PROGRESSES IN RESEARCH ON COUPLED ANALYSIS TECHNOLOGY FOR SPACE VEHICLE AND LAUNCH VEHICLES

With focus laid on loads analysis, some progresses of structural dynamics in the field of space vehicle design are summarized. The paper first presented some fundamental ideas of load analysis which has been applied in space vehicle / launch vehicle coupling systems. And then load analysis methods were explored in the following three directions: 1) Approximate initial load analysis methods by means of basis excitation theory in which coupling effects of the space vehicle / launch vehicles are neglected; 2) A branch modes synthesis method for the coupled space vehicle / launch vehicle system with the coupling effects taken into account. Based on the interface acceleration of constraint modes mass, the load estimation of the space vehicle / launch vehicle coupled system was derived analytically. Furthermore, if only static constraints modes mass is considered, the reduced equation (as a special case of this method) is actually identical to the equation derived by Chen using FEM. Furthermore, a new technique for space vehicle load transient analysis was also established. With the technique, previous analyzing results of space vehicle / launch vehicle coupling systems can be extended to new coupling systems between the same launch vehicle and a new space vehicles; 3) A modal synthesis method for the space launch / launch vehicle coupled systems. Several modal synthesis methods were studied, the fixed-interface modal synthesis method was first presented ,and the method was applied to Ariane-5 launch vehicle dynamic response analysis, a new method for deriving dynamic response of the space launch / launch vehicle system was then given based on coupling interface synthesis; Finally, verification techniques of the load analysis methods were elucidated. After a brief discussion of the importance of the verification techniques, a new technology of structure dynamic test simulation is proposed to combine the experimental results with the theoretical analyzing results. This is a set of new techniques for updating mathematics model, which is named as synthesis techniques based on the substructure experimental modeling. The approach has been applied to the modeling of such complex structures as a large strap-on launch vehicle Long March 2E (LM-2E) and a 40 T shaker system. The proposed techniques were demonstrated with LM-2E as follows: the predicted modes were derived before the modal test of real full scale LM-2E launch vehicle; and the modes were then compared with actual test results obtained thereafter. The two results turned out to be highly consistent between each other. The experiment proves that the modal parameters of the LM-2E had been successfully reproduced by the proposed modal test simulation techniques ,and the reliability of the proposed techniques is thus verified. The vibration test simulation techniques of a 40 T shaker were also discussed. Key simulation techniques for the vibration test are summarized, including the modification technique for the shaker FEA mathematics model; the simulation technique of the table-board control for vibrating tests of a 40 T shaker system and the simulation technique of D satellite shaker vibration tests.