In the past decade, micrometer cantilevers were frequently used to evaluate the fracture toughness of single phases and the fracture toughness of particular grain and phase boundaries. The calculation of the fracture toughness relies on the cantilever geometry and the experimentally determined maximum force. To quantify the toughness, the geometry and force enter analytical models, which are based on simulations that use an isotropic elastic material, perfect beam geometry and in many cases a two-dimensional configuration. However, the vast majority of materials have a limited amount of plasticity and are anisotropic. Moreover, the intentionally prepared pre-crack is seldom straight due to the focused ion beam (FIB) production method. This study uses thousands of 3D finite element method (FEM) simulations to investigate the influence of anisotropy, imperfect pre-crack shape and plasticity on the apparent fracture toughness of the material.
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