FEATURES STRAIN LOCALISATION UNDER IMPACT LOADS

The localization of plastic strain under impulse loads is determined by the sample geometry and is practically independent on the material properties. Deformation bands are a consequence of ultrasonic oscillations, which occurs when waves are reflected (compression and unloading) on the sample faces, and when the reflected waves interact with each other, and flows in the form of standing waves. Localized strain bands originate and develop at the nodes of standing waves under conditions of alternating deformation and are accompanied by mass transfer of particles from the matrix material (interstitial and substitutional atoms, impurity atoms, ultrafine particles of the hardening phase) to the sites of spall damage. The absence of energy transfer through the nodal points of the standing wave increases the duration of the sample deformation after the passage of the shock wave.