Quantitative optimization analysis of lock-in infrared thermography for characterizing delaminations

In this research, the quantitative identification of the characterization limits of lock-in infrared thermography applied to buried flat flaws in materials is aimed. With this goal, first, a numerical dimensionless model is developed in order to obtain an experimentally unconstrained understanding of the technique. In this frame, the complete thermographic problem is noticeably reduced to a set of dimensionless parameters without lack of generality. Second, after successfully validating the model against experimental data, a global sensitivity analysis is fed with the developed numerical model. As a result, the maximum sensitivity and predominancy ranges are quantitatively identified for each dimensionless parameter, leading to an experimental guideline for optimum thermographic inspection. Coming out from this analysis, the particular suitability of infrared thermography for the quantification of very thin delaminations is demonstrated.