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- since 1996 -

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Technical Discussions
Lakshmi Srinivasan
Lakshmi Srinivasan
06:18 Jan-23-2004
Calculating resonant frequency

Hi all,

Could anyone help me with mathematical formulae to calculate resonant frequency of a material. For eg. calculating resonant modes of a cylindrical steel block.

cheers,

Lakshmi


 
 Reply 
 
N.Kuppusamy
Consultant, NDT Level-III Engineer
Advanced Inspection & Testing (S) Pte Ltd, Singapore, Joined Dec 2003, 34

N.Kuppusamy

Consultant, NDT Level-III Engineer
Advanced Inspection & Testing (S) Pte Ltd,
Singapore,
Joined Dec 2003
34
00:27 Jan-24-2004
Re: Calculating resonant frequency
Dear Lakshmi Srinivasan,
I presume that you are asking for Resonance frequency for UT. The resonance condition for UT is established when,
Wavelength = Thickness/2 and its multiples.

For resonance frequency of Eddy current you have to give more details such as Thickness, Capacitance and Inductance of the coil.

N.Kuppusamy

----------- Start Original Message -----------
: Hi all,
: Could anyone help me with mathematical formulae to calculate resonant frequency of a material. For eg. calculating resonant modes of a cylindrical steel block.
: cheers,
: Lakshmi
------------ End Original Message ------------




 
 Reply 
 
M. Kim Johnson
M. Kim Johnson
06:34 Jan-26-2004
Re: Calculating resonant frequency
Lakshmi,

If you are after modal resonant frequencies for cylindrical samples that have aspect ratios (length to diameter) very large (e.g., greater than 30 to 1), you may calculate the longitudinal and transverse mode frequencies quite easily. However, when the aspect ratio decreases, the solution is not nearly as straight forward. There are computer programs out there that will provide solutions for simple shapes (cylinders, parallelepipeds, and spheres) because they are relaticvely straight forward. One reason that textbooks really do not cover solutions to the small aspect ratio problem is that they are very complex (Bessel type solutions in closed forms), but are much easier to solve with modern computer programs. Additionally, the harmonics for most modes, if not all, depending on shape, are no longer even multiples of the funbdamental frequencies. Please contact me and I can give you more information. We have been dealing with this type problem for a some time, now.

M. Kim Johnson.

----------- Start Original Message -----------
: Dear Lakshmi Srinivasan,
: I presume that you are asking for Resonance frequency for UT. The resonance condition for UT is established when,
: Wavelength = Thickness/2 and its multiples.
: For resonance frequency of Eddy current you have to give more details such as Thickness, Capacitance and


Inductance of the coil.
: N.Kuppusamy
: : Hi all,
: : Could anyone help me with mathematical formulae to calculate resonant frequency of a material. For eg. calculating resonant modes of a cylindrical steel block.
: : cheers,
: : Lakshmi
------------ End Original Message ------------



 
 Reply 
 
N. Kuppusamy
Consultant, NDT Level-III Engineer
Advanced Inspection & Testing (S) Pte Ltd, Singapore, Joined Dec 2003, 34

N. Kuppusamy

Consultant, NDT Level-III Engineer
Advanced Inspection & Testing (S) Pte Ltd,
Singapore,
Joined Dec 2003
34
04:06 Jan-27-2004
Re: Calculating resonant frequency
Sorry, I made a mistake. The resonance frequency is not Wavelength = T/2

The resonance condition is established when: Thickness of material = Wavelength/2 and its multiples

In other words, Resonance Frequency = Sound Velocity in the Material/2T

Where T = Material thickness.

This equation can be used to calculate the Piezoelectric crystal thickness also.

N.Kuppusamy
----------- Start Original Message -----------
: Dear Lakshmi Srinivasan,
: I presume that you are asking for Resonance frequency for UT. The resonance condition for UT is established when,
: Wavelength = Thickness/2 and its multiples.
: For resonance frequency of Eddy current you have to give more details such as Thickness, Capacitance and Inductance of the coil.
: N.Kuppusamy
: : Hi all,
: : Could anyone help me with mathematical formulae to calculate resonant frequency of a material. For eg. calculating resonant modes of a cylindrical steel block.
: : cheers,
: : Lakshmi
------------ End Original Message ------------




 
 Reply 
 

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