shape optimization of a 2D circular plate

Rahul_P1

I am doing a shape optimization of a 2D circular plate with some holes in it.
Design variable:-
i)radius of the hole
ii)position of the hole on the plate
Objective:-
Maximize the gap between the natural frequencies of the plate.
constraint:-
i) the center distance between the holes should be greater then a particular value.
( this one is required to ensure the holes should not come very close to each other or should not overlap each other during optimization.)

I can define the design variables with morphing and the objective function with different equations and responses.
My only problem is i don't know how to put a constraint like,
center distance between the holes > some value.

Hence i am wondering, if i can define the coordinate of a node as a response then it will be possible to create an equation and response for the difference of the coordinates which will ultimately give the distance between the points.
Please correct me if i am wrong.
One more thing i want to add, as the plate is circular i have to use cylindrical coordinate system (r and theta coordinate ). thus the distance between the holes can be the difference between the theta coordinates.

Rahul_P1

Satish,

If you refer to the online help for the DRESP2 card, you can define the coordinates of the holes using the DGRID field. Once you have defined those coordinates and you have specified the function that is calculated with those coordinates, you can then constrain the response itself and specify the upper and lower bounds for that response. In this case, the bounds of how close two center distance are to one another.

You may have to define another DRESP2 to calculate the center distance of each hole using three nodes.