Abstract: Geometric objects including points, lines, curves, surfaces and solids are defined and constructed in a system which retains and utilizes relationships and dependencies between objects in a directed graph (digraph) data structure. The primary advantage is automatic updating of the model, preserving dependencies, when an underlying object is changed. Multiple types of parametric curves and surfaces and multiple levels of dependency are easily supported through a recursive program structure. Difficulties of surface-surface intersection and trimming are largely avoided by provision of novel entities which permit construction of accurate and durable joins between surface objects.

Abstract: A method of computer aided design of geometric models including the steps of: defining a set of geometric entities for use in constructing the geometric models, each of the geometric entities being an abstract geometric object type that is adapted to be actualized into one or more geometric objects, the geometric entities including point class entities, curve class entities, and surface class entities; identifying some of the geometric objects by corresponding unique object identifiers; defining a plurality of relational entities along the set of geometric entities, each of which is adapted to be actualized into corresponding relational objects having having a dependency relationship upon one or more other geometric objects whose object identifiers are specified within the relational objects; wherein the relational entities include a curve class entity having a dependency relationship on a point class object; wherein at least one of the relational entities is a surface class entity having a dependency relatio

Abstract: Geometric objects including points, lines, curves, surfaces and solids are defined and constructed in a system which retains and utilizes relationships and dependencies between objects in a directed graph (digraph) data structure. The primary advantage is automatic updating of the model, preserving dependencies, when an underlying object is changed. Multiple types of parametric curves and surfaces and multiple levels of dependency are easily supported through a recursive program structure. Difficulties of surface-surface intersection and trimming are largely avoided by provision of novel entities which permit construction of accurate and durable joins between surface objects. An example model (FIG. 27 ) of a sailing yacht design illustrates six surface objects of several types with the defined dependency relationships. The hull 271, deck 272, cabin forward 273, cabin side 274, cabin aft 275 and cabin top 276 surfaces intersect at joins 278, 279 which are accurate and durable.

Abstract: Methods for lofting flat metal starting blanks and for compounding curved metal plates from the flat starting blanks can be used in lofting and fabricating boat hulls, aircraft and automobile bodies, tanks, containment vessels, and other shell structures. The methods relate starting blanks and compounded plates to specified patches of a defined surface having compound curvature, or more precisely, non-zero Gaussian curvature. The surface is a representation of the shell structure to be fabricated by assembling the plates. In each of the methods the in-plane strain is related to instinsic geometry in a strain equation. The strain is explicitly or implicitly considered and solved for accurate and controlled implementation of both the lofting and cutting of the blanks and the compounding of the blank into the desired plate configuration. Solution of the strain equations for boundary nodes in the plane of the blank for cutting the blank minimizes field trim.