UW - Center for Intelligent Materials and Systems

S T R U C T U R A L H E A L T H M O N I T O R I N G S Y S T E M S

for composite structures in future airplanes

Minoru TayaProfessor and Director

Center for Intelligent Materials and Systems(CIMS)Department of Mechanical Engineering

University of WashingtonEmail:tayam@u.washington.edu

http/: www.depts.washington.edu/cims/

AMTAS Spring Meeting, April 14, 2005

UW - Center for Intelligent Materials and Systems

Health Monitoring Systems – Vehicles & Aircraft

Safety issues in composite structures remain to be studied with cost-effectiveness and easiness of monitoring,but without degrading Structural performance

UW - Center for Intelligent Materials and Systems

What’s out there?

Visual• Dual-Pass Light Reflection (D-Sight)• Edge of Light TM (EOL)Eddy Current• Magneto-Optics Imager (MOI)• Pulsed Eddy Current (PEC)• Superconducting Quantum Interference

Device (SQUID)Radiography• Compute Tomography Scan• Reverse Geometry X-Ray (RGX) Imaging• Microfocus X-Ray MicroscopyUltrasonics• Dry coupling techniques• Air-Coupled transducers• Electromagnetic acoustic transducer (EMAT)• Laser induced ultrasound• Oblique Insonification NDE of composites• Portable Real-time imagesShearographyThermography

UW - Center for Intelligent Materials and Systems

Related research projects at CIMS

We are working on designing a set of new active and sensing materials and devices at Center of Intelligent Materials and Systems(CIMS)

1. Design of active and sensing nano-composites(AFOSR)2. Design of active materials for use in actuators(Darpa)3. Spark Plasma Sintering(AFOSR)4. Energy absorbing materials(ONR)5. High strain-rate deformation of smart materials(Honda)6. Design of smart antenna based on electro-active polymer(NSF)7. Design of electrochromic windows(Boeing)

UW - Center for Intelligent Materials and Systems

Requirements of future SHM system for polymeric composite structures

1. Monitoring only critical data set2. Autonomous system with no connection wires3. Power supply is self-generating4. Monitoring can be done with a portable detector while an airplane is parked at airport5. Stealth, and cost-effective and ultra lightness---detection via portable detector applied to nano-sensing particles embedded in a composite panel

UW - Center for Intelligent Materials and Systems

What are the proposed SHM systems for Composite Structures ?

1. Fiber optics embedded in polymeric composites(Takeda et al,2004)

2. Metal core piezo-fibers embedded in polymer composites(Sekiya et al , 2003)

3. Piezo-sensor system attached on the surface of composite structure(Sato et al,2004)

4. Composite structure with sensing nano-particles embedded (UW-Toray)

1-3 are done as a part of NEDO project where UW(Taya) was involved as an active member of smart materials group.

UW - Center for Intelligent Materials and Systems

Response of Fiber Bragg Grating Sensor to Strain

Small-Diameter Optical Fiber

FBG

0o Ply

0o Ply

90o Ply

Transverse Cracks

Tensile Load

Small-diameter Fiber Bragg Grating (FBG) Sensors can be embedded close to transverse cracks without deteriorating the laminate.

Takeda, 2004

UW - Center for Intelligent Materials and Systems

Response of FBG Sensor to Strain

λ0 λ1

IR

Incident Light

TransmittedLight

λ1 d=0.5µm

Reflection spectrum is narrowband.Strain can be determined from the wavelength shift.

Incident Light Transmitted

Lightλ1λ2

λ3

λ0 λ1

IR

λ2 λ3Reflection spectrum becomes broadband.This phenomenon is applied to detection of damages.

Uniform strain Non-uniform strain

λ1=C1d=C2ε

Takeda, 2004

UW - Center for Intelligent Materials and Systems

Suppression of Transverse Cracks in CFRP Laminates with Embedded Pre-Strained SMA Foils

0 2 4 60

200

400

600

800

Strain [%]

Stre

ss [M

Pa]

100oC 90oC 80oC 70oC

LoadーUnload Stress-Strain Curves of SMA Foils

Pre-strained SMA foil

Heating

°

°

°

Adhesive ply

ply

ply

ply

Transverse crack

0

0

90

Generation of Recovery Stresses

(Taya,et al,1995; Takeda et al, 2004)

UW - Center for Intelligent Materials and Systems

2. Metal core-Piezoelectric Fiber

Piezoelectric Fiber

Metal core(φ50～150μm)

PZT ceramics

•Hydrothermal Method •Extrusion Method

CFRP composite

CFRP (Carbon Fiber Reinforced Plastic)The composite material between carbon fiber and epoxy resin.

Embedded in CFRP composite

Smart board

Sensor, Actuator, and vibration suppressionSekiya, 2003

UW - Center for Intelligent Materials and Systems

Piezo-sensor detecting spectrum of dynamic motion by using fatigue characteristics of piezo-sensor, where sensor system is attached on

the surface of composite structure panel

piezo

piezo

piezo

displacement (strain)

time time

V

UW - Center for Intelligent Materials and Systems

Piezo Sensing System

Piezo Strain filter Mixer Antenna

Circuit ChipSchematic view of the sensor system.

UW - Center for Intelligent Materials and Systems

Battery charging unit schematic

UW - Center for Intelligent Materials and Systems

4. A Future Structural Health Monitoringfor polymeric composite structures by embedding

nano-sensing particles

UW - Center for Intelligent Materials and Systems

Embedded nanoparticlesTagged Composites

UW - Center for Intelligent Materials and Systems

Scanner for monitoring damage from outside composite fuselage

UW - Center for Intelligent Materials and Systems

Failure Detection

UW - Center for Intelligent Materials and Systems

Where do we go in the future for SHM ?

Short-term goal:Design of a cost effective and autonomous sensing unit for monitoring a spectrum of flight loading history, mainly critical loading data set , where the sensor unit is attached to surface of a structural component. The goal of this is to reduce the operational cost while maintaining the maximum safety of the overall flight operation.

Long-term goal: Design of a new composite with sensing nano-particles which can be monitored easily by a scanner while an airplane is parked at airport.

UW - Center for Intelligent Materials and Systems

Hierarchical modeling to optimize The nanostructure of sensing compositesis summarized in a new book(Taya,2005)