The Positives and Negatives of Advanced Technology for Non Destructive Testing

Advanced Technology for

Non-Destructive Testing

Smart Materials Require Smart

Inspection

November 2014 Advanced Engineering NEC 2

Advanced Engineering NEC

The Digital Era Of NDT


NDT Inspection

• Wrought Product

• Post Tooling/Assembly

• In Service


Two Common Methods Used

• Eddy Current Testing - ECT

• Ultrasonic Testing - UT


Two Common Methods Used

• Eddy Current Testing - ECT

• Ultrasonic Testing - UT

Advanced Methods Available

• ECT – Eddy Current Array - ECA

• UT – Phased Array – UTPA

• UT - Full Matrix Capture - UTFMC


Eddy Current

&

Eddy Current Array


Eddy Current Testing

Usually referred to as ECT, this is the best

method for inspecting non-ferrous

components,, for defects. ECT makes it

possible to reliably detect corrosion and

surface cracking, for example.

Such defects cause variations in the phase

and magnitude of the eddy current

generated by a transmitter coil, which are

monitored by a receiver coil or by

measuring the variations in the current

flowing through the transmitter. This is the

core of standard, single-element ECT.


Eddy Current Array Technology

Eddy current array (ECA) probes use several individual

coils, grouped together in one probe. The coils are excited

in sequence to eliminate interference from mutual

inductance (a process referred to as channel multiplexing;

see below). To optimize performance, ECA probes can be

made flexible or shaped to match the geometry of the part

to inspect.

Data from ECA probes, which can be encoded, is

transmitted directly to software for graphical display (C-

scan), record keeping, and reporting. ECA probes can

replace a number of traditional NDT nspection methods,

such as magnetic particles, liquid penetrant, and single-

element ECT (above), by significantly reducing inspection

times, offering improved flaw detection, and allowing for full

inspection records. It is also possible to design ECA probes

in the exact shape of specific parts for simplified, one-pass

inspection.


The Old & Bold Analogue Eddy Current Instrumentation

The 21st Centuary Eddy Current Array Instrumentation


Case Study


The ChallengeLongerons usually carry larger aircraft loads and help to transfer skin

loads to the internal structure. Longerons nearly always attach to

frames, ribs, or the skin of the aircraft. Fatigue and stress cracks

eventually appear around the fasteners used to secure longerons to

structures. Such cracks risk going

undetected because they are small (typically 1.25 mm or 0.05 in.),

they are near and under fastener heads, and often under surface

coatings. The faying surface between longerons and skin is also

prone to corrosion and must be inspected.


The Solution

The instrument and the software to drive the solution — Ectane™ and

Magnifi® — already existed at the moment Eddyfi tackled this application.

What was

therefore necessary was a new type of probe capable of detecting surface

and

subsurface defects. Eddyfi developed a hybrid eddy current array (ECA)

probe that would detect both types of defects within their respective

tolerances.

The probe therefore incorporates two arrays of coils using proprietary coil

topology.

The first is a high-resolution

array using small, high-frequency coils

to detect the surface cracks around

fasteners. The second array is designed

to detect subsurface corrosion.Advanced Engineering NEC

Probe Design

The probe is also designed to be semi-flexible, making it capable of

conforming to skin curves. In addition, the rugged casing is much more

adapted, compared to other available solutions, to the rough handling to

which probes are often

submitted.

Thanks to this powerful all-in-one design, the probe is able to

detect corrosion build-ups ±5 % of the layer thickness (e.g.,down to 0.5 mm

of a 10 mm layer), which is approximately twice as powerful as the initial

requirement.

The probe is also able to detect 1.25 mm (0.05 in.) longitudinal, transverse,

and oblique stress cracks along the load path


Corrosion Inspection


Crack Inspection



The Benefits

Historically, inspecting multi-layered aluminium structures for cracks and

subsurface corrosion required two sets of instruments, two different types of

probes, and sometime even different software. Eddyfi’s unified solution offers

the following benefits:

• Improved planning — By easily identifying cracks and corrosion between skin and

longeron, it is easier to plan long-term maintenance.

• Faster execution — Switching from the crack inspection setup to the corrosion

inspection setup is very quick. Because it does not require a new hardware setup and

that the array probe offers wider coverage, inspections have gone from hours to mere

minutes.

• Better use of qualified personnel — Because they spend less time switching

between inspection setups, qualified personnel can perform more inspections.

• Data archives — Having access to archived inspection data allows performing

advanced trending analysis to, for example, monitor crack/corrosion growth and

extrapolate their behaviour.


Ultrasonic &

Advanced Ultrasonics


The Old & Bold Once Again….!!


One of The New Generation of Advanced Ultrasonic Instruments


Typical Frame Scanner Phased Array Probe & Aqalene Delay Line

Why Advanced Ultrasonics?


The Ability Acquire Ultrasonic Data and Image the

Findings

End

Vie

w

Side

Vie

w

Top

Vie

w

Raw

‘A’ Scan

Data


Full Matrix Capture - FMCFMC is an extension of Ultrasonic Phased Array

technology. It offers advantages over traditional

Phased Array because you can minimise

considerations of where to steer or focus in advance.

Indications that would have otherwise been missed

because of their out of plane orientation are usually

imaged correctly.

Many Phased Array inspections will eventually use

FMC in lieu of predefined focal laws, thus increasing inspection sensitivity and POD.


Other

Application

Specific

Scanners


Typical Roller Style Probe


Chain Scanner + HydroForm


An End To End

Inspection Solution


Digital Era Of NDT


Positive Aspects….. • Intuitive operation

• Recordability

• Accountability

• Repeatable inspection

• Increased POD

• Inspection design

software

• Report generation

• Digital set-up files (UT, ET,) e-mail to site

• E-mail: Data files – Raw

data, AW data, Image

data, ATA, JPG, BMP,

MPEG

• Improved viewing and

measuring capability UT

(PA & FMC), ECA


Negative Aspects……

• Capital cost of equipment

• Cost of maintenance, repair and calibration

• Potential under utilisation

• Inevitable depreciation

• Constantly changing technology

• Training of staff in new technology

• Requirement for technical support


3 Significant Negative Aspects……• Constantly changing technology

• Staff skill levels in new technology

• Requirement for technical support

• Is the best available solution being used?

• Has the method been validated and accepted?

• Is staff training and certification adequate?

• Are staff levels of competency correct?

• Is there good OEM technical support?

How Do These Affect You?


Thank You…ANY QUESTIONS?

Neil Harrap – NDT Market [email protected]

www.ashtead-technology.com


mailto:[email protected]

http://www.ashtead-technology.com/