Abstract:The plastic deformation process on hydroforming of aluminum alloy tube with rectangular sections was carried out by means of experiment and numerical simulation using solid elements. The stress and strain states of typical points were analyzed. The three-dimensional graphic representation of normal stress was done. The stress locus in the yielding-cylinder was obtained. It is shown that the plastic yielding firstly occurred in the outer layer of the corner. The inner layer of the corner at each end about 1/4 region is the last region which came into yielding. The strain state of the corner is shortened in the thickness direction and elongated in the hoop direction. The plastic deformation firstly occurred in the transition point and the equivalent strain of transition point was the largest all the time. The axial stress of the transition point is tensile stress all the time as the internal pressure increases.

Key words: aluminum alloy; tube hydroforming; rectangular section; plastic deformation; solid elements; normal stress figure; stress locus