Failure analysis of mechanical joints glare fatigued after hygrothermal ageing associated with thermal cycling of large amplitude

Abstract

The project aims at achieving the Failure Analysis mixed riveted joints of hybrid laminates Glare with plates of aeronautical monolithic alloy 2024- T3 (Glare / alloy - Al) subjected to mechanical fatigue loading after the application, and combined, hygrothermal ageing (EH) and thermal cycles of large amplitude (CT), in both their chronological sequences, namely EH+CT and CT+EH. The characterizations of these laminates involving destructive and non- destructive testing, tests of Mechanical Fatigue and Inspection by Radiographic X-rays, respectively, for subsequent morphological analysis of faults through Optical Microscopy Reflection, Stereoscopy and Scanning Electron Microscopy. The results are compared to those obtained for the same together Glare / Al - alloy, but as they were in the forms of, respectively, as - manufactured (according to the final report for Proc. FAPESP 2005/54899-8 IC) just hygrothermical ageing (Proc. IC FAPESP 2010/09823-1), and only subject to thermal cycles of large amplitude (IC Proc. FAPESP 2010/09822-5). The survey results will help us understand the macro -, meso - and micro - mechanisms of both processes of initiation and subcritical propagation of fatigue cracks in these aeronautical riveted joints when exposed to extremely harsh environments potentially found in actual service conditions.