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1.
This paper describes the research work of analyzing vibration signal to monitor and diagnose on line the ball bearing fatique. Carrying out a large mumber of life test on ball bearing test machine, it is discovered that in the so called "second effect" vibration signal as the bearing fatique occurs, apart from the two widely used spetrum charactersof "fraverse frequency" and "high frequency shock pulse" , there is another important but rarely known opcctrum characteristic of high frequency peaks existing in the middle-to-high frequency band.The generating mechanism, effect factors and test method of those high frequency peaks are researched tentativ tentatively. Two binds of device for monitoring abnd diagnos sing ball learing fatique on line are developed based ion this new type spectrum characteristic. One consists of a bandpass filter, the other is based on the spetrum characters which corns from the DDS ( Dynamic Data System ) modeling  相似文献   

2.
Chongqing Chaotianmen Yangtze River Bridge is the world's longest-span arch bridge. The node connections on its main truss’s lower chords are to bear millions of large-amplitude stress cycles caused by automobile and light-rail train loads. However, there exists no referential designing and testing experience in such detailing on long-span steel bridges at home and abroad as yet. High-cycle fatigue behavior testing on a detailing model has been conducted to study the fatigue reliability of the bridge’s critical node connections. The testing cycling load on the model is determined according to conventional specifications and the expected traffic flow on the Bridge. The 1/2-scale detailing model is carefully fabricated to simulate the node prototype and undergo the 2 million-cycle testing with the design load. Through testing, fatigue reliability of Chaotianmen Yangtze River Bridge’s main-truss lower-chord node connections during the design service life is verified. In addition, static test data are compared with those calculated by finite element analysis to prove the validity of the node model. In the end, fatigue destruction test of the model was carried out to get the fatigue failure law of the node connection and provide necessary parameters and reference for designing and monitoring of this bridge in the future.  相似文献   

3.
In order to study the vibration characteristics and radiation noise of wind power speed-increase gearbox, a torsional vibration model of wind power speed-increase gearbox is established based on the analysis of supporting stiffness of bearing and contact stiffness of gear pairs. By solving the vibration differential equation with the help of Matlab, the frequency and corresponding vibration mode are obtained. With taking stiffness excitation, error exaction and meshing impact exaction into account, the dynamic finite element model of speed-increase gearbox is set up, and the dynamic response simulation is carried out. Regarding vibration displacement of the nodes on gearbox surface as boundary condition, an acoustic boundary element model of speed-increase gearbox is built. The surface acoustic pressure of gearbox and the radiation noise of field points are solved by the direct boundary element method. The results show that there is a great difference between torsion frequency and excitation frequency of wind power speed-increase gearbox, and so the resonance doesn't occur. The maximum structural noise and radiation noise mainly appear near the double octave of the gears meshing frequency of high-speed grade.  相似文献   

4.
Under the dynamic load of vehicle, the bridge will vibrate and radiate low frequency noise which is harmful to human health. A method for predicting the low frequency noise is proposed based on the analysis of vibration of bridge deck. The prediction includes the analysis of vehicle bridge coupling vibration considering the bridge deck and the analysis of sound radiation and propagation in the air. By taking a bridge with low frequency noise as example, the vibration and sound radiation of the bridge are analyzed respectively by the current method and the previous method based on the grillage model. The results show that the prediction based on the vibration of bridge deck is more accurate. Furthermore, the measures to reduce the noise of bridge are explored, and the results indicate that a smoother road surface leads to lower noise. But when the condition of road surface is up to the extremely good standard defined by ISO, the effect of reducing the roughness of surface is not significant. Also, strengthening the crossbeam in the bridgehead is a simple and effective way to reduce the low frequency noise of bridge.  相似文献   

5.
Because parameter disturbed exist every practical system,so chaos synchronization for different system parameters is availabe. Chaos synchronization of continuous system for different system parameters is studied with the relation between chaotic synchronization and asymptotic stability, parameter adaptive and driving feedback. Lorenz system is used to verify the effectivenss of the proposed method,and the simulation results confirm it.  相似文献   

6.
The robust control theory is used to solve the uncertainty of the optical extra-precise vibration isolation system. The wavelet theory is used to analyze the random vibration signal in the time-frequency domain and get the low frequency signal from the random vibration signal. The robust controller designed by the robust control theory is used to restrain the low frequency vibration. The active vibration isolation exploits the theory of robust control, which overcomes the uncertainty of model and the disturbance, and makes the control system to restrain the uncertainty of the model and the disturbance of the vibration. The simulation results prove that this method has shown good robustness and control precision in the vibration isolation of the optical extra-precise instrument and have good performance on restraining the low frequency vibration.  相似文献   

