PASSIVE DAMPING AUGMENTATION FOR VIBRATION SUPPRESSION IN FLEXIBLE LATTICED BEAM-LIKE SPACE STRUCTURES

For a Timoshenko beam model the equations of motion, representing the anisotropic continuum model of a two-dimensional, latticed, large spac e structure, are extended to include coupling between the extensional, shear and bending modes. This analytical model, applied to a 20-bay, orthogonal, tetrahedral, cantilevered truss structure, is used to dete rmine the transient response when subjected to a unit impulse. It is d emonstrated that for beam-like structures having a fixed bending stiff ness and beam mass an increase in diagonal stiffness, on account of th e stiffness of the vertical girder, leads to a rise in the transverse shear rigidity. This results in higher natural frequencies and a reduc tion in peak displacement. In addition, in an asymmetrical truss confi guration, coupling between the extensional and shear modes raises the maximum peak displacement compared to that obtained for a symmetric tr uss. The model is modified to investigate the introduction of passive damping in the form of several dynamic vibration absorbers. For a fixe d absorber mass budget, a simple yet efficient absorber parameter opti mization procedure, based on the classical steady state criteria of a 2-DOF system, is developed to design several absorbers each tuned to a different modal frequency. It is found that inclusion of transverse s hear rigidity, as a design parameter in damping augmentation studies, reduces settling time for predetermined maximum peak displacements.