Research On The Theory Of Qualitative Modeling Of Structure And Its Application In Mechanical Product Analogy Design

Aiming at the qualitative features of concept design product structure, this dissertation presents a theory of qualitative modeling of product structure in concept design. By abstracting and symbolizing of bond surfaces, functional surfaces and configurations of solid parts, the part symbol models have been presented. By abstracting of the type, relative position, orientation and topology relation of solid part functional surfaces as a qualitative symbol set, the symbol part qualitative models have been presented. Part symbol models are used to assembly modeling to set up symbol assembly models. By qualitative describing of space position relations among the parts in symbol assembly models, the concept design product qualitive assembly models have been presented. Furthermore, by using function-behavior-structure-shape models, a method of mechanical product analogy design based on structure similarity has been presented.The main work of the dissertation is as follows:Chapter 1 gives a review and history of the development situation of qualitative spatial reasoning and the correlative researches on product structure models. The product structure in concept design is discussed. The contents of qualitative modeling theory of concept design product structure and the principle of mechanical product analogy design method based on structure similarity are presented.Chapter 2 puts forward to express the structure of parts by shape symbols. The definition, classification, property, edit, description, quantitative and qualitative merge operation of shape symbols are discussed. The part symbol modeling procedure and symbolizing method based on shape symbols are presented, the symbol expression examples of typical structure parts are given.Chapter 3 puts forward the qualitative model of symbol parts which support concept design and can be used to guide and control part shape design. The basic principle of algebra method of qualitative space reasoning and definition, label and consistency locally reasoning methods of qualitative geometry constraint are discussed and examples are presented.Chapter 4 puts forward assembly modeling by using part symbol models. Symbol assembly relation, qualitative geometry constraint, qualitative geometry constraint graph, constraint consistency maintenance are discussed. The examples of product assembly qualitative modeling and constraint reasoning in concept design are presented.Chapter 5 puts forward to compartmentalize part design resources by using symbol part structure models. The definition and calculation methods of symbol part structure similar degree are discussed. The similar structure part retrieval mechanisms of structure graphs matching and structure graphs similarity are discussed. A part analogy design method based on structuresimilarity is presented by using function-behavior-structure-shape model.Chapter 6 puts forward an assembly analogy design method based on structure similarity by using function-behavior-structure-shape model. The definition and calculation methods of assembly structure similar degree are discussed. On the basis of analyzing retrieval mechanisms of similar structure symbol parts, the retrieval mechanisms of similar structure assemblies are presented, the model and basic mode of assembly analogy design are discussed.In the 7th chapter, on the basis of the theory of qualitative modeling of concept design product structure and the method of mechanical product analogy design based on structure similarity, the prototype system of hierarchical modeling method of structure design is developed. The systems' architecture and main functions are introduced.Finally, conclusions are given along with recommendations for future research in chapter 8.