RHEOLOGIC IMPLICATIONS OF CONJUGATE SHEAR ANGLES

A rheologic theory on conjugate shear angles is proposed based on the maximum lateral displacement rate (MLDR)hypothesis, which states that when compressive or tensile stress is applied to a solid, shear bands are formed in the solid in the orientations that give rise to the maximum lateral displacement rates of the blocks divided by the shear bands.In other words, it is postulated that the sheared blocks are laterally extruded from or fed into the deformation domain at the greatest possible velocity.The merit of this theory is:the sense of shear displacement is reversible.Hence, the same shear bands can be activated in both compressive and tensile stress regimes.In an isotropic model, the angle θ between the driving stress and the shear bands formed is determined by the equation, tan θ=, where n is the power-law index of flow.