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.