Torsion of Nonhomogeneous Anisotropic Bars

This technical note presents the finite element solution for the St. Venant's torsion of nonhomogeneous and anisotropic sections. The mathematical formulation is based on the stress function. In this analysis, the curved, isoperimetric, quadrilateral element with cubic displacement variation has been used instead of simple triangular or quadrilateral elements. The use of the higher order elements has several advantages, including its versatility in mapping the difficult but real configurations involving curved boundaries, better accuracy, and less effort in the preparation of data for the computer program due to the use of fewer elements. Several examples are presented to show the advantages.