The Conceptual Design Methodology For Agricultural Machinery Based On Axiomatic Design And Extencis Theory

At present,the agricultural machinery design in our country still lacks the effective theoretical support in the conceptual design stage,which leads to the lack of innovative design.A set of universal and applicable design theory and method system should be formed to guide the positive conceptual design for agricultural machinery.A design system IMAE(Integrated methodology based on Axiomatic Design and Extenics)was proposed to solve the problems of "how to conduct an innovative conceptual design scheme for agricultural machinery","what steps should be followed in the conceptual design stage","what should be considered in each step and how","how to guide innovative conceptual design" and so on.The conceptual design was conducted with functional analysis and the abstract and disordered thinking was ordered,structured and stylized.The scheme was diverged at the same time and the innovative conceptual design of agricultural machinery would be completed more smoothly.(1)Referring to large number of documents and in-depth research about the present situation of agricultural machinery design and design theories,AD theory was selected to be the basis of the agricultural machinery design theory for that AD theory can greatly simplify the design process and was most wildly used.However,the practical guidance of AD theory was not very strong because of its universality and less focus on the details.To solve this problem,this paper introduced Extenics theory for further improvement of AD,which has effectively description for things and a set of innovation methods.Based on that,this paper analyzed the main problems and solutions during the establishment of the theoretical system for agricultural machinery design,and determined the content and technical route of this paper.(2)This paper analyzed the main influencing factors of the design demand of agricultural machinery and established the customer requirement model of agricultural machinery considering the characteristics of agricultural machinery in the "soil-machine-plant" environment.Evolution theories in TRIZ were applied to analyze the evolution directions of customer requirement and the agricultural machinery techniques from the perspective of dynamic development,providing a macroscopic guidance for the design of agricultural machinery.(3)Based on an in-depth analysis of AD and Extenics,the integration mechanism of the two theories is studied and the corresponding mathematical description model was established for the first time.The functional requirement,design parameter and coupling problem in the AD theory were modeled in detail with the application of the affair-element model,matter-element model and relation-element model in Extenics.Thus the problems of lacking in unified and detailed expressions of elements in the "domains"and coupling problems of the AD theory were solved.Moreover,the basic-element models for the mapping process from functional domain to physical domain in AD theory were established.(4)The process of searching for initial conceptual design schemes were transformed to solving feasibility problems according to the integration model of AD theory and Extenics.And the mapping process from functional domain to physical domain was also improved.The problems in judging the independence of the elements in design matrix,mapping and decomposition between domains and expanding solution space were solved,and finally,the design process based on Axiomatic design and Extenic(DPAE system),which was for guiding the design process was established.(5)In this paper,a general framework of the decoupling method based on AD and Extenics(DMAE)for decoupling was established to solve the difficulty of describing coupling and the lack of specific decoupling method in AD theory.Three decoupling models were constructed in detail with the three theorems in AD providing the guiding directions.(6)DPAE system and DMAE system constituted the integrated methodology based on Axiomatic Design and Extenics,i.e."IMAE system",as the guiding system for agricultural machinery design.In order to verify the feasibility and guiding significance of the system,the design of a small vegetable tool carrier is taken as an example.Moreover,a corresponding IMAE computer aided design platform was developed on the basis of the theoretical framework of the system.