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18 December 2013, Volume 33 Issue 6 Previous Issue    Next Issue

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Adaptive High Precision Displacement Control for Giant Magnetostrictive Actuators 2013, 33(6): 1-4.  DOI: 10.3969/j.issn.1006-1335.2013.06.001 Abstract ( )   PDF (1164KB) ( )   Giant magnetostrictive actuator (GMA) has many applications in the area of precision driving technologies, however, giant magnetostrictive material (GMM) has the inherent nonlinear problem, like hysteresis, during the magnetization process, and the nonlinear error may reach up to 20%. To solve such kind of problem for achieving reliable precision driving performance, GMA needs to be modeled by a precise and effective method, and the model can be applied in precise driving control of GMA. In this research, LMS algorithm is used to do the identification of the GMA system, by which the GMA system can be efficiently modeled online. The identification model capable of achieving up to 0.069 μm precision can accurately approximate the output displacement signal of GMA with input current signals of different types and frequencies. Finally the Fx-LMS algorithm is implemented to execute the displacement control of the actuator. During the experiment, an online identification procedure is employed to reduce hysteresis influence and improve the control precision of displacement driving of GMA. Related Articles | Metrics

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An Inverse Response Surface Method for Finite Element   Model Updating 2013, 33(6): 5-10.  DOI: 10.3969/j.issn.1006-1335.2013.06.002 Abstract ( )   PDF (880KB) ( )   Using the Response Surface Method (RSM) for Finite Element (FE) model updating is to obtain the explicit relationship between the characteristic parameters (such as natural frequencies and mode shapes) and the design parameters (such as density and Young’s modulus) by the regression analysis method. The function of RSM uses the characteristic parameters as dependent variables and the design parameters as independent variables. This paper proposes an Inverse Response Surface Method (IRSM), which is constructed by using the design parameters as dependent variables and the characteristic parameters as independent variables. Compared with RSM, using IRSM for FE model updating is able to obtain the updated values directly, instead of by iteration, based on the target value of the characteristic parameters, which can efficiently improve the calculation speed and accuracy. This paper introduces the IRSM and its application, discusses the advantages and disadvantages, and analyzes the function of IRSM, the design of experiment and the evaluation of regression accuracy. A numerical example of a simply supported beam shows that IRSM updates the FE model efficiently and precisely, and that IRSM notably reduces the cost of FE calculation in the case that the number of output is less than the number of input, which is suitable for the complex engineering structures. Related Articles | Metrics

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An Updating Method for Structural Dynamic Model Applicable for Transient Rocket Response Computation 2013, 33(6): 12-14.  DOI: 10.3969/j.issn.1006-1335.2013.06.003 Abstract ( )   PDF (1127KB) ( )   The structure of a large-scale rocket is very complicated. Different types of connections and multi-branch structures exist. Some typical connections which show the characteristic of low stiffness, such as flanging connection and bolt point connection, are analyzed. Based on the element method, the stiffness of the connections is selected as the updating parameters and a dynamic model updating method is presented. The results show that the physical meanings and the realness are kept. The presented method is well suitable for the structural response, especially the internal force response calculation under transient excitation. The modal results of the updated model fit well with the experimental results. Quite high accuracy is obtained compared with the measured transient response results in the flight, which shows that the method is applicable in engineering design. Related Articles | Metrics

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Modal Testing and Finite Element Analysis of Scroll   Compressor’s Parts 2013, 33(6): 15-17.  DOI: 10.3969/j.issn.1006-1335.2013.06.004 Abstract ( )   PDF (1128KB) ( )   Experimental modal analysis of scroll compressor’s crankshaft was conducted with the hammer through TestLab 5A of LMS. The first three modes parameters were achieved. Modal calculation was carried out on the same conditions through ANSYS. Error is within permissible range according to the comparison of experimental modal parameters and calculated modal parameters. Modal calculations of other major parts were conducted and the first six modes parameters were obtained. The basis for dynamic analysis and structural improvement of scroll compress’s major parts were provided through the analysis of vibration modes of upper shell, shell and assembly. Related Articles | Metrics

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Parameter Identification of Closely Spaced Structural Modals Based on Analytical Mode Decomposition 2013, 33(6): 18-24.  DOI: 10.3969/j.issn.1006-1335.2013.06.005 Abstract ( )   PDF (1325KB) ( )   Closely spaced modes are commonly seen in dynamic responses of long span bridges and high rise buildings, however, up to present, it is still a quite challenge to identify structural modal parameters with closely spaced modes using traditional signal analysis method. In this paper, a combined random decrement technique and analytical mode decomposition method is proposed for modal parameter identification under operational vibration. The random decrement technique is used to extract the free vibration information from a measured response. The analytical mode decomposition is developed with Hilbert transform to decompose the extracted free vibration with closely spaced natural frequencies into a series of modal responses from which modal parameters are evaluated using linear fit technique. Parametric studies with 2-story building are placed on the characterization of frequency resolution, time duration effect. The results show that the modal mixing problem can be eliminated by extracting short time duration free vibration using random decrement technique, and with enhanced analytical mode decomposition method, each short time duration modal responses can be separated and used for modal parameter identification. The new method is then applied to a 36-story shear building with a 4-story light appendage with closely spaced modes, and validated with shake table testing of a 3-story building frame installed with a tuned mass damper. Both simulations and experiments showed high accuracy and effectiveness of the new method for building system identification from operational vibration. Related Articles | Metrics

