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Simulating Strain Along a Compressed Hexagonal Cone: Seeking Advice on Constraints and Loads
Posted May 19, 2023, 6:20 a.m. EDT MEMS & Piezoelectric Devices, Structural Mechanics 5 Replies
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"Hello everyone,
I am new to the Structural Mechanics module in COMSOL Multiphysics and I am facing difficulties in determining the appropriate constraints and loads for my simulation.
I would like to simulate the strain distribution along a compressed hexagonal cone. However, all the examples I have come across in the documentation involve fixing one end of the hexagonal shape.
In my case, I would like to apply compression to both the top and bottom of the hexagonal cone, as shown in the attached figures. I am wondering if there is a way to compress the object on its bottom and top sides without fixing one end.
I would greatly appreciate any help or advice on how to achieve this simulation setup.
Thank you in advance for your assistance.
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You could use a roller boundary condition on one face.
There are other options but in all cases you will probably need to suppress rigid body motion. Either use the domain constrait or think about inserting explicit constraints.
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To perform structural analysis effectively, it is necessary to have at least one point constrained in all directions. Although it is a hexagonal cone, since it is subjected to compressive stress, I recommend creating a symmetric geometry corresponding to a 90-degree sector and applying symmetry conditions on the symmetry plane. This will constrain the x and y directions.
To impose constraints in the z direction, you can apply a roller condition on the bottom surface or use the "Prescribed displacement" condition for a selected point on the bottom surface to constrain the z direction.
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There is no requirement that at least one point be constrained in all directions, but as David pointed out earlier constraints need to suppress all rigid body motion (in 3D, that's 3 rotations and 3 translations). This topic has been addressed many times before in this Discussion Forum, so you will find plenty of advice on how to achieve this. See for instance this thread.
Best,
Jeff
-------------------Jeff Hiller
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Here is a blog post discussing similar matters: https://www.comsol.com/blogs/modeling-parts-without-constraints-in-your-structural-analyses
-------------------Henrik Sönnerlind
COMSOL
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Thank you all for your answers. Have a nice day !