Research On Theory Of Monitorability-based Design In Mechanical System And It's Application In Marine

In the past decades, terrible accidents happen frequently in the plane crashes, spacecraft explosions, bridge collapses, large ship and submarine crashes, nuclear power plant leakages, etc. The safety and reliability of mechanical systems have been hence gained great attentions in practice applications, and at the same time the users have increased their request for the mechanical product properties significantly. Nowadays China is a big country in machinofacture but not a power. Chinese engineering industry searches for original innovation achieve the revitalization of the machinery and equipment in China. As a result, advanced design theories and methods, structures and condition monitoring technologies for mechanical systems, as well as its related fields, has achieved rapid and much progress. Under the pressure of high request of energy saving and emission reduction, the current maintenance mode of mechanical systems faces a huge challenge. How to ensure a high-efficient, reliable, safe and long-time operation of mechanical systems is still a tough nut. Mechanical system condition monitoring and fault diagnosis technology is an important solution for this problem and will be the focus of intense research.Given the low monitorability even ignorance in current mechanical systems, this thesis has presented the design theory of machinery monitorability to provide the possibility of the Condition Based Maintenance (CBM) and Prognostic and Health Management for mechanical systems. By achieving this goal it could make the machinery work in the high-efficient, reliable, safe and economic state. Hence, machinery monitorability has been advanced to the position of equal importance with reliability and maintainability and has been considered in the design procedure in the production life cycle. From the point of view of the combination of condition monitoring technology and advanced machine design, the monitorability-based design theory has been proposed based on the system-theory and life cycle management theory. The monitorability-based design theory can be divided into four aspects. These aspects include (1) study on the connotation of the monitorability-based design theory, (2) research on design methods of the monitorability-based design theory, (3) investigation on allocation methods of the monitorability-based design theory (i.e. the optimization of the monitoring point arrange), and (4) assessment on the monitorability-based design. The main content and achievement of this thesis are as follows:Chapter 1 analyzes the forming background, character and the exiting problems of the monitorability-based design theory. Literature review and questionnaire survey suggest that the condition monitoring technology and advanced machine design have been considered and implemented independently in the current mechanical engineering industry. It is therefore imperative to develop new technology to bridge the gap between them and enhance the communication of the two different scientific fields.To associate the condition monitoring technology with the advanced machine design, the monitorability-based design theory has been proposed in Chapter 2 based on the system-theory and life cycle management theory. The definition, connotation and extension of the machinery monitorability have been described according to the operation and fault characteristics of mechanical systems, and the basic terms involved with the monitorability-based design theory have been specified. Based on these contents, the theory framework of the monitorability-based design and basic application framework of the monitorability-based design theory have been established.Chapter 3 presents the integrated optimization design approach for the machinery monitorability by using the collaborative theory. The distributed system is introduced into the monitorability-based design theory to realize the information synergism.The allocation method of the monitorability-based design theory is firstly interpreted in details in Chapter 4 and the corresponding requirements and strategies have been proposed for the monitoring point choosing. Then the notice of the sensor choosing has been discussed. Lastly, the optimization of the monitoring point arrange has been put forward based on the hierarchy theory and the fault tree theory.Chapter 5 has established the evaluation index system for the mechanical monitorability-based design. The three-phase life cycle overall assessment method is proposed for the mechanical monitorability-based design, and the gray theory has also been applied to mechanical monitorability assessment. The practical application of the proposed monitorability-based design theory has been carried out on the ocean salvage vessels in Chapter 6. The industrial mechanical monitorability-based design framework has been constructed according to the characteristics of the ship design and manufacturing. Based on this development, the future framework of the integrated support system based on the mechanical monitorability-based design theory is prospected.The achievements of this thesis can propel the development of the mechanical system design. The comprehensive study on the monitorability-based design theory and its application can enhance the monitorability level of mechanical systems, and benefit the acquisition and identification of the weak signals in mechanical fault diagnosis. Thus, the ability and the techniques of the mechanical condition monitoring and fault diagnosis can be improved. Taking these advantages, the innovation of productions and the market competition strength of mechanical systems can be promoted. As a result, satisfactory intelligent, reliable and safe operation of mechanical systems can be goaled, and the modern maintenance mode can be achieved.