FRACTURE MODE MIXING AT THE TIP OF CRACKS OF 3D BRAIDED CMC ON THE INTERPHASE

For 3D braided CMC owing to interfacial fracture, it is remarkable that interfacial fracture mode mixing Ψ works on the material fracture toughness. Although the interfacial fracture mode mixing can hardly be determined because its expression involves an uncertain parameter-fracture length eigenvalue, the fracture mode mixing at the tip of crack Ψ_tip, which correlates with Ψ, can be decided uniquely. So the fracture toughness of 3D braided CMC material can be researched on interfacial cracks with Ψ_tip. By numerical simulation, this paper analyses the relation of the mixing Ψ_tip with the declining angle and interfacial thickness, further researches the influence of the 3D braided CMC's cracks path on the mixing Ψ_tip, and finds a way of fracture design of 3D braided CMC.