006-1335.2014.02.009 Abstract ( )   PDF (1271KB) ( )   Abstract :In this study, a new variable structure control method involving a composite reaching law, which is one of the active control algorithms, is applied for seismically excited linear structures with a fixed-order compensator in control. The major advantages of this method over the conventional variable structure control are as follows: (i) it make trade-offs between control efforts and specific response quantities of the structure through the use of linear quadratic optimal control theory, (ii) it provides systematic approach to design static output feedback controllers to facilitate practical implementations of control systems, and (iii) the excessive chattering effect, is avoided by introducing the new method. Finally we give numerical simulations for MDOF (Multiple-Degree-of-Freedom) shear building model containing an active brace system , and the simulation results show preliminarily that the new control method is quite effective. Related Articles | Metrics

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Application of an Adaptive Algorithm to Active Vibration Control 2014, 34(2): 46-49.  DOI: 10.3969/j.issn.1006-1335.2014.02.010 Abstract ( )   PDF (997KB) ( )   Related Articles | Metrics

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Influence of Modal Numbers of Short Thin Cylindrical Shell on Its Forced Vibration Response 2014, 34(2): 50-55.  DOI: 10.3969/j.issn.1006-1335.2014.02.011 Abstract ( )   PDF (1381KB) ( )   An analysis was made to study on response characteristics of a short thin cylindrical shell for forced vibration under a radial harmonic excitation force, and the modal numbers were considered for simply supported-simply supported, clamped-clamped and clamp-free boundary conditions. A dynamic model of a short thin cylindrical shell was constructed according to Love’s shell theory. Secondly, the dynamic equations were solved based on modal superposition method when the cylindrical shell was subject to a radial harmonic excitation force. Under three boundary conditions the vibration response results were got. The results show that the response amplitudes need the forth eight modals to represent the displacement mode. If the modal numbers are more than eight, the precision are no more obvious improvement, and analytic results and experimental results are fundamental agreement. Related Articles | Metrics

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Modal Analysis of Phenolic CCL 2014, 34(2): 56-58.  DOI: 10.3969/j.issn.1006-1335.2014.02.012 Abstract ( )   PDF (1244KB) ( )   Phenolic CCL widely used in PCB was modal analyzed in this paper, first of all, the vibration of a phenolic beam was experimentalized, based on the experiment, the Young’s modulus of the material of phenolic was calculated, after that, the modal characteristics of phenolic CCL under the boundary condition of one end clamped and another end free was analyzed with Ansys software. Through the vibration experiment and hammering test, the natural frequency of the composited board was given, the consistency of the theory and experiment was obtained, thereby, the correctness of the Young’s modulus of the phenolic was confirmed, the results given in this paper can provide the parameter for analysis of the complex structures with the same material. Related Articles | Metrics

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Analysis of Micro-vibration of a Solar Array Drive Mechanism in a Satellite and the Countermeasure for Suppressing the Vibration 2014, 34(2): 59-62.  DOI: 10.3969/j.issn.1006-1335.2014.02.013 Abstract ( )   PDF (1837KB) ( )   Based on the character analysis of solar array drive mechanism, the measurement data and analysis result of the micro-vibration responses for solar array drive system are give firstly; Secondly, based on the exact dynamic model of solar array drive system, the influence of solar array drive to satellite attitude is analyzed; Finally, the influence of solar array drive system to satellite attitude is give by taking a satellite as an example, a integrated measures by using frequency restriction method and active vibration suppression method is proposed, and the simulation result is given. Related Articles | Metrics

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Comparison of Noise Characteristics of Electric and Fuel Vehicles 2014, 34(2): 63-65.  DOI: 10.3969/j.issn.1006-1335.2014.02.014 Abstract ( )   PDF (1008KB) ( )   Electric Vehicles have been serving as taxis and public buses in many cities. The subject of this paper are electric and fuel vehicles. An analysis and comparison of the maximum A sound level and spectrum of electric and fuel cars and buses under different speed is provided in this paper. The aim is to offer some references to the prevention of transport noise in cities. Related Articles | Metrics

