Atomistically calibrated Tsai-Wu criterion for orthotropic layered 2D materials and interpreting accuracy – A study on failure of hBN. (July 2022) - Lahkar, Simanta
Abstract: The calibration, application and interpretation of an optimized quadratic failure criterion for generally-orthotropic two-dimensional (2D) layered materials, based on the Tsai-Wu strength theory, in order to describe the anisotropic failure behavior of multilayer hexagonal boron nitride (hBN) is presented in this study. A systematic approach to calibrate the strength parameters of the general theory in the full stress-space based on selected atomistic failure simulation data is illustrated, which resulted in an optimized failure criterion describing a closed failure surface for hBN. Several parameters to quantitatively estimate the accuracy of any quadratic failure function have been derived, which helped to compare the errors in the prediction of the optimized criterion against other common multiaxial strength theories. The optimized failure function was also used to analyze the failure of hBN in arbitrary orientations from atomistic simulations of tensile and shear tests. The comparative study between several failure results using the optimized criterion revealed significant strengthening of hBN caused by ripples formed during deformation. The strength predictions from the optimized failure criterion are found to agree well with the atomistic failure data for hBN deformed in both principal axes as well as asymmetric orientations. Graphical abstract: Image 1 Highlights: A general Tsai-Wu failure criterion was calibrated for hBN in full stress-space. Framework to quantitatively estimate the accuracy of criteria was proposed. Good agreement with atomistic failure data for different orientations was found. Coherent ripples in layers of hBN significantly increased strength and toughness.