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Title: On compression and damage evolution in two thermoplastics

Abstract

The well-known Taylor cylinder impact test, which follows the impact of a flat-ended cylindrical rod onto a rigid stationary anvil, is conducted over a range of impact speeds for two polymers, polytetrafluoroethylene (PTFE) and polyetheretherketone (PEEK). In previous work, experiments and a model were developed to capture the deformation behaviour of the cylinder after impact. These works showed a region in which spatial and temporal variation of both longitudinal and radial deformation provided evidence of changes in phase within the material. In this further series of experiments, this region is imaged in a range of impacted targets at the Diamond synchrotron. Further techniques were fielded to resolve compressed regions within the recovered polymer cylinders that showed a fracture zone in the impact region. The combination of macroscopic high-speed photography and three-dimensional X-ray imaging has identified the development of failure with these polymers and shown that there is no abrupt transition in behaviours but rather a continuous range of responses to competing operating mechanisms. The behaviours noted in PEEK in these polymers show critical gaps in understanding of polymer high strain-rate response.

Authors:
ORCiD logo [1];  [1];  [1];  [2];  [3];  [1];  [1];  [4]
  1. Univ. of Manchester (United Kingdom)
  2. Univ. of Manchester (United Kingdom); Defence Science and Technology Organisation, Adelaide (Australia)
  3. Science and Technology Facilities Council (STFC), Harwell Campus, Oxford (United Kingdom). Diamond Light Source, Ltd.
  4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Programs (DP) (NA-10)
OSTI Identifier:
1414106
Report Number(s):
LA-UR-17-22185
Journal ID: ISSN 1364-5021; TRN: US1800636
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Proceedings of the Royal Society. A. Mathematical, Physical and Engineering Sciences
Additional Journal Information:
Journal Volume: 473; Journal Issue: 2197; Journal ID: ISSN 1364-5021
Publisher:
The Royal Society Publishing
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Bourne, N. K., Garcea, S. C., Eastwood, D. S., Parry, S., Rau, C., Withers, P. J., McDonald, S. A., and Brown, E. N. On compression and damage evolution in two thermoplastics. United States: N. p., 2017. Web. doi:10.1098/rspa.2016.0495.
Bourne, N. K., Garcea, S. C., Eastwood, D. S., Parry, S., Rau, C., Withers, P. J., McDonald, S. A., & Brown, E. N. On compression and damage evolution in two thermoplastics. United States. doi:10.1098/rspa.2016.0495.
Bourne, N. K., Garcea, S. C., Eastwood, D. S., Parry, S., Rau, C., Withers, P. J., McDonald, S. A., and Brown, E. N. Wed . "On compression and damage evolution in two thermoplastics". United States. doi:10.1098/rspa.2016.0495. https://www.osti.gov/servlets/purl/1414106.
@article{osti_1414106,
title = {On compression and damage evolution in two thermoplastics},
author = {Bourne, N. K. and Garcea, S. C. and Eastwood, D. S. and Parry, S. and Rau, C. and Withers, P. J. and McDonald, S. A. and Brown, E. N.},
abstractNote = {The well-known Taylor cylinder impact test, which follows the impact of a flat-ended cylindrical rod onto a rigid stationary anvil, is conducted over a range of impact speeds for two polymers, polytetrafluoroethylene (PTFE) and polyetheretherketone (PEEK). In previous work, experiments and a model were developed to capture the deformation behaviour of the cylinder after impact. These works showed a region in which spatial and temporal variation of both longitudinal and radial deformation provided evidence of changes in phase within the material. In this further series of experiments, this region is imaged in a range of impacted targets at the Diamond synchrotron. Further techniques were fielded to resolve compressed regions within the recovered polymer cylinders that showed a fracture zone in the impact region. The combination of macroscopic high-speed photography and three-dimensional X-ray imaging has identified the development of failure with these polymers and shown that there is no abrupt transition in behaviours but rather a continuous range of responses to competing operating mechanisms. The behaviours noted in PEEK in these polymers show critical gaps in understanding of polymer high strain-rate response.},
doi = {10.1098/rspa.2016.0495},
journal = {Proceedings of the Royal Society. A. Mathematical, Physical and Engineering Sciences},
number = 2197,
volume = 473,
place = {United States},
year = {Wed Jan 18 00:00:00 EST 2017},
month = {Wed Jan 18 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
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  • Dynamic compressive damage evolution in solids, associated with brittle microcracking and ductile plastic flow, is modeled through plastic flow and tensile microcracking, which are induced by the deformation of preexisting microflaws at grain boundaries, slip bands, and microcavities. The micromechanical aspect of this model is discussed in terms of the dominance of microcracking or plastic flow, and possible transition from microcracking to plastic flow is investigated. The effect of lateral confinement on the dynamic damage evolution is investigated, emphasizing the brittle-ductile transition.
  • This article proposes an elastic-plastic damage model that combines micromechanical modeling with continuum damage mechanics to predict the stress-strain response of injection-molded long-fiber thermoplastics. The model accounts for distributions of orientation and length of elastic fibers embedded in a thermoplastic matrix whose behavior is elastic-plastic and damageable. The elastic-plastic damage behavior of the matrix is described by the modified Ramberg-Osgood relation and the three-dimensional damage model in deformation assuming isotropic hardening. Fiber/matrix debonding is accounted for using a parameter that governs the fiber/matrix interface compliance. A linear relationship between this parameter and the matrix damage variable is assumed. First, themore » elastic-plastic damage behavior of the reference aligned-fiber composite containing the same fiber volume fraction and length distribution as the actual composite is computed using an incremental Eshelby-Mori-Tanaka mean field approach. The incremental response of the latter is then obtained from the solution for the aligned-fiber composite by averaging over all fiber orientations. The model is validated against the experimental stress-strain results obtained for long-glass-fiber/polypropylene specimens.« less
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  • No abstract prepared.