Figure 4
Schematic illustration of the shear-band plane predicted by the Rudnicki-Rice instability theory in the principal stress space.
According to the Rudnicki-Rice instability analysis, the strain field will localize into a narrow band, with its normal in the plane spanned by σ1 and σIII which are the largest and smallest principal stress components, respectively. In other words, the shear-band plane is parallel to the second principal stress component, σII. Note that if θ0 = 45°, the shear band follows the maximum shear stress plane, which however is generally not true.
