Method of modelling engineering design components

A computer program containing instructions, which, when executed by a computer, cause the computer to:

• define a core set of geometric characteristics of at least three occurrences of a shape element in a feature and spatial relationships between the at least three occurrences of the shape element in a pattern, wherein each geometric characteristic and spatial relationship is associated with a constraint determining a behavior of an occurrence of the shape element when changed;
• define a set of optional geometric characteristics of the at least three occurrences of the shape element in the feature and the spatial relationships between the at least three occurrences of the shape element in the pattern, wherein each optional geometric characteristic and spatial relationship is associated with an optional constraint determining the behavior of the occurrence of the shape element when changed;
• define a hierarchical order for the set of optional geometric characteristics and spatial relationships and the associated optional constraints;
• receive a change in the at least three occurrences of the shape element and/or the pattern from a user, the change being carried out by:
• solving the constraints associated with the core set of geometric characteristics and spatial relationships;
• and
• solving the optional constraints associated with the set of optional geometric characteristics and spatial relationships in the hierarchical order in which these are defined;
• and
• display the changed occurrences of the shape element and/or the pattern to the user.

A data processing system adapted to model engineering design components in a Computer-Aided Design (CAD) system, wherein an engineering design component comprises a feature having at least three occurrences of a shape element arranged in a pattern, the data processing system comprising:

• a data processor configured to:
• define a core set of geometric characteristics of the at least three occurrences of the shape element in the feature and spatial relationships between the at least three occurrences of the shape element in the pattern, wherein each geometric characteristic and spatial relationship is associated with a constraint determining a behavior of an occurrence of the shape element when changed;
• define a set of optional geometric characteristics of the at least three occurrences of the shape element in the feature and the spatial relationships between the at least three occurrences of the shape element in the pattern, wherein each optional geometric characteristic and spatial relationship is associated with an optional constraint determining the behavior of the occurrence of the shape element when changed;
• define a hierarchical order for the set of optional geometric characteristics and spatial relationships and the associated optional constraints;
• solve the constraints associated with the core set of geometric characteristics and spatial relationships;
• solve the constraints associated with the optional geometric characteristics and spatial relationships in the hierarchical order in which these are defined;
• and
• output the changed occurrences;
• a user input device configured to receive a change from a user;
• and
• a display device configured to display the changed occurrences of the shape element and/or the pattern output by the data processor to the user.