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How to vary a load applied to the length of a rod using a function?
Posted Sep 20, 2010, 6:06 p.m. EDT 2 Replies
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I have a function of how a force is varied across the length of a test rod. I am having trouble telling COMSOL how to use the function to apply a varied load, as a function of bar length. I am using the Solid, stress-strain (smsld) module. I am able to apply a constant load across the bar using the load setting tab in the sub-domain settings of the test bar, but cannot figure out how to make it follow the function. Any help in the syntax to call a function would be helpful.
2 Replies Last Post Sep 21, 2010, 5:56 p.m. EDT
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Posted:
1 decade ago
Hi
if you are in 2D and you apply a load to an edge you can use the rod length parameter "s" that varies from 0 to 1 along the edge in the direction of the arrow (edge mode). Just type F=F0*s and you get a forceincreasing from 0 to F0 along he edge, you can use a second order function too.
The other way is to use the coordinates x,y, easy if the edge i along one coordinate, but you must normalise to the edge length (that can be calculated via an integration coupling variable.
In 3D for a surface/boundary its slighly more complex as s1 and s2 are not always varying from 0-1 and their orentation is not always trivial. Then the coordinate mapping way is the best.
--
Good luck
Ivar
if you are in 2D and you apply a load to an edge you can use the rod length parameter "s" that varies from 0 to 1 along the edge in the direction of the arrow (edge mode). Just type F=F0*s and you get a forceincreasing from 0 to F0 along he edge, you can use a second order function too.
The other way is to use the coordinates x,y, easy if the edge i along one coordinate, but you must normalise to the edge length (that can be calculated via an integration coupling variable.
In 3D for a surface/boundary its slighly more complex as s1 and s2 are not always varying from 0-1 and their orentation is not always trivial. Then the coordinate mapping way is the best.
--
Good luck
Ivar
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Posted:
1 decade ago
Ivar,
Thank you for response. I was able to apply a function to the edge length, s1, in my 3D model using your suggestion. s1 scaled with the length of the test bar, so it made it easy when calling the length of the test bar in the function to determine the load applied.
Robb Morris
Thank you for response. I was able to apply a function to the edge length, s1, in my 3D model using your suggestion. s1 scaled with the length of the test bar, so it made it easy when calling the length of the test bar in the function to determine the load applied.
Robb Morris