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Analysis of Dynamic Characteristics of  High Speed Spindle-Holder-Tool System 2013, 33(6): 25-30.  DOI: 10.3969/j.issn.1006-1335.2013.06.006 Abstract ( )   PDF (1240KB) ( )   Due to the effects of speed on the stiffness of ball bearing, it is a challenge to determine the frequency response functions of tool point, which is determination on the stability analysis of milling processes. In this paper, based on the receptance coupling method, the model of spindle-holder-tool system is established to obtain the frequency response function of the tool tip at different rotational speed. The speed-varying chatter stability lobe is generated with the semi-discretization method. It is shown that the stability lobe with speed effects shift to the low speed range at high speed milling, also the critical milling depth is significantly reduced. Related Articles | Metrics

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Research of the Vibration of Turbine-generator Units Based on Linear Stepwise Regression 2013, 33(6): 31-35.  DOI: 10.3969/j.issn.1006-1335.2014.01.007 Abstract ( )   PDF (1060KB) ( )   Research on base vibration effected by turbine-generator unit is significant for reducing vibration which transfers to the other equipments linked the base and leads to faults of equipments. Experiment workbench for reason analysis on base vibration is designed by mounting vibration isolators, and RMS of base vibrations with different conditions of turbine rotation speed, air pressure at intake and generator loads are also gained. Statistical analysis on relationship between parameters and vibration RMS are carried out by linear stepwise regression. At last, results from statistical analysis are validated by time-frequency-map variety of base vibration in the processes of turbine-rotation-speed continuous reduction and intake-pressure uprising. The result shows that, the base vibration of turbine-generator unit linear relates with rotation speed and load of turbine, and the linear relation of the rotation speed is more distinct than that of load. The turbine rotation speed effects base vibration significantly rather than load, and air pressure at intake of turbine has less effect on base vibration. The linear stepwise regression method can effectively elicit factors which effect vibration of turbine-generator-unit base, and reliably estimate importance of each factor. Related Articles | Metrics

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Variational Iteration Method for Analyzing Dropping Shock ofSuspended Spring System 2013, 33(6): 36-39.  DOI: 10.3969/j.issn.1006-1335.2013.06.008 Abstract ( )   PDF (956KB) ( )   With suspended spring system as research object, the non-dimensional geometrical nonlinear dynamic equation without damping of dropping shock of the system was established. Variational iteration method was used to solve dynamic equation, and the first-order approximate analytical solution of non-dimensional displacement, and non-dimensional acceleration were obtained. The peak values of non-dimensional displacement, and non-dimensional acceleration, and the period of dropping shock were compared with results of elliptic integral method. The relative errors were less than 4%. The influence of the dropping height and the system suspension angle on the peak value of non-dimensional displacement and non-dimensional acceleration were discussed. Research showed that, in the same dropping height conditions, appropriately reducing the suspension angle of the system could reduce the peak value of non-dimensional acceleration, but the peak value of non-dimensional displacement increased. The purpose was to provide reference for design of shock absorber with suspension spring system. Related Articles | Metrics

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Simulation Analysis of Multi DOF Platform Control in High Precision Plant Based on Actuator Models 2013, 33(6): 40-44.  DOI: 10.3969/j.issn.1006-1335.2013.06.009 Abstract ( )   PDF (1035KB) ( )   To further improve the platform vibration isolation effect in high precision plant. In the control design, the nonlinearity of the giant magnetostrictive actuator has some effect on hybrid control system for a MDOF (Multi-degree of freedom) platform. So the four giant magnetostrictive actuator models are built in the hybrid control system. First, the multi-degree of freedom hybrid control system was established with the air springs and the giant magnetostrictive actuator as the basic components. Then Jiles-Atherton model was used to establish a giant magnetostrictive actuator model and its inverse compensation model and the established model was built in the multi-degree of freedom micro-vibration control system. Finally, the high-precision platform’s response under the actuator model based hybrid control system and passive control systems were compared and it shows that the hybrid control system can achieve a good control effect. Related Articles | Metrics

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High Static Stiffness and Low Dynamic Stiffness Isolation Characteristics of Irregular Elastic Sheets 2013, 33(6): 45-48.  DOI: 10.3969/j.issn.1006-1335.2013.06.010 Abstract ( )   PDF (1170KB) ( )   On the base of the predecessors’ research about placed tilt uniform sheet of elastic’s vertical direction “High Static Stiffness Low Dynamic Stiffness Isolation Characteristic(HSLDS)”, presented the nonlinear statics equation by the potential energy function and Euler-Lagrange method. We analyzed the connection between key parameters and vibration output by numerical analysis technology and optimized, designed prototype machine then completed static test and displacement transfer rate test. Verified the structure have well HSLDS characteristics. Results of this study are of significance for the design of high static stiffness low dynamic stiffness vibration isolator. Related Articles | Metrics

