A methodology for representation and reasoning in conceptual design: Application in creating an integrated design environment for stamped metal parts

Amit Mukherjee, Purdue University


This research proposes a new graph based representation methodology called Sketching Abstraction for representing preliminary designs with an emphasis on the conceptual design of components. In a sketching abstraction the functionally essential geometry of the part is represented using functional features along with a face representation while the nonessential geometry is abstracted using a linkage mechanism. The part functionality is correlated with the sketching abstraction using data structures called function-form matrices. The sketching abstraction is annotated with a set of primitives and a grammar is used to parse the annotations into pairwise canonical relationships between the essential geometry of the part.^ The sketching abstraction and the functional signature of the part can be used for various reasoning activities such as extracting parts from a database that are functionally similar but whose geometry is different. We prove that such a search process can be carried out in polynomial time. We also show the link between a sketching abstraction and a solid model of the part. The application domain for this research is stamped metal parts manufactured by stamping dies. ^ This work presents a set of procedures to evaluate the manufacturability between two sketching abstractions. This includes checking for dimensional constraints, use of standardized tooling, accessibility of tooling for creating a feature and the estimation of costs for die construction. We also present a methodology to represent stamping dies at an early stage of design. Dies are represented using die sketches which are ordered collection of punch-die pairs that on application on a strip of metal result in the desired part design. A methodology is presented to create a die sketch from the sketching abstraction using a combination of domain dependent heuristic knowledge and geometric reasoning algorithms based on the dimensional and tolerance relationships between the key geometric entities in the sketching abstraction. We also present a set of algorithms for the estimation of lead times for die construction which is used to estimate the effect of design decisions on the overall product development lead time. ^ We also address the issue of organizing the design workflow during conceptual design using the sketching abstraction. We present the different collaborative tasks involved and suggest procedures for efficient utilization of design resources during conceptual design which may be utilized to develop a decision support system for conceptual design. (Abstract shortened by UMI.)^




Major Professor: C. Richard Liu, Purdue University.

Subject Area

Engineering, Industrial|Engineering, Mechanical

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