© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document. New Standards. Together...

© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.

New Standards. Together

Presented byKeith Phillips / Head of NDT & Mechanical Testing - UK September 2013


Contents

• Developments on Flexible UT Arrays to optimize curved surface testing

• Single Side Omega Stringer Integrity Check• Advanced Simple to Use Quick Check Methods

• Line Tool• DolphiCam

• Paint thickness measurement on CFRP• Eddy Current with adapted probe (if LSP is present)• Microwave for all cases

• Advanced new wheel probe for curved surfaces• Fast CFRP-Nomex-Sandwich inspection with PAUT

A4A Sept 2013Recent developments in NDT from Airbus Engineering


Flexible UT Array to access narrow curved surfaces

Objective:• Optimised and improved capability for inspection

of radius components • Using a new flexible probe coupling technology • combined with a linear transducer array based on

a flexible foil with sensors



Flexible Array

First 8 element flex array

Next a 64 element flex array

Finally coupling and housing are key elements in the design for easy handling



Flexible Array – Demo on Wing panel



Single Side Omega Stringer Integrity Check

Objective:• Fast inspection method to check a hidden and for

direct NDT inaccessible structure part, which might be damaged with out any detectable/visible impact at the outer skin.

• Use of an advanced commercially available PAUT approach with an advanced PAUT system

• No need to know the exact position of the hidden structure



Single Side Omega Stringer Integrity Check A Conventional Single Transducer Approach

A-Scan, Stringer with delamination

A-Scan, Stringer no damage

Conventional Transducers – it works but:awful to perform this inspection!



Different Array Approaches

Optimized Aperture and Angle of Incidence

Guided Wave approach to becomeindependent from stringer position

Most simple –perpendicular - approach



PAUT – a simple direct inspection approach

- B-Scan configuration with pitch/catch

- Linear scanning with optimized angle of incident

- 1 MHz probe in contact (water delay line possible)

Indication of the

UT signal

travelling along the

Omega-STRG

64 Elements 1 MHz probe



PAUT – Approach with beam steering (Guided Wave)

Sector-Scan configuration with pitch/catch , with beam steering from 0° - 80°.

Combining a PAUT instrument and a 64 Element 1 MHz Probe

with water box delay line for easy coupling.

Use of Wheel probe to be checked later

current wheels too narrow

(wheel internal delay too big at current systems)



Advanced Simple to Use Quick Check Methods

• Line Tool (EADS IW (Innovation Works)) for AIRBUS based on UT Array in a Wheel ProbeTraffic Light Human InterfaceTo be used by Non NDT mechanicsUsing wheel probe offering fast scanning

• DolphiCam (DolphiTech (N) & EADS IW / TESTIA support)2D Array with volume scan capabilityReduced and simplified controlsCustomized inspection APPs on Tablet PCFull A, B & C-Scan Display Dry coupling 30 x 30 mm field of view



Line Tool-Concept for Quick Damage Assessment



DolphiCam – simple UT imaging method (2D)

Full PAUT inspection system Simple user interface (APP-Style)

Uses simple Tablet PC. Features dry coupling.Full A-,B-,C-scan, all volume data stored (if required)

Gate to slice voxel data setFull post processing with NDT-Kit-Software (Airbus Standard)Fits with OMA (remote inspector)



DolphiCam – simple UT imaging method (2D)

DolphiCam uses a novel crossbar approach to excite moving sound fields for areal scanning128 x 128 columns/rows can be switched generating an image 30 x 30 mm with ~16000 pixel4.27 points/mm lateral resolution, recording a full A-scan (CFRP: now 8mm deep – 16 mm follows soon)



Paint thickness measurement on CFRP

For metallic structures paint thickness measurement is a simple task:

Just take Eddy Current and the lift/off effect.Or Ultrasound – as the acoustical impedance difference is high

For CFRP the conductivity is extremely low, paint has similar acoustical impedance to resin, lot of paint layers give confusing echo pattern.

How to proceed?

Now 2 new successful solutions for a long unsolved task:

• Eddy current with large probe diameter if a copper lightning strike protection is present (the cheaper solution)

• Microwave, in all cases (only a little more costly)



Lightning strike protection by surface master

• An Expanded Copper Foil“ (ECF) dissipates the electrical energy in case of a lightning strike.

• It is a slit and expanded foil which forms as a net.

