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Proceedings Paper

Thermal protection system (TPS) monitoring using acoustic emission
Author(s): D. A. Hurley; D. R. Huston; D. G. Fletcher; W. P. Owens
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Paper Abstract

This project investigates acoustic emission (AE) as a tool for monitoring the degradation of thermal protection systems (TPS). The AE sensors are part of an array of instrumentation on an inductively coupled plasma (ICP) torch designed for testing advanced thermal protection aerospace materials used for hypervelocity vehicles. AE are generated by stresses within the material, propagate as elastic stress waves, and can be detected with sensitive instrumentation. Graphite (POCO DFP-2) is used to study gas-surface interaction during degradation of thermal protection materials. The plasma is produced by a RF magnetic field driven by a 30kW power supply at 3.5 MHz, which creates a noisy environment with large spikes when powered on or off. AE are waveguided from source to sensor by a liquid-cooled copper probe used to position the graphite sample in the plasma stream. Preliminary testing was used to set filters and thresholds on the AE detection system (Physical Acoustics PCI-2) to minimize the impact of considerable operating noise. Testing results show good correlation between AE data and testing environment, which dictates the physics and chemistry of the thermal breakdown of the sample. Current efforts for the project are expanding the dataset and developing statistical analysis tools. This study shows the potential of AE as a powerful tool for analysis of thermal protection material thermal degradations with the unique capability of real-time, in-situ monitoring.

Paper Details

Date Published: 20 April 2011
PDF: 7 pages
Proc. SPIE 7983, Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2011, 79833P (20 April 2011); doi: 10.1117/12.882144
Show Author Affiliations
D. A. Hurley, The Univ. of Vermont (United States)
D. R. Huston, The Univ. of Vermont (United States)
D. G. Fletcher, The Univ. of Vermont (United States)
W. P. Owens, The Univ. of Vermont (United States)


Published in SPIE Proceedings Vol. 7983:
Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2011
H. Felix Wu, Editor(s)

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