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This work was pursued to develop and demonstrate in-house capabilities in simulating projectile penetrations using the SPH method. SPH (Smoothed Particle Hydrodynamics) is a numerical method for solving fluid flows by modeling the fluid as discrete particles. Being mesh free, it does not suffer from typical limitations of mesh based techniques like FEA, where moving and distorted grids result in severe non-linearity in governing equation. The current work was of interest to our customers in defense laboratories, who needed a robust and scalable tool for assessing the effectiveness of kinetic penetrators.
The development of SPH solver involves steps like dividing the computational domain into finite number of particles, assigning physical attributes (density, pressure, velocity) to them and then using kernel interpolation to estimate variation of properties in each particle. The kernels depend upon inter particle spacing and the smoothing length. A B-spline kernel was used in all calculations. Artificial viscosity was implemented to model shock waves, which are inherent to penetration physics.
The code was validated against standard cases where 1cm Aluminium / steel sphere at 3.1 km/s impacts 0.2 cm thick Aluminium plate. The predicted values of crater diameter and longitudinal movement of projectile were within 3% of reported values. The code was then applied to a practical penetration scenario of conical kinetic penetrator impacting on a 15O inclined RHA (Rolled Homogenous Armor).