Optimal design of composite sandwich panel with auxetic reentrant honeycomb using asymptotic equivalent model and PSO algorithm

The composite honeycomb sandwich with auxetic reentrant honeycomb (CSP-ARH) is a typical negative Poisson's ratio structure, which has better mechanical properties than composite structure with positive Poisson's ratio. In this study, a 2D asymptotic equivalent model (AEM) based on the variational asymptotic method (VAM) is proposed and used to analyze the vibration and buckling problems of CSP-ARH incorporating CFRP facesheets and an aluminum honeycomb core. After validation with 3D finite element results, a particle swarm optimization (PSO) algorithm is applied to optimize the mesoscopic size of composite facesheets and honeycomb core. The primary objectives of the optimization process involve maximizing the buckling load and natural frequency, minimizing the mass while satisfying specific mechanical properties requirements. Moreover, a few additional optimization iterations are performed to find the optimal shape coefficients of the curved fibers in the CFRP facesheets for variable stiffness composite sandwich panels. The shape of the curved fiber is defined using a cubic polynomial function f(x,y) and is described by a 20 × 20 grid of discrete elements. The results indicate that CSP-ARH with optimal curved fibers shapes exhibit superior performance compared to those with straight fibers, with buckling load and natural frequency increased by 8.18% and 7.09%, respectively.