Papers by Author: Alberto Sapora

Abstract: The coupled Finite Fracture Mechanics (FFM) criterion is applied to investigate brittle fracture in rounded V-notched samples under mode I loading. The approach is based on the contemporaneous fulfilment of a stress requirement and the energy balance, the latter being implemented on the basis of a recently proposed analytical expression for the stress intensity factor. Results are presented in terms of the critical crack advance and the apparent generalized fracture toughness, i.e. the unknowns related to the system of two equations describing the FFM criterion. A validation of the theory is performed by employing varying root radius notched, as-quenched, AISI 4340 steel specimens fracture results.

Abstract: Many biological materials exhibit a hierarchical structure over more than one length scale. Understanding how hierarchy affects their mechanical properties emerges as a primary concern, since it can guide the synthesis of new materials to be tailored for specific applications. In this paper the strength and stiffness of hierarchical materials are investigated by means of a fractal approach. A new model is proposed, based both on geometric and material considerations and involving simple recursive formulas.