Main cause of restenosis after balloon angioplasty is due to the stresses generated in the artery as well as from the stent artery interaction. Understanding the factors that are involved in this interaction, and the ability to evaluate the stresses that are formed in the artery, could help to lessen the number of failures. The goal of the present study is to develop computationally efficient numerical models for estimating the Damage Factor (DF) as the contact stresses, and to investigate their influence upon stent design, artery and plaque parameters. At first the artery was taken as a hollow cylinder with homogenous, linear elastic properties of the material. Later, the artery was taken as a two dissimilar layers model, with non-linear hyper-elastic properties. The variation in the Damage Factor value as a function of the mismatch between stent's and artery's diameters is nearly linear, and as much as the diameter of the artery increases, the Damage Factor for the same mismatch decreases. For arteries with 75% blocking and mismatch of 1mm, the Damage Factor is 3.8.