CRITICAL EVALUATION OF THE FORMABILITY OF AA2024-T3 SHEETDEFORMED BY SINGLE-POINT INCREMENTAL FORMING

Abstract

The evaluation of the enhanced formability in incremental sheet forming processes (ISF), and especially in its simplest variant single point incremental forming (SPIF), has been intensively studied within the sheet metal forming community for the last decade. In general, the formability limit in SPIF is defined by means of the fracture forming limit (FFL). This FFL is usually well above the forming limit curve (FLC), which is the limit controlling failure by necking in conventional sheet metal forming operation on ductile metal sheet. However, low ductility sheet metal such as AA2024-T3 presents usually a fracture-controlled mechanism independent to the forming operation considered. In this context, this paper consist in a critical analysis on formability and failure of AA2024-T3 sheets deformed by SPIF. The study is carried out from a double perspective based on an experimental plan including conventional and incremental forming tests, and numerical simulations using the flow formulation finite element tool DEFORM-3D®. The results show the experimental evidence of a formability enhancement in SPIF above the conventional FFL for this kind of material as well as the necessity of calibrating numerical simulations of these incremental forming processes using experimental data obtained from the corresponding experimental SPIF tests. Keywords: Sheet metal forming, incremental sheet forming (ISF), single point incremental forming (SPIF), formability, fracture.