  Visco-energetic solutions have been recently advanced as a new solution
concept for rate-independent systems, alternative to energetic
solutions/quasistatic evolutions and balanced viscosity solutions. In the
spirit of this novel concept, we revisit the analysis of the variational model
proposed by Francfort and Marigo for the quasi-static crack growth in brittle
materials, in the case of antiplane shear. In this context, visco-energetic
solutions can be constructed by perturbing the time incremental scheme for
quasistatic evolutions by means of a viscous correction inspired by the term
introduced by Almgren, Taylor, and Wang in the study of mean curvature flows.
With our main result we prove the existence of a visco-energetic solution with
a given initial crack. We also show that, if the cracks have a finite number of
tips evolving smoothly on a given time interval, visco-energetic solutions
comply with Griffith's criterion.
