Finite element simulation of the stretch forming of annealed aluminium sheets

The formability of a material is an important consideration in the design of manufacturing processes for that material. Finite Element Analysis (FEA) allows for the relatively rapid and inexpensive determination of material formability and reduces the number of experiments needed to be performed. The validation of a finite element model against established forming experiments, which cover all deformation modes, allows the modelling of more complex components. In this study, aluminium is used to provide a point of reference for the simulation of material forming. Aluminium is one of the candidate materials considered for reducing the weight of automobiles. Experimental specimens were tested and an open die configuration was used in order to facilitate measurement of the surface strain using the ARAMIS three-dimensional strain measuring system. The forming of these experimental aluminium specimens that were stretched over a hemispherical punch was then simulated using ABAQUS/Standard. In order to develop a complete model of the forming behaviour, specimens of varying geometry were assessed to obtain deformation behaviour in the aluminium ranging from uniaxial tension to biaxial stretch. The evolution of strain throughout the forming process was analysed and compared to finite element simulations. The forming limit diagram and the surface strain contours were also compared to the finite element model. Excellent agreement was found between the experimental results and the FEA. This demonstrates that complex components that experience a combination of deformation modes can be simulated using FEA.