Home / Examples / Stress Analysis [Galileo] / Example 15: Harmonic Analysis of Tuning Fork

Example15: Harmonic Analysis of Tuning Fork

General

A tuning fork analyzed in Example 13 is forced to oscillate at certain frequencies.
The deformation, the displacement distribution, and the stress distribution are solved.
Unless specified in the list below, the default conditions will be applied.

Results will vary depending on Femtet version and the PC environment.

Analysis Space

Item	Settings
Analysis Space	3D
Model Unit	m

Analysis Conditions

The analysis type is the harmonic analysis.

Item	Settings
Solver	Stress Analysis [Galileo]
Analysis Type	Harmonic Analysis
Options	N/A

The result of Example 13 shows the fundamental resonant frequency is about 19 [Hz]. The frequency is swept around that frequency. The harmonic analysis is set as follows.

Tab

Item

Settings

Harmonic analysis

Frequency

Minimum: 500 [Hz]

Maximum: 510 [Hz]

Sweep Type

Linear Step by Division Number: Division: 20

Model

The oscillations are forcibly applied on the bottom face of the knob of the turning fork. The oscillation amplitude and direction are set with boundary conditions.

Body Attributes and Materials

Body Number/Type	Body Attribute Name	Material Name
8/Solid	RESONANT	001_Al *

* Available from the material DB

Boundary Conditions

In the harmonic analysis, the amplitude of the applied oscillation is set as the displacement amplitude in the boundary condition.

Boundary Condition Name/Topology

Tab

Boundary Condition Type

Settings

Oscillation/Face

Mechanical

Displacement

Select the Y component.

Uy=1x10-5 [m]

The oscillation is applied in the Y direction at the bottom face of the knob. The amplitude is 10 [um].

Results

The displacement diagrams are shown below. The oscillation frequencies are 500[Hz], 505.5 [Hz] and 510 [Hz], respectively.

The contour diagram shows the displacement.

Displacements shown here are for a certain phase of the oscillation.

500 [Hz]

505.5 [Hz]

510 [Hz]

The frequency characteristics of the displacement at the tips of the tuning fork is shown below.

The displacement becomes quite large when the applied frequency matches the resonant frequency of the tuning fork, which is around 505.5 [Hz].