Preparing for exascale: additive manufacturing process modeling at the fidelity of the microstructure*

In FY17, the USDOE Exascale Computing Project (ECP) initiated projects to design and develop simulation codes to use exascale computing. This application development is organized around computational motifs. Here, we present an overview of the motifs of computational materials science, from the “particles” used by molecular dynamics to the “grids” used by phase-field models and the various solution algorithms. Examples will be taken from the co-design centers ExMatEx and CoPA, as well as the Additive Manufacturing (AM) application development project ExaAM. This project includes an integration of all the computational components of the metal AM process into a coupled exascale modeling environment, where each simulation component itself is an exascale simulation. What has emerged is that exascale computing will enable AM process modeling at the fidelity of the microstructure. Here we discuss what this means, in particular, tight coupling of Process-Structure-Property calculations, and the feedback into AM-specific constitutive models. Macroscopic continuum codes (Truchas and OpenFOAM) are used to simulate melt-refreeze, within which mesoscopic codes (Phase-field and Cellular Automata) are used to simulate the development of material microstructure. This microstructure is then used by polycrystal plasticity codes (ExaConstit) to calculate local material properties. The project is driven by a series of demonstration problems (NIST AMBench) that are amenable to experimental observation and validation. We present our coupled exascale simulation environment for additive manufacturing and its initial application to AM builds.