Dynamics of Shuttle Berthing to Space Station Freedom 922020

In the early stages of development for Space Station Freedom (SSF) the primary means for connecting the Shuttle to SSF was through docking, with Shuttle berthing to be used only in the early building stages. The docking mechanism, an actively controlled load alleviation device, was to be used to limit the docking loads to an acceptable level. In late 1990, as a weight saving measure, Shuttle docking was deleted from the program and Shuttle berthing utilizing the Remote Manipulator System (SRMS) became the primary means of connecting the Shuttle to SSF, thus transmitting the full impact loads into the primary structure of SSF and Shuttle. More recently in early 1992, docking has been brought back into the program for post stage 5 configurations.

A solution sequence for transient dynamic analysis with modal initial conditions was developed. Various techniques for efficient and realistic simulation of the contact between the Shuttle Payload Retention Latch Assembly (PRLA) and the SSF berthing mechanism trunnions were investigated. The “Hit and Stick” approach, in which the Shuttle impacts and instantaneously latches to the SSF trunnions was considered. The “Hit and Bounce” method, where the Shuttle's PRLA impacts the SSF trunnions and bounce off at a to-be-determined time with no re-contact was also investigated. The “Sequential Hit”, in which the PRLA contacts the SSF trunnions at different times and bounce back with the capability to re-contact was the third approach considered. The first approach involved a linear simulation, the latter two approaches required nonlinear solutions.