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Title:Numerical Modeling of Ductile Crack Growth in 3-D Using Computational Cell Elements
Author(s):Ruggieri, C.; Dodds, Robert H., Jr.; Panontin, T.L.
Crack growth
Finite elements
Abstract:This study describes a 3-D computational framework to model stable extension of a macroscopic crack under mode I conditions in ductile metals. The Gurson-Tvergaard dilatant plasticity model for voided materials describes the degradation of material stress capacity. Fixed-size, computational cell elements defined over a thin layer at the crack plane provide an explicit length scale for the continuum damage process. Outside of this layer, the material remains undamaged by void growth, consistent with metallurgical observations. An element vanish procedure removes highly voided cells from further consideration in the analysis, thereby creating new traction-free surfaces which extend the macroscopic crack. The key micromechanics parameters are D, the thickness of the computational cell layer, and fo, the initial cell porosity. Calibration of these parameters proceeds through analyses of ductile tearing to match R-curves obtained from testing of deep notch, through-crack bend specimens. The resulting computational model, coupled with refined 3-D meshes, enables the detailed study of non-uniform growth along the crack front and predictions of specimen size, geometry and loading mode effects on tearing resistance, here described by J-b..a curves. Computational and experimental studies are described for shallow and deep notch SE(B) specimens having side-grooves and for a conventional C(T) specimen without side-grooves. The computational models prove capable of predicting the measured R-curves, post-test measured crack profiles, and measured load-displacement records.
Issue Date:1996-09
Publisher:University of Illinois Engineering Experiment Station. College of Engineering. University of Illinois at Urbana-Champaign.
Series/Report:Civil Engineering Studies SRS-612
Genre:Technical Report
Sponsor:NASA-AMES Research Center
U.S. Nuclear Regulatory Commission. Office of Nuclear Regulatory Research. Division of Engineering.
Contract Nos. N61533-92-K-0030 and NCC2-5022
Date Available in IDEALS:2009-11-16

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