An attempt has been made to modify the original version of the Aage Winther 1995 (AW 95) potential by adding a Gaussian positive part as VRexp(-br2) to investigate the effect of the repulsive cores in the sub-barrier fusion cross sections. In order to achieve this goal, we select and evaluate 6 heavy ion fusion reactions with 392≤Z_1 Z_2≤784 (including 58Ni+54Fe, 58Ni+58Ni, 64Ni+64Ni, 16O+208Pb, 28Si+64Ni, 28Si+100Mo). The obtained results reveal that the original version of the AW potential supplemented with Gaussian positive part has been successful in reproducing the fusion excitation data for various considered systems.