Presentation at 2011 MAUS User Group Meeting , … at 2011...Presentation at 2011 MAUS User Group Meeting , 13 September, 2011 Innovative Materials Testing Technologies, Inc.Technologies,

Presentation at 2011 MAUS User Group Meeting , 13 September, 2011 Innovative Materials Testing Technologies, Inc.Innovative Materials Testing Technologies, Inc.Innovative Materials Testing Technologies, Inc.

1

Detecting Corrosion and Cracks

Hidden in Thick and Multiple Layer

Structures

Potential New Functions Added to

MAUS by Using GRFEC Technique

Yushi Sun, Tianhe Ouyang, Harry Zhu, Weiqiang Wan &

Changhong Sun

Innovative Materials Testing Technologies, Inc.

9769 W. 119th Drive, Suite 27

Broomfield, CO 80021

Tel: 303 554 8000, Email: [email protected]

mailto:[email protected]




2

Fundamental Requirement for

Aircraft High Velocity Maintenance

NDI:

Detection of flaws without a need

of structure disassembly


3

Least Preconditions for Techniques Enabling

HVM or

Flaw Detection without Structure Removal

1. Penetrating through whole thickness of structure;

2. Penetrating through interface gaps between

structure layers;

3. Access only on one side of structure.

4. Reliable algorithm to differentiate flaw from aircraft

structure variations


4

Techniques EC UT X Ray GRFEC

Deep

penetration - √ √ √Thru

interface

gaps√ - √ √

Access one

side only √ √ - √

Capabilities

Technique Capability Comparison

of commonly use NDI methods

GRFEC is the best choice


5

Presentation/Demonstration Content

1. Corrosion detection:

Detecting hidden corrosion on a aluminium plate that is

hidden a thick multi-layer aluminium stack with a up to 0.690”

thickness

• Using a GRFEC sliding probe

2. Crack detection:

Detecting lower layer EDM notches through a up to 0.500”

thick aluminium upper layer structure

• Using a GRFEC ring probe


6

Brief Introduction of

GRFEC Technique and

SSEC III Instrument


7

RFEC for Tube Applications

Defects on tube wall can be detected by Pickup Coil away from Excitation Coil

• Two coupling paths

1) direct coupling path which decays faster

2) Indirect coupling path which decays slower

– Since the directly coupled field decays at a faster rate, coil placement

can be optimized to sense only the indirect coupling signal or remote

field signal.

Direct coupling pathDrive Coil Pickup Coil

Indirect coupling Path

Indirect coupling Path


8

Indirect Coupling Path

Pickup UnitDrive Unit Direct Coupling Path

The probe blocks the direct coupling path. The energy released from

the drive unit is forced to go along the indirect coupling path.

Therefore, the entire signal received by the pickup unit has passed

the wall twice and carries the whole information about the wall

condition.

RFEC for General Applications

GRFEC TechniqueTo have the RFEC phenomenon to occur in objects of other geometries


9

Typical GRFEC Probes (1)

Sliding Probes

RF2 V3A RF4 V5

Footprint: 0.85” x 2.15”Footprint: 0.30” x 0.62”

RF3 V2

Footprint: 0.675x 1.75”


10

Ring #5

ID = 0.350”

OD = 0.910”

Ring #2

ID = 0.500”

OD = 1.250”

Typical GRFEC Probes (2)

Ring Probes

Ring #4

ID = 0.350”

OD = 1.100”


11

Portable Instrument SSEC III

A modification

of conventional

EC instrument;

Capable of

working with

GRFEC probes

as well as

conventional

EC probes


12

Corrosion Detection

1. Detection 0.040” corrosion thru a 0.6”+ multilayer Al stack

using sliding probe RF4

• Previously made C-scan image

• A-scan over a 0.040” deep corroded area

2. Detecting corrosion pits thru 0.200” aluminium layer using

RF4

3. Performances of other GRFEC sliding probes


13

Example 1:5 Layer 2024 T3 Aluminum Specimen

0.1” + 0.1” + 0.19” +0.19” + 0.063”

Total Thickness = 0.643”

Corrosion on Bottom of 5th Layer

Location = 0.603”

3” 3” 0.040”

Rf4 V3

Location = 0.603”

0.5” 0.5” 0.040”

0.100”

0.100”

0.063”

0.190”

0.190”

C-scan images created in 2002


14

Corrosion Standard – the 5th Layer

0.063” thick aluminum, chemical thinning on one side

0.5” 0.5” 0.040"

3.0” 3.0” 0.040"

Standard provided by CNDE, ISU


15

Test Result - Example13” 3” 0.040” 5th Layer Bottom Side Corrosion, f=200Hz

Total Thickness = 0.643”, Location = 0.603”


16

Test Result – Example20.5” 0.5” 0.040” 5th Layer Bottom Side Corrosion, f=200Hz

Total Thickness = 0.643”, Location = 0.603”

Part I – Deeply hidden corrosion detection


17

Detection 0.040” corrosion thru a 0.6”+

multilayer Al stack using sliding probe RF4

4 Layer 2024 T3 Aluminum plate stack with total thickness of

0.690” is placed on top of a 0.063” thick corrosion standard

Corrosion on top of the 5th Layer

3” 3” 0.040”

Rf4 V5

Location = 0.690”

