Effect of shear strain rate on interlaminar shear behavior of 2D-C/SiC composites: A damage transition from notch ends initiation to gauge section initiation

Two-dimensional carbon fiber reinforced silicon carbide composites (2D-C/SiCs) exhibit excellent mechanical properties at high temperature. However, the weak interfacial performance limits range of their applications. In the present work, interlaminar shear strength (ILSS) of 2D-C/SiC was investigated. By using an industrial camera and an acoustic emission (AE) detection system, quasi-static tests at the shear strain rates from 10⁻⁵/s to 10⁻³/s were conducted. Strain contours revealed the damage evolution process. Peak frequencies of AE signals were clustered into three groups, corresponding to matrix damage, interfacial debonding and fiber fracture. Dynamic tests at the shear strain rates of 200/s and 600/s were conducted using a modified split Hopkinson bar (SHPB). The dynamic deformation phenomenon was captured by a high-speed camera. The high-speed images and digital image correlation (DIC) strain contours revealed the damage initiation under dynamic loading. Damage morphologies were observed by a scanning electron microscope (SEM). The real-time images and damage morphologies explained the mechanisms of shear strain-rate effect on ILSS. The proposed experimental method elicited a fresh perspective on designing dynamic interlaminar shear experiments. Moreover, the interlaminar shear performance over a wide range of shear strain rates enhanced our understanding of the strain-rate sensitivity of compressive strength and tensile strength of 2D-C/SiCs.