Stress invariance in plane anisotropic elasticity

Some new results on stress invariance in plane anisotropic elasticity are presented. We show that, for a traction boundary value problem, the stress field in a plane anisotropic elastic body with discontinuous moduli and a variety of interface conditions remains invariant with an appropriate constant shift in elastic compliances. The reduced dependence of stress on elastic constants is then discussed in light of this result. It is also shown that for the same class of interface conditions, the effective compliances of an anisotropic composite undergo precisely the same shift.