Determination of Stress Intensity Factor for Orthotropic Material by the Method of Caustics.

There are many experimental methods for the determination of the stress intensity factor K in the vicinity of the crack tip. The caustics method for estimating the stress intensity factor of two-dimensional cracks has been investigated theoretically and experimentally, and provides a technique for easily obtaining the value of K. However, relatively few theoretical and experimental analyses for orthotropic material using this method have been conducted. In this paper, the optical method of caustics is extended to evaluate the stress intensity factor K for an orthotropic material theoretically and experimentally, and the range of applicability of this method is clarified. In this study, we make a comparison between the orthoropic and anisotropic material, and a plate of "Fiber Reinforced Plastics" (F. R. P. ) is used.