On torsion of random composite beams

Elastic equilibrium of two-phase random composite beams under torsion, with simply and multiply connected cross-sections, is investigated. The analysis is carried out in order to assess the boundary layer effect exhibited by the shear stress field, expressed in terms of the torsional warping function, near the cross-section boundary. The boundary value problem governing the warping function is formulated in variational terms and solved by a FEM analysis. Standard methods of micromechanics are adopted in order to evaluate the eigenstress fields describing cross-sectional elastic inhomogeneities. The shear stress distribution in a beam with equilateral triangular cross-section is numerically evaluated for different microstructures characterizing the elastic phases of the composite material.