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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.
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Figure 1 – NSTX Upper Umbrella Assembly Upgrade Design: Version 4
Figure 2 – Single Segment 3-Strap Assembly Solid Model: Version 4
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.
Merged Volumes Outer-most Lamination Arch Segment with Air Enclosure: Solid Model
Conformal Mesh: Nodes shared at Interface (perfect magnetic coupling) Outer-most Lamination Arch Segment with Air Enclosure: Mesh
Arch Segment w/ Air Magnetostatic Model Results: Current Density (A/m^2)
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)
SOLID186 Stress and reaction force results closely agree with hand-calculated values. Arch Segment w/ Air Static Structural Model Results: von Mises Stress (Pa)
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.