Computer Simulation and Analysis of the Expanding Ring Test
Explosively launched expanding ring tests have been used to extract material flow stress at strain-rates from 103 to 3 x 104 sec−1. Computer simulations of such tests using a strain-rate independent, but work hardening constitutive model were analyzed by the same methods used experimentally. Results of this analysis also showed an apparent strain-rate effect. Further examination of the computer simulations has shown that much, if not all, of the measured strain-rate effect is an increased flow stress due to a plastic strain, ɛL, that is locked in during the initial stages of launch. At a larger launch velocity, hence a larger strain-rate, ɛL is also larger. The value of ɛL is sensitive to details of the launch dynamics.
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