The object of the study was a thin-walled sample made from carbon composite. The studied profile was a z-shaped cross section. The aim of the study was a post critical state analysis by the use of four independent destruction initiation criteria. The numerical analysis was conducted in ABAQUS®. The study presents the critical areas of the composite sample and determines the load values at which initiation criteria were met. The post critical state examination was confronted with previously obtained results of the critical state. In addition, the effect of the laminate layer configuration on the stability and load capacity of the structure is shown.