International Journal for Multiscale Computational Engineering

ISSN for PRINT: 1543-1649

For Online Access

Best Paper Award Selection - Editorial Board Site

2006, Volume4

Issue 5-6

271 pages

DOI: 10.1615/IntJMultCompEng.v4.i5-6

Issue price - $256.00

A.-J. Wang
Onity, Inc., Norcross, GA

R. S. Kumar
ABAQUS, Inc., Providence, RI

M. M. Shenoy
G.W.W. School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0405

David L. McDowell, Professor
Department of Mechanical Engineering, Georgia Institute of Technology, 801 Ferst Dr., N.W. Atlanta, GA 30332-0405, USA

A hierarchical system of microstructure-based constitutive models for cyclic deformation and low cycle fatigue (LCF) behavior of two-phase nickel-base superalloys is developed and implemented. Both precipitate (γ′) and matrix (γ) phases with or without smaller dispersed precipitates are explicitly modeled using crystal viscoplasticity theory with dislocation density as an internal state variable. The constitutive models are capable of capturing most of the important features of the deformation behavior of Ni-base superalloys, namely, (i) anomalous yield stress behaviors with respect to temperature and tension-compression asymmetry of flow stress due to non-Schmid effects; (ii) crystallographic orientation dependence represented by the crystal plasticity model; (iii) effects of γ′ precipitate size and spacing on initial yield strength and work hardening; and (iv) effects of precipitate distribution and morphology on localized cyclic plastic shear strain. The physically based hardening laws are employed to evolve dislocation densities for both phases in each slip system with consideration of dislocation interaction mechanisms. This type of' microstructure-sensitive constitutive model is applicable to the study of the effects of variability of microstructure on variability of LCF and creep behaviors or properties. A combined bottom-up and top-down strategy is used to determine model parameters to support simulations at length scales ranging from approximately 100 nm up to hundreds of microns. Models for γ′ precipitates are calibrated using bulk Ni₃Al single-crystal data. The γ — γ′ two-phase models are calibrated for several superalloys and strain histories, providing good agreement with experiments. The utility of such models in modeling behavior at several characteristic length scales is briefly discussed.

DOI: 10.1615/IntJMultCompEng.v4.i5-6.70 Download article, 663-692 pages

Article price - $35.00

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