Simulation tools are very useful to understand and optimize NDT systems, and particularly the SHM systems. An algorithm has been proposed to quantify the damage detection capability of a fiber optic sensor network, with a finite number of strain measurements. A damage index is obtained by simulation, dependent of the damage size and position, and the number and distribution of sensors, and also of the noise of the signals; by repeating the simulation under random noise, a POD (Probability of Detection) could be calculated. The analysis is applied to a simple representative experiment, a bonded repair patch, under mechanical and thermal loads.