Modal Analysis¶
Use the data in tutorial/15_eigen_spring.
Analysis Target¶
The analysis target is the same spring used in the preceding Nonlinear Static Analysis (Hyperelasticity, Part 2).
| Item | Description | Notes | Reference |
|---|---|---|---|
| Analysis type | Modal analysis | !SOLUTION, TYPE=EIGEN | |
| Number of nodes | 78,771 | ||
| Number of elements | 46,454 | ||
| Element type | 10-node quadratic tetrahedral element | !ELEMENT,TYPE=342 | |
| Material name | MAT1 | !MATERIAL,NAME=MAT1 | |
| Boundary conditions | Restraint | ||
| Matrix solver | Direct method | !SOLVER,METHOD=MUMPS |
Analysis Setup¶
Restrain displacement on the constrained surface shown in Figure 4.4.1 and perform modal analysis through the fifth mode. The Analysis Control Data are shown below.
Figure 4.4.1: Shape of the spring
Analysis Control Data spring.cnt¶
# Control File for FISTR
## Analysis Control
!VERSION
3
!SOLUTION, TYPE=EIGEN
!EIGEN
5, 1.0E-8, 60
!WRITE,RESULT
!WRITE,VISUAL
## Solver Control
### Boundary Condition
!BOUNDARY
XFIX, 1, 1, 0.0
YFIX, 2, 2, 0.0
ZFIX, 3, 3, 0.0
### Material
# define in mesh file
### Solver Setting
!SOLVER,METHOD=MUMPS
## Post Control
!VISUAL,method=PSR
!surface_num=1
!surface 1
!output_type=VTK
!END
Analysis Procedure¶
Run fistr1.
(Run with 4 threads.)
Analysis Results¶
Using the result data file spring.res.0.3, create the third mode shape (compression and extension of the spring in the y direction) in REVOCAP_PrePost, as shown in Figure 4.15.1. The deformation scale factor is set to 10. The list of natural frequencies output to the analysis result log file is shown below as numerical result data.
Figure 4.15.1: Third Mode Shape of the Spring
Analysis Result Log 0.log¶
********************************
*RESULT OF EIGEN VALUE ANALYSIS*
********************************
### NUMBER OF ITERATIONS = 20
### TOTAL MASS = 3.4184E-06
PERIOD FREQUENCY PARTICIPATION FACTOR EFFECTIVE MASS
NO. [Sec] [HZ] X Y Z X Y Z
--- --------- --------- --------- --------- --------- --------- --------- ---------
1 2.245E-03 4.454E+02 1.029E+00 -8.894E-02 -7.052E-01 1.301E-06 9.718E-09 6.109E-07
2 2.239E-03 4.465E+02 6.969E-01 1.075E-01 1.011E+00 6.129E-07 1.460E-08 1.289E-06
3 1.100E-03 9.087E+02 4.862E-03 1.236E+00 -7.917E-02 4.007E-11 2.591E-06 1.062E-08
4 1.014E-03 9.858E+02 -2.965E-02 3.385E-01 -6.782E-03 9.823E-10 1.280E-07 5.138E-11
5 5.525E-04 1.810E+03 -5.867E-01 -5.386E-02 -7.659E-01 2.838E-07 2.391E-09 4.837E-07