How to Check the Fitness of Your Geometry Models

Have you ever thought about the fitness of your geometry models? When you are prepar­ing para­met­ric geometry models for auto­mated work­flows, you need to make sure they are robust and do not break during vari­a­tion. For complex models with a lot of trimming and Boolean Oper­a­tions as well as fillets, there is a good chance that critical geometry shapes lead to problems. In addition, there are typ­i­cally con­straints that you need to consider (e.g. minimum thick­nesses or dis­tances to keep, volumes, hard points etc.). New design can­di­dates should not violate these constraints.

Varying, varying, varying!

It’s sort of a natural thing that you vary your para­me­ters (also called design vari­ables) and see how the model behaves. You can do this manually in the first stage, to get an impres­sion of the shape changes. In order to be sure your model does not collapse or violate con­straints for certain para­me­ter con­fig­u­ra­tions, you need to check a larger set of design variants. In CAESES®, there is an inbuilt mech­a­nism to do a robust­ness check of your model. From the opti­miza­tion menu in the graph­i­cal user inter­face, you can choose a sampling method to create your design set. The design vari­ables along with their lower and upper bounds can be set which will be varied by the strategy.

Visual Check

For each sampling (and opti­miza­tion) method, you can con­fig­ure a screen­shot col­lec­tion. It gives you the pos­si­bil­ity to create dif­fer­ent screen­shots of your geometry from dif­fer­ent angles and for dif­fer­ent zoom levels. After the sampling, the Design Viewer window shows all these pictures, plus an inter­ac­tive 3D geometry to take a closer look at each gen­er­ated variant.

Numer­i­cal Check

CAESES® gives you the pos­si­bil­ity to create expres­sions in para­me­ters to check certain geometry quan­ti­ties. For instance, you can check

• the volume of a closed body,
• the area of a body or surface,
• the number of open and closed edges

and many more. You can involve such a para­me­ter in your sampling method to monitor these values. As an example, if you are always expect­ing a closed body, the number of open edges should be zero. If this is not the case, you know that some­thing goes wrong and your model is not robust for some reasons.

A Few More Examples

Doing these kinds of geometry and validity checks is a typical task in chal­leng­ing engi­neer­ing projects, to also check the design space and the shape vari­a­tions that are created. Here are a few more pictures of the design viewer — note that the last ones also show some CFD results: 

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