Abstract:The hydro-bending of thin-walled aluminum tube was researched by numerical simulation and experiments. The effects of internal pressure and tube ends constraint were analyzed. The stress state of symbol point during bending process was analyzed with tube ends constrain. The results show that wrinkling behavior is lightened when the tube is bent under higher pressure. But if the pressure exceeds the plastic deformation pressure, the tube will be pushed out of the die during the die-closing process. The bending quality is improved with tube ends constraint. The reason is that the inner tensile stress produced due to the constrained tube ends impairs the compressive stress in the inner arc of bending.

Key words: aluminum alloy; hydro-bending; thin-walled tube; constraint; internal pressure