Optical stress sensing alumina nanocomposite coatings for aerospace structures

Gregory Freihofer, Ankur Gupta, Amy Van Newkirk, Sudipta Seal, Seetha Raghavan

Research output: Contribution to conferencePaper

7 Citations (Scopus)

Abstract

Alpha alumina (α-Al2O3) nanocomposites have a multi-functional stress sensing ability via their photoluminescence (PL) spectral peak shifts defined by Piezospectroscopic (PS) relationships. This has prompted the development of α-Al2O3 nanocomposite coatings to enable real-time stress measurements and damage assessment of structures with the potential for unparalleled spatial resolution and sensitivity. Here, two types of stress-sensing coatings were evaluated, including an atmospheric plasma spray (APS) coating on metallic substrates and an epoxy nanocomposite coating on a composite substrate. The stress sensitivity of the APS coating, represented by the slope of the peak shifts against stress or PS coefficient, varied inversely with the thickness of the substrates between 3.2 and 1.7 cm-1=GPa. These values decreased by more than 50% after tensile cycling for all substrate thicknesses due to microstructural damage in the APS coating indicating the need for repeatability and durability studies. The epoxy nanocomposite coating successfully captured the stress gradients associated with an open hole tension (OHT) composite substrate revealing damage initiation at 77% of failure load, earlier than visual appearance of a surface crack (93%). The findings validate the successful development of quantitative and multiscale spatial resolution stress-sensing coatings, capable of detecting subsurface damage of composite structures, that will take structural testing and integrity monitoring to the next level.

Original languageEnglish (US)
DOIs
StatePublished - Feb 28 2014
Event55th AIAA/ASMe/ASCE/AHS/SC Structures, Structural Dynamics, and Materials Conference - SciTech Forum and Exposition 2014 - National Harbor, MD, United States
Duration: Jan 13 2014Jan 17 2014

Other

Other55th AIAA/ASMe/ASCE/AHS/SC Structures, Structural Dynamics, and Materials Conference - SciTech Forum and Exposition 2014
CountryUnited States
CityNational Harbor, MD
Period1/13/141/17/14

Fingerprint

Nanocomposites
Alumina
Coatings
Substrates
Plasmas
Stress measurement
Composite materials
Composite structures
Time measurement
Photoluminescence
Durability
Cracks
Monitoring
Testing

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Mechanics of Materials
  • Building and Construction
  • Architecture

Cite this

Freihofer, G., Gupta, A., Van Newkirk, A., Seal, S., & Raghavan, S. (2014). Optical stress sensing alumina nanocomposite coatings for aerospace structures. Paper presented at 55th AIAA/ASMe/ASCE/AHS/SC Structures, Structural Dynamics, and Materials Conference - SciTech Forum and Exposition 2014, National Harbor, MD, United States. https://doi.org/10.2514/6.2014-0159
Freihofer, Gregory ; Gupta, Ankur ; Van Newkirk, Amy ; Seal, Sudipta ; Raghavan, Seetha. / Optical stress sensing alumina nanocomposite coatings for aerospace structures. Paper presented at 55th AIAA/ASMe/ASCE/AHS/SC Structures, Structural Dynamics, and Materials Conference - SciTech Forum and Exposition 2014, National Harbor, MD, United States.
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abstract = "Alpha alumina (α-Al2O3) nanocomposites have a multi-functional stress sensing ability via their photoluminescence (PL) spectral peak shifts defined by Piezospectroscopic (PS) relationships. This has prompted the development of α-Al2O3 nanocomposite coatings to enable real-time stress measurements and damage assessment of structures with the potential for unparalleled spatial resolution and sensitivity. Here, two types of stress-sensing coatings were evaluated, including an atmospheric plasma spray (APS) coating on metallic substrates and an epoxy nanocomposite coating on a composite substrate. The stress sensitivity of the APS coating, represented by the slope of the peak shifts against stress or PS coefficient, varied inversely with the thickness of the substrates between 3.2 and 1.7 cm-1=GPa. These values decreased by more than 50{\%} after tensile cycling for all substrate thicknesses due to microstructural damage in the APS coating indicating the need for repeatability and durability studies. The epoxy nanocomposite coating successfully captured the stress gradients associated with an open hole tension (OHT) composite substrate revealing damage initiation at 77{\%} of failure load, earlier than visual appearance of a surface crack (93{\%}). The findings validate the successful development of quantitative and multiscale spatial resolution stress-sensing coatings, capable of detecting subsurface damage of composite structures, that will take structural testing and integrity monitoring to the next level.",
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Freihofer, G, Gupta, A, Van Newkirk, A, Seal, S & Raghavan, S 2014, 'Optical stress sensing alumina nanocomposite coatings for aerospace structures' Paper presented at 55th AIAA/ASMe/ASCE/AHS/SC Structures, Structural Dynamics, and Materials Conference - SciTech Forum and Exposition 2014, National Harbor, MD, United States, 1/13/14 - 1/17/14, . https://doi.org/10.2514/6.2014-0159

