Erosion efficiency for different velocities of the incoming projectiles. The errorbars have been determined by using 6 randomly generated targets with equal properties. At velocities below 30 ms^-1 the results we obtain when setting T_vis = 1.25 × 10^-11 s (red crosses) agree well with laboratory experiments by Schräpler & Blum (2011) (purple squares). At higher velocities our micromechanical interaction model is probably no longer applicable as plastic deformation of the monomers will play a larger role. For comparison, we show results obtained by increasing the strength of normal damping mechanism introduced in Seizinger et al. (2012) by a factor of 500 (blue crosses).