Papers by Author: Zhao Hui Ren

Abstract: In connection with the nonlinear dynamic characteristics shown from the performance of fault rotating mechanical system, the authors propose the analysis method of Lyapunov dimension and exponent energy Spectrum to the signal feature of mechanical fault. Using theory of phase space reconstruction, simulating fault signal of rotating machine is reconstructed. In order to reconstruct the phase space which can be adequately reflect the movement characteristics of the system, the time delay and embedding dimension are discussed emphatically, on this basis, calculated the Lyapunov dimension and exponential energy spectrum. From the analysis and calculation on simulation of different fault signals, it shows that under different rotating machinery fault conditions, its Lyapunov dimension and exponential energy are significantly different, which verifies that this two nonlinear feature quantities is effective parameters for fault information

Abstract: Based on the study and analysis that Lyapunov exponent can be used to characterize the motion state of system, in connection with the nonlinear dynamic characteristics shown from the performance of fault rotating mechanical system, the authors proposed the analysis method of Lyapunov dimension on the signal feature of mechanical fault. Using theory of phase space reconstruction, simulating fault signal of rotating machine was reconstructed. In order to let the phase space reconstruction adequately reflect the movement characteristics of the system, the time delay and embedding dimension are discussed emphatically. Based on what mentioned above, the authors calculated the Lyapunov exponent and the Lyapunov dimension. From the analysis and calculation on simulation of different fault signals, it showed that under different rotating machinery fault conditions, its Lyapunov dimension were significantly different, which verified that this nonlinear feature quantities were effective parameters for fault information and they were excellent parameters in terms of extraction and recognition of fault features.

Abstract: Four different fault signals are simulated and collected which are oil whip fault signal, rub-impact fault signal, rub- oil whip coupling fault signal and rub - loose coupling fault signal in the lab. According to the Restructuring the theory of phase space, in foundation of the optimal delay time τ and the embedding dimension d, phase space is restructured to the time sequence of different fault. Simultaneously in connection with the general fractal theory and its algorithm, author has conducted the analysis and study, and the correlation integral is used to the concrete calculation of general fractal dimension, fractal dimensions of four kind of fault are calculated separately by this calculation method. The research goal is attempting to explore one new calculation method of general fractal dimension to improve accuracy and increase the degree of differentiation, to provide the basis for the analysis of the fault signal.

Abstract: Simulated four different fault signals in the lab, the authors then used wavelet scalogram and amplitude spectrum to make analysis on the above four fault signals and abstract each spectrum characteristics. Wavelet scalogram was able to extract the characteristic’s frequency, show the impact components caused by rub-impact, show the beat phenomenon caused by oil whip and show the irreducible high frequency components as well as the complex low-frequency components. Amplitude spectrum was able to show the energy size distribution at various frequency bands and able to analyze and calculate the relationship between various frequency components. Thus they express the relationship between various frequency banks from a quantitative manner. Therefore, combining the wavelet scalogram and amplitude spectrum when making analysis, as they complement and verify each other, it will enhance the reliability when extract and analyze the characteristics of fault signal.

Abstract: In this paper, under House of Quality(HOQ) Fuzzy Theory, taking product planning House of Quality(HOQ) as an example, systematically considers fuzzy auto-correlation matrix of engineering properties influence on engineering properties target value and development cost, by definition some concepts, such as engineering properties plan improvement level, practice improvement level, fuzzy planning cost coefficient and fuzzy actual cost coefficient, establish properties target value optimization model based on House of Quality(HOQ) Fuzzy Theory, and validate this method by a case study.

Abstract: Looseness fault can occur in rotor part, bearing and pedestal for the vibration caused by alteration of operating craft and inappropriate installation. In the paper, a new pedestal looseness model is proposed by comprehensively considering the advantages and disadvantages of current models of pedestal looseness. By using nonlinear finite element method, the nonlinear characters of overhanging dual-disc rotor bearing for pedestal looseness fault are studied. The work has important significance on safe running and prolonging the life span of machines.

Abstract: From the view of the point of the systems engineering, the model of 7D planning of product design is presented in this paper based on the previous work. The planning of products design includes design ideas, design environments, design objective, design process, design contents, design methods and the design quality evaluation methods, so named 7D planning model. Besides the understanding of the customer requirements, the seven aspects of 7D planning should be considered completely and planned systematically. The paper makes a detailed expatiation of the 7D planning model of synthesized design method based on systems engineering.

Abstract: In recent one century more than 60 design methods of products have been proposed and most of them can satisfy the one or several requirements of the general qualities only. So it is necessary to develop some synthesized design method, which can satisfy requirements of general synthesized qualities of product. Up to now, several scientists and technologists have done their efforts to study several synthesized design methods in order to satisfy more requirements of users. These methods are comprehensive design method, QFD method, taguchi design method, axiomatic design method, etc. Based on the classification of the design methods, we have proposed a new synthesized design method, named 1+3+X. The present method meet the need of customers for different general synthesized qualities of product including main and supplementary functions, structural performances, working performances and manufacturing performances and the first 1 is functional optimum design, the 3 are the dynamic optimum design, intelligent design and visual design to satisfy structural performances, working performances and manufacturing performances respectively, and the X is the design to satisfy other requirements.

Abstract: It is important to study system vibration characteristics for improving product quality and ensuring safety operation of units. In this paper, some dynamics of rotor systems are studied in large centrifugal compressor. The models of diaphragm coupling and tilting pad bearing are established by appropriate simplification. The finite element model of rotors with bearing and coupling is set up by taking interrelation of these subsystems into account. The unbalance responses of journal are computed based on the relative standard. The effect of bearing parameters (length-diameter ratio, clearance ratio and lubricating oil number) to journal vibration of rotor systems is analyzed. Finally test results and theoretical results are compared and errors are analyzed. The research results will provide theoretical basis for improving the bearing design of compressor rotor systems.

Abstract: With the development of science and technology, harmonious design will be one of the latest trends in modern mechanical products development. Based on the harmonious design method, the well synthesized quality products will be invented. It will have little negative influence on society and the natural environment, and the high utilization rate of resources and the most comprehensive benefits in the full lifecycle from planning, designing, manufacturing, packaging, and discarded. The harmonious state can be obtained between products with political, economic, cultural, legal, scientific, natural and social environments. The harmonious design is investigated from the harmony of design methods; the harmony of product function with performance; and the harmony of product with product, with human, with technology, with society environment and with natural environment. And the evaluation of harmonious degree and management system are studied in this work, too. Based on system engineering and economic, cultural, legal, scientific, natural and social environment factors, the formula of the complete system of products design is established. Therefore, the new vitality and higher market competitiveness of product can be achieved. Not only the design is for human but also for nature, for the harmony of human and nature.