Applied Mechanics and Materials Vols. 239-240

Abstract: This paper mainly explore application of neural network on self-adaptation system. An framework model of self-adaptation based on theory of artificial network. An active silencing control system is made which adopts a motional feedback loudspeaker as not a noise controlling source but a detecting sensor. The working fundamentals and the characteristics of the motional feedback loudspeaker are analyzed in detail. By analyzing each sound channel, identification of neural network is made. This kind of identifying method can be achieved conveniently, and it wouldn’t bring distribution to working environment. The estimated result of each sound channel matches well with its real sound character, respectively.

Abstract: A modal parameter identification software named as N-Broband is developed in VC++ platform. The software is suitable for EMA and OMA with broband identification feature. Meanwhile it also includes narrow band and selected band modal parameter identification methods. Correlation analysis between experiment and FEA can be performed in N-Broband. The validation of N-Broband is carried out by Test.Lab modal analysis software. The result coincides with Test.Lab very well, which indicates that the developed software can be used in modal analysis of real structure.

Abstract: A method which can be used to analyze and separate the vibration signals of diesel engine is proposed. The vibration signals contain a great deal of information about the engine’s fault state, and it is hard to obtain the fault characteristic parameters because of the complex mechanical movement and operating conditions. Study on vibration by fourth order blind identification is carried out in this paper. And FOBI model that estimate the separation matrix by independent component analysis is established and applied to diesel engine vibration to separate the different signals. The results show that signals of different characteristics can be separated perfectly. This method can be used as the pre-processing step to obtain the fault characteristic parameters.

Abstract: A SVM(Support Vector Machine)-like framework provides a novel way to learn linear principal component analysis (PCA), which is easy to be solved and can obtain the unique global solution. SVM is good at classification and PCA features is introduced into SVM. So, a new recognition method based on hybrid PCA and SVM is proposed and used for a series of experiments on chatter gestation. The results of chatter gestation recognition and chatter prediction experiments are presented and show that the method proposed is effective.

Abstract: An experimental study on the spectrum analysis and sound intensity identification of vibration and noise source was carried out. The study result represents that the primary reasons leading to the volute vibration of turbocharger, whose vibration energy focus on the frequency range of 0~8Kz, are the volute internal rotor shaft frequency of compressor and its harmonic vibration excitation and rotating unsteady air flow excitation. The volute radiation noise is primarily produced by the structural vibration caused by tip clearance noise and rotor shaft frequency and its harmonics. The noise energy of the turbocharger distributes at a wide range of 1k~8kHz and the sound power almost increases linearly with its rotating speed, which increases by about 20dB as the rotating speed increased from 50% to rated speed.

Abstract: In this article, a metal diaphragm coupling is introduced. It is assembled by interference fit with the shafts. Based on two axial vibration styles, self-exited vibration and external exited vibration, of the coupling, physical model of the coupling is established. Stiffness and damping of the coupling are also solved and analyzed. Then, natural vibration of the coupling is researched and natural frequencies are acquired by analyzed and simulated method. Finally, axial vibration response of the coupling was presented based on a calculation example. Techniques are presented which permit the coupling designer to predictably modify the coupling and thereby make in-place retrofits should an axial resonance condition occur in the field.

Abstract: Scanning tunneling microscopy is one of the surface measurement instruments in micro and nano field, and the Z-direction resolution is 0.01nm. So it is easily affected by the external factor in the course of measurement. The influence of vibration has already become one of main obstacles for improving the nano measuring accuracy. In this article, micro vibration measurement based on the tunneling effect is referred. A new sensor design of double displacement stages is brought to study the micro vibration, and both stages have the nano level displacement and resolution. Using this sensor, the tunneling effect is realized and the micro vibration is measured. The experiment results show this design has stable performance, and the results can be used to be a reference for the compensation of scanning tunneling microscopy.

Abstract: Aim at the shortage of traditional Aeolian vibration fatigue tests and theoretical models for transmission line, the Aeolian vibration monitoring system of transmission line based on the ZigBee wireless network was designed. The system transfer real-time field data of meteorological factors, tension of conductor and acceleration of monitoring nodes to background computer. The line vibration curve integrated directly from the acceleration sensor recorded data will present a serious problem of baseline drift. Therefore, based on least-square theory, a new baseline correction method is proposed to eliminate effect on drifts, and then obtain distortion less vibration curve of transmission line by twice integrations. The system running results show that track fitted with monitoring data is in good agreement with the real recorded trajectory. The system can satisfy the needs of the real time monitoring on transmission line site and be well applied to the calculation of conductor fatigue damage.

Abstract: This paper presents a comparison of different measurement techniques for condition monitoring of electric motors. Results are presented for vibration, acoustic and thermal analysis. Vibration signals were measured by piezoelectric accelerometers, acoustic by microphones and temperature data was collected by an infrared camera. Two induction motor cases were examined – healthy motor case and combination of static eccentricity with soft foot case. Vibration monitoring is a well known technique used in condition monitoring and in this work vibration measurements were used as a reference signal for assessment of the value of acoustic and thermal measurements. As presented in result section both acoustic analyses as well as thermal images appear as valuable techniques for condition monitoring of electric motors. All the measurements where conducted in an industrial environment.

Abstract: According to the characteristics and analysis methods of the vibration signal, this paper analyses and processes the vibration signal with the combination of the INV9822A sensor, the PCI-4472 data acquisition card and the signal acquisition system using Fourier Transform. The vibration law is analysed effectively to explain the effectiveness and practicality of the method due to the compressor vibration signal.