Numerical and experimental investigations on the formability of three-dimensional aluminum alloy sandwich panels with egg-box-like cores

Light-weight sandwich panels are commonly used in various industries to improve the stiffness and reduce the weight of structure component. For many applications, sandwich panels are required as three-dimensional shells rather than flat plates. However, sandwich structures with curved mid-planes are difficult to make at the present time. This paper was focused on the plastic forming operation of aluminum alloy sandwich plate with egg-box-like (EBL) cores and the possibility to produce a three-dimensional panel from an initially flat sandwich plate was investigated. Detailed numerical simulations have been carried out and the deformation characteristics and the forming defects in the plastic forming process were investigated. The formability of EBL-cored sandwich panel was analyzed, and the limit curve for forming spherical panel was obtained. Multi-point forming experiments were carried out and doubly curved panels with positive and negative Gaussian curvatures were successfully achieved without any forming defect; the satisfactory forming quality of the formed product shapes demonstrated the feasibility of using plastic forming technique to form EBL-cored sandwich panels.