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Title: Verification of experimental dynamic strength methods with atomistic ramp-release simulations

Material strength and moduli can be determined from dynamic high-pressure ramp-release experiments using an indirect method of Lagrangian wave profile analysis of surface velocities. This method, termed self-consistent Lagrangian analysis (SCLA), has been difficult to calibrate and corroborate with other experimental methods. Using nonequilibrium molecular dynamics, we validate the SCLA technique by demonstrating that it accurately predicts the same bulk modulus, shear modulus, and strength as those calculated from the full stress tensor data, especially where strain rate induced relaxation effects and wave attenuation are small. We show here that introducing a hold in the loading profile at peak pressure gives improved accuracy in the shear moduli and relaxation-adjusted strength by reducing the effect of wave attenuation. When rate-dependent effects coupled with wave attenuation are large, we find that Lagrangian analysis overpredicts the maximum unload wavespeed, leading to increased error in the measured dynamic shear modulus. Furthermore, these simulations provide insight into the definition of dynamic strength, as well as a plausible explanation for experimental disagreement in reported dynamic strength values.
Authors:
 [1] ;  [1] ;  [1] ;  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Report Number(s):
SAND-2018-5914J
Journal ID: ISSN 2475-9953; PRMHAR; 663695
Grant/Contract Number:
AC04-94AL85000; NA0003525
Type:
Accepted Manuscript
Journal Name:
Physical Review Materials
Additional Journal Information:
Journal Volume: 2; Journal Issue: 5; Journal ID: ISSN 2475-9953
Publisher:
American Physical Society (APS)
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1444091
Alternate Identifier(s):
OSTI ID: 1436002

Moore, Alexander P., Brown, Justin L., Lim, Hojun, and Lane, J. Matthew D.. Verification of experimental dynamic strength methods with atomistic ramp-release simulations. United States: N. p., Web. doi:10.1103/PhysRevMaterials.2.053601.
Moore, Alexander P., Brown, Justin L., Lim, Hojun, & Lane, J. Matthew D.. Verification of experimental dynamic strength methods with atomistic ramp-release simulations. United States. doi:10.1103/PhysRevMaterials.2.053601.
Moore, Alexander P., Brown, Justin L., Lim, Hojun, and Lane, J. Matthew D.. 2018. "Verification of experimental dynamic strength methods with atomistic ramp-release simulations". United States. doi:10.1103/PhysRevMaterials.2.053601.
@article{osti_1444091,
title = {Verification of experimental dynamic strength methods with atomistic ramp-release simulations},
author = {Moore, Alexander P. and Brown, Justin L. and Lim, Hojun and Lane, J. Matthew D.},
abstractNote = {Material strength and moduli can be determined from dynamic high-pressure ramp-release experiments using an indirect method of Lagrangian wave profile analysis of surface velocities. This method, termed self-consistent Lagrangian analysis (SCLA), has been difficult to calibrate and corroborate with other experimental methods. Using nonequilibrium molecular dynamics, we validate the SCLA technique by demonstrating that it accurately predicts the same bulk modulus, shear modulus, and strength as those calculated from the full stress tensor data, especially where strain rate induced relaxation effects and wave attenuation are small. We show here that introducing a hold in the loading profile at peak pressure gives improved accuracy in the shear moduli and relaxation-adjusted strength by reducing the effect of wave attenuation. When rate-dependent effects coupled with wave attenuation are large, we find that Lagrangian analysis overpredicts the maximum unload wavespeed, leading to increased error in the measured dynamic shear modulus. Furthermore, these simulations provide insight into the definition of dynamic strength, as well as a plausible explanation for experimental disagreement in reported dynamic strength values.},
doi = {10.1103/PhysRevMaterials.2.053601},
journal = {Physical Review Materials},
number = 5,
volume = 2,
place = {United States},
year = {2018},
month = {5}
}

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