Caustic analysis of stress singularities in orthotropic composite materials with mode-I crack

The stress singularities of mode I crack tip in orthotropic composites are studied by the method of caustics. The parametric equations of the caustic and its initial curve surrounding the crack tip are derived by means of elastic crack solutions of orthotropic composites and the basic principle of reflective caustics. Theoretical formulae of determining the mode I stress intensity factor are obtained. Theoretical caustics and initial curves for three kinds of orthotropic composites are simulated. Some characteristics of stress singularity at crack tip are analyzed. In comparison with numerical results, the caustic experiment is performed for crack along the material axes in glass-fiber–woven epoxy composites under three-point-bend loading.