Buckling optimization of variable-axial composite laminates with non-linear geometry

Unlike conventional laminates with constant orientation along with the plate, Variable-axial (VA) laminates have a stiffness that varies according to the coordinate. This type of laminate can have its characteristics improved instability by choosing its orientation properly, improving its efficiency. The objective of this work is to optimize the critical buckling load in VA laminate plate. Due to the difficulty of modelling the VA laminate analytically, it used the finite element method (FEM) with the subroutine for the implicit User Material model (UMAT). For the optimization process, to maximize the critical buckling load, using the genetic algorithm (GA). Better results of the buckling load were obtained using the bilinear polynomial, compared to the biquadratic, bicubic, and linear variation present in the literature considering the restrictions of the manufacturing process Automated Fiber Placement (AFP).