Accession Number : ADA185170

Title :   Thermal Strain Analysis using Moire Interferometry,

Corporate Author : VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF ENGINEERING SCIEN CE AND MECHANICS

Personal Author(s) : Ifju, P ; Post, D

PDF Url : ADA185170

Report Date : Aug 1987

Pagination or Media Count : 7

Abstract : A method for measuring thermal strains in composites was developed. Strains induced by residual stresses in a cross-ply graphite epoxy specimen were observed. U, V, and W displacement fields were revealed using high sensitivity moire and classical interferomery. A specimen grating was replicated on a composite at its stress-free cure temperature (250 F) and deformations were observed at room temperature. The method determines normal strains on a relative basis and shear strains on an absolute basis. A strong free-edge effect was observed; interlaminar shear strains of 1% were recorded near the free edge. Anomalous variations of strains in plies of the same fiber direction were observed throughout the specimen.

Descriptors :   *EPOXY COMPOSITES, *LAMINATES, *THERMAL STRESSES, STRESS ANALYSIS, GRAPHITED MATERIALS, STRAIN(MECHANICS), CURING, DISPLACEMENT, THERMAL EXPANSION, MOIRE EFFECTS, INTERFEROMETRY, DEFORMATION, SILICONES, SHEAR PROPERTIES

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE