The effect of MMOD porosity on crater depth after hypervelocity impact

A significant amount of research has been conducted in the last decades on the design of spacecraft shielding for the impacts of Micro Meteoroid and Orbital Debris (MMOD). Through the use of hydrocodes, empirical data, and physical testing, researchers have been successful in studying a wide range of shielding configurations. However, a very limited amount of research has been conducted to understand the effect that the porosity and irregular shape of MMOD has on the damage they create on spacecraft components. The work presented in this thesis addresses the modeling of MMDO porosity by using the CTH hydrocode to investigate the difference in crater depth when comparing a porous projectile and a non-porous projectile of equivalent mass impacting at speeds of 4, 6, 8 and 10 km/s. Projectiles having porosities of 0%, 10%, 20%, 40% and 80% have been modeled for every velocity. Aluminum was the material of choice for both projectiles and semi-infinite plates on every simulation. The results of the simulations showed that a crater depth reduction of 13.7% was observed when comparing an 80% porous MMOD particle to a non-porous particle of equivalent mass impacting at a velocity of 10 km/s. A crater depth decrease of 9.09% and 6.09% were also recorded under the same circumstances at velocities of 8 km/s and 6 km/s respectively. At velocities of 4 km/s the crater depth did not show a clear trend. The work in this thesis shows a practical two dimensional approach to model the damage done by dust particles with various level of porosity. Recommendations for future research have also been made to model these impacts in a more realistic way and with higher fidelity