Center for Composite Materials - University of Delaware

Research Summary

Spatial Damage Sensing of Fiber-Reinforced Composites with Carbon Nanotubes

Authors: Gerard J. Gallo and Erik T. Thostenson

OBJECTIVES

• Develop diagnostic algorithm to locate areas of prominent damage in fiber-reinforced composites
• Apply algorithm for spatial damage sensing of various electrically orthotropic materials
• Investigate source/measure patterns and electrode parameters in order to optimize measurement sensitivity

TERMINOLOGY

• P-Phase: Projectile penetrates through the composite until the back layer velocity is non zero
• T-Phase: Projectile begins to perforate through composite until it stops penetrating through composite
• F-Phase: Projectile continues to perforate through until relative velocity between projectile and laminates is zero
• R-Phase: After maximum dynamic deflection, laminates begin to retract back

GLASS FIBER / CARBON NANOTUBE COMPOSITE SYSTEM

Reinforcement:
• Unidirectional non-woven E-glass fiber mats (Jamestown Distributors)

Polymer Matrix Materials:
• EPON 862/Epikure W (Curing Agent) – 100/26.4 by weight (Hexion Specialty Chemicals, USA)
• CNT Sizing Agent
•• SIZICYL XC R2G – fiber sizing agent with dispersed MWCNTs (Nanocyl, Belgium)

ELECTRICAL IMPEDANCE TOMOGRAPHY OVERVIEW

Orthotropic Reconstructions
• Single-Ply E-Glass/EPON 862
• Dimensions: 2” x 2”
• Number of Electrodes: 32
-Electrodes attached using conductive silver epoxy
• Conductivity Ratio: 2:1
• Damage introduced by drilling holes into panel
-Area of each drilled hole measured 1.0% of total panel area

LOCALIZED DAMAGE RECONSTRUCTIONS

• [0/90]s E-Glass/EPON 862/CNT composite subjected to impact testing
-Impact #1: 5 J
-Impact #2: 10 J
-Impact #3: 20 J
• Panel Dimensions: 3.5” x 7”

CONCLUSIONS

• Spatial damage sensing using electrical impedance tomography was demonstrated on fiber-reinforced composites with carbon nanotubes.
• The electrical conductivity change due to damage was reconstructed in electrically orthotropic composites.
• The ability to detect localized damaged regions was demonstrated for cross-ply glass fiber/epoxy/CNT composites.

ACKNOWLEDGEMENTS

This research is sponsored by the Air Force Office of Scientific Research (Dr. David Stargel, Program Director) and Acellent Technologies Inc. under Subaward 090000288 as well as the National Science Foundation (Award No. 1234830)

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