FEM acoustics with Impedance boundary conditions — Welcome to LS-DYNA Examples

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A simple cabin model with seats shows how to set up multiple boundary conditions and how to define impedance boundary conditions. Example 9.4 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

Keywords

```*CONTROL_TERMINATION
*DATABASE_BINARY_D3PLOT
*DATABASE_FREQUENCY_BINARY_D3ACS
*DEFINE_CURVE
*DEFINE_CURVE_TITLE
*ELEMENT_SOLID
*END
*FREQUENCY_DOMAIN_ACOUSTIC_FEM
*KEYWORD
*MAT_ELASTIC_FLUID
*NODE
*PART
*SECTION_SOLID
*SET_NODE_LIST
*SET_SEGMENT_TITLE
*TITLE```

Reduced Input

```*KEYWORD
*TITLE
Acoustic analysis of a car cabin model by FEM
*FREQUENCY_DOMAIN_ACOUSTIC_FEM
1.2100E-12  343000.0      10.0     500.0        99                       2.0e-11
0
1         0
1         2        11         3        10        30        1.
2         2        41                  20        30        1.
200         1
*DATABASE_FREQUENCY_BINARY_D3ACS
1
*CONTROL_TERMINATION
0.187970         0     0.000     0.000 50.000000
*DATABASE_BINARY_D3PLOT
0.001000
0
*PART
acoustic medium
1         1         1
*SECTION_SOLID
1        10
*MAT_ELASTIC_FLUID
1  1.220000     0.000     0.000     0.000     0.000 141.03000
0.000     0.000
*SET_NODE_LIST
200     0.000     0.000     0.000     0.000
8106     20615
*DEFINE_CURVE_TITLE
Velocity
10         0     0.000     0.000     0.000     0.000         0
10.000               7.000
500.000               7.000
*DEFINE_CURVE_TITLE
Impedance
20         0     0.000     0.000     0.000     0.000         0
10.000           4.1503e-7
500.000           4.1503e-7
*DEFINE_CURVE
30         0     0.000     0.000     0.000     0.000         0
10.000               0.000
500.000               0.000
*ELEMENT_SOLID
*NODE
*SET_SEGMENT_TITLE
*SET_SEGMENT_TITLE
*END```