Steady state penetration of rigid perfectly plastic targets

Effect of constitutive models on steady state axisymmetric deformations of thermoelastic-viscoplastic targets

“…Ahead of the penetrator nose surface, the elastic-plastic boundary extends farthest for the LB model. The distance 6.8 on the axial line of the elastic-plastic boundary for the BP and BKA models is about the same as that found when the target material is presumed to be elastic-perfectly plastic [10]. Tate [27], by using a solenoid flow model and assuming that a material point was deforming either elastically or plastically, found that the elastic-plastic boundary was located at an axial distance of 6.71, which compares well with the presently computed results.…”

“…Equation (8) is Hooke's law written in the rate form, and is based on the assumption that the strain rate (D) has additive decomposition into elastic (Qe) and plastic (DP) parts. The superimposed open circle on s indicates its Jaumann derivative, which for steady state deformations is given by the right-hand side of (9). We recall that Pidsley [31] used the ordinary time derivative of s in Eqn (8), which is not frame-indifferent, and equals the first term on the right hand side of (9) for steady state deformations.…”

“…Subsequently, Batra and co-workers [10][11][12][13][14][15][16][17][18] have analysed various aspects of the steady state penetration process. The reader should consult the review articles by Backman and Goldsmith [19], Wright and Frank [20], and Anderson and Bodner [21], and books by Blazynski [22], MaCauley [23] and Zukas et al [24] to gain a comprehensive view of the work completed on the penetration problem.…”

“…Thus, each one of the three models predicts a slightly higher value of R t than that given by Tate. For an elastic perfectly plastic target, Jayachandran and Batra [ 10] found R t = 5.96, and that its value depended weakly upon cc We have plotted in Fig. 7 contours of the hydrostatic pressure in the deforming target 12 r…”

“…For each flow rule, the pressure drops off to nearly 3.0 at the nose periphery from its peak value of more than 12 at the nose tip. However, when the target material was modeled as elastic-perfectly plastic in [10], the pressure at the nose tip equalled at most 10 and dropped off to nearly 2.0 at the nose periphery. The consideration of strain-hardening, strain rate hardening, and thermal softening effects has resulted in an increase in the computed value of the hydrostatic pressure.…”