Rayleigh Waves

[@Artron9001]

Scorpions have a specialised organ that lets them sense Rayleigh waves.

[@hollowayndtengineeringinc.5201]

Now THAT'S a video!!

[@l.t.879]

best ndt channel, thanks for your job.

[@geemarino6066]

Thankyou for the info sir

[@armandocg3380]

Wow to much intreresting and perfect way to explain.

[@haroldishoy2113]

That was Rayleigh interesting, thank you 😊

[@hollowayndtengineeringinc.5201]

Ba-dum. Kish!!

[@haroldishoy2113]

@@hollowayndtengineeringinc.5201 I couldn’t resist, thanks

[@adnanfadhil7047]

Thanks it very helpful video

[@bacelismael8687]

Thanks for your great videos as always! This is the video that I needed to see long time ago 👍. I was trying to make a resin Wedge just to learn about Shear Wave refraction, started with 70 degree and it turns out as a surface wave, by mistake 😁, thanks to snell's law I found my calculations were wrong, now I have to find the proper cut angle to produce 45° shear waves 🌊.

[@Hexagonmedal777]

As usual very informative kudos 👍

[@ndthero]

This video was very helpful. It helped me understand Rayleigh waves better and what may contribute to the unwanted generation of them. Great job as always.

[@CorryDMG]

Nice shirt! One of my favorite albums. And you're a Marillion fan too 👍

[@hollowayndtengineeringinc.5201]

Darn I missed your comment. I think you're the first one to notice the OM shirt. Devin is a super nice guy, too. I met him on the Physicist tour.

[@abouzandilhicham]

I like your videos

[@csabahollo6922]

The aircraft guys know that the less viscous your couplant, the less effect it has. I have always used water with a bit of gel couplant for sliptivity...

[@DoogHoneyman]

Thanks for the video. Do you think it is possible to use Rayleigh waves to get a signal from the end of a pipe with Thickness between 0.7mm & 2mm?

[@hollowayndtengineeringinc.5201]

Possible, if the pipe is clean on the OD and there's nothing in the way (corrosion, couplant flow) to disturb transmission.

[@sgramstrup]

Ha 🙂I'm a generalist and usually have at least a faint idea about what people are talking about, but this time it took me ~3minutes to just get the subject matter. The first many sentences were pure gobbeligob to me. Oh well, can't win them all..

[@hollowayndtengineeringinc.5201]

That's actually really good feedback for me! :) Sometimes I rewatch my videos and wonder what the h.e. double hockey sticks I was shooting for

[@fluxdensity4809]

Great video! Not sure if you humor topic suggestions or not, but I've always been curious about the ins & outs regarding using ultrasound to measure bolt stretch. What exactly is going on? You're technically not adding material to the bolt, but the measured value is different. Guessing it has to do with the grains being stretched and displaced? I've read about using some sort of formula to calculate the true value because the measured value (using a typical flaw detector) isn't actually 1:1 to the actual bolt stretch. I'm not sure if that is the best (or even correct) method, hence the question. Much thanks!

[@hollowayndtengineeringinc.5201]

That's actually a great question. It wouldn't take much to test it... Just a long bolt and a ratchet. I'll add it to my list. Cheers!

[@csabahollo6922]

There are a lot of instruments currently available that have calculations built in for various grades of bolts. Where that falls down is when you encounter a ‘new old stock’ of bolts or studs of unlnown metallurgical properties, and the variables can create insufficient tension on the joint, or cause the bolt to potentially go into its plastic phase. The very best thing is to measure accurately where the backwall of the bolt is, and tension the bolt to the desired value, and note the difference in whatever scale or measurement scheme you client understands. This measurement becomes the target for proper joint tension. I still have written procedures for this work.

[@universalgaming2234]

can we say that the rayleigh wave has both transverse propagation [like S waves] and logitudinal propagation [like P waves] due to which it rolls the particle or ground?

[@hollowayndtengineeringinc.5201]

Yes, a vertically polarized shear motion plus a compression motion combined.

[@universalgaming2234]

@@hollowayndtengineeringinc.5201 Thanks for your reply.

[@lucianraducanu5376]

Thanks for video! Clear, explicit. One question please - when scanned the toe crack (at 2:46 in video) the “shaddow” echo (supposed from bottom of crack) can be used for crack depth measurement? If yes- what are critical variables (frequency? (5 MHz best?), transducer size?, material?, crack depth?, crack tightness?). Thanks!

[@hollowayndtengineeringinc.5201]

Ermm... I guess it's possible but here's the thing. The response you get from UT is a weighted average over the width of the beam. You really gotta cross all your fingers and toes to get the beam to ride the surface, get no interference from couplant blobs, hit the crack, go straight down and not get deflected by any weird facets or branches, hit exactly (and only) the deepest spot, then come straight back to you. That's a pretty big ask!

[@lucianraducanu5376]

I think of a known crack depth measurement. Detected by FPI, expected to be some mm depth…but how deep? It is in front of us but the backwall surface and sides are not accessible. And backwall is curved so can not rely on reflection. Otherwise, if not this Rayleigh technique, what else can be good/better? Phassed array may do? Thanks again for your shared topics! Great content and presentations!