From: Horng-Ming Fan
Sent: Wednesday, January 23, 2008 4:19 PM
To: Lewis Morris
Cc: Michael E. Viola; Phil Heitzenroeder; Thomas G. Brown; Arthur W.
Brooks
Subject: RE: Stage2 Coil Lift Calculation

Attachments: Measuring Preload.doc

Lew,

The accuracy of preload by torque is about ± 25%.  Fastener manufacturers often provide information for determining torque requirements for tightening various bolts.  If this information is not available, the expected torque may be calculated from the equation:

	T = K Po-max D / (1.0 + u)
where:
	T = applied torque, in-lb
	K = typical nut factor, 0.11 to 0.15 for lubricated fasteners and 0.2 	    for unlubricated fasteners,
	Po-max = maximum expected bolt preload, lb
	D = nominal fastener diameter (shank), in.
	u = preload uncertainty factor, in general, 25%

For more details, I have attached part of the NCSX Handbook for Bolted Joint Design for your information.

Using torque wrench for the SAE J429 Grade 8 bolt with yield strength of 130 ksi, the expected maximum, average, and minimum preload is 49.20 kip, 39.36 kip, and 29.52 kip, respectively.  The torque value is 5117 in-lb for lubricated fastener and 7872 in-lb for un-lubricated fastener.  The minimum preload value of 29.52 kip provides a factor of safety of 3.90 for bolt tension and 3.31 for lifting block shear.

The 1.063” I.D. x 2.0” O.D. flat washer yields a maximum bearing stress of 23.0 ksi, which is  smaller then the 36.0 ksi allowable.

The above values involved a lot of calculations.  Will someone make a calculation check following the NCSX Handbook for Bolted Joint Design?

H.M.

-----Original Message-----
From: Lewis Morris 
Sent: Tuesday, January 22, 2008 11:08 AM
To: Horng-Ming Fan
Subject: FW: Stage2 Coil Lift Calculation

Hello HM,
Could you please provide me with the torque value required to achieve the specified pre-load so we can add that info to the assembly drawing of this fixture.
Thanks

Lewis Morris
MS #16
Plasma Physics Laboratory
Princeton University
P.O. Box 451
Princeton, NJ 08543 USA

609-243-2777 (Office)
609-243-3030 (Fax)
lmorris@pppl.gov 

-----Original Message-----
From: Michael E. Viola 
Sent: Monday, January 21, 2008 3:04 PM
To: Lewis Morris
Cc: Horng-Ming Fan
Subject: FW: Stage2 Coil Lift Calculation

Lew,
Notice that HM has a preload requirement on the bolts
For SAE J429 Grade 8 bolt, a effective preload of 46.74 will provide a factor of safety of at least 5 for the shear force and joint separation at the bolted joint.

Please see if these bolts are readily available.
If not, please get an alternative.

You should also ask him for a torque to achieve his desired preload.

Thanks,

Mike Viola, PPPL, (609) 243 3655


-----Original Message-----
From: Horng-Ming Fan 
Sent: Thursday, January 17, 2008 2:11 PM
To: Michael E. Viola
Cc: Phil Heitzenroeder; Thomas G. Brown; Arthur W. Brooks
Subject: Stage2 Coil Lift Calculation

Mike,

Attached is the PowerPoint presentation for the coil lift calculation.  All values are within the allowable.  Please review and kindly give your comments.

If you need to add any things in the calculation, please let me know.

Thanks,

H.M.