Assessment of defect size in brittle fibers

Fiber defects, modeled as inner circular or part-circular surface cracks in planes normal to the fiber axis, are analyzed for computing the relationship between the maximum defect size and the fiber fracture stress. Linear elastic fracture mechanics is applied to compute the critical tensile stress for both surface and inner cracks, taking into account that when an inner crack reaches the surface it can stop growing or become unstable. The minimum critical tensile stress is correlated with defect size when defects are randomly located, and the numerical computations are compared with some available experimental results.