Acoustical Scanning of Airframes, etc

[Flamefront]

Gentlemen,

I'm reviewing a patent for viability - is uses acoustic waves to detect faults in a structure such as an airplane wing. The invention uses a transducer to excite a composite structure and looks at the echo signature for anomalies.

This sounds like an old idea. Hasn't acoustic signature studies for structural integrety been done for a while?

Any input would be appreciated. For the curious amoung you, the patent number is 6,981,418

Thx

 

[ruth44]

I know of acoustic signature analysis that has been applied during a pressure test on a nuclear reactor pressure vessel (probably in the 1980's)in order to detect crack growth.

 

[CoryPad]

This patent certainly is viable. The first "Other Reference" is for MAUS, a similar system already in use.

Acoustic/ultrasound inspection has been used for many years, so it isn't "new".

The patent in question could be considered "novel" in that it uses an existing inspection technique but adds a "turnkey" feature for analysing a structure remotely while minimizing expensive human labor.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Flamefront]

Thanks, Cory and Ruth44

That is good feedback and I appreciate it.

Flamefront

 

[WKTaylor]

flamefront...

suggest You review the following..

ASTM: has a large number of specs related to Acoustic Emission testing. Search ASTM specs with Keywords "acoustic" and "emission"

ASME N-471 Acoustic Emission for Successive Inspections

SAE J1242 Acoustic Emission Test Methods, Information Report

ASNT 130 Vol 5 Sec 12 Acoustic Emission Applications in the Aerospace Industry

Regards, Wil Taylor

 

[Flamefront]

Wil

Excellent information - thanks

Flamefront

 

[737eng]

Boeing Technology presented something similar for composite structure at the 2003 structures conference. I don't know where they currently stand on this issue. I believe the original intent was to make it part of the aircraft health management system and it was to specifically monitor areas around lower deck cargo doors in composite fuselages.

 

[AminG]

I am working with a colleague of mine who came from Russia - this method of detection is not new and can be adapted to several dozen other uses.

 

[prost]

Certainly the use of acoustics to detect corrosion or cracking isn't new; some of you may have seen mechanics or technicians using a coin to slightly rap an aircraft structure to try to use differences in perceived sound to discover anomalies in the structure (the (in)famous "tap test"). The key improvements in this field seem to be in the detection level--how small a fault, defect, crack, or corrosion level the device can detect, and perhaps just as importantly, how reliably that detection method works. If you had a device that could detect an 0.0001 inch flaw or defect with 90% reliability, and it just happened to use some sort of acoustic method, I would think that this would be patentable.

 

[Kwan]

oh to have a system that would detect a .0001 flaw at 90%!! I would never have to work again!!!!!!

 

[kontiki99]

I used to work for the DoN in flight test at Pax River.

During the EMD phase of the F18-E/F flight test program, I used to see Boeing people performing, what I understood to be, ultrasonic scans of the composite structure.

The device I saw looked like a small 4 wheeled (toy truck) with an array of sensors. The sensor array oscillated back and forth as they rolled the truck over the composite surfaces.

There was a cable feed to a notebook computer that painted a very detailed color image on the screen in near real time.

These scans were conducted on a routine basis.

 

[Flamefront]

Gentlemen -

Thank you for the excellent responses to the question. This gives me good focus with which to evaluate the patent - as some of you state the novelty is in the racking of the transducer, and it sounds like from kontiki99 that some clever data acq engineers on the floor at Boeing figured this out already. I'll dig into that, it may be a "prior art" situation at that...

Thanks, guys

 

[GregLocock]

The technique used to be known as Acoustic Emissions (AE)

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[CoryPad]

Greg,

No, AE is different than ultrasonic (or acoustic) scanning.

AE relies upon the sudden release of a mechanical wave (due to plasticity or crack propagation) in a stressed structure. Hence, it requires the structure to have stresses (i.e. service stresses) imposed upon it. The sensor is placed in contact with the structure and detects mechanical waves propagating from any location in the structure. The structure itself is the wave source.

Ultrasonic scanning detects flaws (cracks, voids, unbonded layers) by sending and receiving mechanical waves. An external wave source is used, and the source can also be the detector. The structure does not have to be stressed.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[GregLocock]

Ack, yes you are right.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[PBPouw]

Fokker aircaft started building bondeded aircaft structures in the 1950's . To check the bonding they developed the : Fokker bond tester. Easy to find on the internet

So yes the system is around a while......

Pim