Calculate the natural frequencies of a square cantilever plate.
-Analysis Type
3-D eigenvalue analysis
-Unit System
in, kip
-Dimension
Length 24.0 in Width 24.0 in Thickness 1.0 in
Gravitational acceleration g = 386.4 in/sec2
-Element
Plate element (Thick type)
-Material
Modulus of elasticity E = 29.5 ×103 ksi
Poisson’s ratio ν = 0.3
Weight density γ = 2.835648 × 10-4 kips/in3
-Element Property
Element size a × b = 24.0/19 in × 24.0/19 in
Thickness t = 1.0 in
-Boundary Condition
Nodes 1 ~ 20 ; Constrain all DOFs.
All nodes ; Constrain Dx, Dy and Rz.
-Analysis Case
Self weight is converted to nodal masses automatically.
Number of natural frequencies to be computed = 5
Tested Features
App
Object Link: https://openbrim.org/objid8uibr73u6zjd4t5f0zrxww.project
Library
Object Link: https://openbrim.org/objidzpk4dbzdzhln9lv0ss3u.libobj
Sources
- Harris, C. M. and Crede, C. E., “Shock and Vibration Handbook”, McGraw-Hill, 1976.
- “SAP90, A Series of Computer Programs for the Finite Element Analysis of Structures,Structural Analysis Verification Manual”, Computer and Structures, Inc., 1992,Example 15.
Result Comparison
Mode | Natural Period | ||||||
| Independent | SAP2000 | MIDAS | OpenBrIM | Percent Difference (SAP2000 vs Independent) | Percent Difference (MIDAS vs Independent) | Percent Difference (OpenBrIM vs Independent) | |
|---|---|---|---|---|---|---|---|
| 1st | 0.01790 | 0.01781 | 0.01724 | 0.01723 | -0.5028% | -3.6872% | -3.7430% |
| 2nd | 0.00732 | 0.00648 | 0.00710 | 0.00701 | -11.4754% | -3.0055% | -4.2350% |
| 3rd | 0.00292 | 0.00285 | 0.00284 | 0.00282 | -2.3973% | -2.7397% | -3.4247% |
| 4th | 0.00228 | 0.00223 | 0.00223 | 0.00221 | -2.1930% | -2.1930% | -3.0702% |
| 5th | 0.00201 | 0.00187 | 0.00197 | 0.00194 | -6.9652% | -1.9900% | -3.4826% |