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Title: Large-Strain Time-Temperature Equivalence and Adiabatic Heating of Polyethylene

Abstract

Time-temperature equivalence is a well-known phenomenon in time-dependent material response, where rapid events at a moderate temperature are indistinguishable from some occurring at modest rates but elevated temperatures. However, there is as-yet little elucidation of how well this equivalence holds for substantial plastic strains. In this work, we demonstrate time-temperature equivalence over a large range in a previously studied high-density polyethylene formulation (HDPE). At strain-rates exceeding 0.1/s, adiabatic heating confounds the comparison of nominally isothermal material response, apparently violating time-temperature equivalence. Strain-rate jumps can be employed to access the instantaneous true strain rate without heating. Adiabatic heating effects were isolated by comparing a locus of isothermal instantaneous flow stress measurements from strain-rate jumps up to 1/s with the predicted equivalent states at 0.01/s and 0.001/s in compression. Excellent agreement between the isothermal jump condition locus and the quasi-static tests was observed up to 50% strain, yielding one effective isothermal plastic response for each material for a given time-temperature equivalent state. These results imply that time-temperature equivalence can be effectively used to predict the deformation response of polymers during extreme mechanical events (large strain and high strain-rate) from measurements taken at reduced temperatures and nominal strain-rates in the laboratory.

Authors:
 [1];  [1];  [1]
  1. Los Alamos National Laboratory
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
DOE/LANL
OSTI Identifier:
1043022
Report Number(s):
LA-UR-12-21953
TRN: US201213%%49
DOE Contract Number:  
AC52-06NA25396
Resource Type:
Conference
Resource Relation:
Conference: Society for Experimental Mechanics ; 2012-06-11 - 2012-06-11 ; Costa Mesa, California, United States
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COMPRESSION; DEFORMATION; FLOW STRESS; HEATING; PLASTICS; POLYETHYLENES; POLYMERS; STRAIN RATE; STRAINS

Citation Formats

Furmanski, Jevan, Brown, Eric, and Cady, Carl M. Large-Strain Time-Temperature Equivalence and Adiabatic Heating of Polyethylene. United States: N. p., 2012. Web.
Furmanski, Jevan, Brown, Eric, & Cady, Carl M. Large-Strain Time-Temperature Equivalence and Adiabatic Heating of Polyethylene. United States.
Furmanski, Jevan, Brown, Eric, and Cady, Carl M. Wed . "Large-Strain Time-Temperature Equivalence and Adiabatic Heating of Polyethylene". United States. https://www.osti.gov/servlets/purl/1043022.
@article{osti_1043022,
title = {Large-Strain Time-Temperature Equivalence and Adiabatic Heating of Polyethylene},
author = {Furmanski, Jevan and Brown, Eric and Cady, Carl M.},
abstractNote = {Time-temperature equivalence is a well-known phenomenon in time-dependent material response, where rapid events at a moderate temperature are indistinguishable from some occurring at modest rates but elevated temperatures. However, there is as-yet little elucidation of how well this equivalence holds for substantial plastic strains. In this work, we demonstrate time-temperature equivalence over a large range in a previously studied high-density polyethylene formulation (HDPE). At strain-rates exceeding 0.1/s, adiabatic heating confounds the comparison of nominally isothermal material response, apparently violating time-temperature equivalence. Strain-rate jumps can be employed to access the instantaneous true strain rate without heating. Adiabatic heating effects were isolated by comparing a locus of isothermal instantaneous flow stress measurements from strain-rate jumps up to 1/s with the predicted equivalent states at 0.01/s and 0.001/s in compression. Excellent agreement between the isothermal jump condition locus and the quasi-static tests was observed up to 50% strain, yielding one effective isothermal plastic response for each material for a given time-temperature equivalent state. These results imply that time-temperature equivalence can be effectively used to predict the deformation response of polymers during extreme mechanical events (large strain and high strain-rate) from measurements taken at reduced temperatures and nominal strain-rates in the laboratory.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2012},
month = {6}
}

Conference:
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