General

In Product Information Models there may be dependencies between the objects. These dependencies are nearly always saved as some kind of references to objects or part of objects. This is certainly true for the Product Information Model and specifically for the Hull Model. Such references constitute the topology of the Product Information Model.

In AVEVA Hull each design model object holds references to the objects that are part of its definition, for example, the surfaces, curves or panels defining a plane panel boundary. Thus each object can be regenerated using its references. This might create for example, an updated outer contour if the referred objects have changed its position or shape.

Besides the references defining an object the Hull Model also contains references to the depending objects. For, for example, a deck this would be references to all webs attached to it. This is essentially the same information as the defining references but seen from the other end. The depending references are stored in special topology objects.

In order to benefit from the topology it is essential that it is well defined. This means for example, that a bulkhead that ends at a deck should have a limit definition that is a reference to that deck rather than just a coordinate. Then the bulkhead outer contour will be dependent on both the position of the deck and even the thickness of the deck plating. Also circular references should be avoided. If for example, two deck panels are connected they should not refer each other directly in the boundary definition. Either both can refer a predefined plane or one can be defined by a coordinate and the other refers the first one.

Many references are on component level, for example, a bracket referring a stiffener on the same panel or on another panel. If for example, the boundary definition of a bulkhead refers a deck and then a stiffener on that deck refer a stiffener on the bulkhead this may seem like a circular reference as the bulkhead refers the deck and vice versa. In reality it is not as the topology has to be viewed on component level. Thus the boundary of the bulkhead is dependent on the deck position and plating while the deck stiffener is dependent on the bulkhead stiffener. So it is quite possible to sort out for example, in which order to regenerate the components of the panels.