where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -

1154 views
Technical Discussions
Protopappas Vasilis
Protopappas Vasilis
06:42 Dec-02-2003
Lamb wave dispersion equations

Hello,

Could anyone suggest a way to solve the Lamb wave dispersion equations? I want to plot the dispersion curves for a number of symmetric and antisymmetric modes, the equations, however, need a numerical evaluation.

Thank you in advance,

Vasilis Protopappas


 
 Reply 
 
Michael Conry
Student
University College Dublin, Ireland, Joined May 2002, 3

Michael Conry

Student
University College Dublin,
Ireland,
Joined May 2002
3
07:43 Dec-02-2003
Re: Lamb wave dispersion equations
----------- Start Original Message -----------
: Hello,
: Could anyone suggest a way to solve the Lamb wave dispersion equations? I
: want to plot the dispersion curves for a number of symmetric and
: antisymmetric modes, the equations, however, need a numerical evaluation.
: Thank you in advance,
: Vasilis Protopappas
------------ End Original Message ------------

Plotting the curves can be tricky. The easiest way is as follows:

Divide the frequency/phase-velocity (f/c) space up into small increments.

At each point within this space calculate the value of the
characteristic equation F(f,c)

Then do a contour plot of the resulting numbers, including just a
single contour (at F(f,c)=0)

This is easy to do with Matlab, and I have also done it with Gnuplot and
Python.

This is not an efficient way to plot the curves (it requires a lot of
calculations) but even for a multilayered plate I found it took a pretty
short length of time to prepare a nice dispersion plot.

Doing the job in a more rigorous way requires either that you use curve
following algorithms to plot the curves (e.g. find the solutions for a
particular value of phase velocity, then incrementally reduce the phase
velocity and find solutions at each subsequent point). A difficulty in
this case can be correct handling of the crossovers of the curves.

Best regards,
Michael



 
 Reply 
 
khash
khash
00:29 Nov-25-2006
Re: Lamb wave dispersion equations
Hello
I would really be appreciate if somebody ask me why in the lamb wave dispersion curves, just A0 mode close to zero as frequency be zero?
best regards
khash
khash1979@yahoo.com


 
 Reply 
 

Product Spotlight

Wireless TOFD scanner

Quick, accurate and highly reproducible welds testing. The System operates wirelessly and is compat
...
ible with any type of Windows based Laptop, Desktop or Tablet.
>

Scatter Correction for Industrial Cone-Beam Computed Tomography (CBCT)

Download our white paper on Scatter Correction for Industrial Cone-Beam Computed Tomography (CBCT)
...
Using 3D VSHARP, a fast GPU-Based Linear Boltzmann Transport Equation Solver here: http://bit.ly/2Y0t78P
>

Micro CT

nanoVoxel series has nano-scale resolution upto 500nm by using high voltage X-ray source (from 80-
...
300 kV) with micro/nano focal spot and highly sensitive flat panel detectors and unique Optical coupling detector.
>

32:128PR PAUT & 2-ch TOFD Flaw Detector: SyncScan 2

●32:128PR PAUT with optional 2-ch TOFD to maximize your efficiency ●Support PR mode for corrosi
...
on inspection ●Multiple solutions for welds & corrosion ●Faster scan speed (Approximately 3 meters/minute) ●Light weight: 4kg only including battery
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window