Abstract:The wrinkling behavior in hydroforming of aluminum alloy tubes is investigated by numerical simulation and experiment. Simulation results with folds, dead wrinkles and useful wrinkles produced from three loading paths with different initial pressures are shown and analyzed. It is indicated that accumulation of materials in expanding area by formation of wrinkles is an alternative method for obtaining preforms in hydroforming. The key problem is to obtain "useful" wrinkles instead of "dead" wrinkles. By using this method, the zone of hydroforming process window can be enlarged. The experimental results verify that it is available to the low formability materials such as aluminum alloys and low volume production.

Key words: hydroforming; internal high pressure forming; wrinkling; numerical simulation