Finite element modeling of superplastic sheet forming processes. Identification of rheological and tribological parameters by inverse method

International audienceSuperplastic forming is a thermoforming-like process commonly applied to titanium and aluminum alloys at high temperature and in specific conditions. This paper presents the application of an inverse analysis technique to the identification of theological and tribological parameters. The method consists of two steps. First, two different kinds of forming tests have been carried out for rheological and tribological identification, using specific mold shapes. Accurate instrumentation and measurements have been done in order to feed an experimental database (values of appropriate observables). In a second step, the development of an inverse method has been carried out. It consists of the minimization of an objective function representative of the distance - in a least squares sense - between measured and calculated values of the observables. The algorithm, which is coupled with the finite element model FORGE2(R), is based on a Gauss-Newton method, including a sensitivity matrix calculated by the semi-analytical metho