Influence of Material Properties and Fracture Properties on the Crack Nucleation and Growth

Abstract

<p>In this thesis, we studied the influence of spatial variations in the fracture property and the elastic property on the resulting crack patterns during soil desiccation. Young's modulus is selected as the representative elastic property and the fracture toughness is selected as that for the fracture property. Their well-defined spatially fluctuated random fields are the input of the phase-field fracture simulation, and the resulting damage field is the output. Various postprocessing of the damage field were carried out to analyze the resulting fields. After comparing the morphology of the cracks and fragment size distributions, a preliminary guess was that the two inputs have very close influence on the output. Then the Pearson correlation coefficient, as a first try of sensitivity analysis, also gave an indistinguishable correlation number between the two. A more rigorous approach with highly isolated sensitivity quantity was needed, which brought us to the Sobol' indice based on polynomial chaos expansion, a global sensitivity analysis measure which accounts for the variation of output into the variation of each input and any combination of input.</p>