A prediction of the stress state in Nb3Sn superconducting composites

The critical current Ic as a function of applied tensile strain depends upon the residual stress state that exists in Nb3Sn bronze-process composite conductors after cooling from the reaction temperature to 4.2 K. This paper presents a simple analytical method to predict the residual stress state and the stress-strain curves of Nb3Sn composites at 4.2 K. The method requires only a prior knowledge of the volume fraction of the composite components and the percentage of Nb converted to Nb3Sn. Experimental results and analytically derived values are compared and good agreement is generally found.