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Noise Prediction of Wind Turbines Based on Regression Analysis and BP Neural Network 2013, 33(6): 49-52.  DOI: 10.3969/j.issn.1006-1335.2013.06.011 Abstract ( )   PDF (1109KB) ( )   Abstract: Aiming at current situation of the energy problem and the complicated process of wind turbine noise detection, after studied IEC 61400-11 noise measurement technology standard, this paper put forward a kind of forecasting method combined regression analysis with BP neural network, forecast the A-weighted noise sound pressure level of wind turbine. The plural linear regression equation was established according to collected datum on wind farm, then calculated regression coefficient and simplified equation to r train the BP neural network with less inputs. Finally, the noise prediction model was established. This model was applied to noise measurement on a wind farm in Xinjiang, and made good effect. So the feasibility and effectiveness of this method was verified. Related Articles | Metrics

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Visualization of Sound Intensity Field Based on NAH 2013, 33(6): 53-56.  DOI: 10.3969/j.issn.1006-1335.2013.06.012 Abstract ( )   PDF (1017KB) ( )   A method of visualizing the sound intensity field has been designed to solve the noise sources identification of the underwater-structure. Firstly we figure out the intensity vector field among the medium, and then complete the visualization of this vector field by volume rendering and streamline technology. The noise sources can be identified and also the sound energy distribution and dissipation can be displayed by volume rendering of the absolute values of the sound intensity. The direction of the propagation can be described by the streamline. This paper offers a new way of monitoring and analyzing the radiated acoustic field of underwater structure. Related Articles | Metrics

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Application of Boundary Meshless Method in   Noise Source Diagnosis 2013, 33(6): 57-61.  DOI: 10.3969/j.issn.1006-1335.2013.06.013 Abstract ( )   PDF (1195KB) ( )   The boundary mesh-less method(BMLM) was introduced to the modeling of acoustic radiation and transmission, which was requested by acoustic holography that on arbitrarily shaped boundary. Thus, the Kirchhoff-Helmholtz boundary integral equations those on arbitrary closed 3-D surface were discretized and solved accurately. Furthermore, the basic principle and the illness of acoustic reconstruction process that using arbitrary shaped acoustic holography were researched. A feasible solving method of this ill-posed problem that based on Landweber iterating regulation algorithm and “L” curve parameter selection strategy was established. So, the illness of this inverse problem could be eliminated by this new solving method. A reconstruction experiment of gear motor noise source was carried on, and the results verify that the theories and methods of acoustic holography on arbitrarily shaped boundary that using BMLM which were proposed in this article are feasible and reliable. Related Articles | Metrics

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A Sorting Method of Hearing Protectors Based on Cluster Analysis zhongfuLI 2013, 33(6): 62-65.  DOI: 10.3969/j.issn.1006-1335.2013.06.014 Abstract ( )   PDF (1010KB) ( )   Related Articles | Metrics

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Theoretical and Experimental Study on Vibration Characteristics of Phononic Crystals with Two-dimensional Composite Structure 2013, 33(6): 66-71.  DOI: 10.3969/j.issn.1006-1335.2013.06.015 Abstract ( )   PDF (1783KB) ( )   inite-element model of two dimensional is established to analyze transportation characteristic of composite structure phononic crystals in order to know the impact of the parameters of three components on the initial and ending frequency of band gap and bandwidth.The effect of the material parameters, such as the material, the structure parameters, cycles, the way of range impact on the band gap are analyzed. The phononic crystal sample is made of aluminum, steel, silicone, and the transmission characteristics of experiments is in good agreement frequency response curve of finite element simulation results, which can give an evidence for phononic crystals using in the automotive middle and low frequency anti-vibration. Related Articles | Metrics

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Application of Finite Element Method to Inverse Analysis of Dynamic Parameters of Viscoelastic Slender Bars 2013, 33(6): 72-75.  DOI: 10.3969/j.issn.1006-1335.2013.06.016 Abstract ( )   PDF (884KB) ( )   Viscoelastic materials have been widely used in the noise and vibration control since they can provide high damping capability over wide temperature and frequency ranges. Design or selection of damping structure requires the knowledge of the dynamic performance of viscoelastic materials. Resonant bar technique is a classical method which has been used to the viscoelastic material parameter measurement. In this paper, an inverse method for dynamic parameters estimation of viscoelastic thin bar is presented, in which the measured response of the bar longitudinal vibration is gradually approximated by the forward calculated response form finite element computation. The loss factor is firstly estimated from the displacement magnitude ratio between the driven end and the free end of the bar. Then, the complex-modulus is estimated from the resonant frequency. The proposed inverse method is demonstrated valid and accurate by experiment. Related Articles | Metrics

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Influence of Driver’s Behavior on Traffic Noise 2013, 33(6): 76-81.  DOI: 10.3969/j.issn.1006-1335.2013.06.017 Abstract ( )   PDF (1163KB) ( )   Based on the driving behavior model of the microscopic traffic simulation system, using of the road traffic noise prediction model building by the acoustical society of Japan, the influence of driving behavior on traffic noise was studied. The sensitivity analysis showed that the road traffic noise in congested condition was sensitive to the following behavior and the driver’s reaction to the signal control, and the influence of the car following behavior could reach 2.07dB; in non-congested condition, driving behavior had little influence on traffic noise. It was shown that the influence of the driver's behavior on noise emission energy in the whole area is similar to the value of LAeq by the roadside，nevertheless the influence of the driver's behavior on noise emission energy measured in unit trip distance appears contradiction to the value of LAeq by the roadside. Related Articles | Metrics

