Modal analysis with Ls-Dyna

[korper]

Could anyone give me some hints (eg. example file) to get the natural frequency? It is said to use implict, but how?
Thanks.

 

[korper]

Is there really nobody can help? I don't think so.
maybe i have sent a too simple question?

Ok, let me draw the thread farther.
I found, since the version of 960, it is possible to use the keywords *control_implicit_eigenvalue...
now i got the values, but how to judge they could be correct?
and
but how could the Modal Analysis be done with also contact definitions? and further more possiblely with strain rate?
or ABAQUS?

I really appreciate any advice!
thanks in advance.

 

[dharni]

Hi,

Give me your email, will send you example file for eigenvalue analysis using Dyna.

 

[Spirit]

Sorry for the OT answer, but I think that if dharni had included the example file directly in his post he could have been useful to many more people tan just korper. What should this forum be intended to but to provide an open community where all members can take advantage of the experience of other colleagues?
I mean no polemics, truly.

Cheers



Spirit
'Ability is 10% inspiration and 90% perspiration.'

 

[korper]

Thanks for dharni and other replys!
I have got the .k file and test functioned.
sorry for my coming back late and repling.
see below the file include. (I suppose i could post it)

Due to such a challenge, my question will lead to the contact algorithm and defining the boundary conditions.

Some guy just told me it is impossible to get the natural frequencies. and 'cause it contrary to such math. modelling.

hope that clear and appreciate advices.

