Identification of diffusion properties of composites materials for aircraft applications

The paper deals with the identification of planar anisotropic diffusion properties of carbon-epoxy composite materials for aircraft applications, based on the exploitation of short-time gravimetric tests. The method consists in performing short time gravimetric tests on composites samples and measuring the initial slope of their mass uptake curve with respect to t. The identification is performed by minimizing the sum of squared residuals, the residual being the difference between the measured slope and the analytical slope. The identification protocol allows determining the 2 coefficients of diffusion along the principal directions of orthotropy and the orientation of the orthotropic frame reference with respect to the sample frame. Analysis and discussion of results allow to propose a robust identification protocol.