The Influence of the Constitutive Parameters of the Target on the Penetration Depth During the Penetration Process of the Long-Rod

This paper focuses on the penetration process of a 93W alloy long-rod into a RHA 603 steel target. Using a combined experimental and numerical simulation approach, the influence of the target' Johnson-Cook constitutive model parameters (yield strength A, hardening modulus B, hardening exponent n, strain rate sensitivity coefficient C, thermal softening exponent m) on penetration depth was systematically investigated. A two-dimensional axisymmetric finite element model was established based on LS-DYNA, and simulation results were verified against experimental penetration depths with an average error less than 1.5%. The influence of each parameter on the dimensionless penetration depth (P/L) was analyzed within a range of 0.5 to 2.5 times their baseline values. To verify the reliability of the results, five velocities within the range of 1200–2000 m/s were selected for repeated calculations. The results show that: 1. An increase in A, B, and C significantly reduces penetration depth, with A having the most pronounced effect (at an impact velocity of 1600 m/s, as A/A0 increased from 0.5 to 2.5, the dimensionless penetration depth decreased by 49.52%; increases in B and C resulted in depth reductions of 17.27 and 16.09%, respectively); 2. An increase in n slightly enhances penetration depth (at 1600 m/s, when n/n0 increased to 2.5, the penetration depth increased by only 6.56%); 3. A increase of m affects the penetration depth in a certain range (at 1600 m/s, as m/m0 increased from 0.5 to 1.5, penetration depth decreased by 8.59%, with its influence saturating beyond 1.5). Furthermore, energy analysis indicates that plastic energy dissipation during target crater formation follows the same trend as the change in penetration depth and is the primary energy dissipation mechanism. This research reveals the intrinsic mechanisms through which key constitutive parameters influence penetration depth by regulating target strength, hardening behavior, and thermal softening effects, providing a theoretical basis for optimizing penetration prediction models and rod projectile design.