Thermal Strain Analysis using Moire Interferometry,

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.

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Document Details

Document Type
Technical Report
Publication Date
Aug 01, 1987
Accession Number
ADA185170

Entities

People

  • D. Post
  • P. Ifju

Organizations

  • Virginia Tech

Tags

Communities of Interest

  • Air Platforms
  • Ground and Sea Platforms

DTIC Thesaurus Topics

  • Climate Change
  • Composite Materials
  • Displacement
  • Frequency
  • Graphitic Materials
  • Interferometers
  • Interferometry
  • Materials
  • Mechanical Properties
  • Mechanics
  • Residual Stress
  • Residuals
  • Sensitivity
  • Stresses
  • Thermal Stresses

Readers

  • Mechanical Engineering/Mechanics of Materials.
  • Reinforced Composite Materials