| Summary: | <p>This work aims to develop and implement a linear elastic grain-level micromechanical
model based on the discrete element method using bonded contacts and an improved
fracture criteria to capture both intergranular and transgranular microcrack initiation and
evolution in polycrystalline ceramics materials. Gaining a better understanding of the underlying
mechanics and micromechanics of the fracture process of brittle polycrystalline
materials will aid in high performance material design. Continuum mechanics approaches
cannot accurately simulate the crack propagation during fracture due to the discontinuous
nature of the problem. In this work we distinguish between predominately intergranular
failure (along the grain boundaries) versus predominately transgranular failure (across the
grains) based on grain orientation and microstructural parameters to describe the contact
interfaces and present the first approach at fracturing discrete elements. Specifically, the
influence of grain boundary strength and stiffness on the fracture behavior of an idealized
ceramic material is studied under three different loading conditions: uniaxial compression,
brazilian, and four-point bending. Digital representations of the sample microstructures for
the test cases are composed of hexagonal, prismatic, honeycomb-packed grains represented
by rigid, discrete elements. The principle of virtual work is used to develop a microscale
fracture criteria for brittle polycrystalline materials for tensile, shear, torsional and rolling
modes of intergranular motion. The interactions between discrete elements within each
grain are governed by traction displacement relationships.</p>
|
|---|
