BibTeX
@MISC{Crissman_nationalbureau,
author = {J. M. Crissman and L. J. Zapas},
title = {National Bureau of Standards},
year = {}
}
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Abstract
It is shown that under conditions of uniaxial creep the fracture of high density polyethylene can be categorized as one of three types, depending upon the magnitude of the applied load, molecular architecture, and environment. When subjected to relatively large loads, the specimens neck and then fracture almost immediately. At the other extreme of very small initial loadings, the specimens fracture in a brittle fashion through crack formation and growth. In the intermediate range of loadings the specimens neck and, depending upon the molecular weight and molecular weight distribution, may then elongate substantially before fracture. It is shown that the uniaxial creep behavior for the region where drawing occurs, when plotted in terms of isochrones, represents a type of phase diagram, one boundary of which describes the fracture envelope. In addition, experiments employing different constant rate of loading histories are described and an additivity of damage criterion used to predict the time to failure under constant load conditions, and visa versa.
Keyphrases
national bureau specimen neck constant load condition applied load high density polyethylene crack formation specimen fracture molecular weight distribution molecular architecture damage criterion uniaxial creep behavior large load fracture envelope intermediate range brittle fashion uniaxial creep different constant rate small initial loading visa versa molecular weight phase diagram
