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Modelling Methodology in CATIA V5 - Part 3

Posted by Alex Fernandes on 04-Jul-2017 09:00:00
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The Design Phase

This is the third article of a series concerning how to implement and use modelling methodology in CATIA V5.

In this article, we will discuss the design stage in detail.

This is the first stage of the creation process; we will create a geometrical set called Skeleton and we will insert additional geometrical sets inside it. The component’s design intent is captured in the Skeleton geometrical set. Skeleton methodology has been around for quite some time now and the idea is to have to model’s main geometrical elements editable from one single location in the part’s specification tree. This also means that we will have many elements inserted inside this geometrical set, so for this reason we will rename them and organize them according to a specific logic.

Figure 1 - The Angle Bracket part

Figure 1 - The Angle Bracket part

The Skeleton geometrical set

Let us have a look at figure 2, where we have represented the design stage of the Angle Bracket part we have been using in this series. The Skeleton is a First Level container, just like the PartBody. In it, we will insert sub-sets (Second Level containers). Notice all existing elements were renamed, inserted inside specific geometrical sets, inside the Skeleton. 

Figure 2-The Design stage of Angle Bracket part

Figure 2 - The Design stage of Angle Bracket part


In figure 3, we can see that the Skeleton has four sub-sets. These sub-sets could be First Level containers however having them inside the Skelton creates a cleaner, more organized tree structure that is easier to interpret and use when editing a part.

The sub-sets are sequentially numbered and renamed. The same rule is applicable to the elements inserted inside the sub-sets.

The sub-sets are presented deliberately in a predefined order. 

This has to do with the fact that elements created inside the Skeleton will also respect the Hierarchy Rule, presented in a previous article.

Figure 3-The Skeleton geometrical set structure

The Hierarchy Rule applied in the Skeleton will dictate that we create reference elements before the sketches. This will enforce that no reference element will depend on any sketch.

This will give the model the required robustness at the Skeleton level. The sub-set order, presented in figure 3, will help us guarantee this requirement.

 Figure 3 - The Skeleton geometrical set structure


Figure 4-The Skeleton geometrical set elements

Let us analyse figure 4;

in the first sub-set, called Input data, we are going t

o insert all elements that are defined outside our part file. These are all the imported elements that we need.

They can be imported sketches, surfaces, wireframe, planes or reference elements.

In the second sub-set, Reference geometry, we will insert all reference elements that were created in this part file. In this set, we will encounter reference planes, wireframe elements and points.

The third sub-set, Main sketches, contains all the sketches used to define the part that are parallel to the absolute axis planes.

The fourth sub-set, Auxiliary sketches, contains all the sketches that are supported in planes or reference elements not parallel to the absolute axis planes.

 Figure 4 - The Skeleton geometrical set elements


In this article, we discussed the Skeleton geometrical set’s structure, naming rules for sub-sets and design elements. We also discussed what elements can and cannot be inserted inside each one of the existing sub-sets and their order of creation according to the Hierarchy Rule.

In the next article, we are going to discuss some basic rules for sketch definition while we are in the design stage of a part.


Related articles:    Modelling Methodology in CATIA V5 - Part 1

 Modelling Methodology in CATIA V5 - Part 2


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Topics: Dassault Systemes, Training, CATIA