Investigation of fracture characteristics in basalt fiber/carbon fiber hybrid composites based on the boundary effect model

In the applications of basalt fiber/carbon fiber hybrid composites (BF/CF HC), tiny surface scratches may occur. When the material is subjected to a certain load, these scratches tend to propagate, which can potentially lead to the fracture or failure of the entire material. This research aims to address the fracture issues in BF/CF HC that have sustained surface scratch damage by investigating their fracture characteristics using the boundary effect model (BEM). Firstly, a non-linear elastic fracture mechanics (non-LEFM) analytical model is established. By considering the thickness of the single-layer “composite” fabric as the characteristic composite unit, fracture parameters of the material are derived from this analytical model. Secondly, the goodness-of-fit of three probability distribution methods for the fracture parameters is compared. Based on this comparison, the normal distribution method is selected to fit the fracture parameters, thereby enabling the determination of the mean values of these parameters along with their upper and lower limits within a 95% reliability range. Additionally, it is observed that as the notch thickness ratio increases, the fracture parameters initially exhibit an upward trend followed by a downward trend. Furthermore, under the same thickness conditions, fracture parameters of large-scale components with shallow surface scratches can be accurately predicted using samples of conventional laboratory sizes.