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Experimental Study on Improvement of Interior Sound Quality of Cars by Using Music Control Method 2014, 34(2): 66-69.  DOI: 10.3969/j.issn.1006-1335.2014.02.015 Abstract ( )   PDF (1220KB) ( )   Taking 32 car interior noise samples acquired from 4 types of vehicle under different conditions as evaluation objects, a sound quality model was built to describe the subjective evaluation level by the objective psycho-acoustical parameters. The music masking control experiments on the worse noise sample was performed, and the results show that the dichen of the in- vehicle noise was reduced, but the tonality was raised. The music masking control is proved to be feasible and effective in the vehicle sound quality improvement. Related Articles | Metrics

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Comparative Study on Noise Emission Models of an Individual Vehicle 2014, 34(2): 70-74.  DOI: 10.3969/j.issn.1006-1335.2014.02.016 Abstract ( )   PDF (1111KB) ( )   A comparative study on noise emission model of an individual vehicle that is a significant part of road traffic noise prediction models at home and abroad was conducted in the paper. The paper will analyze those models elaborately in the following aspects: structure and characteristics of those models, noise emission at 7.5 m distance, noise emission difference between different vehicle categories, and noise emission difference between acceleration and steady running condition. Then the paper will offer proposals for future research of road traffic noise prediction models of China. Related Articles | Metrics

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Parametric Model for Low-frequency Character Analysis of  Car’s Interior Noise 2014, 34(2): 75-79.  DOI: 10.3969/j.issn.1006-1335.2014.02.017 Abstract ( )   PDF (1145KB) ( )   low-frequency noise is expressed in the context of car riding comfort. This paper researched the character of the car interior noise, which recorded by using binaural digital head. A jury test is performed in listing room, the subjective results are analyzed and correlated with objective quantities. Mathematical model for low frequency character of car interior noise is developed as a function of 1/3 octave sound pressure levels, sharpness and roughness quantities. The proposed model is verified by data collected from subjective assessment with paired comparison and semantic differential methods. Results indicate a strong correlation between model predicated and subjective data, and therefore proved the developed model an effective index for subjective low frequency perception. Related Articles | Metrics

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Experiment on Vehicle’s Interior Noise Control 2014, 34(2): 80-83.  DOI: 10.3969/j.issn.1006-1335.2014.02.018 Abstract ( )   PDF (1704KB) ( )   Sealing and soundpackage performance affected the level of NVH inside the car directly. Aiming at the problem of the high interior noise and the poor quality of sound in the car at idle, using noise source separation testing method, identified the engine noise is main noise sources inside the car. Through the dash hole sealing improvement and soundpackage improving to the propagation path, blocked the engine noise effectively and improved the interior sound quality eventually. Related Articles | Metrics

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Simulation Prediction and Experimental Test of Radiation Noise of Engine’s Side Covers 2014, 34(2): 84-88.  DOI: 10.3969/j.issn.1006-1335.2014.02.019 Abstract ( )   PDF (1643KB) ( )   Used a method of combing simulation prediction and experimental measurement to analyze for the side cover structural noise of an engine, measured engine left shell vibration acceleration signal with LMS Test. Lab, which was imported in Hypermesh as an excitation to make finite element analysis of the left shell, extracted surface vibration velocity frequency spectrum as the engine left shell noise radiation boundary conditions, used the LMS Virtual. Lab to do acoustic simulation, analyzed the simulation results of the noise precision. The 3560D data front-end of B&K was applied to have a noise test for the left side cover, analyzed the data with Beamforming technology, compared with the simulation and verified the results, these two sound power curves were consistent. Made improvements in the left shell structure, then had a noise test on the improved left cover; the improved effect was proved significantly. It is of greater reference significance to predict side cover structure-borne noise and reduce the noise of the entire engine. Related Articles | Metrics

