torsion in microstructure hollow thick-walled circular cylinder made up of orthotropic material

In this paper, a numerical solution has been developed for hollow circular cylinders made up of orthotropic material which is subjected to twist using micro polar theory. the effect of twisting moment and material internal length on hollow thick-walled circular cylinder made up of micro polar orthotropic material is investigated. finite difference method has been used to exhibit the influence of shear moduli and material internal length on shear stresses and couple stresses. it is found that the effect of small characteristic length on shear stresses is negligible and couple stresses present its significance when characteristic length is large in solid particle. the behavior of couple stresses are nonlinear for large internal length while for small internal length couple stresses are linear in nature except near the free boundaries. torsion in hollow cylinder made up of micro polar orthotropic play vital role in the presence of cracks and holes. therefore, torsional analysis of hollow cylinder plays important role in the field of biomechanics.