Figure 1 – NSTX Upper Umbrella Assembly Upgrade Design: Version 4

Figure 2 – Single Segment 3-Strap Assembly Solid Model: Version 4

Figure 3 – ANSYS Multiphysics Analysis Block Diagram

Figure 4 – Single Segment 3-Strap Assembly FEA Model: Mesh

Figure 5 – Single Segment 3-Strap Assembly Electric Model Results: Voltage

Fig. 6 – Single Segment 3-Strap Assembly Electric Model Results: Current Density

Figure 7 – Single Segment 3-Strap Assembly Electric Model Results: Joule Heat

Fig. 8 – Single Segment 3-Strap Assembly Thermal Model Results: Temperature

Study: Determine Current Best-Practice to Perform Magnetostatic Analysis in ANSYS 12.0 WorkBench New SOLID236/237 magnetic analysis elements –Have both Magnetic Vector Potential (MVP) and Line Edge method capability. Replaces SOLID97 and SOLID117. –Compatible with WB generated Electric, Thermal, and Static Structural analyses meshes. No 3D MVP or Line Edge contact elements –Requires conformal mesh with shared nodes across the joints, which makes modeling assemblies including frictional and pressure-dependent electric and thermal contact impossible, or –Non-conformal/ dissimilar mesh, with duplicate nodes across the joint. Magnetic coupling using CPINTF command requires nearly-matched meshing, which is difficult to achieve in a large assembly. Above problems are greatly reduced if modeling the air enclosure, and modeling the magnetic coupling across the joints, are not necessary –May be valid for materials with a relative magnetic permeablity = 1. –Goal: Prove with a comparison study.

Outer-most Lamination Arch Segment with Air Enclosure: Solid Model Merged Volumes

Outer-most Lamination Arch Segment with Air Enclosure: Mesh Conformal Mesh: Nodes shared at Interface (perfect magnetic coupling)

Arch Segment w/ Air Magnetostatic Model Results: Current Density (A/m^2)

Arch Segment w/ Air Magnetostatic Model Results: Joule Heat

SOLID236: LINE EDGE METHOD Arch Segment w/ Air Magnetostatic Model Results: Magnetic Flux (Metal +Air)

Arch Segment w/ Air Magnetostatic Model Results: Magnetic Flux (Metal Only)

Arch Segment w/ Air Magnetostatic Model Results: Current Density

Arch Segment w/ Air Magnetostatic Model Results: Lorentz Forces (N)

Arch Segment w/ Air Magnetostatic Model Results: Magnetic Flux (Metal Only)

Arch Segment w/ Air Magnetostatic Model Results: Lorentz Forces (N)

Arch Segment w/ Air Static Structural Model Results: von Mises Stress (Pa) SOLID186 Stress and reaction force results closely agree with hand-calculated values.

SOLID236 LINE EDGE METHOD Arch Segment _No Air - Magnetostatic Model Results: Magnetic Flux (Tesla)

Arch Segment _No Air - Magnetostatic Model Results: Current Density (A/m^2)

Arch Segment _No Air - Magnetostatic Model Results: Lorentz forces (N)

Arch Segment _No Air - Magnetostatic Model Results: Magnetic Flux (Tesla)

Arch Segment _No Air - Magnetostatic Model Results: Lorentz Forces (N)

SOLID186 Stress and reaction force results closely agree with hand-calculated values. Arch Segment _ No Air - Static Structural Model Results: von Mises Stress (Pa)

Conclusion SOLID117 results are not valid, but SOLID236 results using line edge method agree with hand-calculated classic solution values. No difference between results with air enclosure modeled and without. Note: Modeling without air enclosure is valid only for cases where all materials have a relative magnetic permeability = 1.