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Analysis of Performance of the Vibration Isolation System of DMU Powertrain 2014, 34(2): 89-93.  DOI: 10.3969/j.issn.1006-1335.2014.02.020 Abstract ( )   PDF (1517KB) ( )   For broadband excitation sources of high-power diesel engine, two-stage vibration isolation system has good high-frequency vibration isolation performance, and has already been applied in various fields such as shipbuilding. However, in the field of locomotives using middle or high speed diesel engines, few researches have been done for the above system in China. Based on the first DMU power train system developed in China, simulations and vibrations were done to study the vibration isolation performance of such system in this paper. First, the characteristics of the exciting force (torque) acting on the diesel generator set were determined by using a combination of theoretical calculation and experiment identification methods; then a multi-body dynamics model of the two-stage vibration isolation system was built, and the theoretical isolation efficiency was obtained through simulation; the actual vibration isolation efficiency was finally tested and proved to be significantly better than the single-stage vibration isolation system. The above work has certain guiding significance to the design and engineering applications of two-stage vibration isolation system. Related Articles | Metrics

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Vibration Measurement and Control of High-speed Train’s Ceiling 2014, 34(2): 94-97.  DOI: 10.3969/j.issn.1006-1335.2014.02.021 Abstract ( )   PDF (1111KB) ( )   In order to reduce the noise and vibration from the high-speed train ceiling. The train roof and ceiling vibration acceleration were investigated when it was going at a rapid rate. Vibration isolation measurement between the train roof and ceiling was taken. The results show the pantograph induces a broadband vibration in the train roof and ceiling. And the amplitude of the vibration mainly induced by pantograph are much great than other region. For the train with pantograph vibration isolation measurement is proved to be very effective, and for the train without pantograph it is useless. Related Articles | Metrics

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Analysis of the Effect of Suspension Parameters on the Dynamic Performance of an Export Train 2014, 34(2): 98-102.  DOI: 10.3969/j.issn.1006-1335.2013.03.022 Abstract ( )   PDF (1628KB) ( )   In order to research the export train with diesel engine generator, a train dynamic model coupled rigid and flexible is established by dynamic analysis software. When the heavy loaded train running on the railway and diesel engine working, the effects of varied of suspension parameters on the dynamic are analyzed. In the selected parameters range, the result has proved the nonlinear critical speed increases with the first order suspension vertical stiffness. The vertical stiffness obviously affects the curve passing property, the coefficient of the train derailment, the rate of load reduction and the lateral force of wheelset on track are all increase with the first order vertical stiffness. The lateral ride index changes little with the vertical damp variations. The vertical ride index falls while the vertical damp increasing, and tends to be stable at last. However the relativity between the second vertical stiffness and vertical ride index is so complex. Related Articles | Metrics

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Effect of Increasing Door on Vehicle Body’s Vertical Bending Stiffness 2014, 34(2): 103-106.  DOI: 10.3969/j.issn.1006-1335.2014.02.023 Abstract ( )   PDF (1106KB) ( )   The research has been conducted on certain high-speed pure vehicle body which had different doors. We obtained the 1 order vertical bending modal by the method of test. We also calculated 1 order vertical bending stiffness by using modal test consequence in the case of the cross section geometric dimensions and the distribution of quality of vehicle body was unknown . Last ,we had curve fitting by using piecewise cubic Hermite interpolation. The study has shown that vertical displacement and 1 order vertical stiffness of vehicle body was "W" type distribution. The result has certain significance in the design of vehicle body's cross section stiffness . Related Articles | Metrics

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Calculation and Testing of Sound Transmission Loss for Interior Panels of Large Aircraft Fuselages 2014, 34(2): 107-110.  DOI: 10.3969/j.issn.1006-1335.2014.02.024 Abstract ( )   PDF (1165KB) ( )   Abstract: Combining acoustic theory of single wall and sandwich panel, the paper provided an analysis method to calculate sound transmission loss of typical aircraft fuselage interior panel. According to sound transmission loss equations, we defined the real parameters of interior panel and put them into calculation process, and then we got the result in flight and ground conditions. With comparing the data from calculation and measurement, we find that the value and trending could be marched well in special frequency range and there are drops at resonance, coincidence and dilatation frequencies of sandwich panel, and level of transmission loss is rising in flight condition. Related Articles | Metrics

