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374 views
09:40 Feb-20-2002

Kamran Eftekharmehr

Student
tehran poly tecqnik,
Iran,
Joined Dec 2001
2
crack depth measureing by tip diffraction method

Dear colleagues

>I'm trying to measure cracks depth by tip
>diffraction method in a steel thin plate.
>
>
>My questions are:
>1. What angle is the best for this job and why?
>
>2. Is the 180 degree phase chenge between root and tip
>signals, for 45 degree refracted wave or for all
>angles?
>
>3. would you please send me some theoretical
>literature(if its possible)or reference?
>
>
> best whishes
>



 
07:27 Apr-10-2002
Patrick bergalonne
Re: crack depth measureing by tip diffraction method : Dear colleagues
.
: >I'm trying to measure cracks depth by tip
: >diffraction method in a steel thin plate.
: >
: >
: >My questions are:
: >1. What angle is the best for this job and why?
: >
: >2. Is the 180 degree phase chenge between root and tip
: >signals, for 45 degree refracted wave or for all
: >angles?
: >
: >3. would you please send me some theoretical
: >literature(if its possible)or reference?
: >
: >
: > best whishes
: >
.
if you want to use TOFD method to measure cracks depth, the best refracted anle(for the logitudinal wave)must be included between 45° and 60°

Pat


 
08:48 Apr-10-2002

J. Mark Davis

Teacher, And Consultant
University of Ultrasonics, Birmingham, Alabama,
USA,
Joined Mar 2000
85
Re: crack depth measureing by tip diffraction method Dear Kamran,

There are several considerations for the Tip Diffraction Methods:

Some people believe that a 52 degree is the best. I like the 45 degree due to the corner trap affect.

Are you using Shear waves or L waves?

What materials are you inspecting, carbon stainless, etc?

What is the thickness of the material? You will have to consider damping factors for thin materials.

Please review the Advanced Flaw Sizing Handbook in the publications section of ndt.net.

Sincerely,

Mark Davis


Dear colleagues
: .
: : >I'm trying to measure cracks depth by tip
: : >diffraction method in a steel thin plate.
: : >
: : >
: : >My questions are:
: : >1. What angle is the best for this job and why?
: : >
: : >2. Is the 180 degree phase chenge between root and tip
: : >signals, for 45 degree refracted wave or for all
: : >angles?
: : >
: : >3. would you please send me some theoretical
: : >literature(if its possible)or reference?
: : >
: : >
: : > best whishes
: : >
: .
: if you want to use TOFD method to measure cracks depth, the best refracted anle(for the logitudinal wave)must be included between 45° and 60°
.
: Pat
.



 


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