Study on the optimization strategy of variable stiffness laminate considering out-of-plane fiber waviness

Aiming at the problem of a large number of out-of-plane fiber waviness defects due to gap/overlap defects formed in the automated fiber placement process of variable stiffness laminate, two optimization strategies of ply offset and cut strategy were proposed to design variable stiffness laminate, and the modeling method considering gap/overlap defects was introduced. According to the characteristics of variable stiffness laminate, the influence of out-of-plane fiber waviness was reflected through the analysis of defect-repeating elements, and the out-of-plane fiber coefficient was proposed to characterize the scale of waviness in variable stiffness laminate. Finally, the bending performance of variable stiffness laminate with different optimization strategies was analyzed. The coefficients of out-of-plane waviness corresponding to the benchmark scheme, the optimization strategy of ply offset method and the cut strategy are 0.83, 0.95 and 0.93. The proposed optimization strategy has an obvious inhibitory effect on the scale of out-of-plane waviness of variable stiffness laminate. The maximum thickness deviation of [±<50/65>]6s variable stiffness laminate optimized by ply offset method is 33%, the corresponding buckling load is 9117.1 N, increasing by 17.6%; The maximum thickness deviation of [±<50/65>]6s variable stiffness laminate optimized by the cut strategy is 50%, the corresponding buckling load is 9716.3N, increasing by 25.3%. © 2023 Beijing University of Aeronautics and Astronautics (BUAA). All rights reserved.