What is structural buckling and how does it affect thin-walled aircraft structures?

Buckling is a sudden instability failure where a structure deflects laterally under compressive or shear loads at stresses below material yield strength. Thin-walled aircraft structures (skin panels, webs) are susceptible to buckling due to their high radius-to-thickness ratios. While local skin buckling between stringers may be acceptable at limit load (post-buckling design), global buckling of the main structure is catastrophic. Stringers, ribs, and frames are designed to divide large panels into smaller sections with higher buckling resistance.