In the performance of the experiment, the normal
stress σ*
N for a certain material sample of constant
density at which the shear stress remains constant
throughout the shearing and the material flows at a
constant sample volume is sought. The point with the
associated shear stress (σ*
N, τe) represents the end point of
a yield locus. In all further experiments, pre-shearing is
first carried out at the normal stress σ*
N until the upper
ring of the Jenike shear cell moves from the original
eccentric position into the centric position