This paper details efforts on minimizing power electrical umbilical stiffness on the International Space Station (ISS) Active Rack Isolation System (ARIS) to improve system performance. The effects of wire conductor material, winding configurations, electrical insulation materials, and umbilical geometry were investigated. Cable stiffness was dynamically measured with a special test rig that attained an extremely low coefficient of sliding friction value of mu = 5 x 10(-6) Sine-sweep excitation and transfer function analyses were used to assess the stiffness of current configurations and various alternates. Because of the very low stiffness of some candidates, the effect of 1-g umbilical sagging on the measurements had to be considered. The paper provides a detailed comparison of the properties of the different umbilical candidates tested. Several candidates provided dramatic dynamic stiffness reductions.
