Superconducting Wire Composite Thermal Elastic Analysis And Calculation Of Equivalent Performance

The fusion energy is valued by more and more countries and it tends to be not noly clean but also efficient in our world nowaday,where the resource is not such abundant.The majority fusion reactors are taken placed in the tokamak device,which needs powerful current and magnet and low-temperature environment.So it is important to put the wires into the several-levels construction called CICC(Cable In Conduit Conductors).CICC construction is made of several sub-constructions and the essential subtance is Nb3 Sn composit strand. Nb3 Sn composit strand is sensitive to the strain of the strand and the variable strain can change the critical current and magnet.Therefore, it is of great importance to study the thermotics and mechanics performance of Nb3 Sn composit strand.In CICC construction,the biggest scale can be thirteen meters high and wherein the scale of Nb3 Sn fliament is several micrometers.If we don’t use of the mesomechanics method to get the eqivalent modulus and construct the model directly,the computational work will be ghastly,which will lead us to fail to caculate the result.So the feasible way to solve the problem is to get the every sub-construction eqivalent modulus.Based on the essential performance of Nb3 Sn composit strand,we take asymptotic expansion homogenization method to solve the poperty such as thermotics and mechanics. Asymptotic expansion homogenization is a semi-analytical and semi-numerical method.The distinction between it and other mesomechanics is that it needn’t special boundary condition.What we should do is to use of perturbation to expand many parameters such as displacement, stress, strain, temperature and others. Then exploiting the material’s constitutive relations,wo can got the balance equation about mesoscale parameters.And we can get not only the mesoscale eqivalent modulus and strain,but also the macro-responses. In this paper,because of the cycloidal cross section of Nb3 Sn composit strand, we take the asymptotic expansion homogenization method in cylindrical coordinate system to solve the Nb3 Sn composit strand plane strain problem and we get the substance’s thermal coefficience, elastic modulus, thermal expansion coefficience.When the environment temperature is under 100 K,the effective thermal conductivity ascends quickly,then declines fastly with the temperature improving. In contrast,the effective thermal conductivity remain steadily at the temperature beyond 100 K. And with the temperature improving,the young modulus and shear modulus strenghthen,the thermal expansion efficience opposite.By exploiting the asymptotic expansion homogenization method to caculate the parameters,the work of FEM becomes easy. In addition,this paper also consider the material’s different volume fraction’s effect to the strand’s performance.