Upper and lower bounds for the maximum shear stress in a configuration
corresponding to a purely distortional deformation originating from a
given undistorted (ground) state are obtained in the framework of pla
ne, isotropic, nonlinear elasticity. The bounds are shown to be expres
sible in terms of the deformation and the boundary traction that is re
quired for maintaining the purely dilatational deformation in the grou
nd state.