Parametric Modelling - Unable to ensure symmetry when running design points

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• Last Post 08 January 2019
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timlim123 posted this 07 January 2019

Is it possible to ensure symmetry in geometry while doing a parameter correlation study in ANSYS DesignXplorer? I am trying to do a parametric study on a plate micro-cantilever.

I have tried using the symmetry constraint in Design Modeler but ANSYS is unable to execute the command. I believe this is because ANSYS is not flexible enough to change the parameters of the geometry while maintaining the constraint in the geometry. There will always be an error message.

I have also tried inserting parametric equation in Design Modeler in order to ensure symmetry. The problem with this is that I have to manually recalculate the dimension as there are no equation that can fulfill symmetry and not alter other parameters that I do not want to change.

My current parametric equation is: L1 = L2 + 2* C1 . My main objective is to test how does changing L2 & L1 affects the structure. To ensure symmetry, C2 = C1 at all times which is what I am trying to achieve with my equation.

To test how the change of L1 affects the structure, I will use C1 as my sole parameter for the design of experiment (DOE), keeping L2 as a constant value. For example, for every 1m change in C1, it is a 2m change in L1.

The problem with this equation comes when I want to analyse the changes of only altering L2. (L1 has to be a constant length)

With my proposed equation,  altering L2 as a parameter in DOE will change the dimension of L1 simultaneously (not what I want). Hence the problem, I am unable to study the affects of increasing L2 symmetrically.

My current solution is to insert my own design points. However, this method has 2 issues which is the design points does not appear in DOE and it is a very inelegant manual method.

Edit: Edit: My manual design points to give you an idea of what I mean when increasing/decreasing L2 symmetrically. (With my parametric equation, I have ensure that L1 is always 500um and C1=C2 at all times while increasing/decreasing L2)

There is an issue with DP1, just ignore the values, the design points in ANSYS is buggy sometimes.

peteroznewman posted this 08 January 2019

Here is a DM sketch that uses Symmetric constraints and has C1 and L2 inputs.

The symmetry automatically makes L1 = L2 + 2*C1

Is this what you wanted?

ANSYS 19.2 archive attached.

Regards,
Peter

Attached Files

timlim123 posted this 08 January 2019

@peter, thank you for the answer. I tried doing it again and it worked, I guess it was just some kind of bug when I tried it the first time. Cheers.