Stress singularities at triple junctions with freely sliding grains

Stress singularities at gain triple junctions due to freely sliding grain boundaries in idealized two-dimensional single-phase polycrystals have been analyzed. The shear stress is assumed to be completely relaxed along the grain boundaries while the normal stress is allowed to be fully transmitted. The singularity exponent was found to be independent of the elastic constants of the grains, and for some triple junction configurations, super-singularities (i.e., stronger than the standard -0.5 as found at the tip of a crack in homogeneous material) were obtained. Interestingly, for most geometrical configurations, the solution structure indicates a fixed mode near the triple junction, irrespective of the far-field load combination.