Dynamics of Simple Cracks

TL;DR

This paper reviews the fundamental dynamics of simple cracks, critically examines the classic scale-free theory of dynamic fracture, and explores how introducing physical scales alters crack behavior and structure.

Contribution

It provides a critical analysis of the assumptions in the classic theory and demonstrates the impact of physical scales on crack dynamics and structure.

Findings

Scale-free theory often fails when physical scales are introduced.

Physical scales significantly influence crack structure and dynamics.

The paper highlights conditions where classic assumptions break down.

Abstract

Cracks are the major vehicle for material failure, and often exhibit rather complex dynamics. The laws that govern their motion have remained an object of constant study for nearly a century. The simplest kind of dynamic crack is a single crack that moves along a straight line. We first briefly review current understanding of this "simple" object. We then critically examine the assumptions of the classic, scale-free, theory of dynamic fracture, and note when it works and how it may fail if certain of these assumptions are relaxed. A number of examples is provided, where the introduction of physical scales into this scale-free theory profoundly affects both a crack's structure and the resulting dynamics.