Fast Coupled Load Analysis through Reanalysis Technique: Formulation and Demonstration on Sample Problems 2024-26-0459

In a typical Launch Vehicle (LV), dynamic responses due to various flight events are estimated through Coupled Load Analysis (CLA) where the launch vehicle is coupled with a spacecraft. A launch vehicle is subjected to various loads during its flight due to engine thrust depletion / shut-off, thrust oscillation, wind and gust, maneuvering loads. In aerospace industry a standard CLA is performed by generating the mathematical model of launch vehicle and coupling it with reduced mathematical model of satellite and applying the boundary conditions. A CLA is a time consuming process as several flight instances and load cases need to be considered along with generation of structural dynamic model at each time instants. For every new mission, the satellites are mission specific whereas the launch vehicle and the loads remain unchanged. To take advantage of this fact, a new method called “Fast CLA through Reanalysis technique” is proposed in the present paper. Fast Coupled Load analysis eliminates the need to generate new coupled mathematical model of launch vehicle and satellite in case only satellite is changed for the new mission. The method uses system frequencies of the original system (launch vehicle + original spacecraft), eigen vectors row corresponding to the launch vehicle original satellite interface, internal points of original satellite and external load application location and mass and stiffness matrix of the original and new satellite to determine responses for the new satellite without performing traditional CLA. This can be performed outside the finite element software. At present, formulation of the analysis is completed and tested for lumped parameter model which gives encouraging results. Methodology is being implemented for the full launch Vehicle.