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Correlation of Subjective Evaluation and Objective Tests for Impact Hardness / Memory Shake When Vehicles Passing Speed Bumpers 2013, 33(6): 82-86.  DOI: 10.3969/j.issn.1006-1335.2013.06.018 Abstract ( )   PDF (1169KB) ( )   This paper describes the method of subjective evaluation and objective tests on impact shake when vehicle passing the typical speed bumper. By analyzing the impact hardness and impact shake response signal and further study on the the signal characteristics a Neural Network is setup to build the correlation between subjective rating and test results. The feasibility of this method applying on small sample group is also been studied. Related Articles | Metrics

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Analysis of Noise-vibration Characteristic and   Optimization Design of Excavator’s Cab 2013, 33(6): 87-90.  DOI: 10.3969/j.issn.1006-1335.2013.06.019 Abstract ( )   PDF (1590KB) ( )   Structure finite element model of a excavator cab is built by Hypermesh in this paper.After set,the structure modal is analyzed in Nastran. In the Virtual-lab, acoustic model is generated and analyzed. Taking the driver’s ear as the farfield, the acoustic frequency response functions by the coupling effect of the acoustic chamber and structure are calculated. Panel contribution amounts to the corresponding frequency of the peak pressure are calculated. According to the analysis results,the scheme of optimization is given, and then the optimization effect is checked. Related Articles | Metrics

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Acoustic Seal Performance Test of a Car Based on Beamforming YangYang 2013, 33(6): 91-95.  DOI: 10.3969/j.issn.1006-1335.2013.06.020 Abstract ( )   PDF (1427KB) ( )   Source identification accuracy of beamforming was verified firstly by identification result of a given beeper source. On that basis, acoustic seal performance test of a car based on beamforming was conducted in an anechoic room. Results show that the bottom rear end of the front door and the rear window have poor performance. The conclusions indicate a direction for improvement of the acoustic seal performance, thereby reducing the interior noise and improving the riding comfort. Related Articles | Metrics

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Rigid-flexible Coupling Analysis for Ride Comfort of Car with Flexible Frame 2013, 33(6): 96-99.  DOI: 10.3969/j.issn.1006-1335.2013.06.021 Abstract ( )   PDF (1202KB) ( )   Based on the modal analysis of frame with FEM, the rigid-flexible coupling model of car with flexible frame is established using multi-body dynamics software ADAMS/Car. The vertical acceleration of body Center of gravitation, suspension dynamical deflection, and tire dynamical deflection are analyzed by comparing with rigid body model. The research results show that the PSD of vertical acceleration of body Center of gravitation reduces by 14.7%, suspension dynamical deflection increases by27.1%, tire dynamical deflection decreases by 14.8%, Compared with rigid model. In addition, the frame flexibility has little effect on body main frequencies and has large effect on the body vertical acceleration in more than 20Hz. Related Articles | Metrics

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Optimization of Vibration Isolation of Powertrain Mounting System and Its Engineering Application 2013, 33(6): 100-105.  DOI: 10.3969/j.issn.1006-1335.2013.06.022 Abstract ( )   PDF (1231KB) ( )   Abstract: Aimed at some vehicle engine, larger shake under the idling condition was represented , the simulation model of mounting system is established by adopting ADAMS, and the correctness of the model is verified by the test data . The stifness parameters of mounting are considered as the design variable，and the reasonable matching of natural frequency is taken as the restraint.Then, decoupling of energy and minimizing the transmission rate of mounting system are selected as target to analyze and optimize powertrain mounting system. The test results show that vibration isolation perfomance of mounting system is significantly improved after changing the mountings. Related Articles | Metrics

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Analysis of Vibration Response of Multi-axle Vehicle Based  on ANSYS 2013, 33(6): 106-109.  DOI: 10.3969/j.issn.1006-1335.2013.06.023 Abstract ( )   PDF (1223KB) ( )   In order to predict efficiently the vibration response characteristics of sprung mass at different locations on multi-axle vehicle under the speed input of road roughness, a 7-DOF dynamics simulation model was established according to multi-body dynamics principle in ANSYS. According to the vehicle engine test with the preset rotary speed, and the theoretical analysis, simulation of the vehicle was made with the established model. It shows that the results of simulation well agreed with the test, therefore, the proposed dynamics model and method has high reliability. Simulation results show that the vibration response characteristics of sprung mass at -6m~-4m is mainly influenced by the first natural frequency and -2m~4m is mainly affected by the second natural frequency under the speed input of road surface roughness, especially at the rear of sprung mass; the second natural frequency is the most important factor that impacts the acceleration vibration response characteristics of multi-axle vehicle, therefore, study should be focused on the 3rd and 4th axle suspension systems to improve its ride comfort. Related Articles | Metrics

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Modal Analysis of Vehicle Alternator 2013, 33(6): 110-114.  DOI: 10.3969/j.issn.1006-1335.2013.06.024 Abstract ( )   PDF (1449KB) ( )   Through noise test, a phenomenon is found that the alternator’s noise exceed significantly under certain speed when it run in condition of 0-5000rpm, which is mainly caused by electromagnetic resonance; as a result , the modal research was done. Both simulation method and test method were used to study modal. In simulation research part, simplified FE model of main components of the alternator was built firstly; then through node coupling, the whole motor FE model was got; and finally, simulation results of the various components and the whole motor were obtained after the FE calculation. In test research part, experiments were done to both unrestrained components and restricted alternator. Lastly, contrasts are done between simulation results and test results and good agreement is reached. Related Articles | Metrics

