Space Station Freedom Mission Build-2 space transportation system loads analyses

Abstract

Detailed structural dynamic analyses are required to demonstrate compliance with the Space Transportation System (STS) interface load, clearance, and minimum frequency requirements for all Space Station Freedom (SSF) Mission Build (MB) launch packages. The structural design of most SSF hardware is governed by the STS flight environment and design loads must be established and verified to cover low frequency transient, quasistatic, and random vibration coupled loads. SSF is to be constructed, launched, deployed and assembled in stages. This paper addresses the analytical methods used to define the maximum flight loads and demonstrate STS compatibility for the second assembly flight known as MB-2. Transient coupled loads, quasi-static, and random vibration loads analyses were completed for the MB-2 launch package. The products of the analyses include: time-consistent discrete internal member load madmin envelopes; grid acceleration maxlmin envelopes; trunnion clearance envelopes; cargo element load factors; trunnion interface loads; shuttldpayload clearances, shock spectra and quasi-static interface loads; random vibration responses; and the definition of combined loads. The results defined maximum flight loads for the launch package cargo elements and demonstrated compliance with the STS structural interface requirements. * Integrated Analysis Manager, Senior Member, A M ** Structural Dynamics EngineerIScientist Copyright O 1994 by the American Institute of Aeronautics and Astronautics, Inc. No copyright is asserted in the United States under title 17, U.S. Code. The U.S. Government has a royalty-free license to exercise all rights under the copyright claimed herein for government purposes. All other rights are reserved by the Introduction The Space Station will be constructed on-orbit from prefabricated truss and pressurized segments. As each component will be launched in the cargo bay of the Space Shuttle, compliance with the STS requirements on interface loads, clearances and minimum frequencies must be shown as well as overall structural integrity. To this end, detailed low frequency transient coupled loads, random vibration and quasi-static analyses must be performed. This paper briefly describes the Space Station Freedom configuration and then addresses the analytical methods used to define the flight response of the second assembly mission, known as MB-2, which contains one segment of preintegrated truss and two propulsion modules. MSC/NASTRAN and its superelement substructuring techniques was used as the primary analysis tool along with in-house developed pre and post-processing tools. S ~ a c e Station Freedom Confi~ration and Stape Definition The configuration used as the basis for modeling and analysis was the program baseline defined at the Critical Design Review as of April 1993. Figure 1 is an illustration of SSF at the Permanently Manned Configuration (PMC) which completes the initial phase of assembly. The PMC station is approximately 350 ft. long and weighs 296 tons. Major components of the station are the solar arrays, pre-integrated truss segments, pressurized laboratory and habitation modules, resource nodes, Propulsion Modules, and thermal control system radiators.