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Title: Flow stress obtained on ductile specimens deforming at high strain rates.

Abstract

No abstract prepared.

Authors:
 [1];  [1];  [2];
  1. (Purdue University , West Lafayette, IN)
  2. (Sandia National Laboratories, Albuquerque, NM)
Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
USDOE
OSTI Identifier:
952123
Report Number(s):
SAND2006-0990J
TRN: US200913%%314
DOE Contract Number:
AC04-94AL85000
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proposed for publication in the International Journal of Plasticity.
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; FLOW STRESS; STRAIN RATE; DUCTILITY; MATERIALS; DEFORMATION

Citation Formats

Chen, W, Song, B, Frew, Danny Joe, and Antoun, Bonnie R. Flow stress obtained on ductile specimens deforming at high strain rates.. United States: N. p., 2006. Web.
Chen, W, Song, B, Frew, Danny Joe, & Antoun, Bonnie R. Flow stress obtained on ductile specimens deforming at high strain rates.. United States.
Chen, W, Song, B, Frew, Danny Joe, and Antoun, Bonnie R. Wed . "Flow stress obtained on ductile specimens deforming at high strain rates.". United States. doi:.
@article{osti_952123,
title = {Flow stress obtained on ductile specimens deforming at high strain rates.},
author = {Chen, W and Song, B and Frew, Danny Joe and Antoun, Bonnie R.},
abstractNote = {No abstract prepared.},
doi = {},
journal = {Proposed for publication in the International Journal of Plasticity.},
number = ,
volume = ,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2006},
month = {Wed Feb 01 00:00:00 EST 2006}
}
  • A technique is developed for measuring the flow stress of metals over a broad range of strains, strain rates, and temperatures, in uniaxial compression. It utilizes a recent, enhanced version of the classical (Kolsky) compression split Hopkinson bar, in which a sample is subjected to a single stress pulse of a predefined profile, and then recovered without being subjected to any other additional loading. For the present application, the UCSD`s split Hopkinson bar is further enhanced by the addition of a new mechanism by means of which the incident and transmission bars of the split Hopkinson construction are moved intomore » a constant-temperature furnace containing the sample, and gently brought into contact with the sample, as the elastic stress pulse reaches and loads the sample. Using several samples of the same material and testing them at the same strain rate and temperature, but different incremental strains, an accurate estimate of the material`s isothermal flow stress can be obtained. Additionally, the modified Hopkinson technique allows the direct measurement of the change in the (high strain-rate) flow stress with a change of the strain rate, while the strain and temperature are kept constant, i.e., the strain rate can be increased or decreased during the high strain-rate test. The technique is applied to obtain both quasi-isothermal and adiabatic flow stresses of tantalum (Ta) and a tantalum-tungsten (Ta-W) alloy at elevated temperatures. These experimental results show the flow stress of these materials to be controlled by a simple long-range plastic-strain-dependent barrier, and a short-range thermally activated Peierls mechanism. For tantalum, a model which fits the experimental data over strains from a few to over 100%, strain rates from quasi-static to 40,000/s, and temperatures from {minus}200 to 1,000 C, is presented and discussed.« less
  • No abstract prepared.
  • No abstract prepared.
  • The mechanical behavior of Zr{sub 41.25}Ti{sub 13.75}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} (LM-1) has been extensively characterized under quasistatic loading conditions; however, its mechanical behavior under dynamic loading conditions is currently not well understood. A Split-Hopkinson pressure bar (SHPB) and a single-stage gas gun are employed to characterize the mechanical behavior of LM-1 in the strain-rate regime of 10{sup 2}-10{sup 5}/s. The SHPB experiments are conducted with a tapered insert design to mitigate the effects of stress concentrations and preferential failure at the specimen-insert interface. The higher strain-rate plate-impact compression-and-shear experiments are conducted by impacting a thick tungsten carbide (WC) flyer platemore » with a sandwich sample comprising a thin bulk metallic glass specimen between two thicker WC target plates. Specimens employed in the SHPB experiments failed in the gage-section at a peak stress of approximately 1.8 GPa. Specimens in the high strain-rate plate-impact experiments exhibited a flow stress in shear of approximately 0.9 GPa, regardless of the shear strain-rate. The flow stress under the plate-impact conditions was converted to an equivalent flow stress under uniaxial compression by assuming a von Mises-like material behavior and accounting for the plane strain conditions. The results of these experiments, when compared to the previous work conducted at quasistatic loading rates, indicate that the peak stress of LM-1 is essentially strain rate independent over the strain-rate range up to 10{sup 5}/s.« less