ALUMINUM-LITHIUM MIXED MODE FRACTURE TOUGHNESS

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Authors
  1. Hull, D.A.
Corporate Authors
Defence Research Establishment Atlantic, Dartmouth NS (CAN);Engineering Material Research, Downsview ONT (CAN)
Abstract
Experimental measurements have been made of the mixed mode fracture toughness of a 12 mm thick aluminium-lithium alloy plate in the S-T orientation. A modified form of mixed mode bending test was employed to determine both pure and combined Modes I and II critical stress intensities and strain energy release rates, using two independently controlled actuators to provide the opening and bending loads. The specimens were deeply side grooved, and fatigue re-cracked using Mode I loading and an electrical discharge machined starter notch. Mixed mode loading was carried out using displacement control at ambient conditions. The onset of crack extension was identified by a departure from linearity in the load versus displacement record. The critical strain energy release rates for different mixed mode loading combinations were compared with reference to expeted trends, and the fracture surfaces were examined in a scanning electron microscope to provide indications of different micro-modes of cracking.
Keywords
Mixed mode;Fractography;8090 Al-Li alloys;SEM - Scanning Electron Microscopy;8090-T8771 alloys
Report Number
DREA-CR-98-415 — Contractor Report
Date of publication
01 Jan 1998
Number of Pages
31
DSTKIM No
98-01437
CANDIS No
508281
Format(s):
Hardcopy;Document Image stored on Optical Disk

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