Publications

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A parallel, adaptive overlay grid procedure is proposed for use in generating all-hex meshes for stochastic (SVE) and representative (RVE) volume elements in computational materials modeling. The mesh generation process is outlined including several new advancements such as data filtering to improve mesh quality from voxelated and 3D image sources, improvements to the primal contouring method for constructing material interfaces and pillowing to improve mesh quality at boundaries. We show specific examples in crystal plasticity and syntactic foam modeling that have benefitted from the proposed mesh generation procedure and illustrate results of the procedure with several practical mesh examples.

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Sculpt is a companion application to Cubit designed to run in parallel for generating all-hex meshes of complex geometry. It uses a unique overlay-grid procedure that extracts surfaces from a volume-fraction representation of the geometry. This allows for fast, automatic, fault-tolerant meshing in a high-performance computing (HPC) environment. Although Sculpt can be driven from Cubit as a GUI front-end, Sculpt was developed as a separate application so that it can be run independently from Cubit on HPC computing platforms. It was also designed as a separable software library so it can be easily integrated as an in-situ meshing solution within other codes. This work provides a brief technical discussion of the algorithms used in Sculpt as well as a complete user's manual. It includes details of the Cubit interface to Sculpt and the complete manual for the stand-alone application, including examples.

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We describe new machine-learning-based methods to defeature CAD models for tetrahedral meshing. Using machine learning predictions of mesh quality for geometric features of a CAD model prior to meshing we can identify potential problem areas and improve meshing outcomes by presenting a prioritized list of suggested geometric operations to users. Our machine learning models are trained using a combination of geometric and topological features from the CAD model and local quality metrics for ground truth. We demonstrate a proof-of-concept implementation of the resulting work ow using Sandia's Cubit Geometry and Meshing Toolkit.

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Researchers review the challenges and opportunities that we are facing in the modeling and simulation of additive manufacturing processes for metals and the predictive representation of their mechanical performance at the different scales. They highlight the current modeling efforts taking place at the US Department of Energy National Nuclear Security Administration (NNSA) Laboratories, such as process modeling, microstructure modeling, properties modeling, performance and topology and process optimization. All these various modeling developments at different scales and regimes are necessary to move toward an integrated computational approach of process-structure-properties-performance that will ultimately enable the engineering and optimization of materials to specific performance requirements. Truchas, a continuum thermo-mechanical modeling tool originally designed for the simulation of casting processes, is being extended to simulate directed energy deposition additive manufacturing processes.

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