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Strain of a specific line
Posted 2 juin 2022, 05:17 UTC−4 Structural Mechanics Version 6.0 1 Reply
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Hello, I would like to determine the strain of a specific line in my comsol model. In particular, I have a 2D cantilever beam, subjected to an axial load. The beam has a circular hole in the middle and I want to determine the strain that occurs specifically at the edge of the circle. Also the final length of the circle would be helpful.
Thank you very much in advance,
Edoardo
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One nice way to accurately measure strains (and stresses) is to create virtual strain gauges by adding truss elements with a very small cross-section area. They will then not contribute significantly to the stiffness.
Just make sure that you
* Use the same discretization order in Solid Mechanics and Truss
* Don't use the Straight Edge Constraint in the Truss interface
This is the most accurate approach, since it measures the strain of the boundary itself.
Another alternative, that works for simple geometries, is to use a suitable local coordinate system in the material model, and then evaluate the local strain components. This works as long as you do not need the local coordinate system for other purposes, like defining an orthotropic material.
About the length measurement: In a geometrically nonlinear analysis, you can just integrate '1' along the edge in the spatial frame to get the current length. For a geometrically linear analysis, there is no difference between the material and the spatial frame. In that case, you can, for example, integrate the strain along the edge to get the change in length.
-------------------Henrik Sönnerlind
COMSOL