 899 views  Technical Discussions   Sebastien Petit
 Sebastien Petit
 05:13 Feb161999 Resonances of Rayleigh waves in ceramic balls ? Hello, I'd like to test Resonant Ultrasonic Detection on ceramic balls, following some ideas of 1993 (Pr Khuri Yakoub, D Royer). But in fact I 've problems to find out exact theorical solutions of the resonances of surface acoustic waves in a sphere ! Problem of diffraction, velocity of the Rayleigh waves (constant ?, Apparent ?) I think this theory could be found in old publications or in the Viktorov book...but I can't reach them from non on! Is the web could help me ? Thanks to reply ALSO directly to my email address:spetit@isen.fr
 
   Godfrey Hands Consultant, PRI Nadcap, United Kingdom, Joined Nov 1998, ^{303}   09:24 Feb171999 Re: Resonances of Rayleigh waves in ceramic balls ? : Hello, : I'd like to test Resonant Ultrasonic Detection on ceramic balls, following some ideas of 1993 : (Pr Khuri Yakoub, D Royer). : But in fact I 've problems to find out exact theorical solutions of the resonances of surface acoustic waves in a sphere ! : Problem of diffraction, velocity of the Rayleigh waves (constant ?, Apparent ?) : I think this theory could be found in old publications or in the Viktorov book...but I can't reach them from non on! Is the web could help me ? : Thanks to reply ALSO directly to my email address:spetit@isen.fr REPLY My company is one of the United Kingdom agents for Quasar International Inc. of the United States of America. Quasar market a commercial instrument (and turnkey systems) for performing Resonant Inspection on small manufactured components, especially of Ceramic and Sinter Metal components. They have applied Resonant Inspection in testing Ceramic Balls for some applications, and are currently working with some USA based Aero Engine manufacturers and worldwide with some Bearing Manufacturers with this technology. Our approach to resonant inspection of components is the Empirical approach, where we record many of the Eigen Frequencies of good components, and also of known bad, similar components, then applying a powerful mathematical analysis software, detect the relationships between the good and bad parts. This has the advantage of being able to compensate for small density differences and small composition differences of the material that the components are made from. Applying a theoretical approach is also possible, but we frequently find that the frequency changes due to the defects that we need to detect are smaller in individual Eigen Frequencies than the variations due to other factors affecting the resonances. Only by applying such mathematical relationships is it possible to reliably detect small defects. If you would like to contact me, I will be pleased to arrange tomake some tests, and also possibly a demonstration for you.
 
   Sebastien Petit
 Sebastien Petit
 08:07 Feb181999 Re: Resonances of Rayleigh waves in ceramic balls ? Hello, Thanks for replying! I was just about emailing you about your web paper anyway... I've some further questions actually.I hope i will be clear enough (for a french, I mean...): Our approach to resonant inspection of components is the Empirical : approach, where we record many of the Eigen Frequencies of good : components, and also of known bad, similar components, then applying a : powerful mathematical analysis software, detect the relationships : between the good and bad parts. : This has the advantage of being able to compensate for small density : differences and small composition differences of the material that the : components are made from. I understand, but how do you evaluate correclty these eigenfrequencies? I 'm trying to solve the determinant equations of Rayleigh waves in a sphere. Well, I've also some problem about numerical solvation (!), but what I would like to be sure is that Resonant Inspection in a ball means resonance of surface ac waves.Is that right ? So for a long time, people thought that resonance could'nt reach the center of the ball, isn't it? My big problem is to have an "idea" of what could and what could not be quantified with the RI method in the specific problem of ceramic balls. I would like to evaluate the performance of such system before using it, OK? Come back to the eigenfreq...What is the relation about exciting freq, Rayleigh eigenfrequencies, depth in the ball and defects size ?!? Some publications says "Rayleigh waves velocity Vr has dispersion: means that Vr=Lambar*Freqr is not good". Then some publications says that "Rayleigh waves velocity do not depend on frequency". I suppose I'm wrong elsewhere but... : Applying a theoretical approach is also possible, but we frequently find : that the frequency changes due to the defects that we need to detect are : smaller in individual Eigen Frequencies than the variations due to other : factors affecting the resonances. : Only by applying such mathematical relationships is it possible to : reliably detect small defects. Well, my purpose is not to evaluate theorically the changes due to defects. For an industry, quantitative test is not always needed. I was just asking basci questions relative to good samples finally! : If you would like to contact me, I will be pleased to arrange to make : some tests, and also possibly a demonstration for you. This could be very interesting, actually. Also we should keep in touch !
And please excuse me if I'm not clear: if I haven't all understood, I may not be understandable! regards, Sebastien Petit
 
