In the Structural Health Monitoring based on Lamb waves, travelling wave scattered on damage act like secondary sources of perturbed signals. Furthermore the interaction between damage and travelling waves is nonlinear with respect to its dynamics. Based on those facts, linear and nonlinear damage Indexes (DIs) are often used to characterize and monitor such damages. Several levels approaches to modelling damage delamination are investigated on a laminate composite plate structure. First, various parameter ranges are explored on a simplified structure modelling propagation path to evaluate respective appropriate values ranges. Secondly the modelling characteristics are transferred to the model of the complete structure with piezoelectric elements and damage. Finally, various DIs are applied and comparatively analyzed in correlation with damage extent. Results demonstrate that delamination growth can be followed using a normalized version of the total harmonic distortion thanks to the nonlinear interaction between travelling waves and damage.