7.
With the developing of the automobile industry, how to control the noise and vibration level of the products come to urgently for the auto factories during their developing and producing period. Finding out the main noise source and vibration source quickly, analyzing the noise and vibration signal effectively, contriving a noise descending algorithm reasonable and economical become the first and most important job for auto corporations. At the mean time it complicate the developing guide line of the noise and vibration testing system. With object oriented technology, we can develop the noise and vibration testing system in a short time and with a low cost. The object oriented technology emphasizes the circulation, exoteric and expandable of the codes. It enables us developing the system follow a flexible, integrable and economical procedure..  相似文献   

8.
Study on Surface Noise Distribution of Three ring Reducer   总被引:1,自引:0,他引:1  
The three ring reducer is a kind of gear drive developed in the past decade. Adopting the new conception of "parallel and movable axis" of multiple mechanisms, this kind of gear drive has many characteristics such as large transmission ratio, high efficiency and so on. As the three ring reducer has been invented only for ten years, up to date the design of the gear drive is only made with analogue method, no design theory can be followed, there exist serious vibration and noise in transmission, which limit its wide application in industry. In this paper, the transmission principle of SHQ50 reducer is studied, the surface noise distribution of the reducer, transmission ratio 49.5 , is measured and analyzed by means of sound intensity method. The 3D distribution maps of noise on top of reducer, input side and output side of reducer, and left side and right side of reducer are drawn. With the sound intensity frequency maps of each measuring point, the sources of giving out noise are analyzed. The reducer of low vibration and noise can be designed rightly according to the analysis.  相似文献   

9.
针对一级行星两级平行轴风电齿轮传动系统,综合考虑齿轮时变啮合刚度、啮合阻尼、传递误差等因素,建立31个自由度的弯扭轴耦合集中参数动力学模型,采用变步长Runge-Kutta法对系统动力学微分方程进行求解,得出齿轮传动系统各级传动误差;借助软件建立风电齿轮箱刚柔耦合动力学模型,并导入传动误差,采用模态叠加法求得齿轮箱轴承支反力,并将其作为声振耦合模型的边界条件,采用声学有限元法对风电齿轮箱进行振动噪声预估,并与试验结果对比分析,两者吻合良好。  相似文献   

10.
ZHOU Ping 《保鲜与加工》2003,(10):104-107
According to the theory of parameters adaptive control and variable driving, for a kind of discrete nonlinear chaotic systems, a method of chaotic synchronization is presented for different system parameters. In the equation of parameters adaptive control, control coefficients are chaotic signal. Because control coefficients are constant usually for the former parameters adaptive control, so the parameters adaptive control method is very universal, namely the former parameters adaptive control methods are special examples in our control method. Simulation results show that this method is available.  相似文献   

11.
The analytic method for the free vibration of plane frame structure is presented. It is achieved by transforming the general eigenvalue problem of natural frequency and vibration mode of continuously distributed property system into typical boundary value problem of ordinary differential equation (ODE). A series of ODE, corresponding to the general eigenvalue problem, is formed, and then is solved by an general ordinary differential equation solver-COLSYS. Each component of a frame structure is regarded as an element in the analytic method. This makes it more efficient than that of finite element method which needs to increase elements to get the value of high-class natural frequency and vibration mode accurately. Some applications of the method show that it can solve the free bending vibration of plane-frame structure with various types of displacement constraint. The result indicates that this method is precise and efficient.  相似文献   

12.
The work principle and abnormal noise test method of hind vehicle hydraulic shock absorber are analyzed, Based on experiment data and signal character analyse ,a test method is found to distinguish the abnormal noise of rear hydraulic shock absorber. Practical validates that the reliability rate of this test method can be over 98 percents, and it can be satisfied with the request of the factory. At last, the reason of abnormal noise is analyzed and simulated, the reason of different signal attenuation is explained, and the research conclusion is educed.  相似文献   

13.
The performance requirements of marine gear box are much higher than that of other gear boxes due to its special working conditions. The structure and transmission principle of a high-power marine gearbox are analyzed, and the experimental test is carried out for the analysis and calculation of its vibration characteristics and intensity. Measured by FFT analysis of vibration signals, the main peak is caused by its octave and the engagement frequency of input stage and middle-class transmission. The vibration severity of high-power marine gearbox reached 4.47 mm/s. In addition, the calculated structure noise of the measuring points is at the 1/3 octaves, and the largest structure noise is 131.27 dB which occurred in the frequency of 329 Hz.  相似文献   

