Dust fragmentation velocity as a function of temperature. At temperatures ≥ 180 K, the dust fragmentation velocity is 1 m s⁻¹, corresponding to the value that was found for silicate grains (Poppe et al. 2000). In the icy regions we test larger values, as found for water-ice grains by Gundlach & Blum (2015). We probe values of 5 and 10 m s⁻¹. In the temperature range of the water-ice line transition (grey area), a simple sine connects the dust fragmentation velocity values.