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Study on the Impact of Noise Stringency of International Civil Aviation Organization (ICAO) on Chinese Fleet 2014, 34(2): 111-113.  DOI: 10.3969/j.issn.1006-1335.2014.02.025 Abstract ( )   PDF (745KB) ( )   Related Articles | Metrics

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Noise Forecast of 30 m Full-turning Tug Cabins 2014, 34(2): 114-118.  DOI: 10.3969/j.issn.1006-1335.2014.02.026 Abstract ( )   PDF (1353KB) ( )   Based on Statistical Energy Analysis, the modeling method in VA One was discussed, the cabin noise prediction model of tug was built, the power flow transmission of tug cabins was analyzed, the locations and the spectra of the excitation sources were confirmed, and the noise sources were ranked in this paper. Contrasting the simulation results with the experimental results of similar type tug, the noise sources’ contribution rates to cabin noise were calculated, the errors between simulation results and experimental results of meeting room, master room and crew room were analyzed, which not only provided an evidence for the feasibility that the cabin noise prediction model of tug was built based on Statistical Energy Analysis, but also provided the theoretical and simulation foundation for tug’s noise control. Related Articles | Metrics

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Prediction and Control of Cabin’s Noise of a Three-hulled High-speed Ship 2014, 34(2): 119-122.  DOI: 10.3969/j.issn.1006-1335.2014.02.027 Abstract ( )   PDF (1177KB) ( )   Based on the statistical energy analysis, using VA One software to predict the cabin's noise of three-hulled ship and to investigate the noise control methods. The SEA model of the ship is built first, and the external excitation on the model is enforced to predict the noise levels of several cabins, and then the sound abatement performance of different sound-absorption materials are investigated. Finally, through the investigation of relationship of energy transmission among the acoustic cavity subsystems, the noise control is performed by considering the energy contributions using hybrid sound-absorption materials, and good noise abatement is obtained. Related Articles | Metrics

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Discussion on Single Stern-tube Bearing Arrangement in Propulsion Shafting System of Rear Engine Room 2014, 34(2): 123-126.  DOI: 10.3969/j.issn.1006-1335.2013.03.028 Abstract ( )   PDF (1148KB) ( )   For a bulk carrier the propulsion shafting arrangement can be three types: two stern tube bearings plus one intermediate shaft bearing (type O),remove the fwd stern tube bearing but intermediate shaft bearing remains original position (type A),remove the fwd stern tube bearing and intermediate shaft bearing moves backward (type B). Alignment calculations have shown that the shafting B has smallest bearing reaction influence coefficient and is not sensitive to construction errors and hull deformation, etc., and also pointed out that for shafting B the slope boring of aft stern tube bearing maybe avoid if use the eccentric design or eccentric installation of the fwd stern tube simplex seal,or use face seal. Related Articles | Metrics

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Flow Field Optimization and Experimental Verification of Multi-stage Centrifugal Pumps 2014, 34(2): 127-132.  DOI: 10.3969/j.issn.1006-1335.2014.02.029 Abstract ( )   PDF (1608KB) ( )   Fluid exciting forces are one of the important vibration sources of centrifugal pump which transmit outward through the pump shell and bearings. So flow field optimization can effectively reduce fluid exciting forces and vibration sources to improve the centrifugal pump vibration characteristic. This paper aimed to decrease vibration and noise of multi-stage centrifugal pump. To begin with, CFD simulation technology was applied to optimize the flow field of the pump from cutting impeller and changing shape of the volute. Then the pressure pulsations and flow field excitation forces, before and after the optimization, were compared and analyzed. After that, the best method of cutting impeller was selected considering the requirements of processing technology. Finally the effectiveness was indirectly verified by analyzing the change of seat vibration response. The results show that: cutting impeller and changing the tongue shape can improve the pressure pulsation and fluid exciting force of the pump under blade frequency and its frequency doubling to some extent, and the seat vibration response after cutting reduces by 4dB. Related Articles | Metrics

