Extension For Independence Axiom And Application Research On Axiomatic Design

This dissertation is supported by the Natural Science Foundation of China (Grant No. 50575083). The functional dependency and the corresponding uncoupling method are deeply researched in this dissertation, which include the strategy of disposing of coupled design based on the independence axiom, and the uncoupling method based on systematic inventive thinking (SIT). The application of axiomatic design in conceptual design of mechanical transmission system is also discussed, in which artificial immune system and set theory are introduced.Firstly, the method of disposing of coupled design based on the independence axiom is studied. Guided by zigzagging mapping between functional requirements (FRs) and design parameters (DPs), the design problem is decomposed. After rearrangement of the created design matrix, the interaction between FRs and DPs can be identified and analyzed. Based on the interaction analysis, the virtually decoupling condition is investigated. The coupled FRs-DPs that satisfy the virtually decoupling condition are disposed by the virtually decoupling method. A satisfaction degree-based decoupling method is also proposed to deal with the coupled FRs-DPs that don't satisfy the virtually decoupling condition. As regards the remained coupled FRs-DPs after decoupling, it is a good way that adopting tearing method to find the better initial ordering of iteration to avoid additional iterations. Based on above work, a method of disposing of coupled design based on the independence axiom is proposed. This method takes into account the interaction between FRs and DPs, and provides guidance for accomplishing design in the case of violating the independence axiom. Two practical examples, the design of plunger rod and the design of condenser, are provided to illuminate this method.Secondly, the uncoupling method based on SIT is investigated. The relationships, compatibilities, and possibility of integration between axiomatic design and SIT at principle, methodological, and tools levels are analyzed, in terms of relationship between independence axiom and qualitative change principle, axiomatic design and closed world principle, hierarchy and SIT, information axiom and SIT. Based on this analysis, a method for uncoupling design with the aid of SIT is proposed. The detailed uncoupling steps of this method are explained and a strategy to upgrade an old system or develop new systems based on an existing one is also proposed in terms of this uncoupling method. In addition, a discussion of the proposed uncoupling method and the possible extension of this method with TRIZ are presented. An example of solving vibration and noise problem of flushing facility is provided to demonstrate how the uncoupling method can lead to a focused formulation of the functional dependency problem and a systematic search for promising solutions. This proposed uncoupling method is different from the conventional approaches, which removes the functional dependency through employing creative technology, and avoids measuring functional dependency, harmonizing parameters, or searching for substitutable technological ideas.Thirdly, the method for conceptual design of mechanical transmission system is discussed. Guided by axiomatic design framework, behavior as the bridge between FRs and DPs, FRs and DPs are formalized in terms of kinematic characteristics set by set theory, and the basic FR elements and basic DP elements are also classified. The basic mapping condition from functional domain to physical domain is studied. The steps of automated creation of FR decomposition rules are given. Then a method for conceptual design of mechanical transmission system is proposed. Based on the description of mapping from functional domain to physical domain, the FR decomposition rules are created firstly to guide FR decomposition and search for sub-solutions for each sub-FR. After constructing the mathematical model of searching for the optimal combinatorial solution, immune algorithm is introduced to dispose of this combinatorial optimization problem,which can speed up search process and deal with the possible combinatorial explosion. A design case of to-and-fro yarn-guiding system is presented to illustrate the application of this method.Finally, the design of latest twister is discussed based on axiomatic design. The overall scheme of the latest twister is given through zigzagging decomposition. The mathematical model of transmission system is constructed, the mechanical kinematic scheme is generated, and the design of mechanical transmission system is fulfilled. Then the twisting principles and basic concept of twisting device– spindle are analyzed. Lastly, the overall design of the latest twister is successfully accomplished.