Optimization of Air Plane Wing Rib Using Finite Element Analysis

Ribs are the stiffening members in the wing of air plane. Ribs usually have a thin flat plate shape accommodating cutouts, stiffeners and attachments. Most of the time there is a failure of rib due to critical buckling load even though the component is stressed well below the ultimate stress. Hence the rib is designed to carry maximum buckling load. The objective was to increase the critical buckling strength and reduce the weight of the rib. Linear static and buckling analysis were performed on the idealized configuration using FEM packages. Simply supported rectangular plate with different number of inline holes subjected to compression load was evaluated. The material considered was aluminum alloy. Various parametric studies were carried out to arrive at the optimum rib thickness and cross section. Once the optimum thickness of the plate was found out, reduction in the weight of the plate was done by providing various in line circular holes. From the study it was found that inserting circular hole in the plate enhances the buckling strength of the plate. The buckling strength of the plate was increased as the number of holes increased.