SHM Design for Space Vehicles

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SHM Design for Space Vehicles
Fu-Kuo Chang Dept. of Aeronautics and
Astronautics Stanford University Stanford, CA
94305
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Structural Health Monitoring
Reliability, Safety, Performance
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PROBLEM STATEMENT
GIVEN SENSOR MEASUREMENTS, DETERMINE EXTERNAL
AND/OR INTERNAL PARAMETERS.
(NONLINEAR INVERSE AND NON-UNIQUENESS)

• EXTERNAL
• LOAD
• TEMPERATURE
• MOISTURE
• ETC.

• INTERNAL
• DAMAGE LOCATION
• DAMAGE SIZE/TYPE
• MATERIAL PROPERTIES
• ETC.

STRUCTURE
SENSOR SIGNALS
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Results of SHM Trade Study by Boeing
Identified Top 5 High Payoff Areas
Identified Top 10 Damage/Data Types
Note the ranking shown in the tables may vary
depending on the engineering judgment, but
basically with the range.
Slide taken from the 1st AFRL ISHM by Boeing
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SHM System
Environmental Inputs
Diagnostic Inputs
Structures
Sensor data
Sensor data
Self diagnosis
Detection
Diagnosis
Decision Making
Interrogation
Prognostics
Decision Making
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Passive SHM System
Environmental Inputs
Diagnostic Inputs
Structures
Sensor data
Sensor data
Detection
Diagnosis
Decision Making
Interrogation
Prognostics
Decision Making
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Impact Monitoring System
Impact
Monitoring System
structure
Impact Monitoring System ? detects impacts
automatically ? makes inspection more efficient
- localize inspection area - inspections
could be scheduled only when necessary
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Result Force Reconstruction (TPS)
Hammer output (V)
- recorded - reconstructed
time (ms)
Hammer output (V)
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Does Size Matter ?
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Impact Identification Methods
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Components of Impact Monitoring Systems

• Impact monitoring system

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Wireless Sensor Network Deployment of SHM
Systems in Aerospace Applications
A, B, C power a gtgt a
A fully wired system requires energy-hungry
devices as N increases.
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Active SHM System
Environmental Inputs
Diagnostic Inputs
Structures
Sensor data
Sensor data
Detection
Diagnosis
Decision Making
Interrogation
Prognostics
Decision Making
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Types of TPS

• TPS panels
• Mechanically fastened joints
• TPS tiles
• Adhesively bonded joints

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Bonded TPS with Built-in Sensors
Front view
SMART layer
Back view
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Generation of Diagnostic Signal

• Wave dispersion in plate causes distortion of
  waveform.
• Narrow-band signal preserves waveform.

Wide-band signal
Actuator Signal
Sensor Signal
Frequency Spectrum
V
V
V
Time
Time
Frequency
Narrow-band signal
V
V
V
Time
Frequency
Time
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Imaging Technique with Active Sensors
Receiver (x,y)
Sensor
Sensor
R2
Image pixel, X (x,y)
R1
Sensor
Actuator
Actuator (x,y)
Sij Scattered signal received at
receiver j by excitation of actuator i RR1R2
Total time-of-flight Cg Group
velocity
Requires only group velocity information
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Bonded TPS with Built-In SHM
Load cycles
disbond crack
C-Scan Image
Diagnostic Image
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Bonded repair monitoring on F-16 component
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Types of TPS

• TPS panels
• Mechanically fastened joints
• TPS tiles
• Adhesively bonded joints

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Bolted TPS
Heat
Aerodynamic acoustics
TPS panel
Base structure
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Bolted TPS with Built-in SHM
Attenuation-based Method

• Loosening location identification
• Torque level assessment

PZT-embedded Sensor Washer

• Sensitivity
• Survivability

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Verification Tests - Shaker
Panel joint 1
Test Condition Noise level 0.5 g 7
g Bandwidth 50 500 Hz Duration
10 minutes Data acq. gap every 2-minute
Shaker tests at the Air Force Research Laboratory
(AFRL) in Dayton, Ohio (Aug. 2004)
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SHM-Embedded Design
Prognosis
Diagnostic imaging
Decision Making
Damage State
Residual life estimate
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SHM-Embedded Structures

• Analysis/Design
• Materials
• Structures
• SHM
• Tests
• Prototyping

• Manufacturing
• Fabrication Techniques
• Quality Control

Integrated Design
Integrated Structures
Analysis and Test Data

• End Users
• Reliability/Safety
• Performance
• Maintenance
• Life Cycle Costs

• Informatics/Software
• Signal Processing
• Intelligent Algorithms
• Communication

Intelligent Software
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Challenging Issue Scaling

• Actuators/Sensors
• High performance, durable materials
• Sensor network
• Damage tolerant, sizable, reconfigurable,
  durable.
• Hardware
• Smart compact electronics (hardware/software
  integration)
• Software
• Robustness, efficiency, data communication
• Integration
• Interface compatibility, Durability,
  Self-diagnosis
• Optimization
• New analytical and computational design tools

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Damage-tolerant, stretchable, and reconfigurable
silicon-based piezo- sensor network ?
Slide provided by Prof. P. Peumans, Stanford
University
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Embedded Control of Conformal Active/Passive SHM
System?
SMART Layer
Thin Film Transistor (TFT)
TFT
Slide provided by Acellent Technologies