A model for the progressive failure of composite materials that considers the materials' non-linearity was developed and implemented with the Abaqus FE software. An extended Puck failure criterion for the 3D stress state was used for the failure prediction. Furthermore, a simplified approach for the simulation of the delamination was considered. For the progressive failure simulation, the stiffness matrix degradation was used and the degradation parameters were a function of the fracture angle. The model was tested on problems of a pin-loaded composite plate and of a composite tube subjected to compressive loading perpendicular to the tube axis. Keywords: progressive failure, composite, Puck criterion, finite-element analysis Razvit je bil model postopnega popu{~anja kompozitnega materiala z upo{tevanjem nelinearnosti materiala, ki je bil uporabljen v Abaqus FE programski opremi. Raz{irjeni Puckov kriterij poru{itve za tridimenzionalno napetostno stanje je bil uporabljen za napoved poru{itve. Poleg tega je bil uporabljen tudi poenostavljen pribli`ek za simulacijo delaminacije. Za simulacijo napredovanja popu{~anja je bila uporabljena degradacija togosti matrice. Degradacijski parametri pa so bili funkcija kota poru{itve. Model je bil preizku{en na problemu obremenjevanja kompozitne plo{~e s konico in kompozitne cevi, izpostavljene tla~ni obremenitvi pravokotno na os cevi. Klju~ne besede: postopno popu{~anje, kompozit, Puckov kriterij, analiza kon~nih elementov