On the essential work of ductile fracture in polymers

Yiu Wing Mai, Brian Cotterell

Research output: Journal article publicationJournal articleAcademic researchpeer-review

409 Citations (Scopus)

Abstract

The essential work of fracture concept has been extended to cover ductile tearing of polymeric materials that neck before fracture. It is shown that the plane stress specific essential fracture work (we) can be obtained from deeply edge-notched tension specimens, containing either single or double notches, by extrapolating the straight line relationship between the total specific fracture work (wf) and ligament length (l) to zero ligament. In this way, specific essential fracture works have been obtained for nylon 66 and two polyethylenes. It seems that weis a material property for a given sheet thickness being independent of specimen geometry. The straight line relationship between wfand l breaks down when the ligament length to sheet thickness ratio is less than about three, since the fracture data fall in the plane stress-plane strain transition region. However, a plane strain specific essential fracture work can still be obtained by extrapolating the least squares curve of the data to zero ligament provided the thickness satisfies plane strain condition. If this condition is not satisfied a near plane strain value is obtained which is dependent upon thickness. This method is also appropriate for ductile polymers like the rubber modified polystyrenes that craze rather than neck. JRcurves have also been obtained for nylon 66 and the polyethylenes. Under strictly J-controlled crack growth conditions, it is shown that the intercept and slope of the JRcurve, i.e. Jcand d J/d a, are related to the intercept and slope of the wfversus l plot. The limited amounts of J-controlled data available have precluded a more definite and general conclusion to be made. But based on what little is available, the comparisons of these two quantities in the JR-Δa and wf-l plots are not unreasonable.

Original languageEnglish
Pages (from-to)105-125
Number of pages21
JournalInternational Journal of Fracture
Volume32
Issue number2
DOIs
Publication statusPublished - Oct 1986
Externally publishedYes

ASJC Scopus subject areas

  • Computational Mechanics
  • Modelling and Simulation
  • Mechanics of Materials

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