Recovered Transient Load Analysis for Payload Structural Systems

Abstract

The integration of the launch vehicle and the payload model and the subsequent computations to obtain payload load are expensive and time-consuming. These difficulties preclude the use of exact structural loads analysis in the early design stages where frequent design changes are occurring. Therefore, approximate methods have been employed during the early design/analysis process. A recovered transient analysis technique is proposed in the present study wherein the results of a previous launch vehicle/payload system can be used to obtain the necessary information of a new payload structure to be launched by an identical launch vehicle. The payload is supported in a statically determinate manner in the present study. The advantage of the proposed method is that the complete design/analysis process can be performed within the payload organization and achieve the same accuracy as that of the full-scale, multiorganization loads analysis. Also, the flight measured interface accelerations can be used as the forcing functions for more realistic representations of the dynamic environments. The method is applied to a real complex payload structure.

A survey of payload integration methods

“…(28) Although expressed here in terms of the higher modes and higher frequencies, residual attachment modes may be computed using only the static flexibility matrix and the lower modes and frequencies. 15 ' 19 The significant difference between Eqs.…”

“…Chen et al 28 proposed a recovered transient load analysis method which is also a base drive technique. The method employs a transient analysis with a reference payload, recovers from it the interface accelerations for the unloaded launch vehicle, and then modifies this interface motion to include the dynamic effects of a new payload.…”

Analytical model accuracy requirements for structural dynamic systems

“…(4) implies that the interface acceleration [Xf] is a function of the payload dynamic characteristics, methods have been developed to obtain the proper interface acceleration from previously analyzed composite systems consisting of an identical launch vehicle and a different payload. 8 In the present study, Eq. (6) will be treated as the governing equation for the payload structural system.…”

“…Here, the effects of errors in frquency and mode shape prediction on the response prediction will be established first. Let (8) where [0] is the normal mode matrix and [q] is the generalized coordinate. Then Eq.…”