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Technical Discussions
Joseph Batt
Joseph Batt
04:28 Jun-02-2000
TOFD

During measurements, is the probes distance so important?
I have found a formula:distance=2/3*2*c*tan a
c=velocity of longitudinal wave
a=angle of the probe

Is that correct?
In some books it is also said that it is better to do measurements
at two different distances between the probes.
Anyway, I find it very difficult to interpret data from the A scan.
I would appreciate if someone could give me some informations.
Thank you.

Joseph Batt



    
 
 Reply 
 
Udo Schlengermann
Consultant, -
Standards Consulting, Germany, Joined Nov 1998, 177

Udo Schlengermann

Consultant, -
Standards Consulting,
Germany,
Joined Nov 1998
177
02:23 Jun-05-2000
Re: TOFD
ls are weak, and TOFD uses (non rectified) Rf-signals, so interpretation of a single TOFD-A-scan makes no sense.
TOFD results of a lot of A-Scans have to be compiled in a B-Scan image.
In this B-Scan image the human eye can easily detect areas with irregularities.
Because of the wide beams used the images do not show the real shape of the irregularity. The pattern has to be interpreted. Only the points of minimum time-of-flight give some idea of the extension of the irregularity.

Kind regards
Udo Schlengermann

+++++++++++++++++++++++++++++++++++++++
: During measurements, is the probes distance so important?
: I have found a formula:distance=2/3*2*c*tan a
: c=velocity of longitudinal wave
: a=angle of the probe

: Is that correct?
: In some books it is also said that it is better to do measurements
: at two different distances between the probes.
: Anyway, I find it very difficult to interpret data from the A scan.
: I would appreciate if someone could give me some informations.
: Thank you.

: Joseph Batt




    
 
 Reply 
 

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