Deformation behavior of sheet metals and viscous medium in viscous pressure bulging process with back viscous pressure

Viscous pressure forming (VPF) is a newly developed flexible sheet metal forming process, the viscous medium can be applied on both sides of sheet metal blank to improve the formability of sheet metals. The influence of back viscous pressure on sheet metal forming is one of the key problems. Numerical simulation and specimens analysis for viscous pressure bulging process with back viscous pressure were conducted, effects of back viscous pressure on velocity, strain rate distributions of sheet metal blanks and viscous medium and the tangent adhesive force of viscous medium on sheet metal blanks were analyzed by numerical simulations. Strain distributions of specimens with and without back viscous pressure were compared. The research results show that back viscous pressure is favored in improving the formability of sheet metals.