The insulating washer that is contemplated is 1.1" O.D. X .5" I.D. thick, and made out of ulteum 2300 resin.
EUL = 938,000 psi, compressive modulus.
The spring constant of a washer may be calculated from the stress-strain relationship:
I will assume that metal washers allow the load to be distributed uniformly over the plastic washer.
The spring constant for the stack of Bellevilles comes approximately from the information that the stack deflects .204 inches at a load of 971.8 lbs (See "Calculating the Parameters of the Disk Springs in the SDSS Camera Stirrup Mechanism," L. Bartoszek, 4/2/97)
The stack is a much softer spring than the plastic washer. What is the change in the overall spring constant when the stack is in series with the washer?
The addition of the plastic washer insignificantly reduces the effective spring constant.BR>
Last modified 04/28/99