Impact and dynamic fracture of tough polymers by thermal decohesion in a Dugdale zone

At low temperatures and high loading rates, normally tough crystalline thermoplastics may undergo a transition from ductile tearing to brittle rapid crack propagation (RCP). It is proposed here that RCP, characterised by low toughness, high crack speed ( > 100 m/s) and a macroscopically smooth fr...

Full description

Saved in:
Bibliographic Details
Published in:International journal of fracture 1995-01, Vol.73 (2), p.109-127
Main Author: LEEVERS, P. S
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Mechanical properties
Physical properties
Polymer industry, paints, wood
Properties and testing
Technology of polymers
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:At low temperatures and high loading rates, normally tough crystalline thermoplastics may undergo a transition from ductile tearing to brittle rapid crack propagation (RCP). It is proposed here that RCP, characterised by low toughness, high crack speed ( > 100 m/s) and a macroscopically smooth fracture surface, occurs by self-sustained melting of a layer, one chain length thick, at each cohesive surface of a crack-tip craze, due to adiabatic heating. Initiation of RCP from a rapidly loaded sharp notch, i.e. impact fracture, requires both the formation of this melt layer, and sufficient crack extension force to propagate it. A schematic linear-elastic analysis based on the Dugdale model accounts both for the measured dynamic fracture resistance, and for the variation of impact fracture resistance with impact speed, in two pipe-grade polyethylenes and in a neat and a rubber-toughened polyacetal. It is concluded that crack initiation resistance, unlike dynamic fracture resistance, cannot be defined as a geometry-dependent material property.
ISSN:0376-9429
1573-2673
DOI:10.1007/BF00055724