The data of the article“Hole Size Dependence of Open-hole Tensile Mechanical Property of MI-SiCf/SiC Composites”

To systematically investigate the aperture effect in MI-SiCf/SiC composites, open-hole tensile (OHT) specimens (labeled K1–K5) with central hole diameters (D) of 1 mm, 2 mm, 3 mm, 6 mm, and 9 mm were designed. The OHT specimens were of straight strip shape, with a uniform width (W) of 18 mm (i.e., W/D ranging from 18 to 2) and a length (L) of 68 mm. To protect the gripping area and ensure effective clamping by the wedge grips of the testing machine, glass‑fiber‑reinforced composite tabs were bonded at both ends of each specimen. The tabs had a length of 20 mm and a thickness (t) of 1.5 mm. Additionally, an unnotched standard tensile specimen (labeled K0) was prepared to obtain the intrinsic material properties. All specimens were fabricated by laser cutting from composite plates.Open‑hole tensile tests were conducted under ambient conditions of room temperature (23±2 °C) and relative humidity (50±5)%, using an Instron 5982 universal testing machine (50 kN capacity, load accuracy ±1% FS). Specimens were clamped with hydraulic flat‑action grips. Deformation measurements combined a contact extensometer (Instron 3442AVG, 10 mm gauge length, mounted on the specimen side) with a full‑field digital image correlation (DIC) system (VIC‑3D, single‑camera 2D mode). Prior to testing, the specimen gauge section was spray‑coated with matte paint to create a random speckle pattern for DIC analysis. The DIC acquisition frequency was set to 5 Hz.To monitor damage initiation and evolution in real time, an acoustic emission (AE) monitoring system (2CHS PCI‑2) was employed. AE sensors were fixed with silicone grease couplant near the central hole on the back side of the specimen. Acquisition parameters were set to a gain of 40 dB and a sampling rate of 1 MHz. Damage onset was defined as the point where the AE event rate consistently exceeded 50 events/s.The testing procedure was as follows: after specimen installation, a pre‑load of 10 N was applied to zero the DIC and AE systems. Subsequently, under displacement‑controlled loading at a rate of 0.2 mm/min, the test machine’s load‑displacement signal, extensometer strain data, DIC images, and AE parameters (event count, energy, peak frequency, etc.) were synchronously recorded. Loading continued until the load dropped to 80% of the peak load.Fig. 4(a) and (b) compare the nominal open‑hole tensile stress–strain curves and net‑section tensile stress–strain curves, respectively, for the unnotched (K0) specimen and the open‑hole specimens with different hole diameters (K1–K5). The strain data were all obtained from extensometer measurements.Fig. 6(a) illustrates the influence of hole diameter (D) on the open‑hole tensile strength (SOHT) and the net‑section strength (SNS). Fig. 6(b) shows the effect of hole diameter on tensile modulus parameters.Fig. 7 presents the evolution curves of AE peak frequency versus normalized cumulative energy for the unnotched specimen. Fig. S2–S6 display the AE peak frequency versus normalized cumulative energy curves analyzed using the same method for the five open‑hole specimens with different hole diameters.Fig. 10(c)–14(c) show the distribution of S11 along the line connecting the hole edge to the specimen edge, as obtained from finite element simulations.Fig. S7 shows the strain variation along the line from the hole edge to the specimen edge for the five open‑hole specimens (K1–K5) at different stress levels, extracted from DIC strain contour maps.