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Noise Analysis and Structure Optimization for an Engine’s Oil Pan 2013, 33(6): 115-119.  DOI: 10.3969/j.issn.1006-1335.2014.01.025 Abstract ( )   PDF (1649KB) ( )   Due to the linear motor vehicle motor suspension system has a special motor suspension structure, so it's vibration characteristics are different from the traditional motor suspension vehicle. In order to study the vibration characteristics of linear motor vehicle, we analyzed the positioning method from it's structure and it's vibration characteristics, then we studied the influence of it's structure to the bogie vibration characteristics and wheel/rail interaction, finally we introduced an innovative idea—underground linear motor initially. The result show that, the vertical and the horizontal vibration of the linear motor exist a certain degree of coupling, and the linear motor positioning structure has a great impact on the bogie vibration and wheel/rail interaction. Related Articles | Metrics

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Study on Characteristics of Internal Noise of Diesel Locomotive’s Cab 2013, 33(6): 120-123.  DOI: 10.3969/j.issn.1006-1335.2013.06.026 Abstract ( )   PDF (1032KB) ( )   In this paper, through testing and analysis interior noise of diesel locomotive cab by using noise and vibration test and analysis system, get the distribution pattern and characteristics of interior noise in the cab. The interior noise in the cab performance low-frequency noise that in the low frequency of 100 ~ 160Hz and IF peaks around 1250 ~ 2000Hz, 1600Hz near especially obvious; the operating speed has little effect on the cab noise when the running speed of the locomotive is less than 120km / h; the noise value inside the cab that near the end of the cooling chamber of the locomotive with double cab is about 2 to 4dB(A) more than that in the remote cab; the cab noise when the locomotive is stationary is about 2 to 5dB(A) less than the test value when the locomotive is run case in same conditions locomotive set. The results of the study provide the basis for design of noise and vibration reduction of the diesel locomotive's cab. Related Articles | Metrics

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Simulation of Exterior Flow Field and Interior Noise for   High-speed Trains 2013, 33(6): 124-128.  DOI: 10.3969/j.issn.1006-1335.2013.06.027 Abstract ( )   PDF (1349KB) ( )   The airflow noise on the surface of high-speed trains mainly depends on the fluctuating pressure on its body surface, so it is of great significance to further research and control the airflow noise of high-speed trains in order to research the fluctuating pressure on the surface of train body. The external flow field of high-speed trains was simulated by means of finite element method. The results show the characteristics of the external flow field of high-speed trains. On this basis some numerical simulation and calculation was conducted on the pulsating pressure of the surface of the high-speed train, and the interior sound pressure was calculated further, some significant conclusions were drawn. Related Articles | Metrics

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Numerical Prediction of Interior Noise of Waiting Hall of   High-speed Railway Station 2013, 33(6): 129-133.  DOI: 10.3969/j.issn.1006-1335.2013.06.028 Abstract ( )   PDF (1365KB) ( )   Abstract: In order to analyze interior noise of high-speed railway station waiting hall, a finite element model and boundary element model and statistical energy analysis model are established in this paper. The interior noise of waiting hall in a low frequency range from 20 to 200 is computed by using direct boundary element method (DBEM), the interior noise in a high frequency range from 200 to 2000 is calculated by using statistical energy method. The results are compared with measurement results, it is shown that the model is accurate for predicting the interior noise of the waiting hall. The panel acoustic contribution analysis (PACA) is done to determine the body panels of the waiting hall contributing most to the noise levels of the interior of the waiting hall. The study finds out that the ceilings of the waiting hall contributing most, it can be used as a guidance of noise reduction of waiting hall. Related Articles | Metrics

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Noise Prediction of Civil Airplane Engine Combustor 2013, 33(6): 134-138.  DOI: 10.3969/j.issn.1006-1335.2013.06.029 Abstract ( )   PDF (1277KB) ( )   Civil Airplane Engine combustor is one of the main sources of aircraft noise. The noise generated by the combustor not only has an effect on airworthiness certification, but also is a reflection of burning quality. Therefore, it is vital important to have an accurate prediction of combustor noise at the beginning of engine design. The noise prediction program is based on the generation mechanism and main influencing factors of combustor noise, developed by using MATLAB GUI. This program can predict SPL, OASPL, dBA and PNDB. Related Articles | Metrics

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Outlines of Anti-shock Design for Electronic Equipments on Ships 2013, 33(6): 139-142.  DOI: 10.3969/j.issn.1006-1335.2013.06.030 Abstract ( )   PDF (1018KB) ( )   Electronic equipments on ships are the foundation of the informatization establishment of warship devices. Under real working environment, electronic equipments would be shocked by underwater explosion load, and improper structure design may result in damage, even failure to them. The paper presented some basic principles for anti-shock design of electronic equipments on ships. Starting from the shock enviroment of ships and the anti-shock requirement of devices on ships, some outlines for design were proposed, mainly in the aspects of electronic cupboard structure design, the dynamic characteristics of engineering materials under shock as well as the isolator design priciples for shock protection. Then, the shock test machines and shock testing criteria are introduced for assessing the anti-shock ability of electronic equipments on ships. Related Articles | Metrics

