Defect Generation in Shock-Wave Deformation

Abstract

A theoretical framework elucidating the generation of shockinduced defects is presented. Three different mechanisms responsible for the generation of point3 line 3 and planar defects (twins

Development of wide-range constitutive equations for calculations of high-rate deformation of metals

“…(1)- (4) was performed basing on various experiments, namely, compression diagrams, Taylor method, compression of cylindrical channels, method of perturbation growth recording, analysis of release wave structure, measurement of elastic precursor, measurement of shock wave front width, as well as basing on metallographic and mechanical researches of samples after shock-wave loading [9][10][11][12][13][14][15][16][17][18][19][20][21]. These methods are briefly listed below.…”

“…It includes competition of various strain mechanisms, structural changes during deformation, violation of flow stability at various scale levels, etc. [9][10][11]. On the one hand, models for calculations of high-velocity dynamic processes should be rather simple and physically clear; on the other hand, they should reflect the main processes, which occur in materials, and to "work" in wide range of flow parameters.…”

“…In our understanding, strain history means the dependences of temperature, pressure, strain tensor and stress tensor on time. Strain history determines structural changes, namely, growth of dislocation density, changes of sizes and orientation of grains, relative sliding of grains, formation of twin structures and bands of localized shift, annealing when reaching critical temperatures [9,[11][12][13].…”

“…Available experimental data point to significant structural changes of metals depending on loading type, and, as a result, change of mechanical properties [9][10][11][12][13][14]. Thus, intensive deformation of coarsegrain copper causes significant change of grain sizes at low pressure and low strain rate.…”

“…The second part in equation (3), on the right, takes account for temperature annealing or annihilation of dislocations for time of temperature relaxation τ a ; Θ -the Heaviside function (Θ = 0 at f < f a and Θ = 1 at f ≥ f a ). Experiments with study of change of material properties after effect of high-rate deformation and shock waves are used for determination of functions ϕ(ε i ), τ a [9][10][11][12]. Table 1.…”