Abstract：The interlaminar tensile strength (ILTS) of ceramic matrix composites (CMCs) is a key factor governing their reliability in demanding aerospace applications. Currently, the measurement of ILTS mainly follows the ASTM D6415 standard. However, the modulus ratio required for the calculation in this standard must be obtained through additional experiments, which leads to increased material consumption and testing time. To address this specific issue, this paper proposes a highly efficient testing method based on the four-point bending test and digital image correlation (DIC) technology. First, this paper establishes the strain field of the curved beam during the linear elastic deformation stage using DIC technology. Second, based on the anisotropic curved beam theory, the mapping relationship between the modulus ratio and the strain distribution of the curved beam under four-point bending loads is constructed. Subsequently, the Newton-Raphson method accurately calculates the material modulus ratio to determine the ILTS, with its effectiveness verified through experiments. Simultaneously, Acoustic Emission (AE) is also utilized for real-time monitoring. The acoustic signals are time-aligned with the load-displacement curves and DIC images to accurately capture the material failure process. The experimental results demonstrate that the proposed method can effectively measure the ILTS of CMCs and reveal the interlaminar delamination failure process. Moreover, it is found that increasing the inner fillet radius can alleviate the stress concentration effect, thereby enhancing the overall strength of the curved beam. Conversely, the ILTS decreases as the inner fillet radius increases. This is attributed to the considerably weaker compaction effect of the large fillet. The experimental results indicate that the proposed method can effectively measure the ILTS of CMCs. The AE energy evolution and DIC images reveal that the dominant failure mode of the CMCs curved beam is interlaminar tensile failure. This research offers a highly efficient experimental method for measuring the ILTS of CMCs.
2026, Vol. 47 
