Experimental and numerical optimization of variable stiffness tensile coupons with a hole for maximum stiffness

Anisotropic stiffness properties of carbon fiber-reinforced polymer composites (CFRPCs) can be designed by arranging the fiber path. In this paper, we propose a novel method to optimize the fiber path using the genetic algorithms (GA) and simulated annealing algorithms (SAA) combined with the quasi-uniform cubic B-spline curves. The optimization goal is to obtain the largest reaction force of an open-hole plate under uniaxial tensile loading. After the finite element method (FEM) and experimental verifications, the optimized variable-stiffness specimen owes the higher strength and stiffness, compared with the unidirectional one. Besides, the stress concentration can be reduced. One of the key points of this paper is to use the GA and SAA to control the slight data points to optimize the B-spline curve. By reducing the number of optimization variables, the computational efficiency is improved greatly. Moreover, by increasing the interval variables of the B-spline curve, we further improve the accuracy of optimization results. The range of values for the control points can be easily adjusted according to the manufacturing and design requirements. We also compare the optimization results of GA and SAA. Both of them can get the similar optimization results, and the SAA has a better convergence speed and accuracy. The proposed optimization method can be extended for three-dimensional preform and structure design in the future.