Numerical analysis of a backward flow forming operation of AA6061-T6 and comparison with experiments

Incremental forming processes can be used to produce thin products (tubes or sheets)[1]. Very high deformation of the material can be reached taking advantage of the local and cyclic loading of the material. In this study we will focus on backward flow forming of aluminum tubes. In this process, tube thickness is reduced by the combined action of a rotating mandrel that imposes the inner radius and 3 rollers that decrease progressively the tube thickness. An experimental campaign is conducted on a laboratory device to study the influence reduction rate. The corresponding configurations are simulated to understand the mechanical loading path. The material characterization is presented to focus on the influence of the chosen behavior law on flow forming simulation results. Different damage criteria coming from the literature are studied to evaluate their capability to predict fracture and to compare the amount of damage reached for each process configurations. Even if none of them is able to predict accurately damaging configurations, the classical Cockroft and Latham seems to be the only capable to reflect the hierarchisation of configurations.