  Our knowledge of the strengths of small bodies in the Solar System is limited
by our poor understanding of their internal structures, and this, in turn,
clouds our understanding of the formation and evolution of these bodies.
Observations of the rotational states of asteroids whose diameters are larger
than a few hundreds of meters have revealed that they are dominated by gravity
and that most are unlikely to be monoliths; however, there is a wide range of
plausible internal structures. Numerical and analytical studies of shape and
spin limits of gravitational aggregates and their collisional evolution show a
strong dependence on shear strength. In order to study this effect, we carry
out a systematic exploration of the dependence of collision outcomes on
dissipation and friction parameters of the material components making up the
bodies. We simulate the catastrophic disruption (leading to the largest remnant
retaining 50% of the original mass) of km-size asteroids modeled as
gravitational aggregates using pkdgrav, a cosmology N-body code adapted to
collisional problems and recently enhanced with a new soft-sphere collision
algorithm that includes more realistic contact forces. We find that for a range
of three different materials, higher friction and dissipation values increase
the catastrophic disruption threshold by about half a magnitude. Furthermore,
we find that pre-impact rotation systematically increases mass loss on average,
regardless of the target's internal configuration. Our results have important
implications for the efficiency of planet formation via planetesimal growth,
and also more generally to estimate the impact energy threshold for
catastrophic disruption, as this generally has only been evaluated for
non-spinning bodies without detailed consideration of material properties.
