Direct Coupled Load Verification of Modified Structural Component

Abstract

An analytical vefification method for structural dynamics subject to partial design change is proposed. The method can predict time-domain structural dynamic responses after the changes are implemented, incorporated with the entire structural characteristics including the unchanged portion, by using small numbers of modal parameters of the original structure and the modified component. The concise computation of the degrees of freedom of the modal representation, which are formulated to retain the residual flexibility in the equation of motion, can correctly provide changed effects. The representation of the component mode synthesis and the force equilibrium between the changed component and the main structure are utilized to develop the algorithm, which yields the modal mass-stiffness conversion in the component modes. Applying this method to the spacecraft redesign, without the physical property information of the launch vehicle or repetition of coupled load analysis, the established algorithm can improve the prediction of the coupled spacecraft and launch vehicle structural dynamics. A reanalysis can be implemented using a limited number of available modal parameters from the coupled analysis for the original structure. Demonstrations applied to simple beam and spacecraft-launch vehicle models presented show the effectiveness of the method.