Archive

18 October 2010, Volume 30 Issue 5 Previous Issue    Next Issue
---
2.振动理论与数值解法
3.运载工具振动与噪声
4.环境振动与环境声学
6.信号处理与故障诊断
7.减振降噪设备和器材


For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

2.振动理论与数值解法

Select

Matching Electromagnetic Counter-force Actuator and Passive Suspension in Hybrid Active Suspension Kun-Shan Chen 2010, 30(5): 1-05.  Abstract ( )   In order to improve the performance of conventional suspension system, a hybrid active suspension is proposed with the description of its structure and its working principle. A quarter car model with hybrid active suspension is established. According to the performance improvement in riding comfort with absorber’s different parameter and fitting position, hybrid suspension offer better riding comfort to passengers and the parameter of actuator can be achieved when dynamic absorber is set on the position of unsprung mass. It’s essential study Active actuator by Analyzing the amplitude-frequency characteristic of hybrid and passive suspension, the vibration of tyre is decreased by active controlling force to improve ride comfort, the maximal value of force of tyre excited by road unevenness as the method of choosing actuator’s controlling force. The research results can provide useful guidance for the similar active suspention design and development. Related Articles | Metrics

Select

Modal Analysis of Active Framed Structure 2010, 30(5): 6-09.  Abstract ( )   This paper is concerned with modal analysis of active framed structure. Analytic results show that left mode shape and right mode shape from the active framed structure take on weighted orthogonality with regard to the above structure. Also, left mode shape and right mode shape have different physical meanings: right mode shape is essential one of the above structure, but left mode shape is only a participant mode of external excitation, in other words, which characterizes disturbed factor of external excitation for the active framed structure. Modes of active structure is a primary indicator of structural properties, also is a target function of structural design, so mode study of active structure is valuable for theory and practice. Finally, a numerical example is adopted to verify the above some conclusions. Related Articles | Metrics

Select

Vibration Response Analysis of Turbocharger’s Compressor Housing based on Experimental Modal Analysis 2010, 30(5): 10-14.  Abstract ( )   Abstract: In real working condition, due to measurement environments and costs, it is impossible to measure and monitor the response of every channel of a mechanical structure. By structural modal analysis, it is of theoretical and practical importance to determine some responses based on other measured responses. In this paper, a turbocharger is researched and a method of determining the compressor housing vibration response based on center housing vibration response and the transfer function in between, which is obtained by experimental modal analysis. The compressor housing’s vibration response can be determined by the center housing’s vibration response and the transfer function. It is showed that the calculated results match the measured results both in time and frequency domains based on this method. Related Articles | Metrics

Select

FEM Simulation of The Characteristics of Rotor With Two Cracks 2010, 30(5): 15-29.  Abstract ( )   Rotor crack is one of the frequently occurring faults in rotary machine. In this study, The FEA method is employed to analyze the dynamic characteristics of a rotor with two transverse cracks. The dynamical behaviors of the cracked rotor with different angles between the two cracks are investigated and the relation of the breathe behavior of the two crack is acquired. The proposed FEA modeling method is validated by a designed test. Related Articles | Metrics

Select

Analysis of Vibration-Absorptional Effect of a Non-uniform Beam on a Plate-Shell Coupling Structure 2010, 30(5): 20-24.  Abstract ( )   In this paper,a non-uniform beam is used to absorb the vibration of a plate-shell coupling structure, and power flow of the structure are calculated and simulated.Conclusions are as follows: the vibration-absorptional effect of the beam to the shell and plate is remarkable at resonate frequencies; the vibration-absorptional effect of the beam is most dependent on the fixed point, and as vibration response of the plate at the fixed point increases, vibration-absorptional effect of the beam reaches better; as the loss factor of the beam gets greater, vibration-absorptional effect of the beam gets better. The method used in this essay about the receptances between points and lines can be applied to analysis of power flow of other structures. Related Articles | Metrics

Select

Viscoelastic Damping Layer Design and Experiment using Modal Combination 2010, 30(5): 25-29.  Abstract ( )   Abstract: Regarding the design of viscoelastic damping treatments, constitutive equations of the viscoelastic material and the design method based on modal calculation are discussed. The modal combination method is demonstrated by numerical calculation and experiments. The results indicate that it is a feasible method in the design of viscoelastic damping treatments to reduce the surface vibration and the noise of structures. Related Articles | Metrics

