SEDL / STP / STP1131-EB / STP23701S

Crack-Tip Displacement Fields and JR-Curves of Four Aluminum Alloys

Dadkhah, MS
Members of Technical Staff, Mechanics of Materials, Rockwell Science Center, Thousand Oaks, CA

Kobayashi, AS
Professor, University of Washington, Seattle, WA

Morris, WL
Members of Technical Staff, Mechanics of Materials, Rockwell Science Center, Thousand Oaks, CA

Pages: 19    Published: Jan 1992

Download this paper for $25 PDF (656K)          View License Agreement
Abstract

The JR-curves associated with small crack growth in 0.8-mm-thick 2024-T3, 2024-0, 5052-H32 aluminum and 2091-T3 aluminum-lithium cruciform specimens and 2024-T3 and 2024-0 aluminum single-edge-notched (SEN) specimens are presented. The cruciform specimens were loaded uniaxially and biaxially. The J-integral values were determined directly through contour integration of the stresses and strains using deformation theory of plasticity and power hardening law. The strains were computed from the measured in-plane displacements that were determined experimentally using moiré interferometry. Path independency of the J-integral values were verified by the 5% scatter band for the near- and far-field Js. The JR results differed substantially from the J-values computed by using the far-field formula of Shih, German, and Kumar. Also the measured crack-tip displacement and strain fields did not agree with the asymptotic solutions of Hutchinson, Rice, and Rosengren computed from the measured J-values. These findings suggest that the current formulas for J calculations may be incorrect and that J may not be a suitable parameter for characterizing the crack tip.