Nonuniform torsion analysis in tapered composite bars by including higher-order warping modes.

Abstract

This paper presents a generalized formulation to describe nonuniform torsion in composite bars with variable cross section including higher-order warping modes. In that, the boundary-element subregion-by-subregion (BE SBS) technique is applied to determine the warping modes for cross sections constituted of any number of different materials. The distribution of the nonuniform warping along the axis is taken into account by multiplying the warping modes by derivatives of the associated twist angle functions. A new process based on the weighted residual method is proposed to solve the resulting global equilibrium equations. One also makes generic comments on the solution of the local coupled boundary-value problems (BVPs), which encompasses preconditioned Krylov solvers (embedded in the BE SBS technique), discontinuous boundary elements, and efficient (low-order) quadratures for singular and nearly-singular integrals. Efficiency and robustness of the technique are verified by comparing the present results with highly accurate 3D responses.