Numerical analysis of the ENF and ELS tests applied to mode II fracture characterization of cortical bone tissue

摘要

The objective of this work is to verify numerically the adequacy of the ENF and the ELS tests to determine the fracture toughness under mode Ⅱ loading of cortical bovine bone tissue. A data-reduction scheme based on the specimen compliance and the equivalent crack concept is proposed to overcome the difficulties inherent to crack monitoring during its growth. A cohesive damage model was used to simulate damage initiation and growth, thus assessing the efficacy of the proposed data-reduction scheme. The influences of the initial crack length, local strength and toughness on the measured fracture energy were analysed, taking into account the specimen length restriction. Some limitations related to spurious influence on the fracture process zone of the central loading in the ENF test, and clamping conditions in the ELS test were identified. However, it was verified that a judicious selection of the geometry allows, in both cases, a rigorous estimation of bone toughness in mode Ⅱ.