Effects of crack arresting delaminations in aluminum-lithium alloys

aluminum;lithium;fracture;delamination

Hernquist, Mark W. ; Beaudoin ; Armand J.

关键词: aluminum;    lithium;    fracture;    delamination;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/16132/Hernquist_Mark.pdf?sequence=3&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Aluminum‐lithium alloys have been studied extensively in the last centuryfor their low densities and increased stiffness over conventional high strengthaluminum alloys. Combined with cryogenic strength and toughness propertiesexceeding those at room temperatures, Al‐Li alloys are an appealing choice inastronautics. However, along with these beneficial properties comes a propensityfor limited ductility contributing to an unconventional fracture mechanism knownas delamination, a secondary fracture along a grain boundary interface similar tothe separation within a laminated composite. In this study, mechanicalexperimentation was coupled with computer simulation to investigate the causesand effects of delaminations occurring along grain boundaries perpendicular to thedirection of a Mode I primary crack. Fracture toughness samples were tested withconcurrent in situ Digital Image Correlation to obtain a means for validation of thetwo finite element models. The models were devised to capture the bulk responseof the sample immediately prior to and after the delamination event. A crystalplasticity framework with rate‐independent kinematic hardening was then used todetermine the local behavior of the crystallographic orientations prone todelamination.