| The objective of this work has been to contribute to the on-going development of Quantitative Fractography (QF) as a rigorous yet practical tool for the analysis of fracture surfaces. Through such evolution, the QF methodology can increasingly provide information contributing to the understanding of failure modes and mechanisms in materials.; A significant portion of this work focusses on theoretical development or refinement of QF concepts. A rigorous and assumption-free technique for measuring surface roughness parameter (R{dollar}sb{lcub}rm S{rcub}{dollar}) has been developed. Through extensive computer-simulated sampling, the conditions for efficient application of this technique and the extent of sampling error involved are established. Other statistical aspects of QF sampling (profilometry) are investigated, including the development of an expression by which the "effort" required for a given statistical sampling accuracy can be estimated.; The concepts and parameters of fractals have recently been invoked in QF analysis. Applications of fractals in fractography are further investigated in this work, leading to an assumption-free expression relating the fractal dimensions of fracture profiles (D{dollar}sb{lcub}rm L{rcub}{dollar}) to fracture surfaces (D{dollar}sb{lcub}rm S{rcub}{dollar}). This technique replaces previous methods which involve assumptions of indeterminate validity.; QF concepts were applied to the study of certain failure processes in materials. In particular, the relationship between fracture surface geometry and the crack closure phenomenon in a commercial Ni-base superalloy were investigated. Fracture surface asperities were extracted from digitized fracture profiles and analyzed. Geometric attributes of surface contact points between opposing crack faces were considered, indicating the predominance of vertical (frictional) contacts in this case. |
