Update model by changing single variable.

[JackIngleton]

Hi,
I am making a simple model of a cabin air filter to use in a CFD analysis. It consists of a rectangular pleated section and an outer housing frame (I'm not sure yet whether I will need these as separate parts for CFD).
I want the dimensions in the model to be defined by variable names rather than fixed numbers. I also want to be able to change a single variable and the entire model update, for example: change the width of the pleated section and the frame to reference this and also widen, or change the pleat count and the angle and dimensions of the pleats change.
The variables I want to include:
- pleated section width
- pleated section height
- pleat thickness
- pleat depth
- pleat count
- housing thickness

I realise this is probably a simple problem, but I didn't know where to look in tutorials etc.

 

[ewh]

Simplified explanation:
Use sketcher to get a base configuration then change expression names to something more descriptive. You can then change the values of those expressions as needed. If set up properly, a single expression change can drive the other expressions.
You can probaly achieve something similar without using sketcher with some work, but the control that sketcher provides is much more preferable.

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[looslib]

One of our engineers at a former company linked expressions in mulriple assembly files that when a single value was changed in the top level file, a forklift boom would extend and rise. His variable was a percentage of the boom range, so 0 was retracted and down and a 1 was fully extended and full height.

What you want to do is very possible, but takes thought and planning to get it all right.

Use your head. It's the best tool you have. Think first, and then model.


Some of the 'Commandments of Parametric Modeling' are:

Always start with a plan
Before beginning, have a modeling plan or strategy in mind. It should incorporate the design intent of the model. It’s not necessary to have it fully developed before beginning, but having a plan is important as it will undoubtedly change as a project evolves. It can be easy to change the wrong plan into the right plan. It can be very difficult to change no plan into the right plan.

It’s all about design intent
Design for "product design intent" first and foremost. Create sketches to ensure they are constrained the way you want and react to changes as you would expect. A majority of problems have to do with poorly constrained sketches that don't accept change easily.

Create and choose references (parent/child relationships) that drive design intent
This is a fundamental concept that is not always properly understood.
It’s important to understand that every time a reference is chosen, a dependency, or relationship is created.
When creating features, of any kind, always be aware of what is being referenced.

Don't readily accept the default references a CAD tool gives you. Think about the design intent and choose references that are stable and reflect that intent. Automatic references do not always reflect intent and are rarely applicable or appropriate.

Choose references that allow features to "move" with the intent as changes are made.



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