GRAVITY EFFECTS ON DAMPING OF A SPACE STRUCTURE WITH PINNED JOINTS

An area of concern for the design of large space structures is the amount of structural damping that will be present. The joints used to assemble a large, light-weight structure like the space station will provide some damping; however, an accepted methodology for predicting joint damping is yet to be established. This paper documents a research effort at Utah State University to better understand joint damping in large space structures. A miniature tetrahedral truss was constructed that uses pinned joints. A large tip mass was attached to the truss to lower the natural frequency to a range associated with the space station. Considerable ground testing has been conducted to characterize the damping of the truss in a l-g environment in different orientations and in a vacuum. It was determined that the contribution of air to structural damping was insignificant for this truss. These experiments show that gravity can dramatically influence the damping produced. © 1990 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.