Design Structure of AVEVA Hull

The Hull design model is organized in a hierarchical structure with three or at most four levels as illustrated by the figure below. It may be considered as a compromise between the assembly view of the product and a functional view. Thus it is not in its concept a pure functionally oriented model but corresponds maybe more ideally to a view for the detail design. However, it is also so general that it lends itself to several different ways of organizing the design work.

Figure 2:1. Hull model structure

At a first glance the structure in the figure above (and the mere vocabulary used) may suggest that the design model is very much like a simple assembly structure. The blocks then correspond to sections or high level assemblies, the panels correspond to sub-assemblies that are built up by parts on the lowest level. (The circular backward reference arrows at the panels indicate that the parts (in plane panels) normally are stored implicitly in the panel itself. More about that later!). The picture does not reveal the fact that brackets may be small "assemblies", that means, contain stiffeners and/or flanges.

For a small yard with a simple organization of the production it can actually be used both as a design model and an assembly model. However, in the general case the design structure and the assembly structure need not be the same. For one thing, the depth of the assembly tree structure is in principle unlimited compared to the limited depth of the design structure.

In principle, the partition into blocks should be considered as a way to divide the ship into regions of a suitable size for the current design stage. In an initial stage the whole ship may be considered as one block. In the detail design for production it is advantageous to let the block coincide with a main assembly of the assembly structure, but this in no way compulsory. Parts from one block may very well go into different assemblies. ( Hull has certain tools to successively modify the break down of the model as the design work proceeds).

Other reasons for breaking down the model may for example, be that the modelling of a block can be assigned to a single designer or a group of designers. Then most of the topological references in a block are local which makes it easy to work independently of the simultaneous design work in other blocks. However, it should be noted that all the time the whole model is available to all designers and there is no problem in making references across block limits.

Finally, a suitable design structure has also implications for the system performance, for example, in case of frequent search operations in the model, especially when the model starts to get big.

The elements of the design structure will be described to some detail below.