A Brazilian disk for measuring fracture toughness of orthotropic materials

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A Brazilian disk test specimen is calibrated for the determination of the mixed-mode fracture toughness of orthotropic materials. The specimen is well-suited for investigating the fracture toughness of orthotropic materials over the complete range of mode mixtures, 0-90°. The K dominance zone around the crack tip exists and can be as large as a/5 for the Brazilian disk, provided that the zone of nonlinear effects is small (a is the half-crack length). The rationale for determining the stress intensity factors under mixed-mode loading conditions and the calibration curves, relevant to a number of orthotropic materials, relating maximum load and loading angle to KI and KII are presented.

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Acta Materialia