Fiber orientation and boundary stiffness optimization of laminated cylindrical shells with elastic boundary for maximum the fundamental frequency by an improved sparrow search algorithm

In this paper, a multivariate improved sparrow search algorithm (MCSSA) is proposed for maximizing the fundamental frequency of composite laminated cylindrical shells and preventing vibrational resonance. The mathematical model for analyzing the fundamental frequency of composite laminated cylindrical shells in free vibration is established based on the first-order shear deformation theory (FSDT). A fundamental frequency optimization model for composite laminated cylindrical shells with elastic boundary is formulated, considering the influence of fiber orientation and boundary stiffness, with the objective of maximizing the fundamental frequency. In the optimization process, in response to the shortcomings of the sparrow search algorithm, Piecewise Linear Chaotic Map (PWLCM), tracking learning strategy, opposition-based learning strategy (OBL) and elite retention strategy are introduced for improvement to obtain the MCSSA with better overall performance for model optimization. The effectiveness and applicability of the algorithm improvements are demonstrated by comparing MCSSA with the whale optimization algorithm (WOA), sparrow search algorithm (SSA), and pelican optimization algorithm (POA) using 13 standard test functions and 2 composite laminated cylindrical shell cases. The numerical calculation results show that the shells optimized with MCSSA have higher fundamental frequency. MCSSA is an effective candidate for solving such problems.