Static and dynamic analysis of Isogrid Stiffened Composite Plates (ISCP) using equivalent model based on variational asymptotic method

Abstract

The isogrid stiffened composite plate (ISCP) can be used to resist bending and buckling loads while being lightweight. In order to reveal the relationship between structural parameters and static/dynamic behavior, the original geometrical nonlinear problem of ISCP is decoupled into a linear constitutive modeling over the unit cell and a geometrically nonlinear analysis over the two-dimensional equivalent plate model (2D-EPM). The equivalent stiffness, static deformation, natural vibration frequencies and buckling mode of ISCP under different layup configurations and structural parameters are calculated based on 2D-EPM, and verified by comparing with the results of three-dimensional finite element (3D-FEM). The results show that the equivalent stiffness, buckling load and natural frequency of ISCP increase with the increase of stiffener thickness and height, while decrease with the increase of stiffener spacing due to the special structural form. Compared with the orthogonal stiffened composite plate and honeycomb stiffened composite plate, the bending stiffness and buckling load of ISCP are greater. More importantly, the model can effectively improve the calculation efficiency under the premise of ensuring sufficient accuracy, which is very important for the preliminary design of ISCP.