Four kinds of complex alloyed steel have been tested under uniaxial strain
conditions within strain rate range of 215Ÿ550 m/s. The kinematics of straining was studied
by using SEM and optical microscopy of post-shocked specimens. The cross-section of
targets is found to contain the mesoscopic rotational structures of complex configuration.
Besides the free surface velocity, interference technique used allows the mean particle
velocity profile and velocity variance to be registered in every shock loading. The spall
strength is theoretically and experimentally found to be maximum at the strain rate where
velocity variance equals to velocity defect. This condition means that local strain rate at the
mesoscale equal to macroscopic strain rate. That strain rate corresponds to maximum density
of rotations at the mesoscale.
Keywords: shock loading; spallation; rotational structures; velocity variance; velocity defect.
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