14.
The article focuses on the method of noise cancellation for EEG signal. The method of notch filter is discussed. According to the frequency of noise and the principle of notch filter, the design result of the notch filter and the denoised signal are presented. Then, the analysis of EEG signal are proposed based on wavelet transform (WT) and noise cancellation using WT. Wavelet transform is a multi-resolution time-frequency analysis method. It can decompose mixed signal into signals at different frequency bands. The EEG signal is analyzed and denoised using WT, then the results are presented respectively. Comparing the experiment results shows that WT can detect and process noise in the EEG signal effectively.  相似文献   

15.
This paper studyies the method of controlling SC6360B's accelerated vehicle Exterior noise. First, the main noise is found, which is from engine compartment and from exhaust noise by the identification of vehicle noise resource. Second, this paper carris out the farther noise identification experiment on engine and the insert-loss experiment on the exhaust gas muffler. In the end, the authors make sure that the noise is mainly infected by direct leaked noise from engine compartment, radiation-noise caused by the vibration of engine accessories and loud exhaust noise because the muffler has dficient elimination . The corresponding methods has been adopted according to the analysis. Through the test, the noise is lowered 2.5 dBA than it was and reach the new requirement.  相似文献   

16.
Vibration & Noise Analysis on Double-ring Gear Reducer   总被引:1,自引:0,他引:1  
Double-ring gear reducer with Central inputting shaft is studied. The basic structure of reducer as well as testing equipment, probe spot and testing method of Structure-borne noise and air-borne noise is presented. Based on frequency spectrum of each point, amplitude spectrum of structure-borne noise and testing results of air-borne noise, the authors analyze the vibration characters and latent faults of double-ring gear reducer, coming to the value and the cause of the noise, providing theoretical basis for proper design of the double-ring gear reducer and method of reducing its vibration and noise.  相似文献   

17.
Tracking control of a nonlinear uncertain Chua's chaotic system is studied. With coordinate transform, Chua's chaotic system is transformed to a general form of a strict feedback control system. Combining the backstepping method with robust control technology, an adaptive parameter control law for a robust output feedback control scheme is developed for output tracking of nonlinear unknown systems. It is shown that the derived robust adaptive controller based on Lyapunov stability theory can guarantee global uniformly bounded ultimate property for all states of the closed loop system, and lead to tracking error decreasing at exponential speed. The simulation results show the effectiveness of the proposed approach.  相似文献   

18.
The mass flowrate of Coriolis mass flowmeter in practical application has slow changes with time. To solve the problem, an improved time-varying signal model whose frequency, amplitude and phase are time-varying based on the random walk model is established firstly. A new algorithm of adaptive notch filter with the capability of tracking frequency variation is applied to filter the sensor output signal of Coriolis mass flowmeter and its frequency is calculated next. An adaptive line enhancer based on the mentioned notch filter extracts fundamental frequency signal from noisy data. Then, by short window intercepting, the revised sliding DTFT recursive algorithm is introduced to calculate the real-time phase difference between two enhanced signals. With the frequency and phase difference obtained, the time interval between the two signals is calculated and then the mass flowrate is derived. The simulations and field test results show that the proposed method can not only track the change of frequency and phase, but also ensure the calculation accuracy when measuring small phase difference. The computational load of the algorithm is simple so that it can be applied to real-time signal processing for Coriolis mass flowmeter.  相似文献   

19.
The mesh stiffness of gear tooth is simulated by spring elements, the connected bolt between various housings are simplified as bar elements, and the sliding bearing and rolling bearing are simplified as spring dumping elements. Based on them, the gear-shaft-bearing-housing coupled finite element model and boundary element model of GWC6066 marine gearbox are established. Finally, the dynamic response under internal dynamic excitation is analyzed and the vibration severity, structural-borne noise and air-borne noise of the gear system are forecasted. Through the experimental modal analysis of gear system, and the test of vibration response and air pressure, the natural frequencies, vibration severity, structural-borne noise and air-borne noise are obtained. Compared with numerical results, two results show good agreement.  相似文献   

20.
Aiming at a muffler of a 400 all terrain vehicle(ATV), a vibration model and an acoustics model of the muffler were built by finite element method(FEM). The vibration and acoustics characteristic analysis of the muffler are carried out according these models, it shows the 3D model is exact and it is possible to generate regeneration noise. Acoustics model can help to know further about the characteristic of each chamber and intention of the designer. According the demand of factory, some projects of improvement are offered. The final result of road test proves that he improved muffler is feasible.  相似文献   

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