Select

The Exact Solution for Dynamic Response of Beam-Type Structure with Multiple Unconstrained Damped Patches 2010, 30(5): 30-33.  Abstract ( )   Dynamic response of beam-type structure with multiple unconstrained damped patches is deduced using equivalent complex stiffness and transfer function method, and the typical frequency response curve of system is obtained. The effect of damping material’s thickness, Young modulus and setting position in the dynamic response are analyzed at the same time. These are good agreements between the results of numerical examples and finite element method, or those published in the related literature. The proposed method has been validated by comparing predictions and analyzing, it can apply academic guidance for the setting and optimizing of damped patches on the beam-type structure. Related Articles | Metrics

Select

Experimental Study on the Influence of Numbers of Damping Sheets on Grinder Y7125’s Vibration 王庆男 Wang Qing-Nan 2010, 30(5): 34-38.  Abstract ( )   In order to improve dynamic performance of Y7125 , the influence on vibration intensity on the vertical and parallel direction of grinding wheel spindlewas analyzed by adjusting the number of damping sheets The rule of variation of grinder Y7125’s vibration as the number of damping sheets was obtained by comparing the vibration displacement amplitude of key part of grinder Y7125 under varied damping sheets and the optimal operating condition of Y7125’s grinding wheel motor was acquired. Related Articles | Metrics

Select

Experiment and Mechanism Study on the Pulsation Reduction of a Seawater Piston Pump by Using Accumulators TAN Juan 2010, 30(5): 39-42.  Abstract ( )   Based on the structure and principle of a swashplate-rod type axial piston seawater pump with check valves, the mechanism of pressure pulsation about the pump was analyzed and the mathematical model was established. Then contrast studies of simulation and experiment on the basis of pressure pulsation of the pump before and after the use of gasbag accumulators ,under different air volume of cassette diaphragm accumulators ,under different pressure of system, had been accomplished. The testing results show that the pressure pulsation of the seawater pump can be obviously reduced after the use of gasbag accumulators and can also be depressed by increasing the volume of the accumulator. The results are directive significance for the vibration and noise reduction of the seawater pump. Related Articles | Metrics

Select

Three Variables Control Algorithm Based On Neural Network For Shaking Table 2010, 30(5): 43-46.  Abstract ( )   To solve the non-linear of shaking table and structure, this article has developed a three variables control outerloop base on the displacement innerloop shaking table, used of computer to build up the acceleration controled outerloop, provided an accurate energy peak of shaking table as seismic waves. And forthe physical parameters of structure are constantly changing, a neural network has added to adjust the power of the three variables on-line. Experiments show that TVC outer-loop can provide better shaking table result. Related Articles | Metrics

Select

Numerical calculation and experimental Research on Vibration Control of Ship Drive System 2010, 30(5): 47-50.  Abstract ( )   Abstract: Ship drive system is the main power of the vibration of the ship, The being vibration analysis of the drive system emphasizes particularly on the torsional vibration of the shafting. The effect of the structural vibration is out of the consideration. In this paper, ship drive system test-bed is carried out by applying the ANSYS software, The experimental results show the reliability of the computationa method. And through change the power of the vibration condition, the structure vibration translated in the ship drive system is researched. Related Articles | Metrics

Select

Numerical simulation of vortex-induced vibration of a circular cylinder using CFX code 2010, 30(5): 51-55.  Abstract ( )   A numerical simulation of vortex-induced vibration of circular cylinder for a fixed Reynolds number equal to 3900 was presented. The CFX code was employed to solve the 2d N-S equations with the k-ω SST turbulence model. The circular cylinder simplified as a mass-spring system with different stiffness was researched with the dynamic mesh and CEL function of CFX code. Research presented the “lock in” phenomena, “self limited” phenomena of vortex-induced vibration and the transition of the model of vortex shedding between “2P” to “2s”. The effect of stiffness to the character of vortex-induced vibration was presented here also. Related Articles | Metrics

