Analysis of notch effect in PMMA using the Theory of Critical Distances

Analysis of notch effect in load bearing capacity, apparent fracture toughness and fracture micromechanisms of ferritic–pearlitic steels

“…Also of great interest is the relation between the macroscopic resistant observations (i.e., load bearing capacity and apparent fracture toughness) and the fracture micromechanisms, as previously reported in [17,18]. This paper focusses the analysis of notch effect on a particularly significant group of materials: ferritic-pearlitic steels, which constitute the core part of structural steels.…”

“…The authors have previously reported [17,18] that, beyond the stress relaxation generated by the presence of a finite notch, the notch effect also generates an evolution of fracture micromechanisms. Thus, for a given material and condition, and assuming brittle behaviour in cracked conditions, the fracture micromechanisms become more and more non-linear (ductile) when the notch radius increases, something that may be related to the corresponding progressive loss of constraint.…”

“…Basically, they all suggestprovide mathematical expressions implying a reduction of the stress acting perpendicular to the notch plane, in such a way that the larger the notch radius the more significant the stress reduction. This generally has direct consequences on the resistant behaviour of structural components (e.g., [10][11][12][13][14][15][16][17][18][19]). Comprehensive reviews of this phenomenon covering thousands of experimental data may be found in [15,16,19], whereas specific results for particular materials may be found in, for example, [13] (ceramics), [14] (alumina and soda-lime glass), [17] (PMMA) and [18] (Al7075-T651).…”

“…On some occasions, however, sharp notches behave like cracks and also blunt notches may not penalise the load bearing capacity (beyond the corresponding reduction of the resistant section). Additionally, the terms "sharp" and "blunt" are not absolute, but rather they depend on the material: there are materials that present a clear notch effect (e.g., increase in load bearing capacity) for very small notch radii (e.g, [18]), and there are others that require a certain notch radius to develop a notch effect (e.g., [17]). …”

“…In any case, the resistant behaviour of structural components containing notches can be analysed through two different parameters: the above mentioned load bearing capacity and, when dealing with fracture assessments, the apparent fracture toughness (K N mat ) (e.g., [15,17,18,45], which is that one obtained by the application of the cracked specimen formulation [24] to notched specimens. Also of great interest is the relation between the macroscopic resistant observations (i.e., load bearing capacity and apparent fracture toughness) and the fracture micromechanisms, as previously reported in [17,18].…”