A Study of the Fracture Behavior of Unindirectional Fiber- Reinforced Composite Using Coherent Gradient Sensing (CGS) Interferometry
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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.
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- A Study of the Fracture Behavior of Unindirectional Fiber- Reinforced Composite Using Coherent Gradient Sensing (CGS) Interferometry
International Journal of Fracture
Volume 90, Issue 4 , pp 355-382
- Cover Date
- Print ISSN
- Online ISSN
- Kluwer Academic Publishers
- Additional Links
- Composite fracture
- optical method
- stress intensity factors
- fracture toughness.
- Industry Sectors
- Author Affiliations
- 1. MST-8, Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, U.S.A.
- 2. Graduate Aeronautical Laboratories, California Institute of Technology, Pasadena, California, 91125, U.S.A