Damping Synthesis for Flexible Space Structures Using Combined Experimental and Analytical Models

A procedure is presented for modal and damping synthesis of flexible space structures from subsystem tests and/or analyses. In view of the various damping mechanism operative in a space structure, their contribution to total system damping and its compatibility with dynamic testing procedures, the spacecraft subsystems are identified as joints and components. The dynamics of joint subsystems is represented via its stiffness, inertia, and damping properties in physical displacement coordinates. Simple static influence coefficient and cyclic hysteresis tests are used for the determination of joint dynamic properties from experimental measurements. Component dynamics is represented in terms of generalized coordinates, defined to include natural vibration modes, with any arbitrary interface boundary conditions. Ritz vectors, physical displacements, or any other set of linearly independent admissible vectors that is convenient for the experimental and/or analytical characterization of the component. An existing damping synthesis method based on empirical correlation of subsystem stored and dissipated energies is modified to permit the use of measured resonance damping data. thus allowing any arbitrary variability of modal damping data. The results of the developed modal and damping synthesis procedure are verified by using a representative flexible space structure including structural joints.