Dove-Tail Tack Block Design Colin Narug 6/27/2019

Tack Block Tack blocks used as a base to weld shell to cold mass While there will be a pre-stress in the shell design if misalignment occurs that removes the pre-stress, can the structure survive this loading condition? 10/22/201910/22/2019

Previous Work Previous work by Bob Wands and Heng Pan have shown issues with tack block. When thermal contraction occurs, displacement will cause high stress in tack block Slots added to allow for deformation Expensive to make and does not work well Slack in connection helps, does not fix major issues 10/22/201910/22/2019 H. Pan, “Stress Analysis on Tack Blocks with Axial Compliance”, LBNL

Current Design A majority of the stress in the tack block occurs due to thermal contraction To absorb the deformation, the tack block was broken into two pieces Connected through a dovetail joint To prevent galling, a coating will be used Hard Chrome Plating or similar coating Tolerances on connection still in progress Will need to be tested Fixed tack block will be used on both cold masses 10/22/201910/22/2019

Slot to allow for airflow/gas flow Current Design Dovetail Connection Bolts attached to lower piece, slot to allow for access prior to welding Slot to allow for airflow/gas flow 10/22/201910/22/2019

Simulation Setup Two loading conditions used for simulations Centered and Offset Positions Loads from another simulation to determine how the cold mass is distributed across blocks Largest values used 10/22/201910/22/2019

Simulation Results, Tack Block 10/22/201910/22/2019

Simulation Results, Offset Tack Block 10/22/201910/22/2019

Simulation Results, Thin Tack Block 10/22/201910/22/2019

Simulation Results, Offset Thin Tack Block 10/22/201910/22/2019

Cold Mass Behavior When cold mass is offset from shell, tack blocks will be only connection Under just the effects of gravity, the shell will deform less than 1 mm If contact is not reestablished, during the shipment of the cold mass, the shell and/or the tack block will fail 10/22/201910/22/2019

Summary Tack block is sufficiently strong to survive normal operation Conservative loads used If tolerance is significantly off on the magnet shell, the structure will fail in shipment Critical failure, significant bends in shell Shell is not designed to be load bearing Deformation of shell under 1g load will cause deformation which will reengage contact with cold mass body and the shell Due to the weight of the cold mass, assuming the shell is not significantly out of tolerance, the magnet will remain in contact with the bottom of the shell 10/22/201910/22/2019