Finite Element Modelling and Optimisation of Sheet Hydroforming for Cryo-rolled AA5083 Sheets

Abstract

Hydroforming is a manufacturing process that is used to form complex geometries by applying fluid pressure. The punchless hydroforming process is the most popular in the race, considering the absence of any punch that helps in reducing the tooling costs. Based on the part geometries formed, the punchless process can be classified into three categories, namely sheet hydroforming, shell hydroforming and tube hydroforming. Sheet metal hydroforming is a hydroforming process that uses hydrostatic fluid pressure for deforming the blank into a die cavity of the desired shape. Owing to the inert advantages, like lower tooling costs, reduced processing steps, remarkable precision, waste reduction and weight reduction, this process finds extensive use in applications requiring a high strength-to-weight ratio, as in complex automobile parts. The presented work involves the development of a nonlinear 2D finite element model for the sheet hydroforming process of AA5182 (aluminium alloy) using the FE package Abaqus/Explicit and validation of the numerical results using the available literature (Daryl in Logan: a first course in the finite element method. Cengage Learning Products, Canada 2007 [2]). The model is first validated by reproducing the research work carried out by Bharatkumar Modi et al., considering the input parameters, like blank holding force (BHF), sheet thickness and internal pressure, and the corresponding output parameters, like material thickness reduction and die corner radius. The research is further extended by replacing the current blank material AA5182 using cryo-rolled AA5083. The effect of varying BHF, at varying annealing temperature of blank considering varying frictional coefficients, is also studied. This work also investigates the optimisation of the process using a well-established design of experiments (DOE) technique—response surface methodology (RSM).