FRF for a rectangular plate — Welcome to LS-DYNA Examples

Home » Knowledge Base » NVH / Fatigue » FRF for a rectangular plate

This example shows how to setup the keywords for FRF computation. A nodal force excitation is defined. Frequency dependent response amplitudes at nodes are computed. Differences between constant and mode dependent modal damping can be studied. Example 4.1 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

Keywords

```*CONTROL_IMPLICIT_EIGENVALUE
*CONTROL_IMPLICIT_GENERAL
*CONTROL_IMPLICIT_NONLINEAR
*CONTROL_SHELL
*DEFINE_CURVE
*ELEMENT_SHELL
*END
*FREQUENCY_DOMAIN_FRF
*KEYWORD
*MAT_ELASTIC
*NODE
*PART
*SECTION_SHELL
*SET_NODE_LIST
*TITLE```

Reduced Input

```*KEYWORD
*TITLE
A rectangular plate for FRF computation.
*FREQUENCY_DOMAIN_FRF
131         0        -3         3         0 2000.0000         0         0
0.000         5         1     0.000     0.000
1         1         3         1
1.000000 400.00000       400         0         0         0
*CONTROL_IMPLICIT_EIGENVALUE
100     0.000         0     0.000         0     0.000         0     0.000
0         0         0         0
*CONTROL_IMPLICIT_GENERAL
1  1.000000         0         0         0         0         0         0
*CONTROL_IMPLICIT_NONLINEAR
1         0         0     0.000     0.000     0.000     0.000     0.000
0         0         0         0
0         0     0.000         1         2
*CONTROL_SHELL
20.000000         2        -1         0         2         2         1         0
1.000000         0         0         1         0         0         0         0
0         0         0
*PART
boxshell
1         1         1         0         0         0         0         0
*SECTION_SHELL
1         6  0.833000         3         3         0         0         0
0.002000  0.002000  0.002000  0.002000     0.000     0.000     0.000         0
*MAT_ELASTIC
1 7870.00002.0700E+11  0.292000     0.000     0.000         0
*DEFINE_CURVE
5         0     0.000     0.000     0.000     0.000         0
1.0000000               0.000
6.0000000               0.000
7.0000000           0.0045000
8.0000000           0.0071300
9.0000000           0.0038600
10.0000000           0.0032800
11.0000000           0.0034000
12.0000000           0.0062400
13.0000000             7.2e-04
14.0000000             8.3e-04
15.0000000               0.000
200.0000000               0.000
*SET_NODE_LIST
1     0.000     0.000     0.000     0.000
131       651         0         0         0         0         0         0
*ELEMENT_SHELL
*NODE
*END

```