Abstract: Two-dimensional continuous fiber reinforced ceramic matrix composites are important application materials in the aerospace field. However, the application of such materials is severely constrained by interlaminar fracture. In order to monitor and evaluate the interlaminar mode Ⅰ fracture toughness of materials, the direct current potential drop test (DCPD) of interlaminar mode Ⅰ fracture was carried out. The loading data during the initiation and propagation of interlaminar mode Ⅰ crack and the potential drop data of corresponding measuring points were obtained. The cause of the change of related characteristics was quantitatively analyzed by establishing a force-electric model. The test results show that at the initial stage of the crack, that is, the inflection point of the linear to nonlinear loading curve, the potential drop at the prefabricated crack tip has a smooth-lifting change. With the further expansion of the crack, the debonding and fracture of the fiber are caused, and the uplift curvature is increased on the potential drop curve. When the crack propagation is subjected to resistance, such as Z-pin pull-out and secondary cracks initiation, the uplift of the potential drop curve will be significantly slowed down. Finally, the validity of the proposed force-electric model to explain the above curve changes is proved by the experimental data. The research results have certain guidance and reference value for the application of electrical properties of materials to monitor and evaluate the interlaminar mode Ⅰ fracture toughness.

Key words: ceramic matrix composites, electrical properties, delamination fracture, non-destructive monitoring