Select

Research on coupling-vibration of large floating raft of vibration isolation system 2010, 30(5): 56-59.  Abstract ( )   The floating raft of vibration isolation system is important for vibration transfer control. The distribution of fore-order modes of raft has obvious influence on isolation effect of vibration isolation system. This research emphasized on the vibration characteristics and coupling-vibration transformation of large vibration isolation system with different isolators. Some conclusions were obtained which were available for improving the low frequency vibration isolation effect of vibration isolation system. Related Articles | Metrics

Select

Improved Variable Step Size LMS Algorithm and Its Application in Auto - adapted Noise Cancellation Lei Shen 2010, 30(5): 60-63.  Abstract ( )   Following a brief discussion on traditional LMS, variable step size LMS algorithm and its improved algorithm, an improved variable step size adaptive filtering algorithm is presented by building a nonlinear function relationship between μ and error signal e, and it is applied to adaptive noise cancellation, the algorithm has a faster convergence speed and less stability maladjustment by analyzing the impact of parameters on algorithm performance. Finally, simulation results are also provided, which prove the theory analysis. Related Articles | Metrics

Select

Near-field Acoustic Performances of Active Sound Absorption Structure HAO Xia-Ying 2010, 30(5): 64-68.  Abstract ( )   Active sound absorption structure proposed in recent years is viewed as a feasible approach to effectively absorb low-frequency reflected sound. Analyzing the near field acoustic performance can offer theoretical help for some key issues, such as design optimization, the arrangements of secondary sources and error sensors, and selection of the control objective. Under the minimization of the reflected sound power output, the changes of sound intensity and absorption coefficient on the near field of the structure before and after control are investigated by numerical simulations. Near-field acoustic performances of active sound absorption structure are analyzed through the amplitude, radiation form and dimensional distribution of normal sound intensity. The changes of absorption coefficient on structure surface more validate near-field acoustic performances of active sound absorption structure. Related Articles | Metrics

3.运载工具振动与噪声

Select

Comparison between fuzzy control and LQR control based on single degree of tracked vehicle 2010, 30(5): 69-73.  Abstract ( )   It was not easy to establish a proper model for tracked vehicle which works in the difficult environment and has complex structure. In order to solve this imprecision of model, there was a good approach of fuzzy control to restrain the vibration of vehicle. According to step response analysis, when adjusting factor equaled to zero, the control effect with the acquired fuzzy rule was best. Under the random excitation of the off-road, no control, LQR and fuzzy control were contrasted. The simulation result indicated, fuzzy control showed better control effect. Under the same maximum force of the actuator, fuzzy control showed better control effect than LQR control, the acceleration of the fuzzy control was reduced to 1/8 of no control, the velocity was reduced to 1/4, and the displace was reduced to 7/10. In the terms of displace and velocity, fuzzy control was nearly comparative to LQR control, however, the control effect of the acceleration under fuzzy control was 1.8 higher than that of LQR. Related Articles | Metrics

Select

Research on Acoustic Stealth Situation Fast Assessment of Underwater Vehicle 2010, 30(5): 74-78.  Abstract ( )   Traditional algorithm on underwater vehicle radiated noise calculation could not satisfy real-time request in practical use due to its long calculating time. Aimed at this disadvantage, the problem can be converted into a pattern recognition problem based on multisensor data fusion, and a new method of fast evaluation acoustic stealth condition of underwater vehicle has been researched. Using the measured acceleration of the cylindrical structure shell, a rapid method of acoustic stealth situation assessment of underwater vehicle based on RBF and LVQ combination neural-network was realized. And the power of each frequency band in analysis band was extracted as the feature vectors. An iron underwater cylindrical structure was simulated as underwater vehicle cabin. A underwater acoustic experiment was made to prove the high accuracy and short calculating time of the method. So this method can be well used for acoustic stealth situation assessment of most kinds of underwater structure. Related Articles | Metrics

