This paper proposes a design procedure to determine the optimal configuration of multi-degrees of freedom (MDOF) multiple tuned mass dampers (MTMD) to mitigate the global dynamic aeroelastic response of aerospace structures. The computation of the aerodynamic excitations is performed considering two models of atmospheric disturbances, namely, the Power Spectral Density (PSD) modelled with the Davenport Spectrum (DS) and the Tuned Discrete Gust (TDG) with the one-minus cosine profile. In order to determine the optimum sets of MTMD, a Multi-objective design Optimization considering Genetic Algorithm (MOGA) is implemented, where the selected fitness functions for the analysis are the minimization of the total mass of the resonators as well as the concurrent minimization of the peak displacements of a specified structural node in all translational degrees of freedom. A case study is presented to demonstrate the proposed methodology, where the optimal sets of MTMD are determined for the concurrent minimization of the pointing error of a truss-like antenna structure as well as the mass of the considered MTMD. It is found that the placement of the MTMD in the primary reflector of the antenna structure provided a maximum reduction in the pointing error of 62.0% and 39.2%, considering the PSD and the TDG models, respectively. Finally, this paper presents an advanced framework to estimate optimal parameters of MTMD control devices under convoluted loading cases as an initial step towards the use of such passive systems in applications that commonly employ active or semi-active solutions.
This paper proposes an optimization procedure to achieve the best configuration of multiple degrees of freedom Tuned Mass Dampers (TMDs) to mitigate the pointing error of Very-Long-Baseline Interferometry (VLBI) Earth-based radio antennae operating under aerodynamic gust conditions. In order to determine the optimum sets of TMDs, a Multi-Objective design optimization employing a genetic algorithm is implemented. A case study is presented where fourteen operational scenarios of wind gust are considered, employing two models of atmospheric disturbances, namely the Power Spectral Density (PSD) function with a statistical profile presented by the Davenport Spectrum (DS) and a Tuned Discrete Gust (TDG) modeled as a one-minus cosine signal. It is found that the optimal configurations of TMDs are capable of reducing the pointing error of the antenna by an average of 66% and 50% for the PSD and TDG gust excitation scenarios, respectively, with a mass inclusion of 1% of the total mass of the antenna structure. The optimal TMD parameters determined herein can be utilized for design and field implementation in antenna systems, such that their structural efficiency can be enhanced for radio astronomy applications.
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