Numerical and Experimental Study on Hydroforming of Thin Metallic Sheets

Hydroforming uses controlled fluid pressure to form the sheet metal to the shape of the die. With reduced friction, precise tolerance and single operation allowing a high drawing ratio make it much more preferable than other forming processes. It is also much suited for small irregular contoured parts to be manufactured for prototype and experimentation purposes. In this work, a miniaturized experimental set-up of the hydroforming process has been fabricated by designing, fabrication of a die, and the experimental set-up. Hydroforming was performed on Al6063-T6 sample sheets of 95 × 95 mm dimension and 0.5 mm thickness. The pressure was applied using a commercial-grade hand pump, in increments of 10 bars until failure occurred. The obtained sample profiles were analysed using a Zeiss Contura X2 CMM (coordinate measure machine) and profile projector. Additionally, a finite element (FE) model of the hydroforming set-up has been developed using 2D simulation in COMSOL Multiphysics. The 2D model has been preferred due to its greatly reduced computational expense compared to a full 3D model. The FE model has been used to obtain deformation across the sheet, depth of compression, and percentage formability for the various pressure of the fluid, until failure. Measurements from the numerical simulation and experiments were correlated, and it was found that the samples were only able to withstand a pressure of 170 bar and beyond that ductile–brittle mixed type, fracture occurred. A good range of formability was observed around 120 bar pressure.