Select

Using Road Vehicle Excitation Spectrum the Auto Electrical Parts Clamp Design in Vibration Test 2010, 30(5): 79-83.  Abstract ( )   During the car driving in order to ensure the auto electrical parts will not damage due to vibration, We need to do some vibration experiments for the car electric appliances , testing their reliability lives. This article describes the clamp structural design process of a car head lamp in the vehicle vibration test. Based on meeting the basic clamping function, the designer analyzed the dynamic characteristics such as frequency, quality, center of gravity location, etc using the finite element analysis method,and these characteristics was optimized and experimented verification after the completion of the structural design Related Articles | Metrics

Select

An Experimental Research on Leaf Spring System Vibration Transfer Characteristics of one Automobile 2010, 30(5): 84-87.  Abstract ( )   To address the violet vibration problems of one automobile, the vibration transfer characteristics of leaf spring system is analyzed. The vibration acceleration on both sides of mounting system of the moving automobile is measured on actual road, by the time-domain analysis, the frequency spectrum analysis, relative analysis and transfer characteristics analysis of vibration signal, the main factor that influencing the transfer characteristic of the leaf spring system is found. According to the results, opportune improvement of leaf spring system is finished; the transfer characteristic of the leaf spring system is improved markedly. Related Articles | Metrics

Select

Study on an Electromagnetic Counter-force Hybrid Active Suspension with Fuzzy Control Method Ji-Lei Lu;Kun-Shan Chen 2010, 30(5): 88-90.  Abstract ( )   The Suspension is one of important parts of automobile. The performance of suspension directly effects the ride comfort and handling stability. Active suspension is able to clearly improve the ride comfort of vehicle, but it requires a number of sensors, excessive energy for the control,and thus it is complex and expensive. In this paper, a suspension-Electromagnetic Counter-force hybrid active suspension is taken out. One-quarter vehicle model with two-degree-of-freedom is established basing on the structure of this suspension, and a mathematical model is addressed through dynamic analysis. A controller with fuzzy control algorithm is formulated for the hybrid active suspension. The simulation of the model is taken in the platform MATLAB/Simulink. The results demonstrate that, compared with the passive suspension, the RMS value of the car body vibration, spring distortion and the tire dynamic loading of the hybrid active suspension with fuzzy controller, were reduced by 24.57%, 8.33% and 12.71% in time-domain and also have a significant improvement compared with one with PID control. The power spectral density of car body vibration acceleration shows that the peak value is remarkable reduced compared hybrid active suspension adopting fuzzy controller with passive suspension, especially in tire resonance frequency, and the active actuator with fuzzy controller could performance well. Related Articles | Metrics

Select

Investigation on the Sound Insulation Characteristics of the Embedded Co-cured Composite Damping Structures 2010, 30(5): 91-94.  Abstract ( )   In this paper, IIR rubber was used as the main component of visco-elastic damping material. Then, the damping layer of specimen was made of the damping material by mold molding. With epoxy glass fabric prepreg, according to the cure curves, some specimens of embedded co-cured composite structure were obtained. Finally, standing-wave-tube method was used to study its sound insulation properties. Test results showed that by adding a thin damping layer, the damping of structure was increased nearly without stiffness changed, and the low-frequency sound insulation property was improved. And by adding a thick damping layer, the change of sound insulation of the component is not sensitive to the change of the thickness of damping layer. Mainly due to the increase of the stiffness of the specimen, the sound insulation of the specimen increased. Therefore, to improve the sound insulation property of the structure by increase the thickness of the damping layer of the embedded co-cured composite damping structures is inappropriate. Related Articles | Metrics

Select

Vibration Investigation of Exhaust System and Optimization of Hangers’ Location 2010, 30(5): 95-97.  Abstract ( )   The FEM is applied on exhaust system’s modal analysis and harmonic analysis. The natural frequency is calculated and mode nodes are found by modal analysis. The law of how hangers’ vertical stiffness impact on exhaust system is obtained. The hangers’ location are optimized according to mode nodes. The force passed to vehicle body though hangers is effectively reduced. The vehicle NVH performance is improved. Related Articles | Metrics

