EADS Innovation Works Damage detection assessment by means of Acousto Ultrasonics Acousto Ultrasonics Wissenschaftstag 2012 – DLR Braunschweig Martin Bach (with contribution of Airbus M&P EADS IW and DLR) (with contribution of Airbus M&P, EADS IW and DLR) 18 th of October 2012
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EADS Innovation Works
Damage detection assessment by means of Acousto UltrasonicsAcousto Ultrasonics
Wissenschaftstag 2012 – DLR Braunschweigg g
Martin Bach
(with contribution of Airbus M&P EADS IW and DLR)(with contribution of Airbus M&P, EADS IW and DLR)18th of October 2012
Content
Damage detection assessment by means of acousto ultrasonics 2012/10/18
Content
• Introduction• Introduction
• Verification approach for damage assessment performance• Verification approach for damage assessment performance
• Conclusion and Outlook• Conclusion and Outlook
Page 2 Property by Airbus and EADS IW SHM development team
Introduction (SHM)
Damage detection assessment by means of acousto ultrasonics 2012/10/18
Introduction (SHM)
SHM in order to…
• Reduce Maintenance Costs
• Increase Aircraft Availability Structural Health Monitoring
• Reduce Weight
Non-Destructive Testing
Interrogation Unit
AdhesiveSensor
Connection
Structural Item
SHM M it i f D St /St i C diti
Page 3 Property by Airbus and EADS IW SHM development team
• SHM: Monitoring of Damages, Stress/Strain, Conditions
Introduction (AU physical principle)
Damage detection assessment by means of acousto ultrasonics 2012/10/18
Introduction (AU – physical principle)
Acousto Ultrasonic (AU) is based on Guided Ultrasonic Waves (GUW, aka Lamb Waves), propagating reasonable distances in plate like structurespropagating reasonable distances in plate like structures
Damage detection is basically achieved byDamage detection is basically achieved by
• A network of permanently appliedpiezoelectric sensors to pitch-catch GUWs
• Comparison of these signal at reference state with an unknown state
• exploiting the physical dependency of GUW-propagation from the state of the structure, i.e. occurence of damages
Applicable for delamination and debonding in CFRP or to crack and corrosion in metal
The wave propagation especially in CFRP is “complex” (disperse, multiple wave modes,...)Robust technique is needed, esp. for analysis algorithmsq p y g
Page 4 Property by Airbus and EADS IW SHM development team
Introduction (AU Systems Components)
Damage detection assessment by means of acousto ultrasonics 2012/10/18
Introduction (AU Systems Components)• Software (on PC/laptop)
DAQ E i tUser interface & control
• DAQ-Equipment
• Sensors data evaluation
i l ti ADC
data storage
signal generation
amplification
ADC
pre-amplification
multiplexing
Single SMART layer
actuator sensorstructure
Demonstration system (2008)
Page 5 Property by Airbus and EADS IW SHM development team
Introduction (Way of Working)
Damage detection assessment by means of acousto ultrasonics 2012/10/18
Introduction (Way of Working)
PP A li ti iA li ti i ‘SHM P tf li ’‘SHM P tf li ’ProgrammeProgramme Application scenarioApplication scenario
= set of SHM technology solutions for generic application scenarios at TRL6 e g CFRP
‘SHM Portfolio’‘SHM Portfolio’
Ageing aircraftFuture aircraft
e.g. stringer debonding detection in A30X fuselage,
i d t ti i A320 scenarios at TRL6, e.g. CFRP stringer debonding detection from CFRP skin)
corrosion detection in A320 rear pressure bulk head
Page 6 Property by Airbus and EADS IW SHM development team
Introduction (Technology Readiness)
Damage detection assessment by means of acousto ultrasonics 2012/10/18
Introduction (Technology Readiness)Stage TRL TRL Definition Requirements Criteria Status
1 System (sensor & interrogation unit) does not exist. It is TRL 1 1 TRL 1 2 TRL 1 1 TRL 1 2 /
Discover1 System (sensor & interrogation unit) does not exist. It is
only an idea on paper TRL 1.1, TRL 1.2, … TRL 1.1, TRL 1.2, … yes/no
2 System (sensor & interrogation unit) does not exist. In depth formulation of how should the equipment be TRL 2.1, TRL 1.2, … TRL 2.1, TRL 2.2, … yes/noRequirement SourcesRequirement Sources
