Analytical modelling of non-uniform deformation in thin-walled orthotropic tubes under pure bending

An analytical model employing both large displacement and Timoshenko beam theories is presented for tubes with circular cross-sections under pure bending. The resulting equations are solved numerically to simulate the inhomogeneous buckling deformation and the moment-curvature relationships for various tubes constructed from orthotropic materials. Not only is this an advancement on classical Brazier buckling theory, but a significant modal interaction is identified that severely reduces the moment capacity of tubes with particular levels of the shear modulus.