Forum Technical Discussions Re: creeping wave? Posted by: Bill Blanshan , E-mail: Address, on July 08, 2008 at 20:13 : In Reply to: Re: creeping wave? posted by : Ed Ginzel    , E-mail: Address, on July 08, 2008 at 15:39 : The technique still works either way you look at it, but with the technology if Ed's Photoelestic Imaging system, we can now see the true origins of the wave modes in high detail, and when I say "high detail”, you can even see and measure the actual pulse "wavelength" which could not be done in the older schlieren films; see http://www.ndt.net/article/v11n05/ginzel1/ginzel1.htm From my knowledge you could not see the "Head Waves" in the older schlieren films either, which is the key component to how you actually see the CE2 signal. Please go to my website and see for yourself; the proof is in the pudding. http://www.autsolutions.net/Creeping-waves.html Mark, would you be able to post on your website some of your Schlieren films which shows a “creeping wave” propagating on the I.D. surface? It would be nice to show the differences between both imaging techniques, pros and cons. Bill ----------- Start Original Message ----------- : Nice try Mark… but giving a “signal” a name does not make it a wave. : Slawomir’s description is most appropriate and very practical. : The so-called creeping wave was mathematically refuted by Langenberg et al. : Your description in http://www.ndt.net/article/1198/davis/davis2.htm uses the term CE-2 to describe what you have just stated to John stresses the events on the far side of a component after the pulse has reached the far side. But your description does not match the echo-dynamics of the signal. The signal you identified as originating from a “creeping wave” is in fact a long-lasting signal (with respect to probe motion) and is accounted for by the shear head-wave and bulk shear wave. : The “practical term” (as described by Slawomir) creeping wave is also called the “lateral wave” in TOFD but there it is the direct compression mode under the near surface. A mode conversion can occur on the far side. The reflecting head-wave and the head-wave formed by the mode converted compression wave reflecting off a notch on the far side of a plate will be difficult to separate. : A more graphic video illustration of the details is available at Bill Blanshan’s website http://www.autsolutions.net/Creeping-waves.html : : John, : : Yes, there is a Creeping Wave. : : The term Creeping Wave is not a new sound source. It is a L-wave energy that skims or creeps along the opposite surface from the scanning surface. The Creeping wave travels a short distance ( about 2 mm to 12 mm) to detect a planar defect at the ID surface. It is : : The Creeping Wave is the result of a shearwave which mode converts to an L-wave from the ID surface. : : See Dr. Wustenbergs Doctorate 1977 Thesis. There are numerous papers on the wave physics and the resulting effects of these critically refracted L-waves and shear waves. : : The main point is that Creeping Waves are very effective for detection, charcaterization and sizing of Cracks. : : Sincerely, : : J. Mark Davis : : : : : Can anyone help? Is there or is there not a 'creeping wave'? Can it be proven either way? ------------ End Original Message ------------ Follow Ups: Post a Followup: Name: E-Mail: Subject: Comments: ----------- Start Original Message ----------- : The technique still works either way you look at it, but with the technology if Ed's Photoelestic Imaging system, we can now see the true origins of the wave modes in high detail, and when I say "high detail”, you can even see and measure the actual pulse "wavelength" which could not be done in the older schlieren films; see http://www.ndt.net/article/v11n05/ginzel1/ginzel1.htm : From my knowledge you could not see the "Head Waves" in the older schlieren films either, which is the key component to how you actually see the CE2 signal. : Please go to my website and see for yourself; the proof is in the pudding. http://www.autsolutions.net/Creeping-waves.html : Mark, would you be able to post on your website some of your Schlieren films which shows a “creeping wave” propagating on the I.D. surface? It would be nice to show the differences between both imaging techniques, pros and cons. : : Bill : : Nice try Mark… but giving a “signal” a name does not make it a wave. : : Slawomir’s description is most appropriate and very practical. : : The so-called creeping wave was mathematically refuted by Langenberg et al. : : Your description in http://www.ndt.net/article/1198/davis/davis2.htm uses the term CE-2 to describe what you have just stated to John stresses the events on the far side of a component after the pulse has reached the far side. But your description does not match the echo-dynamics of the signal. The signal you identified as originating from a “creeping wave” is in fact a long-lasting signal (with respect to probe motion) and is accounted for by the shear head-wave and bulk shear wave. : : The “practical term” (as described by Slawomir) creeping wave is also called the “lateral wave” in TOFD but there it is the direct compression mode under the near surface. A mode conversion can occur on the far side. The reflecting head-wave and the head-wave formed by the mode converted compression wave reflecting off a notch on the far side of a plate will be difficult to separate. : : A more graphic video illustration of the details is available at Bill Blanshan’s website http://www.autsolutions.net/Creeping-waves.html : : : John, : : : Yes, there is a Creeping Wave. : : : The term Creeping Wave is not a new sound source. It is a L-wave energy that skims or creeps along the opposite surface from the scanning surface. The Creeping wave travels a short distance ( about 2 mm to 12 mm) to detect a planar defect at the ID surface. It is : : : The Creeping Wave is the result of a shearwave which mode converts to an L-wave from the ID surface. : : : See Dr. Wustenbergs Doctorate 1977 Thesis. There are numerous papers on the wave physics and the resulting effects of these critically refracted L-waves and shear waves. : : : The main point is that Creeping Waves are very effective for detection, charcaterization and sizing of Cracks. : : : Sincerely, : : : J. Mark Davis : : : : : : : Can anyone help? Is there or is there not a 'creeping wave'? Can it be proven either way? ------------ End Original Message ------------ Optional Link URL: Example: "http://www....html". Alternative write "http://www.ndt.net/wshop/attach/filename.htm" if you transfered a filename.htm via FTP Page Title: is important! Optional Image URL: http://www....gif Attention! Please click the button only once. This may take a moment to process Forum Technical Discussions Help