Verification of finite element predictions of residual stress bondline failures in a full-scale test article

摘要

The Space Shuttle's Reusable Solid Rocket Motor (RSRM) nozzle project has expended a significant amount of effort to understand the response of adhesives to manufacturing induced residual stresses. ^This paper documents full-scale testing that provides data for evaluating the accuracy of key assumptions used in analyses of these conditions. ^The data also provide verification that accurate bondline residual stress analyses can be conducted. ^The full-scale testing was conducted on a modified RSRM nozzle nose inlet assembly (bonded with EA946 adhesive). ^Residual stresses were induced in the bondlines from two of the most significant manufacturing processes: bonding and assembly. ^After inducing high bondline residual stresses the assembly was stored at elevated temperature for several months to simulate long-term storage. ^Failure of the bondlines was monitored using strain gages and several NDE techniques: ultrasonics, AE, and X-ray. ^Predicted times to failure and observed times to failure showed good agreement. ^Lessons were learned about sensitivities to boundary conditions in joint regions. ^The testing indicated that bondline residual stress analyses can be conducted with good accuracy even for very large components, such as the RSRM nozzle. ^(Author)