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Applying external strain

Posted 12.11.2013, 06:33 GMT-5 Structural Mechanics Version 4.0, Version 4.0a, Version 4.1, Version 4.2, Version 4.2a, Version 4.3, Version 4.3a, Version 4.3b 5 Replies

Alberto Garcia-Cristobal
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Hi All

I am doing simulation to study elastic properties of cylindrical abject. I want to apply external strain on top surface of the cylinder. So how can COMSOL handles such cases?
Thanks
5 Replies Last Post 13.11.2013, 10:58 GMT-5
Edgar J. Kaiser Certified Consultant
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Posted: 1 decade ago 12.11.2013, 07:10 GMT-5
Alberto,

it is easy: you apply a strain boundary condition to the surface.

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Alberto, it is easy: you apply a strain boundary condition to the surface. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com
Alberto Garcia-Cristobal
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Posted: 1 decade ago 12.11.2013, 18:24 GMT-5
Dear Edgar

Thank you for the suggestion but I couldn't get any place yo do it in comsol, i.e to select the 2D surface at the top of the cylinder and apply the required strain value.


Thanks
Dear Edgar Thank you for the suggestion but I couldn't get any place yo do it in comsol, i.e to select the 2D surface at the top of the cylinder and apply the required strain value. Thanks
Henrik Sönnerlind COMSOL Employee

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Posted: 1 decade ago 13.11.2013, 07:50 GMT-5
Hi,

There is nothing such as a "Strain boundary condition". It is not a mathematically well defined operation.

If you want to prescribe the strain components tangential to the boundary (which are the only ones that could be prescribed), this can be done using a Prescribed Displacement, where the expressions for the displacements are such that you can retrieve the strains from their derivatives.

Prescribing the individual strain components (even within the plane) is not a well defined operation, since that could violate the compatibility requirement.

Regards,
Henrik
Hi, There is nothing such as a "Strain boundary condition". It is not a mathematically well defined operation. If you want to prescribe the strain components tangential to the boundary (which are the only ones that could be prescribed), this can be done using a Prescribed Displacement, where the expressions for the displacements are such that you can retrieve the strains from their derivatives. Prescribing the individual strain components (even within the plane) is not a well defined operation, since that could violate the compatibility requirement. Regards, Henrik
Edgar J. Kaiser Certified Consultant
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Posted: 1 decade ago 13.11.2013, 09:39 GMT-5

Henrik is right of course: it is prescribed displacement you can apply. I was a little sloppy in my response.

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Henrik is right of course: it is prescribed displacement you can apply. I was a little sloppy in my response. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com
Alberto Garcia-Cristobal
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Posted: 1 decade ago 13.11.2013, 10:58 GMT-5
Thanks all, I got it.
Thanks all, I got it.

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