• Testing TechnologyUnderstand 3 System (sensor & interrogation unit) does not exist. Only
part of it might be in a physical stage TRL 3.1, TRL 3.2, … TRL 3.1, TRL 3.2, … yes/no
4 System (sensor & interrogation unit) expected to be at a laboratory stage TRL 4.1, TRL 4.2, … TRL 4.1, TRL 4.2, … yes/no
Testing Technology
• Surface Technology
• Composite TechnologyAdapt
laboratory stage
5 System (sensor & interrogation unit) expected to be at a laboratory stage and compliant to aircraft environment TRL 5.1, TRL 5.2, … TRL 5.1, TRL 5.2, … yes/no
System (sensor & interrogation unit) expected to be at a
Co pos te ec o ogy
• Bonding Technology
• Metal TechnologyValidate 6 System (sensor & interrogation unit) expected to be at a
prototype stage and compliant to aircraft environment TRL 6.1, TRL 6.2, … TRL 6.1, TRL 6.2, … yes/no
f
7 System (sensor & interrogation unit) expected to be at a prototype stage tested in-flight TRL 7.1, TRL 7.2, … TRL 7.1, TRL 7.2, … yes/no
gy
• Assembling Technology
• Cabin / Fire and SafetyRefine
8System (sensor & interrogation unit) expected to be in its final form, qualified through further ground-tests and in-flight trials
TRL 8.1, TRL 8.2, … TRL 8.1, TRL 8.2, … yes/no
Use 9 System (sensor & interrogation unit) in its final form, TRL 9 1 TRL 9 2 TRL9 1 TRL 9 2 yes/no
• Manufacturing
• SystemsUse 9 y ( g ) ,
further proven through extensive in-service use TRL 9.1, TRL 9.2, … TRL9.1, TRL 9.2, … yes/no
• AuthoritiesPage 7 Property by Airbus and EADS IW SHM development team
Introduction (Damage Assessment Performance)
Damage detection assessment by means of acousto ultrasonics 2012/10/18
Introduction (Damage Assessment Performance)
Damage assessment is key function of the SHM system, however it depends on:
Test Parameter• Frequency / Wave modes• Actuation Signal shape / amplitude• Signal conditioning
f SHM St t ( li ti i ) T t Sfor SHM e.g.: Structure (application scenario), Temperature, Sensor application method, Damage type, damage size, system, set-up etc.
• Damage detection/assessmentfor conv. NDT: POD (29/29, Hit-Miss, etc.)
for SHM: DAP (TBC by A/C OEM and authorities)
Page 9 Property by Airbus and EADS IW SHM development team
Verification approach (DAP)
Damage detection assessment by means of acousto ultrasonics 2012/10/18
Verification approach (DAP)Outcome of classification in reference to
real damage size areal damage size areal
detected damage size adetected
applicable damage limit alimit
Classification out-come actual classificationabove applicable limit below applicable limit
SHM Assessment areal > alimit areal ≤ alimit
above applicable limitadetected > alimit
True-positive(TP)
False-positive(FP)
below applicable limitadetected ≤ alimit
False-negative(FN)
True-negative(TN)
Working assumption: Probability to receive a certain damage size adetected in dependence of real damage areal size is known. Undetected damages are included as of size zero.
Page 10 Property by Airbus and EADS IW SHM development team
Verification approach (DAP con’t)
Damage detection assessment by means of acousto ultrasonics 2012/10/18
Verification approach (DAP, con’t)
The damage assessment performance (DAP) can be characterized byThe damage assessment performance (DAP) can be characterized by
Minimum detectable damage size for a defined probability of detection
Mean assessment accuracy as the difference between adetected|90 and arealy detected|90 real
Applicable limit value vs. applied threshold value for defined probability of classification
False-positive probability for adetected|50 and applicable limit value
Localization bound with a defined probability
for each position of the monitored area and the range of relevant damage sizes andfor each position of the monitored area and the range of relevant damage sizes and the relevant conditions.
Before making any plans for testing: Analyse the influence factors and conditions to be considered in the analysis.y
Page 11 Property by Airbus and EADS IW SHM development team
Verification approach (DAP con’t)
Damage detection assessment by means of acousto ultrasonics 2012/10/18