  In this work we study shear reversals of dense non-Brownian suspensions
composed of cohesionless elliptical particles. By numerical simulations we show
that a new fragility appears for frictionless ellipses in the flowing states,
where particles are able to flow indefinitely in one direction at applied shear
stresses but shear-jams in the other direction upon shear stress reversal. This
new fragility, absent in the isotropic particle case, is linked to the
directional order of the elongated particles at steady shear and its
reorientation at shear stress reversal, which forces the suspensions to pass
through a disordered state in which it might get arrested.
