A homogenization-based theory for anisotropic beams with accurate through-section stress and strain prediction

Abstract

This paper presents a homogenization-based theory for three-dimensional anisotropic beams. The proposed beam theory uses a hierarchy of solutions to carefully-chosen beam problems that are referred to as the fundamental states. The stress and strain distribution in the beam is expressed as a linear combination of the fundamental state solutions and stress and strain residuals that capture the parts of the solution not accounted for by the fundamental states. This decomposition plays an important role in the homogenization process and provides a consistent method to reconstruct the stress and strain distribution in the beam in a post-processing calculation. A finite-element method is presented to calculate the fundamental state solutions. Results are presented demonstrating that the stress and strain reconstruction achieves accuracy comparable with full three-dimensional finite element computations, away from the ends of the beam. The computational cost of the proposed approach is three orders of magnitude less than the computational cost of full three-dimensional calculations for the cases presented here. For isotropic beams with symmetric cross-sections, the proposed theory takes the form of classical Timoshenko beam theory with Cowper’s shear correction factor and additional load-dependent corrections. The proposed approach provides an extension of Timoshenko’s beam theory that handles sections with anisotropic construction.