  We present a continuum model for the propagation of cracks and fractures in
brittle materials. The components of the strain tensor $\epsilon$ are the
fundamental variables. The evolution equations are based on a free energy that
reduces to that of linear elasticity for small $\epsilon$, and accounts for
cracks through energy saturation at large values of $\epsilon$. We regularize
the model by including terms dependent on gradients of $\epsilon$ in the free
energy. No additional fields others than the strain tensor $\epsilon$ are
introduced, and then the whole dynamics is perfectly defined. We validate the
model in controlled cases, and present a couple of non trivial applications.