Select

Self-adaptive Fuzzy Control of Vehicle Active Suspension 2010, 30(5): 98-101.  Abstract ( )   Based on the established full-car active suspension model, the fuzzy adaptive control system of front and rear active suspension were designed by the theory of self-adaptive fuzzy, the road excitation signals of front wheel was introduced into the control strategy of real wheel active suspension, so the properties of active suspension could changed based on road surface and body posture to meet the needs of vehicle working conditions, simulation and analysis of random road input and sine wave input were carried on, the results show that, compared to the traditional suspension system, the peak and standard deviation of vehicle mass vertical acceleration decreased by 38.9% and 36.5%, the peak of rear body acceleration decreased by 43.9% when vehicle go through the sine wave at the speed of 5m/s, the ride comfort was distinct improved. Related Articles | Metrics

Select

Performance analysis and Improvement of the muffler for Motorcycle XX-type 2010, 30(5): 102-104.  Abstract ( )   In order to improve the sound quality of the motorcycle XX-type, the acoustic performance of the mufflers is analyzed and the noise reduction is estimated in this paper,.meanwhil,the suggestion to make sound quality better is proposed according to the principle of noise control . By measuring noise from improved samples and subjective experiment,the results indicated that the sound quality has improved significantly. Related Articles | Metrics

Select

Finite Element Analysis of Exhaust Muffler Acoustic Performance Cai Ke-Qiang 2010, 30(5): 105-107.  Abstract ( )   Muffler is the common noise-elimination equipment in the noise control in vehicle. It is difficult to compute and predict the attenuation of the muffler with complicated structure. Using acoustic software SYSNOISE to calculate transmission loss of muffler. And the effect of expansion ratio and the depth of insertion tube on the noise elimination performance is investigated, which provides the references for design and optimize of mufflers. Related Articles | Metrics

Select

Research of Reliability Life for the Automobile Electric System Vibration Simulate-Test 2010, 30(5): 108-112.  Abstract ( )   For studying reliability life of an automobile electric system. First, carrying out the real vehicle tests by using a new norm of automobile proving vehicle tests ground relating with users. Using the way of acceleration sensors collects real vehicle road spectrum. Then, driving automobile electric system vibration simulation test with the datas of the dealing with the previous real vehicle road spectrum in a strengthening way. The final, using the maps-estimation analysis the results of simulation test, to establish reliability life curves of the car electric system vibration simulation test. The results showed that the test cycle can be shortened and have the value of the use of by calculating the life of automobile electric system by using life curves. Related Articles | Metrics

4.环境振动与环境声学

Select

Analysis on influence of noise reducing of the sound insulation encasing with different thickness and damping 2010, 30(5): 113-115.  Abstract ( )   Sound insulation encasing is an effective device for noise reduction The analysis on the effect of its noise reducing has practical significance In this paper, sound insulation encasing is for the study based on finite element method, using SYSNOISE software, establishing finite element models and analyzing of the influence of noise radiation of the sound insulation encasing with different thickness and damping. Obtained a conclusion of difference in thickness and damping will affect the noise reducing and provide some reference to solve practical problems. Related Articles | Metrics

Select

Research on Test Technique of Flow Regeneration Noise in Muffler ZHAO Shi-Ju 2010, 30(5): 116-120.  Abstract ( )   Abstract: Based on the method of two microphones transfer function, a measuring method for flow generation noise in muffler was developed with different microphones distance groups. The flow field and acoustic field of three type probe tube were studied, and theirs effect of liquid diversion and sound transmission were compared. The result shows the selected probe tube can reflect the acoustic pressure signal in main tube truly, and the structure of probe tube has little effect on flow field and acoustic field in main tube. Under the no flow condition, test testified the result of acoustic simulation. On the designed test bench, a perforated muffler was tested. The result shows the studied measurement and test bench can measure effectively flow generation noise in muffler under series of flow velocity. Related Articles | Metrics

Select

Experimental Study of the Noise Characteristics of Chen Yu 2010, 30(5): 121-124.  Abstract ( )   By means of test study of the noise characteristics of four kinds of counter-rotating axial local fan for coal-mine, the noise spectra curves and the variation curve of A-weighted sound level corresponding to various operation points are acquired. It also analyses the discrete noise spectra characteristics in detail. It is found that the noise corresponding to the blade passing frequency(BPF) of the first impeller and the blade interaction frequency(BIF) between the two stage impellers is the primary discrete noise sources of the counter-rotating axial local fan. It provides a useful reference to decrease contra-rotating axial fan’s noise. Related Articles | Metrics

