Hydro-assisted incremental forming (HAIF): A formability-enhanced incremental forming process; presenting an experimental method for determination of forming limits with generalized non-planar stress state

Hydro-assisted incremental forming (HAIF) as a hybrid process of incremental forming and hydromechanical deep drawing with enhanced formability resulted of simultaneous exertion of normal and through thickness stresses is introduced in this paper. Based on this process, a test method is invented for experimental and finite element assessment of forming limits under generalized non-planar stress state. Previous analytical forming limit curves predicted by the present authors are evaluated using experimental tests and finite element simulations and good compatibility is observed. It is again confirmed that application of normal and through thickness stresses enhance formability in all strain paths specially in plane strain mode.