TWO STEP MODAL COUPLING An Alternate Approach in Treating Component Damping for Space Shuttle Payload Loads Analysis

摘要

There are two methods for applying damping that are widely used in Space Shuttle/payload coupled loads analyses: the System Level Damping (SLD) method, which assigns damping values to all modes at the coupled system level, and the Triple Matrix Product (TMP) method, which assigns damping to modes at the Shuttle and payload component level. The SLD method is used when standard Shuttle system damping levels are considered adequate for all payloads in the analysis. The TMP method, on the other hand, provides a means to incorporate unique payload damping values in the coupled loads analysis. The choice of methods becomes more complicated when, for a mixed cargo manifest, some payloads have unique damping requirements and some payloads prefer to use standard system level damping. The Two Step Modal Coupling (TSMC) method presented here is an alternate approach to use when applying damping for a mixed cargo manifest coupled loads analysis. The TSMC method involves grouping the Shuttle and payload components which have SLD requirements and performing modal coupling as the first step. This super-component then is coupled with the other payloads which have component damping requirements for the TMP dynamics analysis as the second step. The method is proven to be effective in treating mixed cargo manifest Shuttle loads analyses where unique damping requirements exist for certain payloads.