Research on buckling characteristics and placement processability of variable stiffness open-hole laminates

Abstract

For variable stiffness open-hole laminates, the buckling characteristics and the placement processability are studied. In this study, the fiber reference path was defined by a linear variable angle function to generate variable stiffness laminates, and the grid density influence on the simulation results was explored. In order to improve the accuracy of the finite element model, a new open-hole laminate modeling method was proposed based on the Python language, and its accuracy of the analysis results and the fiber angle definition were investigated. Compared with classical open-hole laminates with constant stiffness, the buckling characteristics of open-hole laminates with variable stiffness under different placement paths were analyzed. In order to study the influence of the overlap and the gap ratio between the tows on the buckling performance of the laminates, the placement processability (defects of overlap and gap) was considered, and the fiber angle range without tow wrinkles was given. An open-hole laminates with a layer structure of [<0|±45>]2 s is taken as the example to show the distribution of fiber angles, overlaps and gaps. The results indicated that under ideal conditions, the buckling characteristics of most variable stiffness open-hole laminates are better than those of the constant stiffness open-hole laminates, and considering the placement processability of the laminates, the first-order buckling load of the laminates is positively correlated with the proportion of the overlap area, and when the overlap ratio is 50%, the stiffness of the laminates is the largest.