Crack growth by surface diffusion in viscoelastic media

TL;DR

This paper investigates steady state crack growth in viscoelastic media, revealing distinct behaviors in mode I and mode III, including stability differences and the influence of surface dissipation and viscous effects.

Contribution

It provides a comparative analysis of mode I and mode III crack growth, highlighting the role of surface diffusion and viscous dissipation in fracture stability.

Findings

Mode III shows a transition to unstable crack growth at higher forces.

Mode I behavior is dominated by crack surface dissipation near the Griffith point.

Mixed-mode scenarios can sustain higher crack velocities, suggesting potential instability in mode I.

Abstract

We discuss steady state crack growth in the spirit of a free boundary problem. It turns out that mode I and mode III situations are very different from each other: In particular, mode III exhibits a pronounced transition towards unstable crack growth at higher driving forces, and the behavior close to the Griffith point is determined entirely through crack surface dissipation, whereas in mode I the fracture energy is renormalized due to a remaining finite viscous dissipation. Intermediate mixed-mode scenarios allow steady state crack growth with higher velocities, leading to the conjecture that mode I cracks can be unstable with respect to a rotation of the crack front line.