Manufacturing Process Development for Adhesively Bonded Joints in Large-Scale Space Structures

In order to take full advantage of the weight savings and performance gains offered by the use of composite materials in large-scale space structures, adhesively bonded joints must be considered. While bonded joint manufacturing at laboratory scale can be straightforward, the same manufacturing processes are not trivial at full scale. Surface preparation becomes particularly challenging (a viable process must yield consistent results over a large application area and be repeatable for multiple application sites), as does the application of heat to cure the doublers and/or bond them to the primary structure (the nature and scale of assembled or partially assembled aerospace structures often necessitates an out-of-oven/out-of-autoclave approach). In this work, bonded joint manufacturing processes are adapted for a full-scale (approximately 30 feet in diameter at the aft end) composite payload adapter at the NASA Marshall Space Flight Center. By iterating across a range of variables, process parameters for adhesively bonded joints on a large-scale composite structure have been developed. Primary findings are presented with respect to overarching bonded joint manufacturing concepts so as to maximize the applicability of this work to similar material systems and structures.