Hypervelocity Impact Investigations of Composite Truss Tubes for In Orbit Assembly Risk Assessment

Abstract

The number of threats to space structures due to micrometeoroid and orbital debris (MMOD) impact continues to increase as the density of structures in orbit increases. Upon impact from (MMOD), the structure will have significantly reduced strength, however additionally; the debris shed post-impact causes a compounding risk of damage to the in-orbit assembly field [1]. MMOD impacts have an average velocity envelope between 9 and 10 km/s in the orbit of the International Space Station (ISS). Still, they can range between 3 and 20 km/s depending on the position of the space vehicle at the time of impact [1]. Many space structures, like that of the James Webb space telescope (JWST), and the in-space assembled telescope (ISAT), utilize fibermatrix composites consisting of various shapes and sizes [2]. In particular, the ISAT is designed to use composite truss members to connect instruments to the rest of the telescope and structurally serve as the telescope's backbone [3]. Hypervelocity impact (HVI) damage to flat plate composites has been widely discussed. However little to no research has been published on the effect of HVI on composite tubes. Understanding the effect of the localized damage caused by MMOD impact on the overall strength of the individual truss member and structure as a whole is crucial to providing insight into the state of current structures and aiding in the design of future structures. To simulate MMOD impact, a unique two-stage light-gas gas gun, designed for impact velocities between 2 and 7 km/s is used [4]. Investigating the postmortem inlet and exit diameters, residual compression strength, and in situ debris cloud tracking of characteristic carbon fiber reinforced polymer (CFRP) tubes will provide data used to reinforce current computational models of the event. Combining the results from the Lagrangian finite element (FE) model with the Eulerian hydrodynamic model will allow the verification of damage effects only seen due to hypervelocity impact. These results will be used to aid in understanding the risk of MMOD impact on current structures and assist in developing systems more resilient to HVI.