Abstract

The design of complex flexible multibody systems for industrial applications requires not only the use of powerful methodologies for the system analysis, but also the ability to analyze potential designs and to decide on the merits of each one of them. This paper presents a methodology using optimization procedures to find the optimal layouts of fiber composite structure components in multibody systems. The goal of the optimization process is to minimize structural deformation and to fulfill a set of multidisciplinary constraints. These methodologies rely on the eficient and accurate calculation of the system sensitivities to support the optimization algorithms. In this work a general formulation for the computation of the first order analytic sensitivities based on the direct differentiation method is used. The direct method for sensitivity calculation is obtained by direct differentiation of the equations defining the response of the structure with respect to the design variables. The equations of motion and the sensitivities of the flexible multibody system are solved simultaneously and, therefore, the accelerations and velocities of the system, and the sensitivities of the accelerations and velocities, are integrated in time using a multistep multiorder integration algorithm. Different models for the flexible components of the system, using beam and plate elements, are also considered. Finally, the methodology proposed here is applied to the optimization of the unfolding of a complex satellite made of composite plates and beams. The ply orientations of lamination are the continuous design variables. The potential dificulties in the optimization of composite flexible multibody systems are highlighted in the discussion of the results obtained.

Keywords

flexible multibody dynamics, sensitivity analysis, automatic differentiation, large rotations, floating frame

Authors