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Optimal Bounded Semi-continuous Control of Nonlinear Random Vibration of Taut Cables 2014, 34(2): 133-135.  DOI: 10.3969/j.issn.1006-1335.2014.02.030 Abstract ( )   PDF (1080KB) ( )   The optimal bounded semi-continuous control of nonlinear random vibration of an inclined taut cable is studied. The nonlinear equation of transverse motion of the cable with control and excitation is derived, and converted into the vibration equations with multi-mode coupling by using the Galerkin method. Under considering control boundness, the random optimal control problem on the nonlinear cable system with multi-degree-of-freedom is formed. Then the HJB equation is determined and the optimal bounded semi-continuous control law is obtained based on the random averaging method, dynamical programming principle and variational principle. Numerical results show that the proposed control can achieve better actual effectiveness for the nonlinear random vibration of the cable. Related Articles | Metrics

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Design and Practice of Acoustics of a Small Room 2014, 34(2): 136-139.  DOI: 10.3969/j.issn.1006-1335.2014.02.031 Abstract ( )   PDF (1255KB) ( )   Abstract: This article is based on indoor acoustic field of small room as the research object. According to two of the same size small rooms, we use ODEON and CARA CAD to design and simulate the sound field. After that we decorate the two rooms according to sound field design and simulation results. When the decoration finished we test and analyse the sound field of the two rooms respectively. The whole text aims at expounding the effect and characteristic of ODEON and CARA by the sound quality design and practice in two small rooms. Finally, we verify and analyse the rusults of sound field design from the correctness ,rationality and operability. In the end, the evaluation and suggestion of ODEON and CARA used in design of small rooms are given. Related Articles | Metrics

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Recognition of Damping Ratio of the Cylinder Head of Diesel Engines Based on Hilbert-Huang Transform 2014, 34(2): 140-143.  DOI: 10.3969/j.issn.1006-1335.2014.02.032 Abstract ( )   PDF (1233KB) ( )   Knock test was taken on cylinder of some 12150 diesel，and vibration acceleration signal was collected. Modal response weakening component corresponding to main frequency component in the vibration acceleration signal were extracted by EMD, each component was processed with HT and least square method, and modal frequencies and damping ratio of cylinder system were obtained. The results was used in transient dynamic simulation of cylinder system and gained good effect, which proved modal frequencies and damping ratio of cylinder system obtained by this method were comparatively reasonable and could meet the need of research on cylinder system dynamic. Related Articles | Metrics

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Fractal Characteristics and Fault Diagnosis of Vibration Signal of Diesel Engines 2014, 34(2): 144-147.  DOI: 10.3969/j.issn.1006-1335.2014.02.033 Abstract ( )   PDF (1146KB) ( )   Having research the application of the wavelet packet de-noising and correlation dimension in fault diagnosis of diesel engine, discussing the selection of related parameters in the calculation of correlation dimension. The wavelet packet de-noising processes the engine vibration signal firstly , then the autocorrelation function method for time delay, saturation correlation dimension method to determine the minimum embedding dimension, the improved G-P algorithm to calculate the correlation dimension. The analysis shows, wavelet packet can effectively reduce the noise disturbance, the diesel engine has different correlation dimension in different conditions, this method can be effectively applied to the fault diagnosis of diesel engine. Related Articles | Metrics

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Application of High-pass Filtering in Damage Identification 2014, 34(2): 148-151.  DOI: 10.3969/j.issn.1006-1335.2014.02.034 Abstract ( )   PDF (1198KB) ( )   Abstract: In this paper ,a new damage detection technique using high-pass filtering base on structural mode shape is proposed. This method,with no need of the data of the health structures, the structural mode shape is treated as a group of one-dimensional discrete signal, including　 low-frequency components(mode shapes)which changes slowly and high-frequency components(damage) which changes quickly.In this method, the mode-shape of a cracked beam is first obtained ,then a simple algorithm of high-pass filtering is developed to extract the high-frequency components from the mode shape, the location,number and size of the cracks in the beam can be determined by the peak value.Theoretical calculations is first given in this article,then the effect of the location and size of the cracks by this method of the beam is studied, the experimental result of aluminum beam is analysised at last,the successful detection of crack in the beam demonstrates that the new technique developed in this study can be used efficiently in damage identification and health monitoring of beam-type structures. Related Articles | Metrics

