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prescribed displacement/frequency domain study

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im doing a 3d beam that have a prescribed displacement in the z direction but I needed to be with respect to time using this function below 200sin(120pi*t)[um] how do it add it on comsol

also how do i do a frequency domain study because it giving me a error that t is not defined.


6 Replies Last Post 23 gen 2024, 02:15 GMT-5
Acculution ApS Certified Consultant

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Posted: 9 months ago 21 gen 2024, 08:23 GMT-5

Start out with a frequency domain study (steady-state). Your frequency is seemingly 60 Hz, so that is what you input. Then go to a time-domain study.

-------------------
René Christensen, PhD
Acculution ApS
www.acculution.com
info@acculution.com
Start out with a frequency domain study (steady-state). Your frequency is seemingly 60 Hz, so that is what you input. Then go to a time-domain study.

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Posted: 9 months ago 21 gen 2024, 16:04 GMT-5
Updated: 9 months ago 21 gen 2024, 16:04 GMT-5

that correct my frequency is 60 Hz so i need to do a

  1. frequency domain, then using the result use
  2. frequency to time domain as the next step?
that correct my frequency is 60 Hz so i need to do a 1. frequency domain, then using the result use 2. frequency to time domain as the next step?

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Posted: 9 months ago 21 gen 2024, 19:20 GMT-5
Updated: 9 months ago 21 gen 2024, 19:12 GMT-5

Frequency dependent gets you the sinusoidal steady state solution.

Time dependent with sin(wt) gets you the initial transient when the sinusoidal excitation is turned on at t = 0.

Which one do you want??

Frequency dependent gets you the sinusoidal steady state solution. Time dependent with sin(wt) gets you the initial transient when the sinusoidal excitation is turned on at t = 0. Which one do you want??

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Posted: 9 months ago 22 gen 2024, 16:33 GMT-5
Updated: 9 months ago 22 gen 2024, 16:25 GMT-5

when t = 0

when t = 0

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Posted: 9 months ago 22 gen 2024, 18:13 GMT-5
Updated: 9 months ago 22 gen 2024, 18:06 GMT-5

OK if you are doing a time-dependent study then t is automatically time and the driving function should be written 200[um]sin(2pi60[1/s]t).

(If you do a frequency dependent study all quantities are phasors and time does not explicitly appear.)

(The website seems to remove asterisks from equations so you need to put them where they belong).

OK if you are doing a time-dependent study then t is automatically time and the driving function should be written 200[um]*sin(2*pi*60[1/s]*t). (If you do a frequency dependent study all quantities are phasors and time does not explicitly appear.) (The website seems to remove asterisks from equations so you need to put them where they belong).

Henrik Sönnerlind COMSOL Employee

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Posted: 9 months ago 23 gen 2024, 02:15 GMT-5
Updated: 9 months ago 23 gen 2024, 08:41 GMT-5

A comment on the formatting: The forum uses the 'Markdown' syntax. Asterisk then means italic. If you want the asterisk to be shown as is, put a backslash ( \ ) in front of it. For more details, see https://www.comsol.com/forum/formatting-guide

The expression should then look like 200[um]*sin(2*pi*60[1/s]*t).

Entered as

200[um]\*sin(2\*pi\*60[1/s]\*t)
-------------------
Henrik Sönnerlind
COMSOL
A comment on the formatting: The forum uses the 'Markdown' syntax. Asterisk then means *italic*. If you want the asterisk to be shown as is, put a backslash ( \ ) in front of it. For more details, see The expression should then look like 200[um]\*sin(2\*pi\*60[1/s]\*t). Entered as 200[um]\*sin(2\*pi\*60[1/s]\*t)

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