A NUMERICAL-ANALYSIS OF CRACK-GROWTH IN MICROCRACKING BRITTLE SOLIDS

In this study a set of numerical analyses of crack growth was performe d to elucidate the influence of microcracking on the observed fracture behavior of brittle solids and composites. The random nucleation, ori entation and size effects of discrete microcracks and resulting intera ctions are fully accounted for in a hybrid finite element model. The r esults indicate that for development of R-curve behavior, the formatio n of a wake region is necessary. The near-field microcracks are not th e sole dominating factor in the development of the R-curve behavior, t heir interactions can be strongly amplified or mitigated by the far-fi eld cracks. Therefore, the microcrack zone width as well as microcrack density plays an important role in toughening behavior. The continuum description of microcracking can provide a reasonable estimation of s hielding; however, it fails to distinguish the effects of microcrack l ength and the role of the wake region during the crack extension.