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Improved LMD and Wavelet in rolling bearing fault diagnosis 2014, 34(2): 152-157.  DOI: 10.3969/j.issn.1006-1335.2014.02.035 Abstract ( )   PDF (1763KB) ( )   Local mean decomposition (Local Mean Decomposition, LMD) is a new time-frequency analysis method appeared in recent years，the field of application in fault diagnosis increasingly widespread. This paper presents an improved local mean decomposition and Wavelet denoising method combining and noise reduction with wavelet transform method, based on a collection of empirical mode decomposition (Ensemble empirical mode decomposition, EEMD) and wavelet signal drop noise method were compared using the root mean square error of SNR and compare noise reduction. Finally, an example of inner and outer rings of rolling bearing fault signal spectrum analysis, show that the method can be well mixed in the failure to remove noise in the signal, accurately determine the type of bearing failure and location. Related Articles | Metrics

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Gearbox’s Fault Diagnosis and Residual Life Prediction Based on MoG-BBN Method 2014, 34(2): 158-163.  DOI: 10.3969/j.issn.1006-1335.2014.02.036 Abstract ( )   PDF (1543KB) ( )   A new approach for gearbox fault diagnosis and remaining useful life (RUL) prediction based on Mixture of Gaussians Bayesian Belief Network (MoG-BBN) was presented. State number optimization method was established based on cluster validity measures. One can recognize the gearbox degradation state through identifying the hidden state that best fits the observations. Then, the RUL prediction method was presented at the recognition base. Finally, the data of gearbox’s full life cycle test was used to demonstrate the proposed methods. The results showed that the mean accuracy was 96.47%. Related Articles | Metrics

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Application of Vibration Monitoring Technique in Fault Diagnosis for Rotating Machinery 2014, 34(2): 164-168.  DOI: 10.3969/j.issn.1006-1335.2013.03.037 Abstract ( )   PDF (1547KB) ( )   With the increasing complex structure of rotating machinery, the failure probability is increasing, so higher requirements for the fault detection technology occurring. The vibration monitoring technology is a main method of fault diagnosis, it judges fault characteristics and position with analysis of the vibration signals of mechanical equipment.Firstly, the principle of vibration monitoring technology and the typical vibration faults are introduced in this article, and using of vibration monitoring technology to illustrate application of vibration monitoring technology in fault diagnosis for rotating machinery. Related Articles | Metrics

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Analysis of Noise Reduction Performance of a New Shape-memory Alloy Damper Attached to Recycled Concrete Frame 2014, 34(2): 169-172.  DOI: 10.3969/j.issn.1006-1335.2014.02.038 Abstract ( )   PDF (1425KB) ( )   Abstract: The Shape Memory Alloy (SMA) is a kind of material possessing the brand-new functions. This paper first takes a stress – strain measuring experiment on SMA wire. We propose a new type of hinge-type SMA damper based on stress-strain test results as well as pseudo-elastic phase transition theory, and apply it into the selected three layers of concrete RAC framework model. Through a model under earthquake time-history response with ANSYS analysis showed that：the new type SMA damper is an ideal passive energy dissipation devices, which can effectively reduce small structural displacement, velocity and acceleration response, that damping effect is obvious. Related Articles | Metrics

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Design and Test of a Hydraulic-electric Damper with Vibration Energy Recovery 2014, 34(2): 173-176.  DOI: 10.3969/j.issn.1006-1335.2014.02.039 Abstract ( )   PDF (1198KB) ( )   Abstract: Mechanical energy is one of the most popular energies existing in the environment. To reduce its damage effect, the vibration has been dissipated by the man-made damper, which is in fact a energy-wasting device. In this research, a damper that is capable of harvesting vibration energy was proposed. The device was designed in accordance with the hydraulic-electric generation principle. A prototype device was fabricated and tested in a set-up. The experiment result turns out that both the frequency and the resistance have the effect on the harvested electrical energy. The maximum instantaneous power 49w was obtained at the condition of 2Ω load resistance and 1Hz sinusoidal excitation. Hence it is feasible to transform part of vibration into the electricity during the operation of the damper. Related Articles | Metrics

