Haoxiang Gao

Knowledge based cloud FE simulation of sheet metal forming processes

The use of Finite Element (FE) simulation software to adequately predict the outcome of sheet metal forming processes is crucial to enhancing the efficiency and lowering the development time of such processes, whilst reducing costs involved in trial-and-error prototyping. Recent focus on the substitution of steel components with aluminum alloy alternatives in the automotive and aerospace sectors has increased the need to simulate the forming behavior of such alloys for ever more complex component geometries. However these alloys, and in particular their high strength variants, exhibit limited formability at room temperature, and high temperature manufacturing technologies have been developed to form them. Consequently, advanced constitutive models are required to reflect the associated temperature and strain rate effects. Simulating such behavior is computationally very expensive using conventional FE simulation techniques. This paper presents a novel Knowledge Based Cloud FE (KBC-FE) simulation technique that combines advanced material and friction models with conventional FE simulations in an efficient manner thus enhancing the capability of commercial simulation software packages. The application of these methods is demonstrated through two example case studies, namely: the prediction of a materials forming limit under hot stamping conditions, and the tool life prediction under multi-cycle loading conditions.

Forming limit prediction for AA7075 alloys under hot stamping conditions

In this paper, the forming limits of AA7075 demonstrators with different initial blank shape under hot stamping conditions were predicted using the developed model, named the viscoplastic-Hosford-MK model. The developed model enables the representation of non-isothermal conditions, changes in strain rate and loading path for AA7075 material. Additionally, the developed model was calibrated using the fundamental experiments including uniaxial and formability tests. To assess the capability of the proposed model, the forming limit of AA7075 with different initial blank shape designs were predicted, and the optimal initial blank shape was verified by applying it to the practical forming of a demonstrator AA7075 component.