LAUSR

Abstract This paper presents a rigorous investigation for a two-layered linear elastic half-space containing a cylindrical elastic inhomogeneity with length equal to the thickness of the top layer undergoing forced torsional rotation applied on a rigid circular disc with the same radius as the cylinder, which is welded on the top of the cylinder. To investigate this complicated system analytically, a combination of Fourier sine and cosine integral transforms for depth, respectively in the domain of inhomogeneity and its matrix at the top layer, and Hankel integral transforms for radial distance in the lower half-space as the remaining part of the matrix are used, which translate the related boundary value problem to a system of coupled singular integral equations for the non-dimensional shear stresses resulted from the continuity and boundary conditions. The system of coupled singular integral equations is solved for some collocation points with a smoothed variable of distance, which is adapted with the use of a free parameter. The validities of both the analytical procedure and numerical evaluations are verified with its degenerated case for the homogeneous case, which is the Reissner–Sagoci problem. In addition, the degree of singularities of the shear stresses in between different regions are estimated in terms of material properties of the layer, inhomogeneity, and the half-space. Moreover, some new graphical results are presented for more understanding of related engineering behavior.