Finite Element Analysis of Cohesive Contact Degradation Effects on Stiffened Panel Buckling

Abstract

Buckling instability is one of critical failure mode in thin-walled structures, particularly in weight-sensitive applications like aerospace engineering. Stiffened panels are commonly used to improve structural stability while maintaining lightweight designs. However, the interaction between panels and stiffeners introduces complex mechanical behavior, especially at their interfaces, where contact conditions significantly influence performance. This study investigates the effect of stiffener-panel contact stiffness properties on the buckling behavior of stiffened panels using numerical simulations. Five variations of cohesive elastic properties (20%, 40%, 60%, 80%, and 100%) were analyzed to evaluate their impact on critical buckling load and post-buckling behavior. Linear eigenvalue buckling analysis identified the lowest critical buckling load (85,537 N for mode 1), which was used as an initial imperfection in subsequent non-linear analyses. The non-linear buckling analysis, performed using the modified Riks method, revealed that cohesive stiffness variations had minimal effect on the critical buckling load (ranging from 112.4 kN to 113.1 kN) but significantly influenced post-buckling behavior. Notably, the 80% cohesive model exhibited the highest ultimate collapse load (243.9 kN), while the 20% model showed a sharp load drop post-buckling. The results suggest that cohesive elastic stiffness property is essential for load distribution but not a primary determinant of buckling resistance. These findings provide insights into the role of interface stiffness in structural stability, aiding the design of more resilient stiffened panels.