The Positives and Negatives of Advanced Technology for Non Destructive Testing.

Advanced Technology for
Non-Destructive Testing

Smart Materials Require Smart
Inspection
Advanced Engineering NEC
November 2014 Advanced Engineering NEC 2

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 21st Centuary Eddy Current Array Instrumentation
The Old & Bold Analogue Eddy Current
Instrumentation

Case Study

The Challenge
Longerons 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.

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

Why Advanced Ultrasonics?
Typical Frame Scanner Phased Array Probe & Aqalene Delay Line

The Ability Acquire Ultrasonic Data and Image the
Findings
End
Vie
w
Top
Vie
w
Side
Vie
w
Raw
‘A’ Scan
Data

Full Matrix Capture - FMC
FMC 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
How Do These Affect You?
• 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?

Thank You…
ANY QUESTIONS?
Neil Harrap – NDT Market Manager
Neil.Harrap@Ashtead-Technology.com
www.ashtead-technology.com

The Positives and Negatives of Advanced Technology for Non Destructive Testing.

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The Positives and Negatives of Advanced Technology for Non Destructive Testing.