:Continuum damage mechanics (CDM), as one of the new branches of mechanical engineering, is a powerful complementary for fracture mechanics. Microstructure of materials includes some crack and voids. These defects can be created during loading or manufacturing of material. The main goal of damage mechanics is investigation of damage evolution and its effect on the mechanical strength of material. Definition of microstructure defects by continuous fields variable are common practice in all of the CDM models. According to CDM, in the existing constitutive equations, the effect of damage evolution in material is considered as deterioration of mechanical properties such as strength and stiffness. Prediction of rupture modes and estimation of limiting of drawing ratio is a major challenge in metal forming processes. Rectangular deep drawing processes and automotive panel forming will be considered because of their nonlinear strain paths. In this thesis, initiation and evolution of damage has been predicted using Lemaitre’s damage and FLD damage models and limiting drawing ratio has been determined. Lemaitre’s damage criterion has been implemented by Haji Aboutalebi as a subroutine for an elastic-plastic material and plane stress and finite strain theories. Using this subroutine in ABAQUS/Explicit finite element software, damage initiation and evolution is predicted for the above mentioned processes and the results obtained by FLD and Lemaitre models are compared. In rectangular deep drawing process, both models estimate the initiation and evolution of cracks in the corners and edges of the part. Comparing these results with experimental results show that FLD damage model does not predict the forming limit as good as Lemaitre’s damage model. In an automotive panel forming process, both models predict initiation of cracks in the edges of sheet. However according to the FLD damage model, fracture occurred at a lower depth in the formed sheet. In sheet metal forming processes with complex strain paths, the part is subjected to large plastic deformation. This severe plastic deformation leads to high plastic strain localization zones and subsequent accumulation of those strains. Then internal and superficial micro-defects and in another words ductile damage are created. This damage causes quality problems such as fracture. Therefore, design engineers need to accurately estimate the damage initiation and its growth. In this thesis, comparison between theoretical and experimental fracture results show that Lemaitre’s damage model can predict damage initiation, its growth and fracture better than FLD damage model in sheet metal forming processes with nonlinear and complex strain paths. Key words: prediction of damage evolution, rupture, forming limits, formability, nonlinear strain paths