Re: Emerging NDT Techniques - GWUT Hi Nuno,
Whether it is an emerging technique in its own right is probably a matter of definition or point of view. But I think you should count the guided wave ultrasonic technique (GWUT) in, which is primarily used as a screening tool for pipes. It is sometimes also referred to as Long Range UT (LRUT), but this term in my view does not fully encompass the possibilities this technique offers (for example heat exchanger screening with guided waves is not long range). It started taking off around 2000, but the last couple of years have seen enourmous advances and a spread into other areas - rails, all kinds of tubes accessed with an internal probe, subsea and offshore pipe work, permanently attached monitoring systems.
Please do not hesitate to get in contact with me if you need detailed info.
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: What are the emerging NDT techniques at the moment? Where can i find relevant information? There are improvements in the technology of each technique used at the moment like ultrasound and x-ray, but are there any emerging new techniques in their own right?
: Any help will be appreciated.
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Re: Emerging NDT Techniques Is it guided wave?
Yes and no. we use guided waves since a long time for bond inspection very successfull in the aeronautics. Sondicator, Bondmaster Bondchecker and others all use guided waves in the pitch & catch mode.
We use it with Air coupled PE Ultrasonics. (o.k. this is still not really common...)
It is used or can be with EMAT for crack inspection in layered materials (o.k. even this is not completely commecialized) But in general Guided waves are not new i9n industrial applications
What is with shearography?
Still the excitation is a critical point. Vacuum, Heat/Cold, can be used only with limited success: It is best for e.g. Sandwich structures, where a defect causes a drastical reduction in stiffness. Monolithic materials can be checked only up to limited thickness, and penetration depth of the load is a limiting factor. Lot of expectations are put into vibration loads, as there penetration is not that factor. Another to-do-item is a software to display the true deformation dimesnions - still an open point, you cant really quantify the results. It would be a good in-service technique, but equipment is still bulky.
Same for active Thermography - it is on the step, but still has not completely went into all corners of the market. Flash, Lock-In Burst-Phase, acoustical excitation, electrical/electromagentic excitation... lot of possibilities but realization for real applications sometimes tricky. And still the background knowledge amongst average people is poor. Also qualified personal with necessary level training.
The acoustic emission is a nice, as it needs loads, which cause tiny damages. So we used mainly for monitoring full scale fatigue test. And there are expectaions in the field of SHM. But I am skeptical: You need a lot of infrastructure with sensors, cables, switches, connectors, amplifiers, etc. There is a small hype for aeronautics with this technique, but what is the earning afterwards concerning wheight ballance??? I guess the benefit in structure weight saving will be eaten up the equipment.
LaserUltrasionics might become a good future - rumors tell that there is a lot of iinterest. The JSF-program will distribute the technique as an industrial standards over the world and other manufacturers in the FRP world might be forces soon to join the train. One might think about what you want, but there is a certain dynamic comming up. LM-TAS has sold it to management and Government as a key technology and is now pushing it strongly in their production (any immersion tank anymore, and thats already since about a decade)... we will see.
An interesting future is developing for X-Ray too. Flash tubes which strongly reduces the exposition of the operators to rays, new detector capabilities, new single side tomography capabilities... I expect here a big step forward, and from the viewpoint of easy interpretation of inspection documents - it is still a splendit method. Nowadays mostly a backup technique it could become soon again a premier inspection technique.
Microwaves mightalso become more interesting - I have some ideas in mind which are just emerging.
Use of arrays in fields where in the past people did not think. we have seen the arrays in the beginning only in the field where you use the simple sectorscan. In aeronautics the electronical scan becomes in a short time a major application field. Still a lot of companies (even very famous ones) are sleeping. currently only one company really dominates the market on portable equipment - others do not realy move. Or sit in a niche. and the gap between the market leader and the other is becomming bigger and bigger.
In the field of ut Arrays, things are now quiet common. In the eddy current array field, the equipment industry is still in a hold position. Foil arrays for special applications: yes. E.g. for Turbine disc inspection.
But for Lap joint ispection, corrosoin ispection, surface and subsurface crack scanning, there is little movement. Again the one company, market leader in UT-Arraysystems, is also busy in EC-Arrays. But still with conventional coil arrays. A big advance could be the MR, GMR and other Magnetometer semiconductor decvices. They circumvent some trouble of the induction law and especially for deeper cracks in joint structures they would make a good job. It had been shown already in labs and in application trials, but still no equipment comapany make a step forward.
Resonance techniques with non contact sensors, which also have the benefit of simple scanning devices could be also a step forward. Honeywell once proposed the SAM system. Typical american gigantomanism. And the Sandia Labs POD study showed not much performance. But is that an argument not to improve the technique? Vibration loading, vibrometer as the detector could make a good non conatct system for FRP and bonded structures....
With terra herz people expect too some applications. I guess it will be limited, as penetration is even here a problem. More then with microwaves. So metallic and even poor conductors like FRP might not be an application field. But soem ideas which had been followed in the beginning of that technique is the complete passive system, which uses the background rays, which dayly hit the earth and wich can be now used as detectors have become very sensitive... So such passive systems have already also been realized for X-Ray to inspect trucks...
o.k. thats for now some ideas... but not all
and only about light weight structures