   Godfrey Hands Consultant, PRI Nadcap, United Kingdom, Joined Nov 1998, ^{303}   09:02 Feb191999 Re: Resonances of Rayleigh waves in ceramic balls ? : Hello, : Thanks for replying! : I was just about emailing you about your web paper anyway... : I've some further questions actually.I hope i will be clear enough (for a french, I mean...): : Our approach to resonant inspection of components is the Empirical : : approach, where we record many of the Eigen Frequencies of good : : components, and also of known bad, similar components, then applying a : : powerful mathematical analysis software, detect the relationships : : between the good and bad parts. : : This has the advantage of being able to compensate for small density : : differences and small composition differences of the material that the : : components are made from. : I understand, but how do you evaluate correclty these eigenfrequencies? I 'm trying to solve the determinant equations of Rayleigh waves in a sphere. : Well, I've also some problem about numerical solvation (!), but what I would like to be sure is that Resonant Inspection in a ball means resonance of surface ac waves. Is that right ? : So for a long time, people thought that resonance could'nt reach the center of the ball, isn't it? : My big problem is to have an "idea" of what could and what could not be quantified with the RI method in the specific problem of ceramic balls. I would like to evaluate the performance of such system before using it, OK? : Come back to the eigenfreq...What is the relation about exciting freq, Rayleigh eigenfrequencies, depth in the ball and defects size ?!? : Some publications says "Rayleigh waves velocity Vr has dispersion: means that Vr=Lambar*Freqr is not good". Then some publications says that "Rayleigh waves velocity do not depend on frequency". : I suppose I'm wrong elsewhere but... : : Applying a theoretical approach is also possible, but we frequently find : : that the frequency changes due to the defects that we need to detect are : : smaller in individual Eigen Frequencies than the variations due to other : : factors affecting the resonances. : : Only by applying such mathematical relationships is it possible to : : reliably detect small defects. : Well, my purpose is not to evaluate theorically the changes due to defects. For an industry, quantitative test is not always needed. I was just asking basci questions relative to good samples finally! : : : If you would like to contact me, I will be pleased to arrange to make : : some tests, and also possibly a demonstration for you. : This could be very interesting, actually. : Also we should keep in touch ! : And please excuse me if I'm not clear: if I haven't all understood, I may not be understandable! : regards, : Sebastien Petit Sebastien, I will contact you on this one directly. I think the next stages of discussion are not of general interest to the forum, but if others think differently, please let me know at Godfrey@handsltd.demon.co.uk. Regards, Godfrey
 
   Jiangxi Hengda Group
 Jiangxi Hengda Group
 04:29 Sep132002 Re: establishing business relations Dear Sir:Re: sell technical ceramics (H.S. Code 6903) We manufacture and supply various of ceramics for numerous industrial applications including ceramic nozzles, ceramic tubes, ceramic rods, ceramic crucibles, ceramic balls ceramic tiles & bars and more. Our most common ceramic materials are made of alumina ceramic. Custom boards, cylinders, shapes and preparations are available on request. Welcome to our website: www.hengda.com Please contact me with your special requirements (specify quantity, product type and description by supplying drawings, sketches, written description). We are pleased to contact you if you would like more information or want to discuss custom product availability and pricing. Your kind attention would be highly appreciated Best regards Heather Wang Jiangxi Hengda Group Tel: 86 791 833 2473 Fax: 86 791 830 8145
 
  
