Deformation behavior of thin-walled tube bending with internal pressure

To clarify the deformation behavior of thin-walled tube under combined bending and internal pressure, the hydro-bending experiments of aluminum alloy 5A02 thin-walled tubes with internal pressure ranged from zero to 1.33 times of yield pressure of the tube are carried out. Combined with the numerical simulation, the effect of the internal pressure on the section flattening, wall thickness distribution, and the bending limit of the thin-walled tube are studied. It is shown that even a small value of internal pressure enhances the section stiffness of the thinwalled tube and delays the cross-section flattening. The non-circularity decreases rapidly at the beginning and the decrease rate goes down with internal pressure increasing. The stability and the bending limit of the thin-walled tube are improved evidently with internal pressure increasing. The axial compressive stress magnitude at the intrados decreases gradually as the internal pressure increases, which is beneficial to the prevention the instability and winkling defect.