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 efficient 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 difficulties in the optimization of composite
flexible multibody systems are highlighted in the discussion of the results
obtained.