NONDESTRUCTIVE THERMAL EVALUATION OF DELAMINATIONS IN A LAMINATE .2. THE EXPERIMENTAL LAPLACE TRANSFORMS METHOD

After initial attempts to identify the delamination parameters of a defective slab (thermal contact resistance and depth) presented in Part I, starting from an experimental thermal contrast curve, a new identification method is presented. The definition of a locally normalized contrast that allows us to process real experiments with the one-dimensional model, together with the calculation of Laplace transforms of this contrast, make the construction of identified contact resistance profiles (rear face) or of identified depth profiles (front face) possible. Results, after processing of transient thermal images produced by thermography, compare well with nominal delamination parameters and with measurement yielded on the same slab by an ultrasonic method. The various advantages of this very fast non-destructive transient thermal testing method are presented.