Condition-based Maintenance Plus Structural Integrity (CBM+SI)

& the Airframe Digital Twin

Pamela A. Kobryn & Eric J. TuegelStructural Mechanics Branch

Air Vehicles DirectorateAir Force Research Laboratory

March 2011

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AFRL’s Condition-based Maintenance Plus Structural Integrity Initiative (CBM+SI)

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CBM+SI Technology Focus Areas

6. Prognostics &Risk Analysis

Legend: Emphasis Area Technology Focus Area

1. Non-Destructive Inspection/Evaluation

3. Structural Teardown Assessment

2. Structural Health Monitoring

1.E-14

1.E-13

1.E-12

1.E-11

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

0 2000 4000 6000 8000 10000 12000

Sing

le F

light

Pro

babi

lity

of F

ailu

re

Flight Hours

8. Repair Concepts

9. Replacement Concepts

Reinf. Laser Welded Panels

Reinf. Frames or Stringers

Adv. Fuselage Concept

Reinf. Laser Welded Panels

Reinf. Frames or Stringers

Adv. Fuselage Concept

7. Life Enhancement Concepts

DamageState Awareness

Structural Analysis

Structural Modifications

Usage

5. Characterization, Modeling & Testing

4. Loads &EnvironmentCharacterization

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• In ten years, aircraft lifecycle management and maintenance practices will be completely transformed from an inefficient, inconsistent, disparate, and labor-intensive state to an efficient, standardized, integrated, and semi-autonomous state.

• The structural capability of individual airframes will be known

and predictable based on the capability to characterize the current health status, predict the future health status, and plan usage and maintenance accordingly.

• Risk of structural failure will be quantified and safety will be enhanced.

• The inspection and repair burden will be diminished and cycle times for inspections, repairs, and modifications will be greatly reduced.

• The remaining useful life of airframes will be extended. • As a result of all of these improvements, aircraft availability

will be increased and O&S costs will be reduced.

CBM+SI Mid-term Visionper AFRL Air Vehicles Directorate’s “Vision 2009”

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CBM+SI Far-term Visionper AFRL CBM+SI Workshop - Feb 2009

“Digital Twin”: Real-Time, High-Fidelity Operational Decisions for Individual Aircraft Enabled by Tail Number Health Awareness

• When physical aircraft is delivered, a Digital Model of the aircraft – specific to that tail number, including deviations from the nominal design – will be delivered as well.

• The Digital Model will be flown virtually through the same flight profiles as recorded for the actual aircraft by its on-board SHM system.

• The modeling results will be compared to sensor readings recorded by the SHM system at critical locations to update /calibrate / validate the model.

• As unanticipated damage is found, it will be added to the Digital Model so that the model continually reflects the current state of the actual aircraft.

• Prognostics for the airframe will be developed by “flying” the Digital Model through possible future missions.

• The Digital Model will be used to determine when & where structural damage is likely to occur, and when to perform maintenance.

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Digital Model Functions

88ABW-2011-1428

Structural ResponseDamage

Progression

, , T, environment

properties, geometry

USAGE

FORECASTRepairs, Modifications, Replacements

Damage from Inspections & SHM

PROGNOSIS

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Tech Disciplines & Challenges• Disciplines

– Aerodynamics– Structures– Materials and

Manufacturing– Computer Science– Information

Management

• Challenges– Developing parameterized, multi-disciplinary

computational models of appropriate fidelity for the full-scale aircraft

– Developing high-fidelity computational models of the relevant capability-controlling phenomena at physically appropriate length and time scales

– Linking computational models across length/time scales at varying levels of fidelity

– Understanding and incorporating all influential sources of uncertainty and variability into the models at each length/time scale

– Developing analysis techniques for assessing and optimizing both capability and reliability of the aircraft

– Integrating materials and manufacturing phenomena into the aircraft-level digital twin framework

– Developing technologies and methods to track and update the state and behavior of both the actual aircraft and the digital twin based on real-world experience

88ABW-2011-1428

AFRL POC: Dr. Eric Tuegel, eric.tuegel@wpafb.af.milUpcoming Cross-organization Discussion Opportunities: AIAA SDM, AA&S2011, ICAF2011, ISHM Conference…

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