The upper diagram shows the orientation of grains´ long axes with  increasing shear strain at different experimental conditions. The solid black line reflects the rotation path of the long axis of the finite strain ellipse.

A stable grain SPO at angles of 50-60° can be  recognized in all experiments. Thus, the bulk SPO does not rotate above shear strains of 1.7 and all SPO's are more steeply oriented than the long axis of the finite strain ellipse.

In the lower diagram, the b/a (short/long) ratio of the grains is plotted against shear strain for the different experiments. The solid black line shows changes in axial ratios of the finite strain ellipse.

The b/a axial ratios of the grains are much larger than the those of the finite strain ellipse.

In light of these observations, the following question arises: By which mechanism is a steady state grain SPO preserved during continuous sample shearing?