  The formation of planetesimals requires the growth of dust particles through
collisions. Micron-sized particles must grow by many orders of magnitude in
mass. In order to understand and model the processes during this growth, the
mechanical properties, and the interaction cross sections of aggregates with
surrounding gas must be well understood. Recent advances in experimental
(laboratory) studies now provide the background for pushing numerical aggregate
models onto a new level. We present the calibration of a previously tested
model of aggregate dynamics. We use plastic deformation of surface asperities
as the physical model to bring critical velocities for sticking into accordance
with experimental results. The modified code is then used to compute
compression strength and the velocity of sound in the aggregate at different
densities. We compare these predictions with experimental results and conclude
that the new code is capable of studying the properties of small aggregates.
