The thesis takes an insight look into two different models(two-zone and three-zone models)for describe the deformation and fracture behaviour of the tearing ligament.By earlier works,these two different models based on Essential Work of Fracture approach was proved to be capable for predicting the specific total work of fracture along the tear path across all plastic zones. A comparison of these two models was made based on the results from an early experiment. The investigation was based on two-leg trousers tear specimen with constant pre-crack length. The materials used in this work were PET and a laminate composed of PETG/PET. And a finite element simulation will be presented also to show the stress around the crack tip and the deformation of the tear specimen. The commercial software of ABAQUS will be selected to performance the simulation.