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Author McDonald, Russell J
Title Characterization of delamination in 2099-T861 aluminum-lithium
book jacket
Descript 218 p
Note Source: Dissertation Abstracts International, Volume: 71-05, Section: B, page:
Advisers: Peter Kurath; Armand J. Beaudoin
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009
Aluminum-lithium alloys provide a lower density and higher stiffness alternative to other high strength aluminum alloys. However, many Al-Li alloys exhibit a non-traditional failure mechanism, delamination. Delamination refers to the failure along the grain boundary interface. The delamination phenomenon is often observed from fracture toughness testing as cracking along grain boundaries perpendicular to the mode I primary crack. In this investigation, delaminations were also observed after cyclic deformation of both uniaxial and torsion experiments. Many of the experimental observations, such as rate insensitivity and crystallographic orientation, were incorporated into a cyclically stable crystal plasticity framework with rate independent kinematic hardening. It was hypothesized that texture lead to interface stresses that could not be obtained by a continuum approach. Local grain boundary interface stresses were estimated using the uniform deformation and bi-crystal models. These models were computationally amenable to provide both orientation dependence and the statistical nature of the grain boundary stresses for a given bulk texture and nominal loading. A coupled shear-normal damage parameter was formulated to quantitatively characterize the nucleation of delamination. The damage estimated for a wide range of simulations (uniaxial, torsion, fracture) correlated well with the experimental trends
School code: 0090
Host Item Dissertation Abstracts International 71-05B
Subject Applied Mechanics
Engineering, Mechanical
Engineering, Materials Science
Alt Author University of Illinois at Urbana-Champaign
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