Multiscale Method for Estimating the Thermal Properties of Sandwich Materials Using Infrared Thermography

Characterizing the thermal properties of sandwich materials remains complex because it demands a method that can independently analyze both the thin and thick layers within the same sample. We propose combining flash and step thermography methods with analytical modeling based on the quadrupole method, which allows the thermal response to be reproduced over a period of six orders of magnitude. This approach facilitates the identification of the thermophysical parameters of each layer. The method is applied to two different materials: a two-layer aluminum-cork system and a more complex flax-cork sandwich system, subjected to impacts at different temperatures. The results demonstrate the ability of this joint strategy to improve the estimation of the characteristics of the different layers and to better describe heat diffusion in sandwich structures.