Amplitude function error

1

Hi，
I was using calculix, precice, openfoam to implement fluid-structure coupling and was having strange problems running calculix, so I tried to run calculix’s inp file separately and the inp file looked like this:

*INCLUDE, INPUT=all.msh
*INCLUDE, INPUT=fix1.nam
*INCLUDE, INPUT=surface.nam

*MATERIAL, Name=EL
*ELASTIC
5.6000E+6, 0.4
*DENSITY
 1000
*SOLID SECTION, Elset=Eall, Material=EL
*STEP, INC=1000000
*DYNAMIC, ALPHA=0.0, DIRECT
0.0005, 0.5

*BOUNDARY
Nfix1, 1, 3

**------The "MyTimeFunction-sin-fun.txt" file is a sin function and the "mynewamplitude-line-fun.txt" file is a linear function.
**------File "MyTimeFunction-sin-fun.txt" runs incorrectly, and file "mynewamplitude-line-fun.txt" runs successfully.

*AMPLITUDE,NAME=MyAmplitude
*INCLUDE, INPUT="MyTimeFunction-sin-fun.txt"
**INCLUDE, INPUT="mynewamplitude-line-fun.txt"
**0,0,0.36,0.05

*BOUNDARY,AMPLITUDE=MyAmplitude
Nfix1, 2, 2 ,1


*CLOAD
 Nsurface, 1, 0.0
 Nsurface, 2, 0.0
 Nsurface, 3, 0.0
	
*NODE FILE
 U
*EL FILE
 S, E
*END STEP

The diagram below is a schematic of my simulation model

0000
00001920×2234 258 KB

The question is this:
Give the fix1 node set a sin function displacement amplitude, the plate produces a chaotic motion:

error1
error11649×659 97.2 KB

Given the fix1 node set linear function displacement amplitude, the plate moves normally:

linear-correct
linear-correct1672×601 88.2 KB

I used the same inp file and changed only these three lines of code,but the results varied widely.What is the reason for this?

*AMPLITUDE,NAME=MyAmplitude
*INCLUDE, INPUT="MyTimeFunction-sin-fun.txt"
**INCLUDE, INPUT="mynewamplitude-line-fun.txt"

MyTimeFunction-sin-fun.txt file looks like this：

0,0
0.0005,0.000125
0.001,0.000249999
0.0015,0.000374996
0.002,0.000499992
0.0025,0.624985
0.003,0.000749972
0.0035,0.000874955
0.004,0.000999933
0.0045,0.001124905
0.005,0.00124987
......

mynewamplitude-line-fun.txt file looks like this：

0,0
0.0005,6.94E-05
0.001,0.000138889
0.0015,2.08E-04
0.002,0.000277778
0.0025,3.47E-04
0.003,0.000416667
0.0035,4.86E-04
0.004,0.000555556
0.0045,0.000625
0.005,6.94E-04
0.0055,0.000763889
0.006,8.33E-04
......

The simulation files are stored here:
https://drive.google.com/drive/folders/1PQcixcik2-4xOIXbKCXKt1DsvhPx0TwI?usp=sharing
Any help is appreciated!
xiangxiang

2

The running results of the two functions (sin and linear) are stored here, which is the result file of steps 0-100
Very strange results:
[linear-fun.avi - Google Drive, sin-fun.avi - Google Drive]

3

Different attempts:

I tried to modify the time step and elastic modulus, which did not seem to be the cause of the problem, because I only modified the *AMPLITUDE function.

4

@daxiangxiang
Your sine function has some weird errors, look below, I believe if you correct these values the sine function will run comparable to your line function.

0,0
0.0005,0.000125
0.001,0.000249999
0.0015,0.000374996
0.002,0.000499992
0.0025,0.624985    <<<<<< value doesn't belong to the sine function
0.003,0.000749972
0.0035,0.000874955
0.004,0.000999933
0.0045,0.001124905
0.005,0.00124987
0.0055,0.001374827
0.006,0.001499775
0.0065,0.001624714
0.007,0.001749643
0.0075,0.001874561
0.008,0.001999467
0.0085,0.212437    <<<<<< value doesn't belong to the sine function
0.009,0.002249241
5

Thank you, Sir. I will carefully examine the cause of the problem. Have a good weekend.