Reshaping End-of-Life components by sheet hydroforming: An experimental and numerical analysis

Abstract

In this study, a numerical/experimental analysis is proposed to investigate the possibility of reshaping sheet metal-based End-of-Life (EoL) components using sheet Hydroforming (SHF). Returned EoL components are challenging to be reformed, they are usually characterised by high heterogeneity as there are localised thinning areas (caused by the original forming processes), and the overall formability is reduced with respect to the original flat sheet material. The reshaping route was replicated: a deep drawing process was adopted to impart a square feature; subsequently, SHF was performed. The capability of remove the deep drawn feature was analysed with varying Blank-holder force, oil pressure profile and the location of the previous deep drawn feature. A 3D finite element model of the entire manufacturing route was used to analyse the strain paths of the reshaping process. The change in the strain paths when considering a component previously subjected to deep drawing was analysed and discussed in comparison with SHF using an undeformed blank. This study for the first time provides an insight on the reshaping process mechanics as well as attempts at quantifying the quality of the reshaped components. Results revealed that SHF can be successfully adopted for reshaping purposes as it performed well under two analysed aspects: capability of removing the existing feature and imparting a brand-new shape and thickness/strain path analyses (avoiding fracture and excessive thinning). Nevertheless, the developed analyses revealed that reshaping is more challenging than conventional forming and new design rules, identified in the present paper, need to be followed.