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Help about deformed shape fitting to a curvature

Posted 30 janv. 2012, 15:16 UTC−5 Version 3.5a 3 Replies

Hongyi Mi
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Dear All,

I am trying to do a work: make a membrane (1cm*1cm*0.05mm) bend to fit a fixed curvature (such as r=1cm) and then detect its strain distribution.
But now I don't how to define load/constrait to make the membrane perfect fit the the curvature.
Could you give any help.
Thank you.

Best,
Hongyi Mi

3 Replies Last Post 2 févr. 2012, 01:42 UTC−5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 30 janv. 2012, 16:06 UTC−5
Hi

try something like:
Define an interpolation function interp1(R) as the deformation you desire w.r.t. a variable R=sqrt(X^2+Y^2) I assume here your deformation is regular in X,Y.
Set up your solid model (or shell), add a boundary pressure load Fp acting on the membrane
Define a variable R = sqrt(X^2+Y^2) (upper case on the material frame pls check for 3.5)
Define an integration on the membrane domain where it deforms
Define a ODE (Global equation) with Variable Fp and equation intop1(w-interp1(R)) = 0 intop1() in 3.5 is a boundary integration coupling (if I remember right, names have changes)
Solve
this should work, it will get an average pressure load that deforms the membrane up to the interp(R) values, in a least square way

If you have the solid/structural doc in 3.5, you can check the example of the torque load, this uses a similar approach to apply a torque on a bar

--
Good luck
Ivar
Hi try something like: Define an interpolation function interp1(R) as the deformation you desire w.r.t. a variable R=sqrt(X^2+Y^2) I assume here your deformation is regular in X,Y. Set up your solid model (or shell), add a boundary pressure load Fp acting on the membrane Define a variable R = sqrt(X^2+Y^2) (upper case on the material frame pls check for 3.5) Define an integration on the membrane domain where it deforms Define a ODE (Global equation) with Variable Fp and equation intop1(w-interp1(R)) = 0 intop1() in 3.5 is a boundary integration coupling (if I remember right, names have changes) Solve this should work, it will get an average pressure load that deforms the membrane up to the interp(R) values, in a least square way If you have the solid/structural doc in 3.5, you can check the example of the torque load, this uses a similar approach to apply a torque on a bar -- Good luck Ivar
Hongyi Mi
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Posted: 1 decade ago 1 févr. 2012, 23:21 UTC−5
Thank you for reply.

But I am still confused.

For a 2D case. If the curvature R is fixed eg. 1cm. Do I still need to define a variable R=sqrt(x^2+y^2). If this related to the membrane position (x,y).
For Fp, which direction should it be, or in both of x and directions.
Also could you tell me what the w is in equation intop1(w-interp1(R)) = 0.

Thank you.
Thank you for reply. But I am still confused. For a 2D case. If the curvature R is fixed eg. 1cm. Do I still need to define a variable R=sqrt(x^2+y^2). If this related to the membrane position (x,y). For Fp, which direction should it be, or in both of x and directions. Also could you tell me what the w is in equation intop1(w-interp1(R)) = 0. Thank you.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2 févr. 2012, 01:42 UTC−5
Hi

sorry but you did not give that much explanations about your model options, I was in 3D, you can perfectly analyse this in 2D with membrane deformation in Z, you are right and it solves quicker ;)

w is the displacement in Z (you have u,v,w for the resulting "solid/structural) deformations along X,Y,Z respectively

--
Good luck
Ivar
Hi sorry but you did not give that much explanations about your model options, I was in 3D, you can perfectly analyse this in 2D with membrane deformation in Z, you are right and it solves quicker ;) w is the displacement in Z (you have u,v,w for the resulting "solid/structural) deformations along X,Y,Z respectively -- Good luck Ivar

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