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Quantifying Uncertainty in Emulations (LDRD Report)

Crussell, Jonathan C.; Brown, Aaron B.; Jennings, Jeremy K.; Kavaler, David; Kroeger, Thomas M.; Phillips, Cynthia A.

This report summarizes the work performed under the project “Quantifying Uncertainty in Emulations.” Emulation can be used to model real-world systems, typically using virtualization to run the real software on virtualized hardware. Emulations are increasingly used to answer mission-oriented questions, but how well they represent the real-world systems is still an open area of research. The goal of the project was to quantify where and how emulations differ from the real world. To do so, we ran a representative workload on both, and collected and compared metrics to identify differences. We aimed to capture behaviors, rather than performance, differences as the latter is more well-understood in the literature.

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TYPE SAND Report YEAR 2019
DOIOSTI

Complex Fracture Nucleation and Evolution with Nonlocal Elastodynamics

Journal of Peridynamics and Nonlocal Modeling

Lehoucq, Richard B.; Lipton, Robert P.; Jha, Prashant K.

A mechanical model is introduced for predicting the initiation and evolution of complex fracture patterns without the need for a damage variable or law. The model, a continuum variant of Newton’s second law, uses integral rather than partial differential operators where the region of integration is over finite domain. The force interaction is derived from a novel nonconvex strain energy density function, resulting in a nonmonotonic material model. The resulting equation of motion is proved to be mathematically well-posed. The model has the capacity to simulate nucleation and growth of multiple, mutually interacting dynamic fractures. In the limit of zero region of integration, the model reproduces the classic Griffith model of brittle fracture. The simplicity of the formulation avoids the need for supplemental kinetic relations that dictate crack growth or the need for an explicit damage evolution law.

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TYPE Journal Article YEAR 2019
DOIOSTIScopus
Results 1801–1825 of 9,998
Results 1801–1825 of 9,998