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Anechoic Performance Analysis of Porous Ceramics 2014, 34(2): 177-180.  DOI: 10.3969/j.issn.1006-1335.2014.02.040 Abstract ( )   PDF (1220KB) ( )   The application of porous ceramic to acoustics domain was summarized, and acoustics theory was expatiated when porous ceramic was used as sound absorption material, sound insulation material and muffler. However, the research on porous ceramic used as muffler was less. In order to determine the major factors affecting anechoic properties, exhaust experiments on different porous ceramic were carried out under the two different conditions. Porosity is the basic parameter of porous ceramic, related to physical performance. The porosity of porous ceramic chose in the experiments was about 40% to eliminate effect. The results show anechoic property is better when the porous ceramic is thicker, and anechoic property of porous ceramic with aperture of 20μ is highest. When the temperature rise, the anechoic spectrum curve of porous ceramic moves towards high frequency. Related Articles | Metrics

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Application of Tuned Mass Damper to Cabin Booming Noise Reduction 2014, 34(2): 181-184.  DOI: 10.3969/j.issn.1006-1335.2014.02.041 Abstract ( )   PDF (1438KB) ( )   The interior noise measurement and modal test of the Secondary Car Frarme are used to diagnose the contribution of the cabin booming noise. It is found that the forced dynamic response of the 1st order Secondary Car Frarme in 2400r/min leads to the cabin booming noise. Base on this, A Tuned Mass damper with optimal parameters is designed to reduce the booming noise. Road test proves the engineering proposal effective. Related Articles | Metrics

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Damping Design of Onboard Electronic Equipment 2014, 34(2): 185-187.  DOI: 10.3969/j.issn.1006-1335.2014.02.042 Abstract ( )   PDF (891KB) ( )   As to the issue of onboard equipment’s poor performance and fatigue damage caused by vibration, a method is proposed to design vibration damper. According to experiment data and forced vibration theory, a model of equivalent vibration damper is established, and two groups of metallic wire mesh vibration damper are designed, and some experiments are used to test vibration dampers performance. The experimental results show that the two group of vibration damper can weaken onboard electronic equipment vibration, and the second group damper’s performances are superior to the first ones. This verifies that the vibration damper method is reasonable, and it can improve system performance and the life of the onboard equipment. Related Articles | Metrics

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Introduction and Experimental Analysis of Floating Rail Fasteners with Tuned Dampers 2014, 34(2): 188-191.  DOI: 10.3969/j.issn.1006-1335.2014.02.043 Abstract ( )   PDF (1342KB) ( )   　　　　This paper introduces the structural characteristics of a tuned damper system for a floating rail fastener used on rail subway system. The tuned damper system has been designed based on the dynamic absorber theory to reduce rail vibration in the frequency range below 2000Hz. The side supporting rubber wedge of the fastener contains several tuned masses. The rail vibration energy can be transferred and absorbed by the tuned mass so that the rail vibration and its noise radiation can be reduced. The measured results in Chengdu Metro Line one show that the rail vibration insertion loss of 1.5dB in the vertical direction and 0.8dB in the lateral direction has been achieved by tuned damper floating rail fastener, compared with that on DVTI2 fastener track. This system provides a solution to solve the problem of rail vibration increase caused by a softer rail fastener. Related Articles | Metrics

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Study on Sound Insulation Performance of Sandwich Panels with Rubber Cores 2014, 34(2): 192-195.  DOI: 10.3969/j.issn.1006-1335.2014.02.044 Abstract ( )   PDF (1137KB) ( )   Based on Hoff theory of sandwich panels and acoustical mechanism of reflection, transmission and radiation, a vibro-acoustic theoretical model was established, which was solved through orthogonality property of modal functions and interface fluid-structure coupled boundary condition. And sound transmission loss formulas of sandwich panels simply located in the mixed sound field environment were derived according to sound field property. Finally, a research on the influence of different damping factors, thicknesses, elastic modulus of core layer and the panel structure dimensions on sound transmission loss of sandwich panels was carried out by using numerical simulations, which had some guiding significance on the engineering practice. Related Articles | Metrics

