Papers by Keyword: Vibration

Abstract: In nuclear power plants, the steam generator heat transfer tube is the weakest part of the primary circuit pressure boundary. Flow induced vibration is one of the main reasons for the failure of the heat transfer tube. In this paper, an ANSYS finite element software is used to carry out the modal analysis of the heat transfer tube, and to simulate the dynamic response of the heat transfer tube in the harmonic load based on the modal analysis.

Abstract: Transformer vibration research is an effective diagnosis of DC bias fault. The vibration signal acquired is actually the mix signal of vibration from both the core and windings, and this makes it difficult to analyze the above two separately. Therefore the paper presents a new approach to separate vibration signal of core and windings by Fast-ICA algorithm. The simulated results of core and windings vibration are given and compared with experiment test. Comparative analysis verify that transformer vibration in no-load is core vibration and vibration in short circuit is windings vibration. Transformer vibration signals under different DC bias are tested by experiment. Vibration signals are separated by Fast-ICA algorithm. Core vibration signal and windings vibration signal are respectively obtained. The research lays the groundwork for further research of transformer DC bias vibration.

Abstract: The research and curiosity about outer space had been always constant. Looking for others planets, ways, civilizations wherever the exploration of the space will be a thing which the human desire. The challenge here for several years was the obtaining energy sufficient for the application of the missions. So, presently the major objective in the missions is offer more autonomy to the spacecrafts and consequently to lower the cost of the missions. Solar Sails have long been envisaged as an enabling technology because is a promising low-cost option for space exploration for it uses for propulsion an abundant resource in space: solar radiation. In this paper a simple model of solar sail is shown and studied your performance of Control System.

Abstract: The traditional elastic theory believes that there exists normal stress in pure bending body (PBB) and shear stress in pure torsion body (PTB). However, the author proved that there is no normal stress but ‘Bent Point Moment’ (BPM) in PBB. And it also concluded that there is no shear stress but ‘Shear Point Moment’ (SPM) in PTB. This article overturns the preliminary theorems of the Elasticity Theory, which believes that the value of the moment (Bending moment & Torsion moment) on a unit area converges to zero. Just as the completely different natural frequencies of the forced vibration can lead to completely different resonant conditions. Besides, this theory has also been validated in the Damage Mechanics National Key Laboratory of Tsinghua University. Therefore, it is significant to avoid destruction produced by resonance.

Abstract: In the search for productivity increase, industry has invested on the development of intelligent, flexible and self-adjusting method, capable of controlling processes through the assistance of autonomous systems, independently whether they are hardware or software. Notwithstanding, simulating conventional computational techniques is rather challenging, regarding the complexity and non-linearity of the production systems. Compared to traditional models, the approach with Artificial Neural Networks (ANN) performs well as noise suppression and treatment of non-linear data. Therefore, the challenges in the wood industry justify the use of ANN as a tool for process improvement and, consequently, add value to the final product. Furthermore, Artificial Intelligence techniques such as Neuro-Fuzzy Networks (NFNs) have proven effective, since NFNs combine the ability to learn from previous examples and generalize the acquired information from the ANNs with the capacity of Fuzzy Logic to transform linguistic variables in rules.

Abstract: In order to profoundly study on the dynamic characteristic of crankshaft, this thesis applies planar bearing element Combi214 to simulating the bearing supports on both sides of the crankshaft. This study carried out the modal analysis of the crankshaft in multi-step load, and has calculated the low-order vibration mode and frequency of the crankshaft, besides, the top four critical speed and resonant frequency of the crankshaft is obtained via the Campbell chart. The safe range of first critical rotate speed has also been worked out, which is an important reference for the study of structural design and dynamics optimization of crankshaft, and the analysis results and reference in this thesis would provide some valuable basis to improve the four-cylinder engine’s dynamics characteristics.

Abstract: Most often observation with a thermal camera is not static; the platform on which the surveillance equipment is mounted is affected both by motor vehicle exterior vibrations and amplitudes of the movement in field. In this paper a case study is shown starting from some tests made on a moving boat and a visual method to analyze the motion is presented. Some images acquired in real time are fast and automatic analyzed using NIVision software to quantify the random and the sinusoidal motion made by the motor vibrations and the motion of the platform. Due to this phenomenon the images seems to be blurred but this blurring can be anticipated and avoided through a proper design of platform stabilisation if the motion parameters are known.

Abstract: According to the lower shaft structure feature of a pneumatic and mechanical agitation flotation machine in the practical application, a finite element model is established on the basis of modality analytical theory of vibration structure. Through analyzing the modality characteristics of the lower shaft, the vibration mode of lower shaft is obtained. Moreover, through analyzing the modal characteristics of the lower shaft in condition of different impellers material and lower hollow shaft wall thickness, the conclusion is obtained that more lighter the impeller’ material is, more great the difference between natural frequencies and vibration excitation frequencies is. Another conclusion is that the lower shaft still do not resonate when the wall thickness of lower shaft thin appropriately. The conclusions of this paper have great theoretical and practical significance of further optimization of the flotation machine lower shaft structure.

Abstract: The subject comesfrom major national special project in Kunming Machine Tool Factory which oursupervisor is working on currently. This report is the analysis of overallstructure of magnetorheological dampers,main technical features andperformance. It also provides a brief introduction to the main features of MRFand rheological principle, as well as the calculation of magnetorheologicaldamper size design, and also constructs the magnetorheological damper simulationmodel based on the magneto-rheological dampers structural features. With theTHM65160 CNC machine structure, we designed specifically on the localapplication of magneto-rheological dampers for varying magnetic flux dampermounted machine made ​​dynamic performance test responses. Based on this,magnetorheological dampers combine structural and performance characteristics,simulating the motion by using ADMS.

Abstract: This paper presents a novel method to diagnose turbine blade faults by analysing wavelet result based on fingerprint recognition method. The study focuses on applying the fingerprint features extraction method to extract faults information from wavelet displays. Fingerprint recognition method studied in this paper is known as fingerprint bifurcations points. Experimental results show that this method could potentially be used as a features recognition method to identify the different types of machinery faults such as rubbing and rotor unbalance.