Poroelastic toughening in polymer gels: A theoretical and numerical study

TL;DR

This paper investigates how poroelastic effects in polymer gels enhance fracture toughness, combining theoretical derivations, a cohesive zone model, and numerical simulations to understand the micromechanics of crack propagation.

Contribution

It introduces a poroelastic cohesive zone model and derives an expression for energy release rate, revealing crack velocity-independent toughening mechanisms.

Findings

Poroelasticity contributes to crack toughening in gels.

Theoretical and numerical results agree on toughening effects.

Solvent pressure plays a key role in fracture micromechanics.

Abstract

We explore the Mode I fracture toughness of a polymer gel containing a semi-infinite, growing crack. First, an expression is derived for the energy release rate within the linearized, small-strain setting. This expression reveals a crack tip velocity-independent toughening that stems from the poroelastic nature of polymer gels. Then, we establish a poroelastic cohesive zone model that allows us to describe the micromechanics of fracture in gels by identifying the role of solvent pressure in promoting poroelastic toughening. We evaluate the enhancement in the effective fracture toughness through asymptotic analysis. We confirm our theoretical findings by means of numerical simulations concerning the case of a steadily propagating crack. In broad terms, our results explain the role of poroelasticity and of the processes occurring in the fracturing region in promoting toughening of polymer gels.