Fiber-reinforced titanium matrix composites (TMCs) offer high specific strength and stiffness and are commonly used in unidirectional components such as turbine shafts and blade rings. During fabrication, fiber fracture may occur, which induces stress concentration in the surrounding fibers and consequently affects the service performance of the composite ring components. In this study, a multiscale macro–micro coupled model was developed, and the cases of fractured fibers were analyzed and classified into two categories, for which the corresponding failure criteria were established. The macroscopic model predicts stress distribution under rotational loading, while the microscopic representative volume element (RVE) model with randomly distributed fibers calculates stress concentration factors (SCFs) k around fractured fibers. This method analyzes the effect of fiber fracture on the limiting rotational speed of composite rings and can be used to guide their engineering applications, ensuring safety under stringent service conditions. Overspeed tests and fracture surface analyses were conducted to understand failure mechanisms. The results show that fractured fibers near the inner diameter significantly reduce the limiting rotational speed of the composite ring (up to 13.34%), whereas those near the outer diameter have a smaller effect (up to 8.86%). Thus, fiber fractures should be minimized during manufacturing, and if unavoidable, positioned away from the inner diameter of the ring to maintain performance.
Yuan et al. (Sun,) studied this question.