Mesoscale Simulation of Shaped Charge Jet Forming and Free Flight Based on B-spline and Domain Interpolation Material Point Method.

• This paper verifies the applicability of BSMPM, GIMP, and CPDI in mesoscale simulating the SCJs. • BSMPM based on cubic and quartic splines is most suitable for mesoscale simulating, whose SCJs are in great continuity with little cavity and small surface roughness. • For SCJs material, the strain evolution is hierarchical and the particle trajectories can be classified as a laminar layer, transition layer, and turbulent layer from outer to the axis, consistent with the grain size evolution. Shaped charge (SC) generates a fluid-like high-speed jet (SCJ) undergoing extremely large ductile stretching without fracture. It is a formidable challenge to accurately track and monitor the mesoscale deformation characteristics of materials using fluid simulation algorithms. To address this issue, the Material Point Method (MPM) is introduced as an efficient particle-based method that discretizes the continuum into Lagrangian particles moving through a fixed Eulerian grid. By possessing all material properties, these particles facilitate tracking throughout the deformation process and enable the implementation of history-dependent constitutive models. Regrettably, the utilization of MPM in the study of SCJ formation is restricted. The objective of this study is to assess the capability of 2D-axisymmetric MPMs in modeling SCJ formation and free flight at the mesoscale, thereby providing valuable guidelines for their application in SCJs. The MPMs employed in this study are based on the B-spline (BSMPM) and domain interpolations (generalized and convected particle domain interpolations in MPM). The numerical results indicate that BSMPM with cubic and quartic splines is the most suitable method for calculating SCJs due to its exceptional continuity and alignment with the experimental data. The mesoscale evolution of particles reveals that the material undergoes impact crushing and tensile tearing, transforming into a low-speed slug and a high-speed jet. The equivalent plastic strain (EPS) in SCJs exhibits a radial expansion from the exterior to the axis in a layered manner. Particles in the outer layer with a thickness of approximately 1/2 exhibit a 'laminar' distribution, while particles near the axis exhibit 'turbulent' distribution and undergo severe deformation. The hierarchical progression of EPS and particle motion traces provides insight into the underlying causes of mesoscale experimental phenomena, such as the axial elongation of voids in the SCJ slug and the radial distribution of the material in three concentric circles. [ABSTRACT FROM AUTHOR]