Mechanics of Nb-Ti Superconducting Composites

Abstract

Nb-Ti superconducting composites with copper matrices have been modeled using solid mechanics and finite element analysis to examine the effects of composite design on the mechanical behaviors of the composite. Input data for the mechanical behaviors of the composite components was determined from extensive measurements of Nb-Ti fibers extracted from composite wires, and mechanical tests of the composite wires. Two models were developed; a three dimensional finite element model to investigate the micro-in-plane mechanical behavior of the composite wire, and an analytical model to study the macro-inplane mechanical behavior of the composite wire. Using symmetry arguments, boundary conditions are established to set the problem as a special case of the mixed boundary problem of elasticity. The influence of several parameters on the mechanical behavior of the Nb-Ti composite was studied and a graphical presentation of the results is made. The conclusions are that the mechanical behavior of Nb-Ti composites is complicated, dependent on the processing, component geometries and properties and how the components are interconnected and mixed to form the composite. The mechanics of the Nb-Ti composite is three dimensional, and in-plane stresses always exist. Although the in-plane stresses are small relative to the applied axial stress, they are potentially more harmful to the performance of the composite than the axial stress.