The double-torsion testing technique for determination of fracture toughness and slow crack growth behavior of materials: A review

The double-torsion testing technique for fracture toughness and slow crack growth determination has been critically reviewed. The analytical compliance and finite element stress analyses of the double-torsion test specimen are summarized. The fracture toughness and crack growth testing procedure using this test configuration is described along with the applicable relationships. The strengths and limitations of this testing technique vis-à-vis other standardized techniques have been critically evaluated. While the double-torsion test method has some limiting features it has been demonstrated that its applicability is not limited as long as these are addressed correctly. Recommendations for conducting double-torsion experiments have been provided and potential avenues for improvement of this test method have been identified. It is concluded based on the review that standardization of this test method is required in order to make it more practicable.