Select

The Current Monitor Condition and Dissemination Characteristic of Traffic Noise in Urban Road Wang Wen-Tuan 2010, 30(5): 125-131.  Abstract ( )   Related Articles | Metrics

6.信号处理与故障诊断

Select

The Limitation of Operational Transfer Path Analysis in Application Qiao Yu-Feng 2010, 30(5): 132-136.  Abstract ( )   Operational transfer path analysis (OPA) is a new developed technique for the noise and vibration problem of mechanical system. It’s a high efficiency approach and getting more concerns in practical application. Using the classical transfer path analysis (TPA) as reference, three significant limitations are revealed in this paper by the methods of theoretical analysis and case study. Because the correlation between the input transfer paths caused by the structure modal behavior, cross coupling of the input paths may be happened and make the analysis failure. It’s the first limitation. The second limitation is the transmissibility estimation error from the operational data constraint conditions. It will lead to unreliable results in many cases. The third limitation is the potential error of missing transfer path in analysis. However, the synthesized summed contributions can’t reveal this type of error. Related Articles | Metrics

Select

Study on the Fault Sources Identification and Localization of Multi-machineries based on SVDD Method 2010, 30(5): 137-140.  Abstract ( )   In a system comprised of multiple machineries, the rapidity and small sample set are important problems for identifying the acoustic fault sources of system. A new method based on Support Vector Data Description（SVDD） was presented to identify and locate line-spectrum power increase acoustic fault source of system . According to the data description template based on normal state samples, line-spectrum power increase acoustic fault was detected. Combining the fault detection result with the signal of sensors installed on each machine, the exact fault machinery localization was realized. The experiment results show that the method is feasible in engineering application. Related Articles | Metrics

Select

Study on Noise Separation of a Diesel Engine Based on Independent Component Analysis 2010, 30(5): 140-144.  Abstract ( )   The basic principle of Independent Component Analysis (ICA) and its application on noise separation of a diesel engine are introduced in this paper. FastICA algorithm, which is widely used in dealing with engineering cases, is carried out. Under a pilot-injection condition, a 6-cylinder diesel engine’s noises are tested according to authoritative rules and analyzed by ICA method. It is shown that 3 components which are independent with each other are noises from piston knocking, pilot-injection and combustion respectively. Related Articles | Metrics

Select

Studying of Wavelet Neural Network in De-noising of Ultrasonic signals of coarse-grained material 2010, 30(5): 145-148.  Abstract ( )   Abstract： Because of the scattering characteristic of the coarse -grained material, the useful signals are covered up by the scattering waves which come from the micro-structures of the material. In order to minimize the influence of the scattering wave on the useful signals and improve the signal-to-noise ratio (SNR), wavelet neural network is introduced in the field of de-noising of Ultrasonic signals of coarse-grained material. Improved gradient descent algorithm has been used to train the neural network. In the process of training, the network has a dynamic weight, which can be updated automatically according to gradient descent with adaptive learning rate. The experimental results show that wavelet neural network is an effective method in de-noising of ultrasonic signals. Related Articles | Metrics

Select

The application of Bandelet transform in metal fracture image denoise 2010, 30(5): 149-152.  Abstract ( )   Bandelet transformation is based on the edge of the image that the method of images can be adaptive to track the direction of the geometric regularity. This article first method using wavelet denoising with the noise of metal fracture image pre-processing, the use of soft-threshold function to obtain threshold T, thereby obtaining images after denoising quadtree structure, and block Bandelet along the direction of the best geometry Bo to transform, the final use of the Sure Shrink method Bandelet block adaptive threshold, and then the use of multi-layer soft-thresholding to remove noise, the reconstructed image Bandelet inverse transform。 Experiments show that with the traditional multi-sub-band wavelet threshold denoising method, the algorithm not only improves the image de-noising of the peak signal to noise ratio (PSNR), and has a stronger ability to maintain the edge. Related Articles | Metrics

