Design with Nonhomogeneous Materials—Part II: Torsion of Thin-Walled Prismatic Bars

Abstract

Theories have been developed for the torsion of nonhomogeneous thin-walled prismatic bars of open section and thin-walled tubes. The mechanical response of these members has been shown to be equivalent to the corresponding homogeneous case with the modulus of rigidity replaced by a suitable average of the variable rigidity modulus of the material. These average moduli, which are different for each geometry, are shown to be moments of the variable modulus of the nonhomogeneous material. Interpretations for the average moduli, which would be determined by torsion tests on nonhomogeneous materials, have been considered.