FEAC

Simulation shows design and coupled multiphysics FE models of Nb3Sn superconducting accelerator magnet for the Large Hadron Collider (LHC) at CERN.

Problem:

The 11T project aimed to create space for additional (cryo) collimators by replacing 8.33 T NbTn dipole magnets with 11 T Nb3Sn dipoles compatible with LHC lattice and main systems.

Challenges include:

  • Iron saturation effects
  • Transfer function matching with MB
  • Coil magnetization effects (conductor development and cable development)
  • Quench protection (heater development)
  • Rigid mechanical structure must accommodate massive forces (almost double the forces that currently installed dipoles experience)
  • Coil fabrication technique (reproducibility and handling)
  • Thermal (resin impregnated coils)
  • Integration (optics, cold-mass, collimator and machine systems)

Solution:

In developing a new methodology for R&D of superconducting magnets, the goal was to combine advanced CAD tools with coupled multiphysics finite element analysis in the integrated design environment of ANSYS Workbench. This method allows:

  • Controlling all used Workbenches from the same platform
  • Easy and safe file management
  • Bidirectional interface and integration of CAD tools
  • Managing and sharing all parameters through a single table shared by all applications
  • Direct linkage and data exchange between Workbenches
  • Possibility to easily explore design space and perform optimization iterations

The parametric design was made in CATIA and all parameters were transferred to ANSYS Workbench. All necessary boolean/body operations and modifications were done in ANSYS DesignModeler. The electromagnetic analysis in was run in Emag (3-D) and ANSYS Maxwell (2-D and 3-D) to compare results with different mesh densities, element types, solution setups and algorithms. The same parameters are shared, in terms of current excitation, geometry, number of strands and turns.

APDL macros were used to transfer Lorentz forces from Emag to the structural analysis. In ANSYS Maxwell, the Lorentz forces were transferred in the structural analysis as body force densities via the direct linkage between the two analyses.

Since the operational temperature of the superconducting accelerator magnet is at 1.9 K, ANSYS Mechanical was used to conduct the 2-D and 3-D thermal and structural analysis, along with APDL macros. DesignXplorer was used to explore the design space. The whole design was optimized.

During the assembly phase of the structure, tests at cryo temperature and powering tests, the results from the FE Analysis were compared with the strain gauges values derived from the data acquisition systems and proved to have excellent correlation.

Business Benefit:

The methodolgy proved to be reliable, fast and convenient. Simulation also led to:

  • New product innovations
  • Improved processes
  • Reliable results
  • Combination of all software and analyses in the same platform
  • Easy file management leading to easy collaboration
  • High-quality final product
  • Rapidly produced optimal solution

Software used:

  • ANSYS DesignModeler
  • ANSYS DesignXplorer
  • ANSYS EMAG
  • ANSYS Maxwell
  • ANSYS Mechanical