An efficient method for postbuckling optimization of composite laminated plates with holes under compression and shear loading

Abstract

Laminated composite plates with hole are commonly used in aeronautic and aerospace structure design, subjecting to the in-plane compression and shear loading. The existing of hole reduces both the in-plane and out-of-plane stiffness and influences the postbuckling behavior of the plate. The structural lightweight design can be further explored when the external load is allowed entering into the postbuckling regime. However, the lamination optimizations to maximize the postbuckling stiffness have high computational burden when the standard nonlinear finite element method is applied in each function call for postbuckling analysis. Thus, we propose a reduced-order modeling method based on the improved Koiter perturbation theory for buckling and postbuckling analysis. The low-scale reduced order model, instead of the full-scale FE model, is constructed and solved to obtain the initial postbuckling response. The postbuckling stiffness is defined to be the slope of the load-end shortening relation curve at the bifurcation point. A multi-start searching strategy based on the gradient-based algorithm is developed to maximize the postbuckling stiffness, efficiently and accurately. Laminated composite plates with different hole sizes, loading conditions and ply numbers, are considered to validate the excellent performance of proposed method.