Process Simulation and Springback of Vacuum Forming of Double Curvature Reflector Panels with Sandwich Structure Based on Reconfigurable Mold

Abstract

High-precision reflector panels are essential components in millimeter-wave devices, including antenna test ranges, radio telescopes, and radar systems. This study introduces a vacuum forming technique for double curvature sandwich structure panels based on reconfigurable discrete molds. To ensure optimal mold conformity during the forming process, slitting is employed to release forming stresses. Finite element analysis (FEA) using Abaqus software is conducted to systematically investigate the stresses, stiffness, and springback behavior of single-layer aluminum panels before and after slitting. Drawing on principles of elastic mechanics and material mechanics, calculation method for the springback of double-curvature sandwich structure panels after shaping is derived and validated against numerical simulation results. The results show that the established finite element model has high accuracy, with relative errors of 1.51% and 6.08% for the springback of single sheets and sandwich structures, respectively. Numerical simulations further reveal that, while maintaining a stiffness of over 4000 N.mm^‐1, slits effectively reduce forming stresses, with stress components S11, S22, and S12 consistently controlled within the range of -1.5 to 2.5 MPa. Experimental validation confirms that this process effectively controls springback, and final reflector panel surface accuracy achieves 34 um (Root Mean Square, RMS).