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Example 20: Resonant Frequency of Cantilever


General

Analysis Conditions

Item

Settings

Solver

Piezoelectric Analysis [Rayleigh]

Analysis Space

2D

Thickness in Depth Direction

1 [mm]

Analysis Type

Resonant Analysis

Unit

mm

Analysis Plane

2D section

Variables to Constrain

Select [Electric Potential] and [Y Displacement]

Deselect [X Displacement] and [Z Displacement]

 

Options

Deselected

 

 

Graphical Objects

Left end is fixed.

Body Attributes and Materials

Body Number/Type

Body Attribute Name

Material Name

0/Solid

Body_Attribute_001

Material_Property_001

Material Name

Tab

 

Material_Property_001

Piezoelectricity

Piezoelectricity: No

Anisotropy: Isotropic

Young's Modulus: 1x1010 [Pa]

Poisson's Ratio: 0.0

 

Boundary Condition

Boundary Condition Name/Topology

Tab

Boundary Condition Type

Setting

fix/Face

Mechanical

Displacement

Select all UX, UY, and UZ.

UX=0, UY=0, UZ=0

 

Results

The resonant frequency calculated by Femtet is compared to the theoretical value of cantilever.

 

The difference between the measured and the theoretical values is given in the following equation.

 

Difference = (Resonant Frequency/Theoretical Value of Cantilever) - 1.0

 

The theoretical value is given in the following equation.

 

 

f0: Resonant frequency [Hz]

E: Young's Modulus [Pa]

I: Second Moment of Section (=(Depth x (Height^3))/12) [m4]

ρ: Density [kg/m3]

A: Section Area [m2]

l:: Length [m]

λ=1.8751