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Analysis on the Low-frequency Acoustic Radiation Signature of the Shaft-hull Coupling System Under Propeller Exciting Load 2013, 33(6): 143-147.  DOI: 10.3969/j.issn.1006-1335.2013.06.031 Abstract ( )   PDF (1393KB) ( )   Numerical modeling on a scaled shaft-hull model is made using the finite element method firstly. Then the experimental data is used to verify and modify the dynamics model. Direct boundary element method is applied to compute the acoustic radiation signature of the hull when subjected to the propeller exciting force in both transverse and longitudinal direction. The acoustic pressure and far-field pressure distribution is obtained. The energy method is also used to compare the acoustic power under different loading conditions. Related Articles | Metrics

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Weak Modulation Signal Detection Based on Difference   Oscillator Time Course 2013, 33(6): 148-152.  DOI: 10.3969/j.issn.1006-1335.2013.06.032 Abstract ( )   PDF (1701KB) ( )   Abstract: Single differential oscillator can only detect a certain frequency component in the periodic signal detection. In order to determine the interval of side band of the signal under strong noise background, it is feasible to test frequencies of the multiple differential oscillator array one by one. But it will undoubtedly bring great amount of calculation which is uneconomical. Hilbert transform can be used to obtain the low frequency component of the signal in the modulation signal envelope analysis. But, if the low frequency component contains strong noise, the following traditional spectrum analysis will be failure, which is undesired. To solve the problem, the time history of differential oscillator can be used to test the gained envelope signal that consists of strong noise. So, in this paper, a new weak modulation signal detection method, based on time history of differential oscillator, is proposed. First, Hilbert transform is used in the envelope demodulation to gain the envelope component of the signal. Then ,do envelope demodulation test on the gained component which contains strong noise through the method of differential oscillator time history. The method had been successfully applied in the early fan fault detection. Related Articles | Metrics

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Analysis and Improvement of Independent ComponentAnalysis Algorithm 2013, 33(6): 153-157.  DOI: 10.3969/j.issn.1006-1335.2013.06.033 Abstract ( )   PDF (1460KB) ( )   The algorithm of FastICA, as it has been presented for processing a batch of the received sample data, it is unsuitable under the circumstance of channel matrix changing; although the Infomax algorithm based on Natural gradient could adjust the separation matrix according to the sample data of single observation, it is only appropriate for processing single type of source signal. In this paper, under condition of constant and variable information channel, advantages and disadvantages of the algorithms above are shown in simulation, meanwhile, an improved algorithm is proposed in order to solve the contradiction between convergence speed and steady-state error of the online algorithm. This improved algorithm created interrelation between variable step-size and degree of separation, and adjust step-size according to the similarity measure of the separation signals. The simulation shows that the algorithm has a better practical performance. Related Articles | Metrics

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Rub-impact Fault Diagnosis Based on Finite Element Method and   Envelop Analysis 2013, 33(6): 158-162.  DOI: 10.3969/j.issn.1006-1335.2013.06.034 Abstract ( )   PDF (1614KB) ( )   The characteristic of stator vibration signals under rub-impact status is studied through finite element and envelop analysis method. Firstly, the vibration season of stator is analyzed. The pulse force from rub-impact may lead to stator resonance, so the envelop analysis technology can be brought out to diagnose rub-impact faults. Aim at the structure characteristic of stator, the finite element method is presented to analyze the vibration performances of stator. Secondly, envelop analysis is performed to stator vibration signal, then the course of rub-impact faults diagnosis is completed. Lastly experiments with one-point rub-impact and local rub-impact are analyzed, results reveal that the stator resonance envelope signals can indicate rub-impact faults. Related Articles | Metrics

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Roller Bearing Fault Diagnosis Based on Hierarchical Entropy and SVM 2013, 33(6): 163-167.  DOI: 10.3969/j.issn.1006-1335.2013.06.035 Abstract ( )   PDF (1102KB) ( )   The sample entropy method of measuring the complexity of vibration signals is unable to describe the multiple time scales inherent in such time series, while the multiscale entropy method only consider the low frequency component of the original time series. In order to overcome the above-mentioned problem, a new feature extraction approach for roller bearing fault based on the Hierarchical Entropy (HE) is proposed. We analyze the experimental signals with the HE method, and use the sample entropy of the hierarchical decomposition nodes as the fault feature vector for roller bearing fault diagnosis. Then support vector machine is used as a classifier to identify different types of faults. The analysis results about the experimental data show its effectiveness. Related Articles | Metrics

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Analysis of Vibration and Crack Growth of a Cracked Plate 2013, 33(6): 168-171.  DOI: 10.3969/j.issn.1006-1335.2013.06.036 Abstract ( )   PDF (935KB) ( )   According to vibration and fatigue problems, the vibration analytical model with crack terms of a plate was derived. The crack was replaced by an external force based on the principle of similarity deformation, and the principle of mechanical equilibrium was used in the equation derivation in the first. In addition, the crack terms were obtained by using stress relational expression and the cracked plate was simplified to a one single freedom system through Galerkin method. Then the model was transformed into a nonlinear vibration equation via Berger’s experience. The vibration model of the cantilever cracked plate was used to discuss the vibration characteristics and the crack propagation behavior based on the Paris equation in the end. Results indicate that the impacts of damping and exciting force on vibration and crack growth of the cracked plate is obvious. The vibration analytical model of the cracked plate is a good tool for vibration analysis and crack propagation. Related Articles | Metrics

