Numerical simulation of high velocity impacts on thin metallic targets I and II

Spacecraft encounter various impact phenomena in space, among which orbital debris impacts are of most concern. These impacts occur at a wide range of velocities. Impact velocities from a few hundreds m/s to one km/s are common in geostationary orbit and even occur in low Earth orbit. However, these high velocity impacts are not fully characterised. It’s required to study the shielding performance in order to assess the spacecraft survivability in the event of high velocity impacts. The paper is divided into two parts. Overall it investigates the capability of hydrocodes to simulate high velocity impacts. Particular interest is given to the post-penetration debris cloud characterisation and the material failure mode identification. Three different methods were used to simulate the impact of an aluminium sphere on a thin aluminium plate. The first part, considers analyses performed using a finite element model with element erosion and a discrete element method where the problem is modelled with discrete finite elements with nodes tied with breakable linkages. The second part of the paper considers the same problems with the Smoothed Particle Hydrodynamics (SPH) method using the MCM solver developed at Cranfield University. All three methods showed good agreement in terms of target damage with the available experimental results. However, their performances are different in terms of debris cloud and failure mode characterisation. As a large number of elements are deleted, the element erosion method shows problems in the petaling failure mode representation and doesn’t allow the post-penetration debris cloud to be characterised. In order to be more reliable, the SPH method needs improvements, in particular to avoid tensile instability. The discrete element method allows good representation and identification of the failure modes even if some improvements in the definition of the node linkage failure criterion are requi