<title>Life cycle testing of viscoelastic materials for Hubble Space Telescope solar array 3 damper</title>

Abstract

During the March 2002 Servicing Mission by Space Shuttle (STS 109), the Hubble Space Telescope (HST) was refurbished with two new solar arrays that now provide all of its power. These arrays were built with viscoelastic/titanium dampers, integral to the supporting masts, which reduce the interaction of the wing bending modes with the Telescope. Damping of over 3% of critical was achieved. 1 Figure 1. HST with Solar Array 3 (SA3) on orbit and SA3 finite element model showing damper locationTo assess the damper's ability to maintain nominal performance over the 10-year on-orbit design goal, material specimens were subjected to an accelerated life test. The test matrix consisted of scheduled events to expose the specimens to pre-determined combinations of temperatures, frequencies, displacement levels, and numbers of cycles. These exposure events were designed to replicate the life environment of the damper from fabrication through testing to launch and life on-orbit. To determine whether material degradation occurred during the exposure sequence, material performance was evaluated before and after the accelerated aging with complex stiffness measurements. Based on comparison of pre-and post-life-cycle measurements, the material is expected to maintain nominal performance through end of life on-orbit. Recent telemetry from the Telescope indicates that the dampers are performing as intended.Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/22/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx * The SA3 arrays are not rigid in the traditional mechanical sense, as the primary modes of these arrays are around 1 Hz. But SA3 is considered rigid compared to SA2; the primary modes of SA2 were about 0.l Hz.

Active Vibration Control of a Large Flexible Appendage Using a Novel Joint Mechanism

“…e following two major types of control strategies have been reported in literature: the passive control methods based on viscoelastic damping materials and the active control methods based on piezoelectric materials. e implementation of passive control is easy, and its structure is simple [7,8]. Vibrations can be isolated through appropriate arrangement of damper materials at the appropriate positions of mechanisms/structures.…”

Multi-degree-of-freedom vibration reduction strategy of the solar array drive system

“…As shown in Figure 1(a), this damper consists of upper and lower shear plates, and the damping layer fixes on the yoke of solar array. [5][6][7][8] The damping layer goes through shear deformation and dissipates the vibration energy due to the relative displacement between the upper and lower shear plates in the vibration process. Brugarolas et al 9 reported the structural redesign plans on this damper, as shown in Figure 1(b).…”