Some convexity considerations for a two-dimensional traction problem (Q1102777)

A rectangular strip, consisting of homogeneous, isotropic, elastic material, is in an equilibrium state of plane stress, due to actions applied to a pair of opposite edges, the remaining pair being traction- free. The convexity of certain cross-sectional measures of stress is established; and a generalized convexity property is also established for one such measure, leading to an explicit decay estimate for the measure in the case of a semi-infinite strip, one end of which is subjected to a self-equilibrated load.