GLTRS--Glenn
TITLE AND SUBTITLE:
Feasibility of Various NDE Techniques to Assess and Monitor Damage in Ceramic Composites at Elevated Temperatures

AUTHOR(S):
Anil Tiwari and Edmund G. Henneke II

REPORT DATE:
March 1998

FUNDING NUMBERS:
WU-523-21-13-00
NAS3-26827

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
Engineering Science and Mechanics Department
Virginia Polytechnic Institute and State University
Blacksburg, Virginia 24061-0001

PERFORMING ORGANIZATION REPORT NUMBER:
E-11011

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135-3191

REPORT TYPE AND DATES COVERED:
Final Contractor Report

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA CR-1998-206315

SUPPLEMENTARY NOTES:
Project Manager, George Y. Baaklini, Structures Division, NASA Lewis Research Center, organization code 5920,
(216) 433-6016.

ABSTRACT:
Custom made ovens were integrated with Instron type load frame to test ceramic matrix composites at 1600 degrees Celsius. A Lab View program was written to monitor the area under the histeresis loop to evaluate damage progression in composites at elevated temperatures. Dynamic stiffness was also calculated throughout the test and used as a damage parameter. It was demonstrated that acoustic emission signals with 0.5 to 3 MHz in frequency are generated due to fiber fracture and matrix cracking in SiC/CAS-II. This damage was beyond the detection capabilities of stress waves by a laser based Ometron system and a stress pattern analysis by thermal emission (SPATE) approach. It was concluded that
1) hysteresis loop and dynamic stiffness can be used to monitor damage in ceramic matrix composites at elevated temperatures, and 2) more work is needed to establish laser-based acousto-ultrasonic for damage monitoring during high temperature loading of ceramic composites.

SUBJECT TERMS:
NDE; Acousto-ultrasonics; Ceramic composites; Damage monitoring; SiC/CAS

NUMBER OF PAGES:
16

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