Influence of internal pressure on hydro-bending of thin-walled aluminum alloy tube

The influence of internal pressure on faults was investigated for a 5A02 aluminum alloy thin-walled tube in hydro-bending process by experiment and finite element method. The effects of internal pressure on wrinkling on the inner arc, cross-section distortion and wall thickness distribution were analyzed, and the thickness variation regularity was achieved. The mechanism of defect was revealed through stress state given by numerical simulation. The results show that the absolute value of axial compressive stress can be reduced by improving the internal pressure, and the wrinkling tendency declines. The wrinkles can be completely eliminated while the internal pressure reaches a critical value, and the critical value is 2.8 MPa for a 5A02-O aluminum alloy tube with an outer diameter of 63 mm and a wall thickness of 1 mm. The cross-section distortion decreases with the internal pressure increasing. The biggest thickness thinning of the specimen appears at the bottom of the outer arc. The axial stress and hoop stress enhance as the internal pressure rises, and the tendency of thickness thinning on the outer arc increases.