A VAM-based Reduced-Order Model for M-shaped Folded Core Sandwich Plates

The added bonding platform of the M-shaped folded core is expected to address the issue of facesheet-core interface debonding in sandwich plates. A two-dimensional reduced-order plate model based on variational asymptotic method is proposed to investigate the effective performance of the original composite sandwich plate with an M-shaped folded core (CSP-MFC). The effective plate properties of CSP-MFC are obtained by constitutive modeling over the unit cell, and inputted into the two-dimensional reduced-order plate model (2D-REM) for global and local analysis. The novelties of cell tailoring and local field recovery within the unit cell are very important features compared to traditional finite element models and significantly facilitate the engineering analysis of CSP-MFC. By comparing the global and local responses of the 2D-REM with those of the three-dimensional refined plate model (3D-RPM) under various boundary conditions, the accuracy and efficacy of the 2D-REM were validated. In addition, a comprehensive investigation of the structural responses to various parameters, including the layup configuration and core geometric parameters (e.g., opening angle, core height, side length, wall thickness, and form of the folded core), was also performed. It was determined that the CSP-MFC with a layup of ±45°/0°/90°s, a larger opening angle and width of the bonding platform, as well as a smaller side length and core height had the most balanced performance.