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How to apply a space and time dependent boundary condition?
Posted Oct 19, 2017, 5:01 a.m. EDT Version 5.3 4 Replies
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Hi everyone,
I am trying to apply a sinusoidal prescribed displacement to the edge of a plate for 5 periods of the signal.
The applied signal has the form of F1(y,t)=u1(y)cos(2.pi.f0.t)+u2(y)sin(2.pi.f0.t) for prescribed component in x direction and F2(y,t)=v1(y)cos(2.pi.f0.t)+v2(y)sin(2.pi.f0.t) for prescribed component in y direction.
The variable y is associated with the mesh grid, i.e. the values of y are the values of the node positions along the extremity of the plate.
The four functions u1, u2, v1, v2 are interpolation functions which the discrete data sets I already have.
Is there any possible way to set up this kind of boundary conditions in COMSOL? I really appreciate if anyone can help me with this troublesome issue.
Bests,
Ngoc
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Hi Ngoc,
Basically, you just type in the expressions in the text fields for the prescribed displacements.
u1(y)*cos(2*pi*f0*t)+u2(y)*sin(2*pi*f0*t)
f0 can be defined as a parameter.
For a more general discussion of how boundary conditions can be modified, see also
https://www.comsol.se/blogs/how-to-make-boundary-conditions-conditional-in-your-simulation/
Regards,
Henrik
-------------------Henrik Sönnerlind
COMSOL
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Hi Henrik,
Thank you for answering my question. I have applied the prescribed BCs for my model and it worked when I used only Solids Mechanics physic. However, when I added Electrostatic and Piezoelectric effect for time analysis, COMSOL could not find converged solutions. Can you help me figure out where I did it wrong? I attached both models (before and after the electrostatic physic is added) here.
Bests,
Ngoc Nguyen
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Hi Ngoc,
The first sanity check would be that the electric problem is grounded somewhere.
Regards, Henrik
-------------------Henrik Sönnerlind
COMSOL
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Hi Henrik,
Yes, it is indeed due to the lack of electrical boundary conditions. The simple plate model works now. I am moving on to a more complicated structure. Thank you and have a good day.
Bests,
Ngoc