A_T_I_2015_04_

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APRIL 2015

AEROSPACETESTINGINTERNATIONAL.COM

z Automating NDT

as non-parallel front and back surfaces
and highly varying thickness are
addressed by a combination of relative
positioning of transducers when
working in through transmission mode,
and post-processing of the data.
In enhanced scan imaging, the
permanent data record is used together
with CAD data to produce 3D imaging
of parts and flaws using software
developed as part of the project.
“Acquiring high-resolution data is
great,” comments Cooper, “but the job
of the inspector can be made much
easier if the data is displayed in such
a way that flaws are easy to identify,
characterize and size.”
The 3D images are fully scalable and
can be manipulated intuitively by the
user to show the area of interest or the
whole part. Selectable views include the
usual A- and B-scans and the 3D view,
and features such as the display of the
CAD image with scan data plotted on it.
Clicking on the center mouse button
normalizes the view at the cursor
position on the surface for convenient
sizing of flaws using the included suite
of measurement and mark-up tools.
Cooper says the next phase of the
IntACom project has already begun.
So pleased were the partners with the
work achieved that the industrial
partners have provided funding support
for another year, while a proposal for a
larger program of work for a further
three years is submitted.

In the short term, he says, work

will concentrate on the integration

of metrology equipment to provide

automated part identification and

verification: “This will allow parts to be

positioned in approximately the correct

position and the system will adjust scan

paths to suit. It will also detect if parts

do not conform to CAD data within set

limits and either adjust scan paths or

reject the part.” Other work will include

the inspection of thicker components

and the detection of damage under

metal fasteners or erosion shields using

full matrix capture (FMC) techniques

optimized for use on composites.

Looking ahead to the larger project,

a larger cell will be constructed with

multiple robots on tracks and part

translation systems aimed at the

inspection of larger components such

as wing spars and skins, wind turbine

blades and boat hulls. Development

scope will be extended to include high

accuracy inspection of complex metal

parts such as those produced by the

latest additive manufacturing methods

such as laser metal deposition.

FUSELAGE INSPECTION

Lufthansa Technik is developing the use

of active thermography for inspection of

carbon fiber composite structures. One

project, looking at the optimization of

NDT methods for composite materials,

also involves industrial image processing

specialist Automation Technology and

Hamburg University of Technology

(TUHH). Another, involving TUHH plus

NDT systems manufacturer edevis and

joining technologies consultant IFF, has

applied the technology in an automated

system that uses a robot to carry out

inspections of aircraft fuselages.

Active – or heat flux – thermography

uses a brief thermal pulse from a heat

source such as a halogen lamp to heat

the surface of the objects to be

measured. As the heat moves from the

surface to the interior of the material,

any subsurface faults or defect areas

with lower thermal conductivity prevent

the heat from spreading. The surface

above defective areas therefore remains

hot for longer, enabling infrared

cameras to make the temperature

differences visible.

In composite materials, the

technique enables concrete indications

of damage or of defects such as

delaminations to be detected in ribs

and stringers. Its advantages include

the ability to examine areas of up to

0.5m^2 in a single pass. The four-year

optimization project included the

development of software for the

automated detection of defects. And

while the method is limited so far to

materials 4mm or less in thickness,

that already covers around 80% of

the fuselage of a Boeing 787. z

Bernard Fitzsimons is an aviation journalist

specializing in the air transport business,

technology and operations

FUSELAGE INSPECTION ROBOT

Manual application of NDT procedures

to an entire fuselage is time-consuming

and expensive, so Lufthansa Technik

set out to develop a robot–assisted

inspection procedure. The result is a

demonstrator named Morfi (Mobile Robot

for Fuselage Inspection).

Morfi uses active vacuum pads to move

and position itself even on vertical and

overhanging surfaces. Two coils induce a

brief electrical pulse in the control area on

the fuselage surface, heating it by a few

degrees, and an infrared camera records the

change in temperature. Cracks stand out

because they heat up more strongly,

exhibiting a distinctive temperature profile,

particularly at their tips. The demonstrator

was designed to inspect the 10 x 9.6in

chemically milled pockets used to

reduce the weight of Boeing 737 Classic

fuselage plates. During each positioning

operation, it gathers data on four control

areas, each comprising two pocket edges.

The entire inspection cycle, including saving

all the recorded data, takes less than 30

seconds.

Follow-up work focuses on reducing the

demonstrator’s 75kg weight and extending

its application to alternative materials used

on current production aircraft, such as

carbon fiber reinforced composites and

glass fiber reinforced aluminum (Glare).

BELOW: The

IntACom software

enables data to be

displayed in a way

that makes flaws

easy to identify,

characterize

and size

RIGHT: The
IntACom software
enables the user
to analyze the
collected data
through
visualization of
B-scans (right hand
side of the screen)
and the A-scans