NSTX Center Stack Upgrade Workshop Brainstorming on Design Solutions for TF Joint C Neumeyer Jan 22, 2009
Introduction (1) Objective –identify one or more concepts to pursue for TF joint attachment and structural support –take advantage of the synergy and expertise of the group Proposed prize –joint can be named after its inventor (e.g. a “Titus Joint”)
Introduction (2) Criteria –concept must meet technical requirements provide suitable load paths while… –maintaining adequate contact area and pressure for I 2 t of 5 second pulse –respecting stress allowables –accomodating thermal expansion –concept must be reliable not subject to fatigue, wearout, loosening, etc. immune to procedural errors during installation, maintenance, etc. amenable to monitoring and inspection –electrical resistance (assume similar to exisiting system) –fastener tension –concept must be practical accommodate dimensional uncertainty of parts facilitate assembly and disassembly –concept should be economical complexity should be minimized –faciliate engineering analysis –faciliate design and fabrication of parts –faciliate assembly and disassembly
Boundary Conditions OH shall not be trapped on TF* –Joints must be demountable on one end, if not both No permanent features can protrude beyond radius of TF bundle on demountable end(s) Joint shall be fixed, not sliding* Joint shall follow principles for conductor geometry alignment established thus far* –uniform current density lap joint with vertical current flow resulting in inward magnetic force –constant cross section, current density and temperature rise up to outer leg flag connection –constant tension shape between inner and outer leg flag connections –TF current following OH flux pattern to minimize out-of-plane Joint shall interface with existing TF outer legs Modification of top/bottom umbrella covers and/or increase in +/- z dimension is allowed *negotiable but preferred boundary condition for this discussion
Design Conditions (1) L ~ -.039” (12 o C) ” (100 o C) LL F flex F flex ~ 42.75kN 9610lbf In-plane F rad F rad ~ 0 < F ≤ 500kN/m 0 < F ≤ 2855lbf/in (e.g lbf for 6”) P rad ~ 0 < P ≤ 21kN/m 2 0 < P ≤ 1700psi (based on width = 1/36 of bundle circumference) F rad can nullify F flex_r
Design Conditions (2) Out-of-plane F ~ +/- I oh F ~ k I pf OH force can be in either direction relative to PF
Electrical joint region (0 ~ 100% current heated by Rcu + Rjoint) 100% current, hot Zero current, cold 100% current, hot Current Flow Regions
Electrical joint region requires P > 2ksi, avoid reducing conductor CSA or contact area*, requires thermal displacement Possible collar attachment region but avoid reducing inner leg conductor CSA, requires thermal displacement Structural attachment region for IP Principles of Attachment & Support Allow for water passage and connections Flex allows thermal Z, eliminates IO/OOP moments on flag, but requires OOP support Umbrella connection to outer VV load path for torsion LOCK INNER LEG TO FLAG, DECOUPLE FLAG FROM OTHER LOAD PATHS!! Structural attachment region for OOP * may be tolerable, TBD
Shear Bolt Connection w/o Collar
Double Shear Bolt Connection w/o Collar Only if bolting in contact region is acceptable!!
Locking Insert Connection w/o Collar
Shear Bolt Concept Locking Insert Concept
Shear Bolt Connection w/Collar
Prior Collar Designs Original 2003 Designs (never implemented)
“Advanced” Collar Concepts Shear Pin CollarFriction Collar
Earlier Concept