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Title: Shock Compression and Strain Rate Effect in Composites and Polymers

Abstract

Polymers are increasingly being utilized as monolithic materials and composite matrices for structural applications historically reserved for metals. High strain and high strain-rate applications in aerospace, defense, and automotive industries have lead to interest in utilizing the ability of many polymers to withstand extensions to failure of several hundred percent, often without localization or necking and their strong rate dependence. A broad range of characterization techniques will be presented for semi-crystalline polymers and composites including elastic-plastic fracture, split Hopkinson pressure bar (SHPB), plate impact including soft-recovery and lateral gage measurements and Taylor Impact. Gas-launched, plate impact experiments have been performed on pedigreed PTFE 7C, mounted in momentum-trapped, shock assemblies, with impact pressures above and below the phase II to phase III crystalline transition to probe subtle changes in the crystallinity, microstructure, and mechanical response of PTFE. Observed strong anisotropy on the hugoniot and spall behavior of fiber-reinforced composites will be discussed. Polymers are known to exhibit a strong dependence of the yield stress on temperature and strain-rate that are often observed to be linear for temperature and logarithmic for strain-rate. Temperature and strain-rate dependence will be reviewed in terms of classic time-temperature superposition and an empirical mapping function for superpositionmore » between temperature and strain-rate. The recent extension of the new Dynamic-Tensile-Extrusion (Dyn-Ten-Ext) technique to probe the dynamic tensile responses of polymers will be discussed, where more irregular deformation and stochastic-based damage and failure mechanisms than the stable plastic elongation and shear instabilities observed that in metals. The opportunity to use of Dyn-Ten-Ext to probe incipient damage at very high strain-rate by linking in situ and post mortem experimental observations with high-fidelity simulation will be introduced. The potential to study polymer deformation under even more extreme conditions by employing explosive drive to induce Rayleigh-Taylor (RT) growth linking with in situ diagnosis by proton radiography will be proposed. Finally, a case study of collaboration between experimentalists and modelers to study the shock induced phase transition of PTFE presented. Building on a history of shock and Diamond Anvil Cell data it has long been know that PTFE exhibits a pressure induced phase transition at 0.7 GPa. The transition has historically been assumed and reported to be dependent on the hydrostatic pressure. However, studies employing neutron diffraction have suggested the phase transition is driven by only the principle stress applied to the compliant direction of crystalline domain. A multiphase model based on the Maxwell-type viscoelastic formulation was developed to include the stress deviator to drive potential martensitic transition and time to reflects the kinetic nature of the transitions demonstrating the need to account for both a martensitic nature and kinetics of the transition to capture subtle experimental observables.« less

Authors:
 [1]
  1. Los Alamos National Laboratory
Publication Date:
Research Org.:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
DOE/LANL
OSTI Identifier:
1044132
Report Number(s):
LA-UR-12-22383
TRN: US201214%%329
DOE Contract Number:  
AC52-06NA25396
Resource Type:
Conference
Resource Relation:
Conference: 15TH EUROPEAN CONFERENCE ON COMPOSITE MATERIALS ; 2012-06-24 - 2012-06-28 ; Venice, Italy
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANISOTROPY; COMPOSITE MATERIALS; COMPRESSION; DEFORMATION; DIAGNOSIS; DIAMONDS; ELONGATION; EXPLOSIVES; HYDROSTATICS; KINETICS; MATRICES; MICROSTRUCTURE; NEUTRON DIFFRACTION; PLASTICS; POLYMERS; PROBES; PROTON RADIOGRAPHY; SHEAR; STRAIN RATE; STRAINS

Citation Formats

Brown, Eric. Shock Compression and Strain Rate Effect in Composites and Polymers. United States: N. p., 2012. Web.
Brown, Eric. Shock Compression and Strain Rate Effect in Composites and Polymers. United States.
Brown, Eric. 2012. "Shock Compression and Strain Rate Effect in Composites and Polymers". United States. https://www.osti.gov/servlets/purl/1044132.
@article{osti_1044132,
title = {Shock Compression and Strain Rate Effect in Composites and Polymers},
author = {Brown, Eric},
abstractNote = {Polymers are increasingly being utilized as monolithic materials and composite matrices for structural applications historically reserved for metals. High strain and high strain-rate applications in aerospace, defense, and automotive industries have lead to interest in utilizing the ability of many polymers to withstand extensions to failure of several hundred percent, often without localization or necking and their strong rate dependence. A broad range of characterization techniques will be presented for semi-crystalline polymers and composites including elastic-plastic fracture, split Hopkinson pressure bar (SHPB), plate impact including soft-recovery and lateral gage measurements and Taylor Impact. Gas-launched, plate impact experiments have been performed on pedigreed PTFE 7C, mounted in momentum-trapped, shock assemblies, with impact pressures above and below the phase II to phase III crystalline transition to probe subtle changes in the crystallinity, microstructure, and mechanical response of PTFE. Observed strong anisotropy on the hugoniot and spall behavior of fiber-reinforced composites will be discussed. Polymers are known to exhibit a strong dependence of the yield stress on temperature and strain-rate that are often observed to be linear for temperature and logarithmic for strain-rate. Temperature and strain-rate dependence will be reviewed in terms of classic time-temperature superposition and an empirical mapping function for superposition between temperature and strain-rate. The recent extension of the new Dynamic-Tensile-Extrusion (Dyn-Ten-Ext) technique to probe the dynamic tensile responses of polymers will be discussed, where more irregular deformation and stochastic-based damage and failure mechanisms than the stable plastic elongation and shear instabilities observed that in metals. The opportunity to use of Dyn-Ten-Ext to probe incipient damage at very high strain-rate by linking in situ and post mortem experimental observations with high-fidelity simulation will be introduced. The potential to study polymer deformation under even more extreme conditions by employing explosive drive to induce Rayleigh-Taylor (RT) growth linking with in situ diagnosis by proton radiography will be proposed. Finally, a case study of collaboration between experimentalists and modelers to study the shock induced phase transition of PTFE presented. Building on a history of shock and Diamond Anvil Cell data it has long been know that PTFE exhibits a pressure induced phase transition at 0.7 GPa. The transition has historically been assumed and reported to be dependent on the hydrostatic pressure. However, studies employing neutron diffraction have suggested the phase transition is driven by only the principle stress applied to the compliant direction of crystalline domain. A multiphase model based on the Maxwell-type viscoelastic formulation was developed to include the stress deviator to drive potential martensitic transition and time to reflects the kinetic nature of the transitions demonstrating the need to account for both a martensitic nature and kinetics of the transition to capture subtle experimental observables.},
doi = {},
url = {https://www.osti.gov/biblio/1044132}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jun 20 00:00:00 EDT 2012},
month = {Wed Jun 20 00:00:00 EDT 2012}
}

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