Two Level Optimization of Fiber-Placed Laminated Cylindrical Shells of Revolution for Closed-Section Rotor Blade Spar Design

Automated Fiber Placement (AFP) is highly automated manufacturing process which allows for varying fiber orientations resulting in variable stiffness structures. Variable fiber orientation can be sought in an optimization framework for favorable structural response. The purpose of this paper is to show how the structural behavior of cylindrical shells changes through the use of fiber placement in the manufacturing of layers of the cylindrical shell of revolution instead of using constant angle straight fiber layers. For this purpose, two level optimization of fiber placed cylindrical shell of revolution is performed. The first step is the stacking sequence optimization. The outcome of the first step gives the optimum fiber angle to be defined at the center of the unwrapped cylindrical shell of revolution. By using the outcome of the first step, reference fiber path is defined in the second step assuming that fiber orientation angle changes in a linear fashion from the center of the laminate to the sides of the laminate and fiber path optimization is done. For the optimization purposes, Particle Swarm Optimization (PSO), a robust stochastic optimization technique based on the movement and intelligence of swarms, is used for both steps. PSO algorithm is written by using MATLAB®. Structural analyses are carried out using the finite element program MSC.NASTRAN®. Sample results presented show that the developed PSO algorithm is very successful in optimizing fiber paths of the laminated cylindrical shell of revolution that is studied in the present study.