Folks,
The weekly telecon was held with ORNL again this past
Monday. Notes and presentation material are posted at the following
URL:
http://ncsx.pppl.gov/NCSX_Engineering/Meetings/CY-2007/January/070129_MondayTelecon/070129_index.htm
- Reiersen reviewed
progress against our current top-down schedule.
- Gettelfinger reviewed
the results of the preliminary screening of high friction surfaces. His
conclusions were as follows:
G10-on-SS and SS-on-SS
both exhibited a low COF (<0.25)
"Light" versus
"Standard" nickel binder made no change (COF=0.53)
CTD540 was marginally
better than Stycast (COF=0.51 versus 0.46) and easier to use
Larger (12 mil)
diamonds marginally better than smaller diamonds (COF=0.56 versus 0.51) but may
make dimensional control more difficult
CTD540 appeared
marginally better than the nickel binder (COF=0.56 versus 0.53 with 12 mil
diamonds). The diamond coated surface appeared unchanged in the
post-mortem for the nickel binder. The diamond particles appeared loose in
the post-mortem for the CTD540 binder. The relative permeability in the
nickel binder was 1.7-1.9.
Depositing the diamond
coating on a 4mil grit blasted sheet of SS with a nickel binder provided
marginally better performance (0.55 versus 0.53) than the same coating applied
to the thicker bar.
Future screening tests
with focus on using CTD540 (no permeability issues) and smaller (6mil) diamonds
(easier for dimensional control). The configuration issue of using a
separate high COF SS gasket or depositing the high COF material directly on the
shim needs to be addressed. The shear strength of a glass-epoxy joint will
also be addressed in the next round of testing.
- Paul
Fogarty presented a concept
for measuring the eccentricity of a stud in a hole. A gage measures the
minimum wall thickness of the bushing. Once known, a 2" G11CR
bushing can be put in a lathe and taken down to the correct OD. It would
be fitted by press fitting or gluing. The concept was very well
received. He later went out to the test cell to try it out on the actual
coils with the FPA technicians.
- Len Myatt provided an
update on the shear loads in the bolted joint using a nonlinear model with
friction. He concluded that with modest friction, shear loads on the
bolts would be low except for a few holes where a higher coefficient of
friction would be required to prevent motion. When friction is present,
the shear loads take the stiffer friction path.
- The PDR for the
bolted joint has been postponed. A meeting will be held on Friday to [1]
adopt a design methodology and criteria for the bolted joint based on HM Fan's
paper which was circulated for review; [2] determine what additional bolts
will be added and where high COF shims will be installed on the inner leg; [3]
establish a reference bolted joint geometry which is consistent with tool grip
needs for pre-tensioning the bolted joint and providing UT testing to
ascertain the preload; and [4] establishing the material properties to be used
in evaluating bolted joint performance. . These things must be done
prior to assessing the worst-case shear loads and evaluating bolted joint
performance which would be reviewed at the PDR. The PDR is expected to
be held in two weeks around February 14.
- Drawings are needed
to prepare the Stellalloy specimens for the bolted joint tension and shear
tests. The Stellalloy specimens will be cut from the prototype winding
form. ORNL (Williamson) agreed to generate the drawings.
The next telecon will
be next Monday at the regular time and place.
Wayne