E06 : Eigenvalue analysis of a cantilever plate

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 ×10ksi
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
IndependentSAP2000MIDASOpenBrIMPercent Difference (SAP2000 vs Independent)Percent Difference (MIDAS vs Independent)Percent Difference (OpenBrIM vs Independent)
1st0.017900.017810.017240.01723-0.5028%-3.6872%-3.7430%
2nd0.007320.006480.007100.00701-11.4754%-3.0055%-4.2350%
3rd0.002920.002850.002840.00282-2.3973%-2.7397%-3.4247%
4th0.002280.002230.002230.00221-2.1930%-2.1930%-3.0702%
5th0.002010.001870.001970.00194-6.9652%-1.9900%-3.4826%