External surface protection

Pigmented resin with ECF

CFRP

Expanded Copper Foil (ECF)

< limit !

Paint above ECF must not exceed a maximum thickness !!Must be checked!



Check of layer thickness above Expanded Copper Foil

EDDY Current Thickness measuring

works only on CFRP containing

metallic LPS / ECF

Typical Thickness Meter has a small ball pen sensor –

result has a high inaccuracy dependig where you hit the surface: on top of a copper cross point or in the hole of the net

Consequence:

A large sensor diameter is the key to reliable measurement.



Check of layer thickness above Expanded Copper Foil

Together with commercially available equipment suppliers an appropriate sensor was found, which fits to standard gauges:

A 10mm diameter Sensor

Result: It increased the accuracy by more than a magnitude

The bigger sensor now integrates over a larger area with always a sufficient averaging of Copper and CFRP



Microwave for Paint Thickness measurement

CFRP has a conductivity which rises with frequency. Carbon fibres itself are good conductors, resin is a dielectric medium in between, which lets the fibres act as a capacitor. This is for micro waves a perfect reflector having a very small penetration depth.

Challenge:

• the fibres of the top layer reflect anisotropic

• Specific permittivity of different paint layers(Resin above the first layer of carbon fibres (or ECF LSP) adds to the measured thickness – but this does not matter if checking the LSP quality)

Solution: An advanced and specific microwave antenna design and the well adapted detector unit, which is completely insensitive to permittivity changes and anisotropy (fiber orientation in surface layer)



µ wave Paint thickness gauge for CFRP

Microwave is applicable on ECF as well as on the CFRP substrate without ECF.



µ-wave paint thickness gauge - accuracy

• Equipment suppliers realised a device with measurement results being independent of permittivity of (non-conductive) layer composition.

• Diagrams show measurement results of layers being partly paint and partly foils.



Advanced Wheel Probe for Large Area Inspection

• Portable device, quick and easy deployment

• rapid scanning of large areas of even thick CFRP structures

• New hand held approach with easier ergonomics for use under wing or other difficult areas - for vertical or overhead inspection

• Lighter: e.g. simple trolley design for lower weight – approx 1.9 kg

• For curved and geometrically challenging surfaces

• Fixed array height

• Simple guide wheels (could be rollers etc as required), wheel diameter ~ 35 mm, Wheel alignment flexible in scan and index axis, Flexible thin tyre



New wheel probe – design challenges

Different Normalization Tasks



The new Airbus Wheel Probe



General Procedure UT for Sandwich, NTM 51-10-24

A - delamination between plies of outer CFRP skin

B - disbond between outer skin and honeycomb core

C - cracked honeycomb core

D - crushed honeycomb core

E - disbond between inner skin and honeycomb core

F - fluid ingress in honeycomb core

It’s a kind of guided wave approach tuned to core height (membrane length = ½ λ) with equipment fulfilling specific needs:

• Square wave pulse excitation (preferred)• good filter capabilities to tune the receiverTransducer runs best with tuned bandwidth: Debonding causes resonance shift to ¼ λ = octave down. Debonding echoes have > 6db less amplitude



1 ... 16 48 ... 6410 ... 25

96 mm probe length (64 Elements)

~ 72 mm Scan (Index) - Axis

1. 5 mm Pitch

1 . . . 64

Back wall echo (BE)

Front surface echo (FSE)

Wasservorlaufstrecke

1L64E96-221L64E96-22

Water Delay Water Delay

1L64E96-22PHASED ARRAY – probe; 1MHz 64Elements (Array: 96mm x 22mm)

Setting for linear electronic scanning for sandwich

The linear scan is achieved by multiplexing of a single, constant Focal Law along a Linear-Array



UT Array for CFRP-Nomex-Sandwich Inspection

Method for single transducer to cover even non parallel areas using an average tilt angle – limited to non steep ramp structures - with PAUT also very steep ramp structures can be accessed




Typical screen setup with TCG, Gates and B & C scan of de-bonded area

Three areas of rear side disbond – C-scan & B scans

Probe configurations:• Direct contact• Water box /water delay• Wheel Probe (1MHz or 0.5 MHz

necessary – not available yet)



Thank you for your time

Any Questions?


© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document. New Standards. Together...

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Transcript of © AIRBUS S.A.S. All rights reserved. Confidential and proprietary document. New Standards. Together...