Concurrent stacking sequence and layout optimization of stiffened composite plates using a spectral element method and an index-based optimization technique

Stiffened composite panels are increasingly used in aerospace, marine, and automotive industries due to their lightweight and high-strength properties. However, determining the optimal stacking sequence and/or layout of stiffeners concurrently while adhering to manufacturing guidelines and empirical rules is challenging. To address this issue, we propose a novel one-step optimization framework that couples a highly accurate and computationally efficient spectral element modeling technique with an index-based optimization approach that inherently satisfies the manufacturing guideline and empirical rules. Spectral element modeling (SEM) combines the high accuracy of spectral (meshless) methods with the geometric flexibility of finite element methods. To determine the optimal design, an index-based optimization is proposed to decrease the number of design variables and remove the constraints. We demonstrated the accuracy and computational performance of SEM with results obtained by finite element analysis on composite laminates with and without a cutout. Finally, we applied the proposed optimization framework to various stiffened composite (balanced and symmetric) laminates of up to 200 plies to demonstrate its capability and efficiency.