Abstract: | The multi-filamentary Bi_2 Sr_2 CaCu_2 O_(8+x)(Bi-2212) round wires are made of superconducting filaments, metal Ag and Ag alloy, which are typical composite structure. Since the filament is brittle, there are various defects and cracks in the Bi-2212 round wire after heat treatment. In this paper, we assume that the filaments in the wire are uniformly arranged. Adopting the bridging model which is often used in the fiber-reinforced composite, we calculate the ultimate strength of the round wire. The effects of the volume fraction, elastic modulus and interface shear strensgth are discussed in detail. |