Prediction of crack location and propagation in stretch flanging process of aluminum alloy AA-5052 sheet using FEM simulation

The stretch flanging process is significantly affected by various geometrical, material and process parameters. The punch-die clearance and initial flange length are main parameters which have major effects on the edge crack location and strain distribution along die profile radius in the flange. Non-axisymmetric stretch flanging process of AA-5052 sheet metal blanks was carried out by numerical simulation to predict the deformation behavior of flange, location and propagation of crack in flange and to investigate the effect of punch die clearance, flange length, die and punch profile radius and friction in the stretch flanging process. The experimental investigations were made to validate the simulations results. The results reveal that the crack length increases with the increase in the flange length. It is found that the flange length has a significant effect in circumferential direction as compared with the radial direction. The punch die clearance has the most significant effect in crack propagation in comparison with flange length. The circumferential strain is found to be larger in the case of punch having the profile radius less than the die profile radius, which leads to faster edge crack propagation. A close agreement is found between simulation and experimental results in terms of location of edge crack and forming load.