### Eigenmodes from thermal expansion

Posted:

**02 Feb 2018, 17:47**Hi Elmer Users!

I am new to Elmer and finite element modeling and I am working on a thermal expansion problem in which I want to see how the vibrational modes change with the resultant thermal stress of a temperature distribution. I am using the eigenmode option in the linear elasticity solver to calculate the frequencies and modes. I've attached my different test runs to help figure out what's wrong. First, I calculated the eigenmodes without any thermal load and I find that it reproduces what is expected from theory. Then I apply two thermal boundary conditions and I find that there is no change in the eigenmode frequencies. I also ran a test without the eigenmode option to verify that the deflection was calculated from the thermal load. From the models manual I see that thermal contributions are included in the linear elastic pde, as well as the eigenmode calculation. Am I not putting in my putting in my constraints properly? Is the eigenmode option not the correct one?

Your help is greatly appreciated! Please let me know if I can clarify my any questions.

Sincerely,

Matt

I am new to Elmer and finite element modeling and I am working on a thermal expansion problem in which I want to see how the vibrational modes change with the resultant thermal stress of a temperature distribution. I am using the eigenmode option in the linear elasticity solver to calculate the frequencies and modes. I've attached my different test runs to help figure out what's wrong. First, I calculated the eigenmodes without any thermal load and I find that it reproduces what is expected from theory. Then I apply two thermal boundary conditions and I find that there is no change in the eigenmode frequencies. I also ran a test without the eigenmode option to verify that the deflection was calculated from the thermal load. From the models manual I see that thermal contributions are included in the linear elastic pde, as well as the eigenmode calculation. Am I not putting in my putting in my constraints properly? Is the eigenmode option not the correct one?

Your help is greatly appreciated! Please let me know if I can clarify my any questions.

Sincerely,

Matt