Cups/cones are being used to provide a shear load transfer capability on a large separation interface that uses multiple discreet retention and release (R&R) devices (such as frangible nuts, separation nuts, separation bolts, etc.). To both provide good shear load-sharing among all R&Rs and to prevent relative motion between the mating structures, the cups/cones must be designed with minimal (and sometimes zero) radial clearance. This tight fit requires that the cup and the cone on the mating structures are precisely located to each other.
The cup and cone features are included in separate, removable parts (i.e., a plate with a cone feature and a second plate with a cup feature). The cup and cone are located concentric to the R&R device (the R&R passes through the center of the cup/cone), and the cone plate includes a round boss machined to a precise diameter on the opposite side of the plate as the cone is located. The center axis of the boss is located concentric to the cone feature axis. This boss will transfer shear between the cone plate and the launch vehicle structure.
The cup plate has three precision pins (such as dowel pins) located in a radial pattern that is concentric to the axis of the cup feature. These pins will transfer shear between the cup plate and the payload structure. The payload has a through-hole for the R&R, and there are also three through-holes located in a radial pattern that is concentric to the axis of the R&R through-hole. Finally, there is a selection of shim bushings used to fill the gap between the hole on the payload interface and the pins on the cup plate.
This work was done by Jake D. Crine of Lockheed Martin Space Systems Company for Johnson Space Center. For further information, contact the JSC Technology Transfer Office at (281) 483-3809. MSC-24678-1