A novel experimental method for determination of forming limits with generalized non-planar stress state using hydro-assisted incremental forming

Abstract

Several studies have explored analytically predicting forming limits in processes like hydroforming and incremental forming, yet there’s a lack of discussion on effective experimental methods. This paper introduces hydro-assisted incremental forming (HAIF) as a hybrid technique combining incremental forming and hydromechanical deep drawing, resulting in improved formability through simultaneous application of normal and through-thickness stresses. A novel test method is devised based on this process, and forming limits are assessed through both experimental and finite element approaches. The authors' earlier analytical forming limit predictions are scrutinized using experimental tests and simulations, revealing a good match. The study reaffirms that the application of normal and through-thickness stresses enhances formability across various strain paths, especially in plane strain mode.