Crystal-Plasticity on Robert Carson

BCC Crystal Plasticity & High Strain-Rate Mechanics

Tue, 15 Apr 2025 00:00:00 +0000

Overview
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Body-centered cubic (BCC) metals are among the most mechanically interesting crystalline solids to model. Unlike FCC metals, where slip occurs on well-defined {111}⟨110⟩ systems and the dislocation physics is relatively well understood, BCC plasticity is governed by thermally activated screw dislocation motion with non-planar core structures. This produces strong temperature and strain-rate sensitivity, and a persistent debate about which slip planes are actually active under different loading conditions.

ExaCMech: GPU-Native Crystal Plasticity Constitutive Library

Tue, 15 Apr 2025 00:00:00 +0000

The Problem ExaCMech Solves
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Crystal plasticity finite element codes spend a large fraction of their time doing one thing: the constitutive update. Given a material’s current state (its crystal orientation, internal hardening variables, elastic strain) and a prescribed deformation over a time step, compute the resulting stress and update the material state. This has to be done at every quadrature point in the mesh, which in a production micromechanics simulation means evaluating physically complex, iterative nonlinear equations simultaneously at tens of millions of points. For the problem to be tractable at scale, those evaluations need to run on the GPU, and the models need to be structured in a way that maps naturally to how GPUs actually execute work.

ExaConstit: High-Performance Micromechanics Finite Element Code

Tue, 15 Apr 2025 00:00:00 +0000

Where ExaConstit Came From
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When I joined the ExaAM project at LLNL, the project needed a crystal plasticity finite element code that could run on GPUs at scale. ExaAM is a DOE Exascale Computing Project effort to model metal additive manufacturing from the melt pool all the way up to the part scale, and the part that connects microstructure to part-scale mechanical response requires simulating thousands of individual grains with their own crystal orientations, phases, and slip systems. At the time, no open-source code existed that could do this on GPUs in a serious way. Most comparable codes either had no GPU support or treated it as an experimental add-on that barely worked. So we built ExaConstit from scratch with GPU execution as a first-class target from day one.

Intragranular Deformation & Crystal Lattice Methods

Tue, 15 Apr 2025 00:00:00 +0000

Overview
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Fatigue is one of the grand challenges in engineering. The first published study appeared in 1837 on mining conveyor chains that failed in service. By the end of the 20th century, over 100,000 papers had been written on the subject, and the problem is still not solved. The reason is that fatigue failure depends on a wide range of interacting factors: residual stress, thermal processing, surface condition, environment, and most fundamentally, the microstructure of the material itself. The Aloha Airlines Flight 243 accident, where fatigue cracks in fuselage lap joints caused a section of the cabin roof to separate in flight, is one example among many that drove enormous investment in understanding how cracks initiate and grow under cyclic loading.

Crystal-Plasticity on Robert Carson

BCC Crystal Plasticity & High Strain-Rate Mechanics

Overview #

ExaCMech: GPU-Native Crystal Plasticity Constitutive Library

The Problem ExaCMech Solves #

ExaConstit: High-Performance Micromechanics Finite Element Code

Where ExaConstit Came From #

Intragranular Deformation & Crystal Lattice Methods

Overview #

Overview
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The Problem ExaCMech Solves
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Where ExaConstit Came From
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Overview
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