Abstract: A numerical method was developed to study the delamination onset and growth characteristics during
the post-buckling process for the delaminated composite advanced isogrid stiffened plates subjected to a uniform axial compressive load. A finite element post -buckling analysis model was established based on the first -order shear deformation theory in conjunction with Von-Karman geomet rically nonlinear theory. The total energy release rate criterion combined with the virtual crack closure technique and the self-adaptive grid moving technology were used to analyze the delamination growth process , considering the contact effect of front contours of the delamination. By some numerical examples , the effect s of radius of delamination and rib stiffness upon the delamination growth process were discussed. Comparing the result s between the isogrid and the orthogrid stiffened plates with the same dimensions shows that the isogrid stiffened plate has good resistance ability against delamination onset and growth. The analysis method and conclusions provided in the paper would be valuable to estimate the load capability and optimal design for composite advanced grid stiffened st ructures.