thanks and regards!
===========================================================
*KEYWORD
$
*TITLE
cantilevered shell strip w/ end moment
$============================================
*CONTROL_IMPLICIT_GENERAL
$ imflag dt0 iefs
-9 0.0005 0
*CONTROL_IMPLICIT_NONLINEAR
$ nlsolvr ilimit maxref dctol ectol rctol lstol
0 0 0 0.00 0.00 0 0
$ dnorm divflag inistif
0 0 0
*CONTROL_IMPLICIT_LINEAR
$ lsolvr prntflg negeig
0 0 0
*CONTROL_IMPLICIT_AUTO
$ iauto iteopt itewin dtmin dtmax
0 0 0 0.00 0
$
*CONTROL_IMPLICIT_EIGENVALUE
$ neig
5
$============================================
*CONTROL_TERMINATION
0.025
$
*DATABASE_BINARY_D3PLOT
0.0001
$============================================
$
$ Define Material
$
$============================================
*MAT_ELASTIC
1 7.000E-04 3.000E+07 3.000E-01
$
*SECTION_SHELL
1 6 8.333E-01 3.000E+00 3.000E+00 0.000E+00 0
1.000E-01 1.000E-01 1.000E-01 1.000E-01 0.000E+00
$
*PART
cantilevered shell
1 1 1 0 0 0 0 0
$
$--------------
$
*LOAD_NODE_POINT
$ nsid dof lcid sf
16 7 98 0.5
32 7 98 1.0
48 7 98 0.5
$============================================
$
$ DEFINE_CURVE
$
$============================================
*DEFINE_CURVE
9
0.00000, 1.0
0.00999, 1.0
0.01000, 0.0
1.00000, 0.0
*DEFINE_CURVE
98
0.00000, 0.0
0.01000, 150.0
0.01001, 0.0
1.00000, 0.0
$============================================
$
$ Deifine Nodes
$
$============================================
*NODES
1 0.000000000E+00 0.000000000E+00 0.000000000E+00 7 7
2 3.333333433E-01 0.000000000E+00 0.000000000E+00 0 0
3 6.666666865E-01 0.000000000E+00 0.000000000E+00 0 0
4 1.000000000E+00 0.000000000E+00 0.000000000E+00 0 0
5 1.333333373E+00 0.000000000E+00 0.000000000E+00 0 0
6 1.666666627E+00 0.000000000E+00-1.110223025E-16 0 0
7 2.000000000E+00 0.000000000E+00 0.000000000E+00 0 0
8 2.333333254E+00 0.000000000E+00-1.110223025E-16 0 0
9 2.666666746E+00 0.000000000E+00 0.000000000E+00 0 0
10 3.000000000E+00 0.000000000E+00-1.110223025E-16 0 0
11 3.333333254E+00 0.000000000E+00 0.000000000E+00 0 0
12 3.666666746E+00 0.000000000E+00 0.000000000E+00 0 0
13 4.000000000E+00 0.000000000E+00 0.000000000E+00 0 0
14 4.333333492E+00 0.000000000E+00 0.000000000E+00 0 0
15 4.666666508E+00 0.000000000E+00 0.000000000E+00 0 0
16 5.000000000E+00 0.000000000E+00 0.000000000E+00 0 0
17 0.000000000E+00 0.000000000E+00 5.000000000E-01 7 7
18 3.333333433E-01 0.000000000E+00 5.000000000E-01 0 0
19 6.666666865E-01 0.000000000E+00 5.000000000E-01 0 0
20 1.000000000E+00 0.000000000E+00 5.000000000E-01 0 0
21 1.333333373E+00 0.000000000E+00 5.000000000E-01 0 0
22 1.666666627E+00 0.000000000E+00 5.000000000E-01 0 0
23 2.000000000E+00 0.000000000E+00 5.000000000E-01 0 0
24 2.333333254E+00 0.000000000E+00 5.000000000E-01 0 0
25 2.666666746E+00 0.000000000E+00 5.000000000E-01 0 0
26 3.000000000E+00 0.000000000E+00 5.000000000E-01 0 0
27 3.333333254E+00 0.000000000E+00 5.000000000E-01 0 0
28 3.666666746E+00 0.000000000E+00 5.000000000E-01 0 0
29 4.000000000E+00 0.000000000E+00 5.000000000E-01 0 0
30 4.333333492E+00 0.000000000E+00 5.000000000E-01 0 0
31 4.666666508E+00 0.000000000E+00 5.000000000E-01 0 0
32 5.000000000E+00 0.000000000E+00 5.000000000E-01 0 0
33 0.000000000E+00 0.000000000E+00 1.000000000E+00 7 7
34 3.333333433E-01 0.000000000E+00 1.000000000E+00 0 0
35 6.666666865E-01 0.000000000E+00 1.000000000E+00 0 0
36 1.000000000E+00 0.000000000E+00 1.000000000E+00 0 0
37 1.333333373E+00 0.000000000E+00 1.000000000E+00 0 0
38 1.666666627E+00 0.000000000E+00 1.000000000E+00 0 0
39 2.000000000E+00 0.000000000E+00 1.000000000E+00 0 0
40 2.333333254E+00 0.000000000E+00 1.000000000E+00 0 0
41 2.666666746E+00 0.000000000E+00 1.000000000E+00 0 0
42 3.000000000E+00 0.000000000E+00 1.000000000E+00 0 0
43 3.333333254E+00 0.000000000E+00 1.000000000E+00 0 0
44 3.666666746E+00 0.000000000E+00 1.000000000E+00 0 0
45 4.000000000E+00 0.000000000E+00 1.000000000E+00 0 0
46 4.333333492E+00 0.000000000E+00 1.000000000E+00 0 0
47 4.666666508E+00 0.000000000E+00 1.000000000E+00 0 0
48 5.000000000E+00 0.000000000E+00 1.000000000E+00 0 0
$=======================================================================
*ELEMENT_SHELL
1 1 1 17 18 2
2 1 2 18 19 3
3 1 3 19 20 4
4 1 4 20 21 5
5 1 5 21 22 6
6 1 6 22 23 7
7 1 7 23 24 8
8 1 8 24 25 9
9 1 9 25 26 10
10 1 10 26 27 11
11 1 11 27 28 12
12 1 12 28 29 13
13 1 13 29 30 14
14 1 14 30 31 15
15 1 15 31 32 16
16 1 17 33 34 18
17 1 18 34 35 19
18 1 19 35 36 20
19 1 20 36 37 21
20 1 21 37 38 22
21 1 22 38 39 23
22 1 23 39 40 24
23 1 24 40 41 25
24 1 25 41 42 26
25 1 26 42 43 27
26 1 27 43 44 28
27 1 28 44 45 29
28 1 29 45 46 30
29 1 30 46 47 31
30 1 31 47 48 32
*END