| Issues of constraint management, the identification and solution of constraints, are critical to any CAD/CAE system seeking to combine component and assembly design. Physical contact between components and other engineering considerations create constraints on the relative position of the components, their nominal dimensions, and the tolerances on those dimensions. The number of such constraints can be large even for relatively simple assemblies. Specialized techniques are needed to account for the distinctive nature of these geometric constraints.; The constraint tools developed in this work address some of these challenges. The general approach is to: (1) Identify the constraining relationships among the assembly components; (2) derive algebraic expressions that properly express the effect of the identified constraints, and; (3) solve the resulting constraints with numerical approaches appropriate to the domain of interest. The incorporation of these techniques into a CAD environment allows the designer to assemble a set of parts in an intuitive and robust manner, have the assembly constraints extracted automatically including those that may involve unanticipated mating conditions, propagate changes in the component nominal dimensions to the entire assembly, specify desired clearances between parts and have those clearances automatically synthesized, and perform tolerance analysis on the assembly for a given component tolerance specification. |
