Journal ArticleDOI
An energy-based microstructure model to account for fatigue scatter in polycrystals
TLDR
In this article, the authors proposed an approach to model the energy of a persistent slip band (PSB) structure and use its stability with respect to dislocation motion as a failure criterion for fatigue crack initiation.Abstract:
Scatter observed in the fatigue response of a nickel-based superalloy, U720, is linked to the variability in the microstructure. Our approach is to model the energy of a persistent slip band (PSB) structure and use its stability with respect to dislocation motion as our failure criterion for fatigue crack initiation. The components that contribute to the energy of the PSB are identified, namely, the stress field resulting from the applied external forces, dislocation pile-ups, and work-hardening of the material is calculated at the continuum scale. Further, energies for dislocations creating slip in the matrix/precipitates, interacting with the GBs, and nucleating/agglomerating within the PSB are computed via molecular dynamics simulations. Through this methodology, fatigue life is predicted based on the energy of the PSB, which inherently accounts for the microstructure of the material. The present approach circumvents the introduction of uncertainty principles in material properties. It builds a framework based on mechanics of microstructure, and from this framework, we construct simulated microstructures based on the measured distributions of grain size, orientation, neighbor information, and grain boundary character, which allows us to calculate fatigue scatter using a deterministic approach. The uniqueness of the approach is that it avoids the large number of parameters prevalent in previous fatigue models. The predicted lives are in excellent agreement with the experimental data validating the model capabilities.read more
Citations
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Journal ArticleDOI
The physics of fatigue crack initiation
TL;DR: In this paper, the authors focus on experimental observations of strain localization and the theory and numerical analysis of both slip irreversibilities and low energy configuration defect structures, which are the early signs of damage during cyclic loading.
Journal ArticleDOI
Plastic strain localization in metals: origins and consequences
TL;DR: In this paper, the mechanisms and consequences of plastic strain localizations exhibited in tensile stress-strain behaviors, fracture and fatigue are discussed, including important practical considerations and historical background; then dislocation mechanics based details are developed in subsequent sections.
Journal ArticleDOI
Defects in additive manufactured metals and their effect on fatigue performance: A state-of-the-art review
TL;DR: In this paper, the authors review the literature on the influential microstructural attributes on fatigue performance of additive manufacturing (AM) parts with a focus on generated defects, including defect-based, microstructure-sensitive, and multiscale models.
Journal ArticleDOI
Dislocation interactions with grain boundaries
TL;DR: In this article, a review of recent progress in understanding dislocation interactions with grain boundaries and interfaces in metallic systems via static and in situ dynamic experimental approaches is reviewed, as well as a comparison of different experimental approaches.
Journal ArticleDOI
Computational-experimental approaches for fatigue reliability assessment of turbine bladed disks
TL;DR: Results indicate that stochastic FE analysis-based scheme provides more conservative predictions than the probabilistic S-N curves-based one.
References
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Journal ArticleDOI
The Phenomena of Rupture and Flow in Solids
TL;DR: In this article, the authors investigated the effect of surface scratches on the mechanical strength of solids, and some general conclusions were reached which appear to have a direct bearing on the problem of rupture, from an engineering standpoint, and also on the larger question of the nature of intermolecular cohesion.
Book
Fatigue of materials
TL;DR: In this article, the cyclic deformation and fatigue crack initiation in polycrystalline ductile solids was studied and a total-life approach was proposed to deal with the problem.
Journal ArticleDOI
Dislocation nucleation and defect structure during surface indentation
TL;DR: In this paper, an atomistic imaging of dislocation nucleation during displacement controlled indentation on a passivated surface is presented, where defects are located and imaged by local deviations from centrosymmetry.
Journal ArticleDOI
The structure of high-angle grain boundaries
TL;DR: In this paper, a superimposed dislocation network is proposed for the cubic system, which is a natural extension of previous dislocation models and models based on coincidence relationships, and explains many of the observed properties of grain boundaries.
Journal ArticleDOI
Ductile versus brittle behaviour of crystals
James R. Rice,Robb Thomson +1 more
TL;DR: In this article, a necessary criterion for brittle fracture in crystals is established, in terms of the spontaneous emission of dislocations from an atomically sharp cleavage crack, and the stability of a sharp crack against emission of a blunting dislocation for a number of crystals and crystal types in two dimensions and the energy to form a stable loop of dislocation from the crack tip in three dimensions.
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