The discussion by Lagzdin¸sˇ and Tamuzˇs is deeply appreciated. It introduces interesting points worthy of consideration.

One point made in the discussion is that the microplane model MP1—the first of the three versions of the microplane model examined by numerical simulations— is not equivalent to the $J2$ theory of plasticity if yielding does not occur on the microplanes of all possible orientations, and that the third invariant $J3$ must also influence the response. This is of course true. But this fact was not really contradicted in the paper. Indeed, even though the dependence on the third invariant was not explicitly mentioned in the paper, it was stated below Eq. (5.5) that “after yielding saturation, the performance of this model (ie, MP1) is very similar to that of the usual models of the $J2$ flow theory.” This statement implies that before the yielding...