A Concurrent Design Method for Functional Tolerance and Structure based on the Principle of Decomposition and Reconstitution

To assure feasibility and economy of mechanical product design, tolerance design should be incorporated into conceptual structure design phase. The completion of the evolving procedures from functional requirement to tolerance scheme resolution in the early stage, greatly promotes selection of structure scheme and optimization of cost. The paper provides a concurrent design methodology for functional tolerance using the principle of decomposition and reconstitution using growth design based on functional surfaces. A concurrent design methodology is given, including growth design-supported structure-tolerance design process, assembly information model and TTRS-based tolerance representation model. A recursive design method for function to structure mapping is proposed, and the tolerance design in every step of the iteration is focused on. Geometric variation model is introduced to infer key parts and key features, helping forming tolerance specification while assuring rationality and sufficiency of structure decomposition. In the whole process, structure and tolerance are constrained to each other and an optimization framework is put forward.