Select

Application Research on Genetic Algorithm and BP Neural Network in Motor Fault Diagnosis 2010, 30(5): 153-156.  Abstract ( )   Artificial intelligence method was applied in motor fault diagnosis, which made motor fault that can be predicted and diagnosed in time, and ensured the safe operation of motor. The principle and composition of BP neural network and genetic algorithm were introduced, In view of the problem that BP neural network was easily to fall into local minimum point, The diagnosis performance of BP neural was improved by using genetic algorithm optimization weight and threshold value of BP neural network; A result shows that GA-BP network better than BP network on diagnosis Speed and accuracy by simulation experiment of motor fault diagnosis. Related Articles | Metrics

Select

Damage Detection Method of Cylindrical Shell Structure 2010, 30(5): 157-161.  Abstract ( )   Abstract: The damage position and degree detection of cylindrical shell structure is an important link in safety evaluation of cylindrical shell structure. The dynamic properties of structure before and after damage were analyzed, and the change coefficients of modal shape were deduced from element damage using perturbation method. The relation between variation of modal strain energy (MSE) and damage of element was deduced. The variation rate of modal strain energy was taken as the signature for damage diagnosis, and it was proved that the element of modal strain rate was sensitive to damage. The method of damage detection of cylindrical shell structure was studied, which only needs low measured modal information and stiffness matrix before damage. Finally, a concrete cylindrical shell structure was studied as an example. Calculation results under different damage situations are analyzed. It is seen that the proposed method can identify the damage situation and degree under different combined damage situations. The method can also identify small damage correctly. Therefore, the method is proved to be accurate and effective. Related Articles | Metrics

Select

Identification of Live Chick Embryo Based on Measurement of Sound Signal 2010, 30(5): 162-164.  Abstract ( )   Acoustic analysis instruments were applied to identify bird embryos for the first time and a new semi-invasive method is advanced to measure heart rate of chick embryos in this paper. A small hole in this method is made by a pin on the top of the egg chamber in order to let the sound signal come out, and then the embryo is placed in a tapered container-sealed. The microphone is employed to measure this signal finally. So we can know whether the embryo is alive or not by measuring the signals. Taking advantages of high reliability and simple operation, the method can identify live bird embryos without affecting the development of embryos, which makes great sense in breeding selection and long-term automatic monitoring of process of egg incubation. Related Articles | Metrics

Select

Application Study on SOM-BP Composite Neural Network for Gear Box Failure Diagnosis 2010, 30(5): 165-168.  Abstract ( )   According to complex nonlinear relations between gear boxs breakdown mold type and characteristic quantity, SOM-BP composite neural network is used, and diagnosis mold is established with common breakdown condition and relative parameters of gear box cited as the training sample .Under the Matlab environment, through the simulation test and comparison with BP network, correctness and accuracy of the composite neural network to be used in the gear box failure diagnosis are confirmed, and have certain application perspective in the project. Related Articles | Metrics

7.减振降噪设备和器材

Select

Magnetic Finite Element Analysis Of The Intelligent Laminated MRE Isolator TU Jian-Wei;Wei Ren;Ping Wu 2010, 30(5): 169-172.  Abstract ( )   Magnetorheological elastomer (MRE) is a new smart material made up of natural rubber or silicon rubber matrix and magnetic particles. Its shear properties and storage modulus can vary with the applied magnetic field. By using the magnetorheological effect of this smart material, it is proposed that the substitution of MRE for ordinary rubber, which applies a new design for the intelligent laminated rubber isolator, furthermore, the magnetic finite element analysis of the designed isolator is carried out in this paper. Two-dimensional finite element models with unicoil and twin-coil magnetic energy input are designed, by changing the members’size of the isolator, the number of turns in the coil, and the strength of electric current respectively, the variation of the magnetic intensity in the MRE can be obtained and the relationship between them is found. The analysis indicates that the maximum magnetic flux density at the area of MRE material is up to 1.2T, the range of which can take full advantage of its magnetorheological effect. This new design is fully feasible. Related Articles | Metrics

