International Journal of Fracture

, Volume 90, Issue 4, pp 355–382

A Study of the Fracture Behavior of Unindirectional Fiber- Reinforced Composite Using Coherent Gradient Sensing (CGS) Interferometry

  • C. Liu
  • A.J. Rosakis
  • R.W. Ellis
  • M.G. Stout
Article

DOI: 10.1023/A:1007479709559

Cite this article as:
Liu, C., Rosakis, A., Ellis, R. et al. International Journal of Fracture (1998) 90: 355. doi:10.1023/A:1007479709559

Abstract

The feasibility of using Coherent Gradient Sensing (CGS) interferometry for studying the fracture behavior of unidirectional fiber-reinforced composites is investigated in this paper. First, the solution for the deformation field surrounding the tip of a crack in an orthotropic material is summarized. Specifically, the most singular term in the asymptotic expansion is explicitly presented. Then, the quantities that relate to the CGS measurements are derived in terms of the spatial position, stress intensity factors, and material constants. Based on these results, synthetic CGS fringe patterns are plotted numerically, and the effects of material anisotropy and crack-tip mixity on the shape of CGS fringe pattern are investigated. In addition, a finite difference interpretation of CGS fringes caused by the finite spacing of the CGS diffraction gratings is taken into account in the simulation. Finally, the initiation fracture toughness and the subsequent resistance curve behavior of a particular unidirectional graphite/epoxy composite are measured using the CGS method. The optically measured stress intensity factors compare successfully to values obtained from the load measurements and the available analytical solutions.

Composite fracture optical method stress intensity factors fracture toughness. 

Copyright information

© Kluwer Academic Publishers 1998

Authors and Affiliations

  • C. Liu
    • 1
  • A.J. Rosakis
    • 2
  • R.W. Ellis
    • 1
  • M.G. Stout
    • 1
  1. 1.MST-8, Materials Science and Technology DivisionLos Alamos National LaboratoryLos AlamosU.S.A.
  2. 2.Graduate Aeronautical LaboratoriesCalifornia Institute of TechnologyPasadenaU.S.A