Moire interferometry for thermal expansion of compositesMoire interferometry by reflection is described and demonstrated for the case of a real reference grating of 1200 lines/mm. Extraneous beams can be displaced and stopped by using a wedge-shaped air gap between reference and specimen gratings. Double-order dominance, the use of diffraction sequences for reflection, the isolation of preferred sequences, and the use of two-beam interference are discussed. Experimental accuracy is enhanced significantly by using several data points to establish displacements along a line, and random errors characterized by one standard deviation can be as small as one microstrain. The method is well adapted to thermal environments, coefficients of thermal expansion of selected graphite-epoxy laminates being determined in the temperature range of 297-422 K. Very good precision was achieved for a wide range of thermal expansion coefficients, from approximately zero to 27 microstrains/K.
Document ID
19820053476
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Bowles, D. E. (NASA Langley Research Center Hampton, VA, United States)
Tenney, D. R. (NASA Langley Research Center Hampton, VA, United States)
Post, D. (NASA Langley Research Center Hampton, VA, United States)
Herakovich, C. T. (Virginia Polytechnic Institute and State University Blacksburg, VA, United States)
Date Acquired
August 10, 2013
Publication Date
January 1, 1982
Subject Category
Composite Materials
Meeting Information
Meeting: Spring Meeting
Location: Dearborn, MI
Start Date: May 31, 1981
End Date: June 4, 1981
Sponsors: Society for Experimental Stress Analysis