Optimization analysis of NURBS curved variable stiffness laminates with a hole

Based on cubic NURBS curve, the optimization design of the variable stiffness laminates with a hole are carried out. Firstly, the reference trajectory of the fiber prepared by variable angle placement is defined by cubic NURBS curve, and the parameterized expression of variable-angle fiber placement is derived. Secondly, the linear buckling analyses of all constant stiffness laminates with a hole are carried out to obtain the constant stiffness laminates with the maximum first-order buckling load, the +/- 45 degrees placement of the constant stiffness laminates with a hole is replaced by the variable-angle fiber placements. The linear buckling analysis of the variable stiffness laminates with a hole is carried out. Then, the radial basis function is used to build an optimization model to optimize the variable stiffness laminates with a hole. Finally, under the constraints of curvature radius, MATLAB is used to conduct the optimization of variable stiffness laminates with a hole, and the optimal results under different curvature constraints are obtained. The results show that the buckling load coefficient of [+/-<10 (0.1)(0.6)(0.6)53 > ](2sH) laminates is 32.93% higher than that of [45/-45](2sH) laminates. Using cubic NURBS curve to design laminates with a hole can avoid stress concentration and improve the buckling property of laminates with a hole.