Torsion of Polygonal Bar with Core of Different Material

Abstract

The torsion of a compound bar is studied by eigenfunction expansion and collocation. The bar has a regular polygonal cross section bonded with a circular core of different material. It is found that the torque is insensitive to the core size when the latter is less than 0.2 of the maximum dimension. Otherwise, the torque is highly dependent on the core size ratio and the shear moduli ratio of the two materials. The results obtained should be useful in the design of torsion members.