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The dependence of acoustic emission on strain rate in 7075-T6 aluminum

The aim of this experimental investigation was to determine the effect of strain rate on the acoustic emission from a polycrystalline metal

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Abstract

The dependence of RMS acoustic-emission output on strain rate was determined during tensile tests on 7075-T6 aluminum over a range of strain rates from 0.015 min−1 to 0.230 min−1. A special normalization technique was developed to eliminate the inherent differences in the acoustic emission from supposedly identical specimens tested under identical conditions. It was found that the RMS acoustic-emission output increases approximately linearly with strain rate, and that the slope of the linear dependence decreased with increased plastic strain. The effect of pinned dislocation breakaway on the acoustic-emission output vs. plastic-strain relationship is the subject of a preliminary theory.

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Abbreviations

A :

constant

B :

constant

H :

hardening coefficient

L i :

pinned-dislocation length per unit volume

n i :

number of dislocation segments

n :

constant

RMS :

acoustic-emission voltage output

t :

time

\(\dot \in \) :

strain rate

∈ p :

plastic-strain rate

\(\dot \in _p \) :

plastic-strain rate

ρ t :

total-dislocation density per unit volume

ρ m :

mobile-dislocation density per unit volume

ρ m′ :

mobile-dislocation density per unit volume associated with unpinning

\(\mathop \Sigma \limits_{i = 1} \) :

summation overi

σ i :

root-mean-square shear stress

v :

crosshead rate

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Authors and Affiliations

  1. Lawrence Livermore Laboratory, Livermore, CA

    M. A. Hamstad

  2. University of California, Davis, CA

    A. K. Mukherjee (Professor of Mechanical Engineering)

Authors
  1. M. A. Hamstad
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  2. A. K. Mukherjee
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Work was performed under the auspices of the U.S. Atomic Energy Commission.

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Hamstad, M.A., Mukherjee, A.K. The dependence of acoustic emission on strain rate in 7075-T6 aluminum. Experimental Mechanics 14, 33–41 (1974). https://doi.org/10.1007/BF02324858

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  • DOI: https://doi.org/10.1007/BF02324858

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