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Muffler Optimization Design with Design of Experiment Methods 2013, 33(6): 172-176.  DOI: 10.3969/j.issn.1006-1335.2013.06.037 Abstract ( )   PDF (1243KB) ( )   On the test and CAE method, find out the weak frequency of muffler. Make the internal structure of the muffler as design factors, design the test. solve mutual restraint problems between factors. Using ANOVA methods to analyze the results. Identify the structure contribution rate, and the main effect to the target. Make the parameter optimization. It calculated to improve significantly in the target. Related Articles | Metrics

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Acoustic Performance Analysis of Expansion Chamber Mufflers with Different Intubation Tubes 2013, 33(6): 177-179.  DOI: 10.3969/j.issn.1006-1335.2013.06.038 Abstract ( )   PDF (1038KB) ( )   This article focuses on acoustic performance of expansion chamber mufflers with intubation pipes, Transmission losses of expansion muffler is obtained by using the finite element method, the difference was analyzed with intubation expansion muffler and without intubation, and the influence on acoustic performance with different intubation structure is compared. The calculation suggests that there is no noise reduction for some pass frequency without intubation expansion muffler, and it can eliminate these pass frequency increase intubation. When the flow area is maintained constant, the acoustic performance is improved using parallel structure with multiple intubations at high frequency substantially. Related Articles | Metrics

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Improvement of Acoustic Performance ofan Excavator’s Exhaust Muffler 2013, 33(6): 180-183.  DOI: 10.3969/j.issn.1006-1335.2013.06.039 Abstract ( )   PDF (1498KB) ( )   Firstly, acoustic analysis was carried out on a particular excavator’s exhaust muffler by using a acoustic software（LMS Virtual.Lab） to calculate the transmission loss (TL) of the muffler in each frequency band. Secondly, the influence of different structure parameters on noise elimination performance was analyzed emphasizingly , according to the result of which the structure was optimized. The noise elimination performance is improved and a powerful value is provided for design and optimization of the muffler. Related Articles | Metrics

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Experimental Study on Acoustic Characteristics of the Porous Muffler Tube with Non-woven Fabrics 2013, 33(6): 184-187.  DOI: 10.3969/j.issn.1006-1335.2013.06.040 Abstract ( )   PDF (1078KB) ( )   Porous muffler tube with non-woven fabrics is proposed to attenuate the wide-band noise generated by the air intake system. The principle of the two-load method is discussed, Then highlights of the apparatus are discussed to confirm the accuracy of the experiment. Finally, the experiment apparatus is set up based on the theory to measure the transmission loss of the muffler tube. Through the experiment, the result shows that the transmission loss exhibits a broadband attenuation effect and fluctuates in the total frequency range. However, according to the experiment, 8dB attenuation can be achieved at least in all frequency range. It is expected that the conclusion will provide the application support for sound design of air intake system. Related Articles | Metrics

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Acoustic Performance of SCR Catalytic Converter Muffler ofDiesel Engines 2013, 33(6): 188-191.  DOI: 10.3969/j.issn.1006-1335.2013.06.041 Abstract ( )   PDF (1406KB) ( )   Three dimension finite element analysis method is adopted for simulating transmission loss of the reactive muffler. Then the SCR substrate catalyst is coupled into the reactive muffler. The attenuation performance of side extended inlet muffler and side perforated tube muffler is investigated. Based on the side extended inlet muffler, the end chamber is revised to extended muffler; the arrangement of the extended tubes and perforated outlet tube for acoustic attenuation is studied. Then the substrate catalyst is coupled into the muffler, the transmission loss of the SCR catalytic conversion muffler is calculated. The results show that this kind of muffler structure has better acoustic performance during the whole frequency range. Related Articles | Metrics

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On the Effect of Cladding in Diffsorber Design 2013, 33(6): 192-196.  DOI: 10.3969/j.issn.1006-1335.2013.06.042 Abstract ( )   PDF (1434KB) ( )   When in resonance, diffsorber has a low sound absorption at high frequency, because the internal impedance in the tube and the radiation impedance outside the tube often can not match. To solve this problem, a cladding on the surface of the diffsorber would have some positive improvement. Using acoustic cladding can increase the acoustic impedance in the tube, and the internal resistance and radiation resistance at high frequencies will better match to further improve the sound absorption at high frequencies, so the diffsorber can reach a good sound absorption in a wide frequency range. Experiments show that selecting the appropriate cladding allows diffsorber to have up to 1.4m2 absorption areas per unit area at low frequencies, while 1.2m2 at high frequencies, so the sound absorption is very efficient. The theoretical model proposed is in good agreement with the experimental results, so it can be used to further optimize the performance of diffsorber. Related Articles | Metrics

