Forum Technical Discussions Re: creeping wave? Posted by: John Howard (PID_3644), E-mail: Address, on July 10, 2008 at 00:06 : In Reply to: Re: creeping wave? posted by : J. Mark Davis , E-mail: Address, on July 08, 2008 at 13:33 : Thank you for your quick response. As you appear knowledgeable on the subject can you answer this question? I understand that the shear wave sound 30° will travel to the bottom surface and generate a small L wave that will propagate forward. If this L wave strikes an ID connected crack it will be reflected. Can you explain in simple English how does this reflected weak L wave gain the intelligence to know when it is aligned to the 30° to mode convert and head back to the probe? ----------- Start Original Message ----------- : 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: Re: creeping wave? Slawomir Mackiewicz 14:37 Jul-10-2008 (0) Post a Followup: Name: E-Mail: Subject: Comments: ----------- Start Original Message ----------- : Thank you for your quick response. : As you appear knowledgeable on the subject can you answer this question? : I understand that the shear wave sound 30° will travel to the bottom surface and generate a small L wave that will propagate forward. If this L wave strikes an ID connected crack it will be reflected. Can you explain in simple English how does this reflected weak L wave gain the intelligence to know when it is aligned to the 30° to mode convert and head back to the probe? : : 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