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Home / Examples / Stress Analysis [Galileo] / Example 12: Resonance of Metal Bars
Example 12: Resonance of Metal Bars
General
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The model consists of three metal bars. The resonance is analyzed.
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The deformation, the displacement distribution, and the stress distribution are solved.
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Unless specified in the list below, the default conditions will be applied.
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Obtain this session's project file. (Right-click and choose 'Save link as')
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Results will vary depending on Femtet version and the PC environment.
Analysis Space
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Item |
Settings |
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Analysis Space |
3D |
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Model Unit |
m |
Analysis Conditions
The analysis type is the harmonic analysis.
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Item |
Settings |
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Solver |
Stress Analysis [Galileo] |
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Analysis Type |
Resonant Analysis |
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Options |
N/A |
The resonant analysis tab is set up as follows.
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Tab |
Setting Item |
Settings |
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Resonant Analysis |
Number of Modes |
6 |
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Approximated Frequency |
0 [Hz] |
Model
Three metal bars and two support rods are created as box-shape solid body.
The bottom faces of support rods are fixed with the displacement boundary condition.
Body Attributes and Materials
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Body Number/Type |
Body Attribute Name |
Material Name |
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0/Solid |
RESONANT |
001_Al * |
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1/Solid |
RESONANT |
001_Al * |
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2/Solid |
RESONANT |
001_Al * |
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8/Solid |
BASE |
M_BASE |
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9/Solid |
BASE |
M_BASE |
* Available from the material DB
The material properties are set up as follows:
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Material Name |
Tab |
Properties |
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M_BASE |
Elasticity |
Young's Modulus: 2×109 [Pa] Poisson's Ratio: 0.3 |
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Density |
Density: 0.1x103 [Kg/m3] |
Boundary Conditions
The bottom faces of support rods are fixed with the displacement boundary condition.
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Boundary Condition Name/Topology |
Tab |
Boundary Condition Type |
Settings |
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FIX/Face |
Mechanical |
Displacement |
Select all X/Y/Z components. UX=0, UY=0, UZ=0 |
Results
The following will be output on the output window.
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<<Eigenvalue analysis>> Eigenvalue (resonant frequency):[Hz] Mode[ 0] = 8.61552809e+002 Mode[ 1] = 1.06874655e+003 Mode[ 2] = 1.21598202e+003 Mode[ 3] = 1.24695787e+003 Mode[ 4] = 1.56876049e+003 Mode[ 5] = 1.69339225e+003 |
The resonant frequencies can be checked on Table.
The displacement diagrams of Mode[0] to Mode[ 2] are shown below.
The contours are the Z displacement.
The minimum and maximum values are manually set to
-4.000e+000 and 4.000e+000 respectively.
Mode[0]:8.615528e+002 [Hz]
Mode[1]:1.068747e+003 [Hz]
Mode[2]: 1.215982e+003 [Hz]
The shorter bar exhibits the higher resonant frequency.