Non-universality in Micro-branching Instabilities in Rapid Fracture: the Role of Material Properties

TL;DR

This paper explores how micro-branching instabilities in brittle materials are governed by different physical mechanisms depending on material properties, highlighting the limitations of current theoretical models.

Contribution

It introduces a scaling theory linking pattern characteristics to material properties and emphasizes fundamental differences between plastics and glass.

Findings

Pattern length- and time-scales vary greatly between materials.

Material properties like molecular weight influence micro-branching patterns.

Current models lack some fundamental physics of the phenomena.

Abstract

In spite of the apparent similarity of micro-branching instabilities in different brittle materials, we propose that the physics determining the typical length- and time-scales characterizing the post-instability patterns differ greatly from material to material. We offer a scaling theory connecting the pattern characteristics to material properties (like molecular weight) in brittle plastics like PMMA, and stress the fundamental differences with patterns in glass which are crucially influenced by 3-dimensional dynamics. In both cases the present ab-initio theoretical models are still too far from reality, disregarding some fundamental physics of the phenomena.