Incremental sheet forming process of an AA3003-H12 part: Simulation study and experimental validation

Abstract

A three-finite element model to simulate the single point incremental forming (SPIF) of AA3003-H12 parts is developed. Tool motion in the simulation environment and the CNC milling machine is controlled using new protocols developed especially for SPIF process of pyramidal parts. Numerical measured part thickness and geometry are found to best agree with the experimental ones. Due to the lack of tools, enabling a proper selection of numerical factors to overcome computation convergence problems and product conformity error, trial and error method is applied alternately and proves to be effective. Thickness distribution, equivalent stress distribution, finite element size and friction coefficient effect on the final thickness distribution, geometric profile and computation time are studied. In order to understand the failure and fracture mechanisms in the produced part, the stress state, thickness and equivalent stress history at the thinned finite element are equally studied. Results show a critical thinning occurs at the part corners more dramatic than in the walls. Equivalent stress presents great values first at the part corners and second at the fillets. Failure areas do not coincide with fracture ones due to different deformation mechanics. The increase of the finite element size increases the thickness and the geometry error, but reduces significantly the computation time. The friction coefficient does not significantly affect the thickness and geometry, leading to a significant computation time reduction.