Example16 Harmonic Analysis of Standing Bars

General

  • Forced oscillation is applied on two standing bars.
     

  • The resulting vibrations are analyzed.
     

  • Unless specified in the list below, the default conditions will be applied.
     

 

Analysis Space

Item

Settings

Analysis Space

3D

Model unit

mm

 

Analysis Conditions

The analysis type is the harmonic analysis.

Item

Settings

Solvers

Mechanical Stress Analysis [Galileo]

Analysis Type

Harmonic analysis

Options

N/A

The resonant frequencies of each tower are 1250[Hz] and 1650[Hz], which are acquired by individual analyses.

Therefore, the sweep range is around those frequencies.

The harmonic analysis is set as follows.

Tab

Setting Item

Settings

Harmonic analysis

Frequency

Minimum: 1000[Hz]

Maximum: 2000[Hz]

Step

Linear step: Division number: 20

Model

Two bars (TOWER) are standing on a plate (GROUND).

The boundary condition is set on the face topology of GROUND to force the displacement in the Y direction. It is named VIBE_Y

Body Attributes and Materials

Body Number/Type

Body Attribute Name

Material Name

0/Solid

TOWER

001_Al *

1/Solid

TOWER

001_Al *

2/Solid

GROUND

001_Al *

* Available from the Material DB

 

Boundary Conditions

The forced displacement is applied on on the face of GROUND in the Y direction. The displacement in X and Z directions are fixed.

Boundary Condition Name/Topology

Tab

Boundary Condition Type

Settings

VIBE_Y/Face

Mechanical

Displacement

Select all X/Y/Z components.

UX=UX=0.0, UY=1×10^-3[m]

This means the magnitude of Y displacement is 1[mm].

Results

The displacement diagrams are shown below. The oscillation frequencies are 1000[Hz], 1250[Hz], 1450[Hz], 1600[Hz] and 2000[Hz] respectively.

The contour diagram shows the displacement.

1000[Hz]

1250[Hz]

1450[Hz]

1600[Hz]

2000[Hz]

 

The displacement is high at the resonant frequencies: 1250[Hz] and 1600[Hz]. (Watch out for the color scales)

 

The vibrations are out of phase for the non-resonant frequencies.