  In the last decade many research efforts have been focused on understanding
the rheology of disordered materials, and several theoretical predictions have
been put forward regarding their yielding behavior. Nevertheless, not many
experiments nor molecular dynamics simulations were dedicated to testing those
theoretical predictions. Here we use computer simulations to study the yielding
transition under two different loading schemes: standard simple shear dynamics,
and self-propelled, dense active systems. In the active systems a yielding
transition is observed as expected, when the self-propulsion is increased.
However, the range of self-propulsions in which a pure liquid regime exist
appears to vanish upon approaching the so-called "jamming point" at which
solidity of soft-sphere packings is lost. Such an "active yielding" transition
shares similarities with the generic yielding transition for shear flows. A
Herschel-Bulkley law is observed in both loading scenarios, with a clear
difference in the critical scaling exponents between the two, suggesting the
existent of different universality classes for the yielding transition under
different driving conditions. In addition, we present direct measurements of
length and time scales for both driving scenarios. A comparison with
theoretical predictions from recent literature reveals poor agreement with our
numerical results.
