Fracture of disordered solids in compression as a critical phenomenon: II. Model Hamiltonian for a population of interacting cracks

TL;DR

This paper develops a Hamiltonian model for 2D crack patterns in disordered solids, capturing interactions and heterogeneity, to analyze fracture as a critical phenomenon.

Contribution

It introduces a functional Hamiltonian linking crack configurations to their formation energy, incorporating crack interactions and heterogeneity effects.

Findings

Hamiltonian models crack interactions in disordered solids.

Captures localization transition in fracture patterns.

Relates crack energies to elastic moduli via Griffith's criterion.

Abstract

To obtain the probability distribution of 2D crack patterns in mesoscopic regions of a disordered solid, the formalism of Paper I requires that a functional form associating the crack patterns (or states) to their formation energy be developed. The crack states are here defined by an order parameter field representing both the presence and orientation of cracks at each site on a discrete square network. The associated Hamiltonian represents the total work required to lead an uncracked mesovolume into that state as averaged over the initial quenched disorder. The effect of cracks is to create mesovolumes having internal heterogeneity in their elastic moduli. To model the Hamiltonian, the effective elastic moduli corresponding to a given crack distribution are determined that includes crack-to-crack interactions. The interaction terms are entirely responsible for the localization transition analyzed in Paper III. The crack-opening energies are related to these effective moduli via Griffith's criterion as established in Paper I.