Investigation of damage and fracture in inert shell–solid propellant double-layered plates under projectile impact

The response of solid rocket motors to fragment impacts is critical for ensuring their safety in applications such as aerospace propulsion. The damage and fracture characteristics of the double-layer plates, including solid propellant, were investigated through impact experiments using spherical projectiles. The experiments comprehensively captured projectile penetration and the propellant damage process. Particular attention was given to the effects of the impact velocity and inert plate materials on the damage of a double-layer plate. The results showed that the impact velocity of a projectile is positively correlated with the number and velocity of fragments created by impact. Compared with that of the steel plate, the ignition of a carbon fiber plate required a lower impact velocity (approximately 1167–1518 m/s). The variation in impact velocity alters the internal damage mechanism of the propellant from interfacial debonding to particle fragmentation, and the equivalent diameter of the pore area in the propellant samples initially decreases and subsequently increases along the impact direction. Combined with the Lambert and Jonas model, a projectile penetration model using the smoothed particle hydrodynamics (SPH) method was established to quantitatively assess the impact process of projectiles. The model was validated in cases with different projectile impact velocities and inert plate materials. The results indicated that the deviation between the residual projectile velocity in the experiment and the simulated values was within 15 %.