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Comprehensive Property of Composite Loaded Rubber Isolators 2013, 33(6): 197-200.  DOI: 10.3969/j.issn.1006-1335.2013.06.043 Abstract ( )   PDF (1523KB) ( )   Most of rubber isolators cannot satisfy the requirements of loads and vibration isolation simultaneously as they can only sustain a single load. Composite rubber isolator, with the advantages of rubber material, can sustain various loads and satisfy various performance requirements. Through FEA simulation and various performance experiments on static and dynamic characteristics, overload, shock resistance property, isolation effect and so on, the main performance characteristics of the isolator are obtained, and the simulation and the experimental results meet the design requirements. It is shown that the isolator can sustain large loads, has great effects on vibration isolating and shock resistance, and also it exhibits the same property when it is under opposite direction loads. Related Articles | Metrics

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The Kd/Ks Influencing Factors of Rubber Isolators 2013, 33(6): 201-206.  DOI: 10.3969/j.issn.1006-1335.2013.06.044 Abstract ( )   PDF (986KB) ( )   The strengh properties of damping rubber had connections with vibration property of rubber vibration isolator. Through the analysis of the cure of tensile strengh ,it looked for the effect of tensile strength at 200% on dynamic property of damping rubber. It has been found that tensile strength at 200% of rubber was larger, which would make Kd/Ks of damping rubber. Addionally,through the analysis of the cure of, the rerult showed that the angle of σ-ε cure with ε axe,the Kd/Ks of the rubber was small. The effect of rubber and CB and sulfur amount on mechanical properties and Kd/Ks were also studied. It was shown that Kd/Ks decreased and tensile strength increased as the particle size of CB increased. So reinforcing agent with middle particle size or different particle size (bigger and smaller) added together could meet the requirements of strength and vibration effect at the meantime. Additionally, increasing the amount of sulfur properly could make 200% TS improving and vibration effect better. Related Articles | Metrics

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Structural Design and Experiment of a New Compressed Rubber Flexible Hose 2013, 33(6): 207-210.  DOI: 10.3969/j.issn.1006-1335.2013.06.045 Abstract ( )   PDF (1333KB) ( )   Based on compressed displacement compensation theory , a new compressed rubber flexible hose has been invented, and the performance of the flexible hose has been tested , the result shows that: The hose always stays in compressed state when been pressed, the reliability has been increased; Greater Self-balancing ability, the hose almost have no distortion when been pressed; Lower structure stiffness, greater displacement compensation ability,the maximun deformation can reach 20mm above; higher damping capacity,the insert loss can reach 15dB above. Related Articles | Metrics

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Design of Vibration Isolator in Ship’s Thrust Bearing 2013, 33(6): 211-215.  DOI: 10.3969/j.issn.1006-1335.2013.06.046 Abstract ( )   PDF (1356KB) ( )   Abstract: A vibration isolator embed in ship thrust bearing is introduced in this paper. It can reduce the longitudinal vibration induced by the pulse inspired thrust from propeller. Firstly, the isolated system model is set up in this paper and the stiffness parameter of rubbers is optimized by the calculation analysis; secondly, the shape and dimension of rubbers is designed based on the stiffness parameter and related experiential formula; finally, the intensity of designed rubbers is check, it shows that the designed isolator can satisfy the intensity index. On this base, the collocation and assembly of rubbers is suggested. The method can use for reference to the design of longitudinal vibration isolator in ship thrust bearing. Related Articles | Metrics

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A Case Study of Gas Burner Noise Control Technology 2013, 33(6): 216-219.  DOI: 10.3969/j.issn.1006-1335.2013.06.047 Abstract ( )   PDF (1731KB) ( )   Gas burner, although it is not big in size, is one kind of high noise equipment in industrial production lines. To resolve the noise pollution problem of residential area outside the factory boundary the author made the design of a sound-proof booth for noise reduction of the burners based on noise measurement data and frequency analysis. This paper presents the structure of the sound-proof booth including sound insulation walls and ceiling, absorption and ventilation system silencer,etc. The results after installation of the sound-proof booth are: the boundary noise level has been reduced from 67.9dB(A) to 44.5 dB(A) which conforms with the limit value of class 1 in GB12348. This case provides a good example for reference in noise reduction design of similar equipments. Related Articles | Metrics

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Analysis of Noise Control of a 220 kV Indoor Substation 2013, 33(6): 220-223.  DOI: 10.3969/j.issn.1006-1335.2013.06.048 Abstract ( )   PDF (902KB) ( )   Abstract: This paper described the characteristics, major noise source, noise intensity, frequency characteristics of the 220kV indoor substation. It analyzed the noise propagation of the 220kV indoor substation. Systematically analyzed the noise control measures of the 220kV indoor substation, and briefly described an engineering example, which can be reference to the same project. Related Articles | Metrics

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Noise and Vibration Reduction Design of Centrifugal Fans and ItsApplication 2013, 33(6): 224-226.  DOI: 10.3969/j.issn.1006-1335.2013.06.049 Abstract ( )   PDF (945KB) ( )   Related Articles | Metrics

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Ventilating and Noise Reduction Practice ofOxidation Blower Workshop 2013, 33(6): 227-232.  DOI: 10.3969/j.issn.1006-1335.2013.06.050 Abstract ( )   PDF (1170KB) ( )   Related Articles | Metrics