Modular Design Method For Complex Product Based On Generalized Function-Structure Modeling

With the development of industry and the improvement of people’s individual needs for products, the modular design has become an advanced design method for the majority of mechanical products. Typically conceptual design determines the70%cost and efficiency in the development of products. Effective module partition during the conceptual design period will benefit the whole process of product design. In addition, with the increase of product function, high degree of coupling in function and structure is not conducive to the modular design, but with the shortening of product full lifecycle and the growing of the innovation, modular design for complex products is still an effective method. For the above requirements, a systematic method for modular design and evaluation in conceptual design stage of complex mechanical product is proposed in this paper.Firstly, a method of generalized function-structure modeling is proposed based on the study of traditional method of function-structure modeling. By operation activity diagram, abstract function on the top-level is decomposed, and then an improved functional analysis method based on the generalized process is put forward to realize the decomposition of the secondary function and the mapping between function and structure. As results, difficult issues such as the top-level function decomposition and correlation analysis of the coupling function for complex mechanical products are overcome effectively.Secondly, correlation factors between components are analyzed on three aspects of function, physical and geometry. Quantitative calculation of the correlation factors is achieved by AHP(Analytic Hierarchy Process) and scale calibration method. Combining the basic theory of design structure matrix with function structure model, numerical DSM of components is constructed. Module partition of complex mechanical products is achieved by IGCA(Intelligent Genetic Clustering Algorithm).A module assessment method is proposed based on change risk for the results of module partition. Through the analysis of the effective path for change propagation and the importance degree between the components, directly probability matrix, the indirect probability matrix for three propagation depth and impact matrix are constructed in order to get a comprehensive risk matrix of each module. Through normalization process of the comprehensive risk matrix, modular performance evaluation about anti-interference ability and propagation interference ability is realized.Finally, upon completion of the modular design and performance evaluation, module interface characteristic is analyzed from four aspects including functionality, geometry, materials and manufacturing, and module interface data structure system are built as well. At the same time, basic structure of interface is constructed based on analytic hierarchy process and interface serialization process as well as standardized encoding rules are formulated. Thus a systematic method for standardized design of module interface is formed and it is validated by bogies.