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Abstract:
The research was conducted to demonstrate that a new NDE method based upon thermoelasticity can be utilized to quantify damage in composite materials, to identify damage mechanism, and to be generally applicable as a lifetime prediction tool. Funding from the DURIP award was used to purchase an IR camera system and a photoelastic imaging system. The IR camera is a Stress Photonics DeltaTherm1OOO closed cycle cooled system with a temperature resolution of 0. 003K at a spatial resolution of 120 microns. A sapphire zoom lens was purchased to improve the resolution to 20 microns. A broad range of experiments were carried out to characterize local damage and stress concentrations in several composite systems. Experimental measurements of damage and the resulting stress distributions across the surface of test specimens were used to quantify damage evolution in each composite material. Damage evolution was quantified by using experimental measures of stress concentration factors derived from the observed IR signal. These measures of damage were used to relate changes in the composite properties to the experimentally measured stress redistribution. We found that the system could identify the operative damage mechanism, the current state of damage, and predict the residual fatigue lifetime of the tested materials. As a result, a new method has been developed for evaluating and tracking damage in composite materials and for accurately predicting the remaining service lifetimes of those materials.
| Limitations: |
 APPROVED FOR PUBLIC RELEASE |
| Description: |
Final rept (June 99 DURIPAward). |
| Pages: |
12 |
| Report Date: |
JUN 1999 |
| Contract Number: |
F49620-99-1-0215 |
| Report Number: |
A736883 |
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