Abstract: In order to simulate the precise forming of a double curvature panel based on "nails die, vacuum and honeycomb sandwich" by the finite element method, a simplified mechanical model for the two forming phases is established. The forming process for each phase is analyzed by means of the geometrically nonlinear quadrilateral four node multi layer plate element based on a kind of generalized conforming thin plate bending quadrilateral displacement element with public transverse displacement freedom degrees. The geometrically nonlinear equations are solved by the Newton Raphson method combined with the incremental method of load and displacement constraint. The numerical technique in this paper can be applied to the processing simulation and the springback prediction for precise forming of sandwich panels.

Key words: multi-sandwich panel, pr ecise forming, finite element method simulation, r eflector