It doesn’t seem like IfcShapeAspect is used that often.
Why do you think that is?
The only use-case you can see on the Figure 8.18.3.12 follow your link - constituent material.
You will also see some test-cases if decided to be certified for IFC4 RV.
On my mind this material construction is an ugly monster that was born on ISG meeting one hard Friday morning 
and should be withdrawn as soon as possible
The doc says " The IfcShapeAspect together with the IfcMaterialConstituent can be used to associate distict material information to parts" - ok, just use IfcBuildingElementPart and IfcMaterial, it will provide the same information in much simple and comfortable way.
1 Like
ShapeAspect though is the only way to represent multi layered (Walls) and multi material (Windows) entities in Reference View though.
But I agree that ShapeAspect schema can be intimidating in the beginning.
@igor.sokolov But IfcBuildingElementPart is itself an object and using it implies using IfcRelAggregates to combine parts into one, right? So Windows or Walls or anything sort of become assemblies and it doesn’t always make sense afaik. 
1 Like
I believe correct way to implement multi-layer wall is exactly IfcBuildingElementPart, or (if you want give information about uniform geometry construction) IfcMaterialLayer, and it is used long time.
Generally if a product has 2 or more materials I think it can be treat as made of 2 or more parts and see nothing wrong in IfcRelNests or Aggregates, it is simple, clear and provide full information.
For shape aspect implied relationships by material name=aspect name is absolutely wrong, and total picture is overcomplicated.
2 Likes