Effect of Fiber Orientation on Grinding Characteristics and Removal Mechanisms of Cf/SiC

Carbon fiber-reinforced silicon carbide ceramic matrix composites (Cf/SiC) ex-hibit advantages such as high-temperature resistance, low density, and high spe-cific strength, making them widely applicable in aerospace, new energy ve-hicles, and other fields. However, their heterogeneous nature and hard-brittle fracture mechanisms lead to poor machined surface quality. To clarify the in-fluence of fiber orientation on grinding characteristics and material removal mechanisms, single-grit scratching experiments were conducted, and a finite element model (FEM) of Cf/SiC composites was established. Two machining di-rections, MA (transverse direction) and MB (longitudinal direction), were de-fined based on fiber orientation, and the effects on normal force (Fn) and sur-face morphology were investigated. A finite element numerical model of Cf/SiC composites was developed, incorporating the mechanical properties of fibers, matrix, and inter-faces. Simulation results revealed that Fn increases with cut-ting depth, and the average Fn magnitude followed the order MB > MA. Cracks propagated along the fiber axis: transverse fibers were removed via wear, frac-ture, and peeling, with some fibers exposed due to brittle matrix fracture; longi-tudinal fibers were re-moved via wear and debonding, primarily influenced by the contact area be-tween fibers and abrasive grits.