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Testing Technique of Sound Pressure Levels of Miniature Mute Bearings 2014, 34(2): 196-199.  DOI: 10.3969/j.issn.1006-1335.2014.02.045 Abstract ( )   PDF (1530KB) ( )   A kind of driving and loading device of miniature quite bearing is developed according to existing testing standard of foreign countries. Signal collection and processing system of miniature quite bearing is constructed and A-weighted sound pressure levels of type 618/1.5 bearing are measured. By analyzing and comparing the test results, it is shown that the testing system can work stably and it can basically satisfy the testing requirements of sound pressure of miniature quite bearing. The results can provide references for sound pressure testing of miniature quite bearing. Related Articles | Metrics

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Measurement and Study of Loss Factors for Inseparable Structures 2014, 34(2): 200-202.  DOI: 10.3969/j.issn.1006-1335.2014.02.046 Abstract ( )   PDF (952KB) ( )   Abstract: Base on an actual project, a method of measurement of dissipation and coupling loss factors for inseparable structures is presented. The dissipation loss factors can be considered as an approximation of total loss factors of inseparable structures according to the method. Then the coupling loss factors can be calculated using dissipation loss factors and steady energy ratio. Additionally the deviation between total and dissipation loss factor which would be affected by coupling loss factors was simulated. The result showed that total loss factors were much closed to dissipation loss factors when coupling loss factors were far less than dissipation loss factors. Finally, loss factors of a coupled bi-cylinder shells were measured, the experiment results shows that the proposed method is resonable and reliable. Related Articles | Metrics

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Dynamic Measurement and Analysis of Pressure on Volute Wall of  a Centrifugal Fan 2014, 34(2): 203-206.  DOI: 10.3969/j.issn.1006-1335.2014.02.047 Abstract ( )   PDF (1317KB) ( )   The fluctuation of static pressure at 4 points on the volute of a centrifugal fan were measured with the high response pressure transducer. Through the analysis of the test results, the amplitude and frequency of the pressure fluctuations along the volute axial was abtained Related Articles | Metrics

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Dynamic Stiffness Test and Its Application in Analysis of  Unbalance Response of Rotor 2014, 34(2): 207-211.  DOI: 10.3969/j.issn.1006-1335.2014.02.048 Abstract ( )   PDF (1359KB) ( )   A test method about the dynamic stiffness was presented in this paper, The method is base on the linear relation between unbalance vibration force and the unbalancing response of the rotor. Based on dynamic stiffness, the dynamic balancing method without trial weight was presented through the constraint between the dynamic stiffness and the influence coefficient. A double disk single rotor tester was built at first, then calculated the dynamic stiffness at different speed after getting the curve of the unbalancing respond tester .Through this work, the dynamic balance theory was verified. The result show that the method gains a significant effect. Related Articles | Metrics

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Measurement of Transmission Loss and Improvement of Structure of a Car’s Dash Panel 2014, 34(2): 212-215.  DOI: 10.3969/j.issn.1006-1335.2014.02.049 Abstract ( )   PDF (1280KB) ( )   The transmission loss of a car dash panel was measured based on reverberation room-anechoic room method with sound intensity. Results show that the change-over valve for the inside cycle and the outside cycle in the air inlet of the air conditioner is the primary acoustic weak link because its poor fit with the valve port. On this basis, some sealing material was pasted on some parts of the change-over valve, where the valve body touches the valve port. Besides, the original acoustic material, EVA + Low Melting Point Felt, was replaced by a modified one, EVA + Low Melting Point Felt+ Bi-component. Corresponding measurement results show that the transmission loss of the car dash panel is improved by about 7dB on average in 500~6300Hz. This work is of great significance on the improvement of the sound insulation property of the dash panel and the acoustic environment in the car. Related Articles | Metrics

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A Method for Isolator Impedance Testing Based on  Acceleration Measurement 2014, 34(2): 216-221.  DOI: 10.3969/j.issn.1006-1335.2014.02.050 Abstract ( )   PDF (988KB) ( )   Related Articles | Metrics