Modelling and Simulation of Hypervelocity Impacts on Spacecraft in Low Earth Orbit

Orbital debris is an increasing threat to current and future missions in low Earth orbit (LEO), and spacecraft shielding is vital for future space exploration efforts. Experimental hypervelocity impacts (HVI) are expensive and can only be performed at a few laboratories worldwide, making numerical simulations an essential tool in the development and design of debris shields. A debris shield is a sacrificial plate that shatters an impactor into a cloud of particles, distributing the momentum of the impactor over a large area, thus preventing it from perforating the spacecraft. In this study, HVI were modelled in LS-DYNA using a coupled finite element-discrete particle method (FEM/DES), through the *DEFINE_ADAPTIVE_SOLID_TO_DES keyword. The results were compared to experimental data from the literature as well as to simulations applying the smoothed particle hydrodynamics (SPH) method. First, impacts by projectiles with diameter below 1 cm and impact velocities up to 6.7 km/s were simulated to study the debris cloud after perforation of a single plate. Here, aluminium alloy AA6061-T6 was used as both the target and the projectile material. The FEM/DES method was able to predict the shape of the debris cloud as a function of impactor shape, impactor velocity and shield thickness. Then, the FEM/DES method was applied to a dual-wall Whipple shield configuration and was able to accurately describe the damage from the debris cloud on the rear wall.