0.5” 0.5” 0.040”

0.063”

A-scan over a 0.040” deep corroded area


RF4 0.690” on top of 3”x3”x 0.040” Corrosion (5.8%)

@ f = 200Hz

Impedance Strip ChartX

Y

~270 mv

Y

~270 mv


19

Detecting corrosion pits on back

side of a 0.200” aluminium layer

using RF4

GRFEC sliding probe can be

focused on a small spot


20

Corrosion Pits Test Sample provide By Lockheed Martin

U1U2U3U4U5

L5 L4 L3 L2L1

U5U4U3U2U1

L1 L2 L3 L4 L5

Scanned Side

Corroded Side

24”

0.2

0”

U5U4U3U2U1

L1 L2 L3 L4 L5

.265×.141×.014 .228×.120×.012 .180×.160×.011 .170×.150×.014 .130×.130×.020

.265×.170×.018 .263×.200×.017 .210×.190×.021 .190×.180×.026 .150×.150×.041

Approximate dimensions of the corrosion pits


21

C-scan images made in April, 2008

@ 2kHz

@ 2kHz


Performances of other GRFEC

sliding probes


RF3 0.190” on top of 2”x2”x 0.006” corrosion (3.2%)

@ f = 800Hz


Y

~135mv

~135mv


RF2 0.100” on top of 1”x1”x 0.006” corrosion (6.0%)

@ f = 4.0kHz


Y

~1,100mv

~1,100mv


25

Crack detection

Detecting lower layer EDM notches

through a up to 0.500” thick aluminium

upper layer structure

Using a GRFEC ring probe


26

Example # 1 - C130 lower wing box

application:

Detecting 2nd layer EDM notches through 0.250”/0.500” thick

first aluminium layer

Front Side

1st lay 0.25” steel fasteners

Back Side

0.100”– 0.600” long EDM made in these holes

2nd layer aluminum strip 0.140” thick &1.0”wide

Standard #1 – 0.250” thick first layer


Mode 1 - Place probe on

top of each fastener


No

ED

M

No

ED

M

0.1

00

”

0.2

00”

0.3

00

”

0.4

00

”

0.5

00

”

0.6

00

”

Y

Number of data acquisition points

C-130 Lower wing box standard with

2nd layer horizontal EDM notches

Mode 1 - Place probe on top of each fastener

~120mv

~750mv


No

ED

M

No

ED

M

0.1

00

”

0.2

00

”

0.3

00

”

0.4

00

”

0.5

00

”

Y



2nd layer vertical EDM notches



No

ED

M

No

ED

M

0.1

00

”

0.2

00

”

0.3

00

”

0.4

00

”

0.5

00

”

Y



2nd layer vertical EDN notches


~50mv~70mv

~280mv~380mv


31

Standard #2 – 0.500” thick first layer

31

A1

A2

B1

B2

Top View

Bottom View

0.200” long EDM 0.200” long EDM

Flush-head steel fastener Raised-head steel fastener

Example # 1 - C130 lower wing box

application:

Detecting 2nd layer EDM notches through 0.250”/0.500” thick

first aluminium layer


32

Standard 2 - Detecting 0.200” EDM below a 0.500” thick Al

layer with steel flush head fastener on @ f = 100Hz


2nd layer horizontal EDN notches


0.004v

0.004v

0.464v

0.464v 0.5” thick 1st layer flush head fastener


33


2nd layer horizontal EDN notches


Standard 2 - Detecting 0.200” EDM below a 0.500” thick Al

layer with steel raised head fastener on @ f = 100Hz

0.5” thick 1st layer Raised head Fastener


Mode 2 – Using a GRFEC

ring probe as a sliding

probe


No

ED

M

No

ED

M

0.1

00

”

0.2

00

”

0.3

00

”

0.4

00

”

0.5

00

”

0.6

00

”

X

Y


No

ED

M No

ED

M


2nd layer horizontal EDM notchesMode 2 – Using a GRFEC probe as a sliding probe

@ f = 80Hz


No

ED

M

No

ED

M

0.1

00

”

0.2

00

”

0.3

00

”

0.4

00

”

0.5

00

”

0.6

00

”

X

Y


No

ED

M

No

ED

M


2nd layer horizontal EDM notchesMode 2 – Using a GRFEC probe as a sliding probe

@ f = 80Hz Zoom-in


No

ED

M

No

ED

M

0.1

00

”

0.2

00

”

0.3

00

”

0.4

00

”

0.5

00

”

Y


X @ f = 80Hz


2nd layer vertical EDM notchesMode 2 – Using a GRFEC probe as a sliding probe


No

ED

M

No

ED

M

0.1

00

”

0.2

00”

0.3

00

”

0.4

00

”

0.5

00

”

Y


X


2nd layer vertical EDM notchesMode 2 – Using a GRFEC probe as a sliding probe

@ f = 80Hz Zoom-in


39

Summary

SSEC III + GRFEC technique is

capable of detecting deeply hidden

corrosion and cracks.

Potentially it could be a powerful tool

to add new functions to MAUS


40

Thanks and

please questions

Documents

Presentation at 2011 MAUS User Group Meeting , … at 2011...Presentation at 2011 MAUS User Group Meeting , 13 September, 2011 Innovative Materials Testing Technologies, Inc.Technologies,