MICRO-BRANCHING AS AN INSTABILITY IN DYNAMIC FRACTURE

 

The proceedings of the IUTAM conference (Cambridge, 1995)

 

J. FINEBERG†, S. P. GROSS‡ AND E. SHARON

The Racah Institute of Physics

The Hebrew University of Jerusalem

Jerusalem, Israel

The Center for Nonlinear Dynamics

The University of Texas

Austin, TX 78712, U.S.A.

Abstract

Experiments in brittle, amorphous PMMA indicate that the process of dynamic fracture is governed by a micro-branching instability. At a critical velocity, vc, a single crack undergoes an abrupt, well-defined transition to microscopic crack branching. As a result, the velocity of the crack develops oscillations, the mean acceleration decreases and structure is formed on the fracture surface. Beyond vc the total fracture surface created is a linear function of the energy release rate. Micro-branch profiles follow a power law and develop into macroscopic crack branching.