FEM acoustics of a simplified compartment model II — Welcome to LS-DYNA Examples

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This is an example of a simplified compartment model with tetrahedal elements. It is shown how to set up a model for frequency domain FEM acoustics with *FREQUENCY_DOMAIN_ACOUSTIC_FEM and how to post-process with *DATABASE_FREQUENCY_BINARY_D3ACS. Results can be compared with the example ”BEM acoustics of a simplified compartment model” and ”FEM acoustics of a simplified compartment model I”. Example 9.2 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

Keywords

*CONTROL_TERMINATION
*CONTROL_TIMESTEP
*DATABASE_BINARY_D3PLOT
*DATABASE_BINARY_D3THDT
*DATABASE_BINARY_RUNRSF
*DATABASE_FREQUENCY_BINARY_D3ACS
*DEFINE_CURVE
*ELEMENT_SOLID
*END
*FREQUENCY_DOMAIN_ACOUSTIC_FEM
*KEYWORD  
*MAT_ELASTIC_FLUID
*NODE
*PART
*SECTION_SOLID
*SET_NODE_LIST
*SET_SEGMENT
*TITLE

Reduced Input

*KEYWORD  
*TITLE
Acoustic analysis of a simplified compartment model by FEM
*FREQUENCY_DOMAIN_ACOUSTIC_FEM
1.2300E-12   340000.       10.      500.       491                        2.e-11
         5         0
         1         2        11         5         3         2       1.
       200         1
*DATABASE_FREQUENCY_BINARY_D3ACS
         1
*CONTROL_TERMINATION
  0.187970         0     0.000     0.000 50.000000
*CONTROL_TIMESTEP
     0.000  0.800000         0     0.000     0.000         0         0         0
     0.000         0         0
*SET_NODE_LIST
       200     0.000     0.000     0.000     0.000          
    113123         0         0         0         0         0         0         0
*DEFINE_CURVE
         2         0     0.000     0.000     0.000     0.000         0
               0.000               0.000
        1000.0000000               0.000
*DEFINE_CURVE
         3         0     0.000     0.000     0.000     0.000         0
               0.000           7.0000000
        1000.0000000           7.0000000
*DATABASE_BINARY_D3PLOT
  0.001000         0         0         0         0
         0
*DATABASE_BINARY_D3THDT
 5.0000E-4         0         0         0         0
*DATABASE_BINARY_RUNRSF
 5000.0000         0         0         0         0
*PART
New part from tetrahedron mesher
         5         5         5 
*MAT_ELASTIC_FLUID
         5  1.220000     0.000     0.000     0.000     0.000 141.03000
     0.000     0.000
*SECTION_SOLID
         5        10 
*ELEMENT_SOLID
*NODE
*SET_SEGMENT
*END

Figures

image_002.png

image10.png

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