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DTSTART;TZID=America/New_York:20221202T140000
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DTSTAMP:20260405T081143
CREATED:20221114T193221Z
LAST-MODIFIED:20221114T193221Z
UID:7885-1669989600-1669993200@seasevents.nmsdev7.com
SUMMARY:PICS Seminar: "A Non-local Plasticity Model for Porous Metals with Deformation-induced Anisotropy: Mathematical and Computational Issues"
DESCRIPTION:A non-local (gradient) plasticity model for porous metals that accounts for deformation-induced anisotropy is presented. The model is based on the work of Ponte Castañeda and co-workers on porous materials containing randomly distributed ellipsoidal voids. It takes into account the evolution of porosity and the evolution/development of anisotropy due to changes in the shape and the orientation of the voids during plastic deformation. A “material length” λ is introduced and a “non-local” porosity is defined from the solution of a modified Helmholtz equation with appropriate boundary conditions. At a material point located at x \, the non-local porosity f (x) \, can be identified with the average value of the “local” porosity floc (x) over a sphere of radius 3Rλ centered at x. \nThe same approach is used to formulate a non-local version of the Gurson isotropic model. The mathematical character of the resulting incremental elastoplastic partial differential equations of the non-local model is analyzed. It is shown that the hardening modulus of the non-local model is always larger than the corresponding hardening modulus of the local model; therefore\, the non-local incremental problem retains its elliptic character\, and the possibility of discontinuous solutions is eliminated. A rate-dependent version of the non-local model is also developed. \nAn algorithm for the numerical integration of the non-local constitutive equations is developed\, and the numerical implementation of the boundary value problem in a finite element environment is discussed. An analytical method for the required calculation of the eigenvectors of symmetric second-order tensors is presented. The non-local model is implemented in ABAQUS via a material “user subroutine” (UMAT or VUMAT) and the coupled thermo-mechanical solution procedure\, in which temperature is identified with the non-local porosity. Several example problems are solved numerically and the effects of the non-local formulation on the solution are discussed. In particular\, the problems of plastic flow localization in plane strain tension\, the plane strain mode-I blunt crack tip under small-scale-yielding conditions\, the cup-and-cone fracture of a round bar\, and the Charpy V-notch test specimen are analyzed.
URL:https://seasevents.nmsdev7.com/event/pics-seminar-a-non-local-plasticity-model-for-porous-metals-with-deformation-induced-anisotropy-mathematical-and-computational-issues/
LOCATION:Zoom – Email MEAM for Link\, peterlit@seas.upenn.edu
CATEGORIES:Colloquium
ORGANIZER;CN="Penn Institute for Computational Science (PICS)":MAILTO:dkparks@seas.upenn.edu
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