Numerical modeling and experimental validation of axially loaded slender sandwich panels with soft core and various rib configurations

摘要

In this paper experimental and analytical investigations of axially loaded sandwich panels are presented. Large scale slender panels with and without ribs were tested. A robust analytical model applicable to panels of various slenderness ratios was developed. It accounts for geometric non-linearity through a rigorous P-Delta analysis, including the initial out-of-straightness profile and end eccentricities. The excessive shear deformation of the soft core and its effect on the overall stiffness and global buckling is accounted for. Additionally, the model detects localized skin wrinkling or crushing. The model showed reasonable agreement, within 20%, with test results for strength and stiffness and was used in a parametric study. It was shown that the addition of a longitudinal rib connecting the skins at mid-width resulted in 180% increase in axial strength, by changing failure mode from skin wrinkling to global buckling. Adding longitudinal external ribs to the internal one changed failure mode to skin crushing and increased stiffness by 40% but did not enhance strength. Axial stiffness and strength also increased as skins or ribs became thicker, or their Young's modulus increased, or as core shear modulus increased, however, failure mode varied depending on length. As the amplitude of out-of-straightness increased, failure load always reduced, weather governed by global buckling or skin wrinkling. (C) 2016 Elsevier Ltd. All rights reserved.