Electro-mechanical properties of PIT Nb3Sn wires under transverse stress: experimental results and FEM analysis

Nowadays there is a great deal of interest in the scientific community in developing next-generation accelerator magnets based on high-Jc Nb3Sn Rutherford cables. Inside a cable the wires are subjected to the combined effect of axial and transverse load. Since Nb3Sn is a strain sensitive material, electromechanical characterization of cables is essential for magnet design. Testing a full-size Rutherford cable is an extremely complex and involved task. For this reason special Walters springs have been developed at the University of Geneva to test single wires under longitudinal and transverse load. In this work we analyze three PIT wires under transverse compressive load. To better understand the experimental results, a finite element model was developed. This model enabled better understanding of the mechanical behavior of the three samples and investigation of the mechanisms that determine wire performance degradation upon loading.

[1]  L. Chiesa,et al.  Transverse stress effects in ITER conductors , 2005, IEEE Transactions on Applied Superconductivity.

[2]  N. Mitchell.  Finite element simulations of elasto-plastic processes in Nb3Sn strands , 2005 .

[3]  J. Ekin.  Effect of transverse compressive stress on the critical current and upper critical field of Nb3Sn , 1987 .

[4]  Y. Nabara,et al.  Strain and Magnetic-Field Characterization of a Bronze-Route ${\rm Nb}_{3}{\rm Sn}$ ITER Wire: Benchmarking of Strain Measurement Facilities at NIST and University of Twente , 2012, IEEE Transactions on Applied Superconductivity.

[5]  L. Bottura,et al.  Critical Current Measurements of High-$J_{c}$ $\hbox{Nb}_{3}\hbox{Sn}$ Rutherford Cables Under Transverse Compression , 2014, IEEE Transactions on Applied Superconductivity.

[6]  H. T. ten Kate,et al.  Critical current degradation in Nb/sub 3/Sn cables under transverse pressure , 1993, IEEE Transactions on Applied Superconductivity.

[7]  P. W. Bridgman.  Studies in large plastic flow and fracture : with special emphasis on the effects of hydrostatic pressure , 1964 .

[8]  C. Senatore,et al.  Toward a standard for critical current versus axial strain measurements of Nb3Sn , 2012 .

[9]  G. Nishijima,et al.  Effect of transverse compressive stress on internal reinforced Nb3Sn superconducting wires and coils , 2004 .

[10]  A. Nijhuis,et al.  Effect of periodic cyclic deformation on the voltage current transition of Nb/sub 3/Sn strands tested in the novel 'TARSIS' setup , 2004, IEEE transactions on applied superconductivity.

[11]  T. Boutboul,et al.  Transport Properties up to 1000 A of ${\rm Nb}_{3}{\rm Sn}$ Wires Under Transverse Compressive Stress , 2007, IEEE Transactions on Applied Superconductivity.

[12]  Xi Xu,et al.  Testing and Demonstration of a 10-kA HTS DC Power Cable , 2014, IEEE Transactions on Applied Superconductivity.

[13]  C. Senatore,et al.  Effect of quasi-hydrostatical radial pressure on Ic of Nb3Sn wires , 2012 .

[14]  K. Tanabe,et al.  Exploration of new superconductors and functional materials, and fabrication of superconducting tapes and wires of iron pnictides , 2015, Science and technology of advanced materials.

[15]  D. A. Finley,et al.  Measurement of mechanical properties of three epoxy adhesives at cryogenic temperatures for CCD construction , 2006 .

[16]  J. Ekin.  Strain dependence of the critical current and critical field in multifilamentary Nb 3 Sn composites , 1979 .

[17]  C. Senatore,et al.  Extensive Characterization of the 1 mm PIT ${\rm Nb}_{3}{\rm Sn}$ Strand for the 13-T FRESCA2 Magnet , 2012, IEEE Transactions on Applied Superconductivity.

[18]  T. Boutboul,et al.  Transport Properties of a PIT- ${\hbox{Nb}}_{3}{\hbox{Sn}}$ Strand Under Transverse Compressive and Axial Tensile Stress , 2008, IEEE Transactions on Applied Superconductivity.