Optical stress sensing alumina nanocomposite coatings for aerospace structures. / Freihofer, Gregory; Gupta, Ankur; Van Newkirk, Amy; Seal, Sudipta; Raghavan, Seetha.

2014. Paper presented at 55th AIAA/ASMe/ASCE/AHS/SC Structures, Structural Dynamics, and Materials Conference - SciTech Forum and Exposition 2014, National Harbor, MD, United States.

Research output: Contribution to conferencePaper

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T1 - Optical stress sensing alumina nanocomposite coatings for aerospace structures

AU - Freihofer, Gregory

AU - Gupta, Ankur

AU - Van Newkirk, Amy

AU - Seal, Sudipta

AU - Raghavan, Seetha

PY - 2014/2/28

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N2 - Alpha alumina (α-Al2O3) nanocomposites have a multi-functional stress sensing ability via their photoluminescence (PL) spectral peak shifts defined by Piezospectroscopic (PS) relationships. This has prompted the development of α-Al2O3 nanocomposite coatings to enable real-time stress measurements and damage assessment of structures with the potential for unparalleled spatial resolution and sensitivity. Here, two types of stress-sensing coatings were evaluated, including an atmospheric plasma spray (APS) coating on metallic substrates and an epoxy nanocomposite coating on a composite substrate. The stress sensitivity of the APS coating, represented by the slope of the peak shifts against stress or PS coefficient, varied inversely with the thickness of the substrates between 3.2 and 1.7 cm-1=GPa. These values decreased by more than 50% after tensile cycling for all substrate thicknesses due to microstructural damage in the APS coating indicating the need for repeatability and durability studies. The epoxy nanocomposite coating successfully captured the stress gradients associated with an open hole tension (OHT) composite substrate revealing damage initiation at 77% of failure load, earlier than visual appearance of a surface crack (93%). The findings validate the successful development of quantitative and multiscale spatial resolution stress-sensing coatings, capable of detecting subsurface damage of composite structures, that will take structural testing and integrity monitoring to the next level.

AB - Alpha alumina (α-Al2O3) nanocomposites have a multi-functional stress sensing ability via their photoluminescence (PL) spectral peak shifts defined by Piezospectroscopic (PS) relationships. This has prompted the development of α-Al2O3 nanocomposite coatings to enable real-time stress measurements and damage assessment of structures with the potential for unparalleled spatial resolution and sensitivity. Here, two types of stress-sensing coatings were evaluated, including an atmospheric plasma spray (APS) coating on metallic substrates and an epoxy nanocomposite coating on a composite substrate. The stress sensitivity of the APS coating, represented by the slope of the peak shifts against stress or PS coefficient, varied inversely with the thickness of the substrates between 3.2 and 1.7 cm-1=GPa. These values decreased by more than 50% after tensile cycling for all substrate thicknesses due to microstructural damage in the APS coating indicating the need for repeatability and durability studies. The epoxy nanocomposite coating successfully captured the stress gradients associated with an open hole tension (OHT) composite substrate revealing damage initiation at 77% of failure load, earlier than visual appearance of a surface crack (93%). The findings validate the successful development of quantitative and multiscale spatial resolution stress-sensing coatings, capable of detecting subsurface damage of composite structures, that will take structural testing and integrity monitoring to the next level.

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Freihofer G, Gupta A, Van Newkirk A, Seal S, Raghavan S. Optical stress sensing alumina nanocomposite coatings for aerospace structures. 2014. Paper presented at 55th AIAA/ASMe/ASCE/AHS/SC Structures, Structural Dynamics, and Materials Conference - SciTech Forum and Exposition 2014, National Harbor, MD, United States. https://doi.org/10.2514/6.2014-0159