Abstract：Imperfection sensitivity is one of the main problems faced in the design of thin-walled cylindrical shell structures. A knockdown factor is usually used to quantify the degree of sensitivity to imperfections in the cylindrical shell structure. However, most of the existing imperfection sensitivity analysis methods aimed at predicting the lower limit of the shell knockdown factor, and did not consider the influence of different geometric tolerance levels on the shell knockdown factor. Aiming at this problem, this paper proposes a method to determine the knockdown factor of thin-walled cylindrical shells considering the geometric tolerances. The method is based on the worst perturbation load method of multiple points to search for the worst imperfection modes, and obtains the lower limit of the knockdown factor under different geometric tolerances of the cylindrical shell, thereby determining the knockdown factor of the thin-walled cylindrical shell considering the geometric tolerance, and the incomplete reduced stiffness method is used to accelerate the calculation process. The results of the calculation examples show that the knockdown factor determination method proposed in this paper can effectively improve the prediction accuracy of the knockdown factor and eliminating unnecessary safety margins under the premise of ensuring safety and reliability, which has positive effect on structural weight savings. Based on this method, the research on the new knockdown factor design criteria of aerospace structure thin-walled cylindrical shells can be carried out, and can further improve the design of aerospace shell structure and the level of refinement and light-weight.
2022, Vol. 43 
