Assessment Of Numerical Simulations for Hypervelocity Impacts Of Space Debris

Abstract

The Japanese Experiment Module (JEM) and the Centrifuge Accommodation module (CAM) developed by JAXA are manned pressurized modules used as research laboratories on orbit and planned to be attached to the International Space Station. Numerical simulations were conducted using the SPH (Smoothed Particle Hydrodynamics), Euler and Lagrange techniques to simulate hypervelocity impacts on the JEM debris shields. In the simulation, we found the phenomenon in the SPH method that the total energy of the system decreased when the Debris Cloud started to impact to the Pressure Wall. We need to know the cause of the phenomenon and take care of it when using SPH technique to simulate Hypervelocity Impacts. The numerical simulation techniques of the SPH, Euler and Lagrange methods are compared and evaluated in their comparative accuracy. As to the SPH method applicability in the range of “Vaporization Velocity Range (VVR)” where the impact velocity is more than around 7km/sec and the Debris vaporizes after the impact to the Front Bumber, there is possibility that the damage of the Pressure Wall in the simulation is severer than the actual damage, while the damage in “Non-Vaporization Velocity Range (NVVR)” can be simulated well. It is concluded that the SPH method cannot simulate the conservation of internal energy correctly when the density of the particles of the Debris Cloud decreases after the impact to the Front Bumper.