Fast Coupled Load Analysis through Reanalysis Technique: Formulation and Demonstration on Sample Problems

Abstract

<div class="section abstract"><div class="htmlview paragraph">Design of Launch vehicle is multidisciplinary process in which designers of all the domain of engineering like mechanical, electronics, chemical, materials etc contribute. For the mechanical design, Coupled Load Analysis (CLA) is statutory requirement without which no launch vehicle will be allowed to fly.</div><div class="htmlview paragraph">In CLA, 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 payload 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 payloads 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.</div><div class="htmlview paragraph">Fast Coupled Load analysis eliminates the need to generate new coupled mathematical model of launch vehicle and payload in case only payload is changed for the new mission. The method uses system frequencies of the original system (launch vehicle + original payload), eigen vectors row corresponding to the launch vehicle original payload interface, internal points of original payload and external load application location and mass and stiffness matrix of the original and new payload to determine responses for the new payload 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.</div></div>