Monitoring damage evolution of SiCf/[SiBC]m composites using electrical resistivity: Crack density-based electromechanical modeling

The introduction of Ceramic Matrix Composites parts in civil aeronautical engines requires a thorough understanding of their mechanical behavior. In this respect, a SiCf/PyC/[SiBC]m composite was submitted to room temperature tensile tests with electrical resistance monitoring and acoustic emission recording. The evolution of the electrical resistance as a function of strains was modeled using a network of resistances in series and parallel, with the introduction of locally higher resistances representing potential discontinuities in the material due to matrix microcracks. The evolution of the effective matrix crack density was deduced from the interposed unloading-reloading cycles. A high-quality correlation was found between the measured and predicted evolution of (i) the electrical resistance as a function of strains and (ii) their residual behavior observed upon unloading. A relationship is therefore established between the electrical resistance of the sample and the density of matrix cracks leading to a hindering of mechanical properties.

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