Select

Finite Element simulation of Rubber Absorber’s Vibration test Liu Xiao-Dong Liu;Zhang Yu-Lei;Wei Jun Guo 2010, 30(5): 173-176.  Abstract ( )   In this paper non-linear finite element method was introduced to simulate the environmental test of a set of rubber-structured absorber, which is used in aerospace. At first the stress-strain curve of silicone rubber and corresponding hyperelastic model were created by material experiment. To simulate the sinusoidal vibration test, Incremental Analysis was used for the frequency response analysis of the absorber considering behavior of large deformation of silicone rubber material, and boundary conditions were determined according to the amplitude and frequency of vibration test system. The appropriate error between the simulation result and vibration test proves that application of non-linear FEM is available to perform simulation of complicated process. Related Articles | Metrics

Select

Analysis on Elastic Properties and Volume Feature of Air Spring 2010, 30(5): 177-180.  Abstract ( )   Mathematical expression of air spring’ elastic properties was established by virtue of the theories of engineering thermodynamics. Based on the study of the mechanics features of air spring including the nonlinearities in material, geometry, contact, the nonlinear finite element analysis was applied to study nonlinearity characteristic and volume of air spring. The three-dimensional finite element model of a cystiform air spring was established and analyzed with the method of nonlinear finite element analysis. The results show that load capacity of air spring increases with increasing inflation pressure, and show a non-linear characteristics. Cavity pressure, volume and effective area show a non-linear relationship with deformation of air spring. Cavity pressure and the effective area increase with increasing of the air spring deformation, but the volume shows the opposite trend. Cavity pressure on the effective area and volume of air springs has little impact. Related Articles | Metrics

Select

Calculation and Analysis of the Damping Force of Lateral Eddy Current Damper 2010, 30(5): 181-185.  Abstract ( )   The eddy current damper has widespread application prospect in vibration control field which has advantages of non-contact and non-mechanical wear etc. A novel lateral eddy current damper was uesed for lateral vibration suppression of rotating disk. The electrical model of eddy current damper was established based on electromagnetic field theory, the radial and axial force of formulas were deduced combined with disc structure parameters. The relationship of the damping force and current, clearance(the distance between the end face of damper coil and disk) and the speed of disc was simulated and analyzed. The study laid a theoretical foundation for the implementation of vibration control and practical application of lateral eddy current damper. Related Articles | Metrics

Select

Development of Muffler Acoustic Performance Analytical System 2010, 30(5): 186-190.  Abstract ( )   With secondary development of APDL, the development of Muffler’s Analytical System realizes the function of users’ visual modeling and automatic simulation of acoustic performance. Based on the platform of VB.NET, DirectX9.0 and environment of ANSYS11.0.Finally,it proves the high reliability to compare the experiment result with system process outcome. Related Articles | Metrics

Select

Application of Steam Ejector at the Reduction of Noise Caused by Steam injection Underwater 2010, 30(5): 191-195.  Abstract ( )   when the start-up hydrophobic of supercritical once-thorough boiler was jetted into the deaerator, the start-up hydrophobic would flash into steam due to sudden drop in pressure. The noise caused by steam jetted into water was nearly 100 (dBA). To solve this problem, steam ejector and micropore muffler was be used for noise reduction and contrasted by experiment. The results showed that the noise caused by steam jetted into water was reduced to 80(dBA) following, because the steam was cooled by heat transfer with supercooled water in the steam ejector. The micropore muffler could not cool the steam before it was jetted into the deaerator, so the minimum noise caused by steam jetted into water for more than 80(dBA). By this token, the steam ejector is batter than micropore muffler in reducing the noise caused by steam jetted into water. Related Articles | Metrics

Select

Research And Experimental Analysis Of Sound Absorption Properties for Aluminum Foam Compound Panels on Low Frequency 2010, 30(5): 196-198.  Abstract ( )   Abstract：Foam metal is a new type of sound absorbion material, and has excellent absorption properties in high frequency. To improve it”s absorption properties by Applying Aluminum Foam Compound Panels. The results shows that this structure has better sound absorption properties in low frequency, the absorption coefficient is greatly improved in 500-1KHz. It is further improved by adding a back lining, it has the best absorption coefficient happens in the cavity thickness is 30 mm, the maximum absorption coefficient 0.82 apperas in 400Hz. Related Articles | Metrics