Abstract: An elastic plastic finite element method based on incremental theory of plasticity accounting for large strain is made for the prediction of the residual strength of crack stiffened curved panels under biaxial loading. Using the crack tip opening angle (CTOA) as the fracture criterion controlling stable crack extension, the entire process from the initiation of crack growth up to the instability of crack extention is simulated, the residual strength and crack tolerance are presented and some complex mechanics phenomena are found.The results show that the analytic method presented and the fracture criterion adopted are suitable for the residual strength prediction of cracked stiffened structure, the increasing curvature of the cracked stiffened curved panel can change remarkably the stress, strain and displacement field around crack tip and will reduce considerably the loading capability of the cracked stiffened structure.

Key words: residual strength, elastic plastic finite element method, curved stiffened panel, fracture criterion