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TOWARDS A computational FRAMEWORK FOR HYPERVELOCITY-INDUCED ATMOSPHERIC PLASMA MODELING

TOWARDS A COMPUTATIONAL FRAMEWORK FOR HYPERVELOCITY-INDUCED ...

ASME 2024 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, IDETC-CIE 2024

作者： Graber, B.D. Iliopoulos, A.P. Michopoulos, J.G. Steuben, J.C. Birnbaum, A.J. Apetre, N.A. Computational Multiphysics Systems Laboratory Materials Science and Technology Division U.S. Naval Research Laboratory WashingtonDC20375 United States

ISBN: (纸本)9780791888346

The work presented in this paper estimates the spectral radiance emitted from plasma induced by the interaction of hypervelocity moving structural/material systems with the atmosphere. The motivation for this effort originates from the need to compute the radiative heat fluxes imparted to hypersonic vehicles to facilitate their design, control, and maintenance. In response to this need, a computational framework was established to predict the fluid dynamics fields around a hypervelocity vehicle that in turn is coupled with the plasma physics that enables the calculation of the plasma fields and species dynamics. This framework implements a one-way coupling between fluid dynamics and plasma physics models. The framework solves the fluid dynamics partial differential equations representing the conservation of mass, momentum, and energy. The computed pressure, velocity, and temperature fields are subsequently utilized to drive the plasma physics PDEs describing the mass transport and energetics of all the nitrogen-oxygen 11 species present according to the so-called Dunn plasma model. An application of this framework for a spherical body for a wide range of velocities is presented as a verification of the framework’s functionality. Typical distributions of the fluid and plasma dynamics are presented. Finally, the plasma radiance spectra are produced by employing statistical mechanics principles. © 2024 by The United States Government.

关键词： Statistical mechanics

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DATA–DEFINED MACHINE INTELLIGENCE FOR MECHANICAL PROPERTIES IDENTIFICATION

DATA–DEFINED MACHINE INTELLIGENCE FOR MECHANICAL PROPERTIES...

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ASME 2024 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, IDETC-CIE 2024

作者： Iliopoulos, A.P. Michopoulos, J.G. Steuben, J.C. Apetre, N. Computational Multiphysics Systems Laboratory Materials Science and Technology Division U.S. Naval Research Laboratory WashingtonDC20375 United States

ISBN: (纸本)9780791888353

In this work we are introducing a Machine Intelligence (MI) concept that belongs to the set of approaches that emphasize data over artificial intelligence model. The development of the concept was motivated by the need to eliminate training as the means to enable fast or perpetual system adaptation and update, and also vastly reduce pre-processing times. This characteristic can be extremely valuable in situations when new data are regularly becoming available and utilized to increase the MI accuracy with minimal delay, or when the represented system changes with time. A characteristic of the proposed data–defined MI approach is that of introspection;it can be queried to locally estimate the system error at any data point that is part of its data set and potentially act accordingly. To provide evidence of the validity and performance of the approach, we first demonstrate on classical hand-writing classification of numerical digits. We then apply it to a challenging problem of identifying the properties of bi-linear elastoplastic material using a single full-field strain tensor image of a synthetic experiment. The validation test is performed for many untrained instances, and the histogram, mean and maximum errors are discussed. We also discuss several interesting capabilities that a data–defined concept enables. Copyright © 2024 by The United States Government.

关键词： Tensors

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GENERALIZED ANISOTROPIC MULTIOBJECTIVE TOPOLOGY OPTIMIZATION FOR NAVAL ADDITIVE MANUFACTURING

GENERALIZED ANISOTROPIC MULTIOBJECTIVE TOPOLOGY OPTIMIZATION...

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ASME 2024 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, IDETC-CIE 2024

作者： Steuben, J.C. Iliopoulos, A.P. Birnbaum, A.J. Graber, B.D. Michopoulos, J.G. Computational Multiphysics Systems Laboratory Materials Science and Technology Division U.S. Naval Research Laboratory WashingtonDC20375 United States

ISBN: (纸本)9780791888346

The use of topology optimization algorithms for engineering design has become widespread. Motivated by the objective of producing lightweight, high-performance components, a wide variety of approaches have emerged, and many alternatives now exist for every stage of the associated computing pipeline. The present work introduces a generalized topology optimization framework for use in the area of additive manufacturing (AM), with a focus on naval applications. The development of this framework is outlined, with particular attention paid to the development of an anisotropic experimental data-driven material constitutive model. Additionally, methods for handling arbitrary numbers of objectives, design constraints imposed by additive manufacturing process physics, and boundary conditions particular to naval applications are explored. Steps for post-processing and refining the optimizer output in order to produce manufacturing-ready files are also discussed. The approach is demonstrated on a pair of test cases. The first is the design of an optimized "conformal" pressure vessel, which departs from the typical sphere / cylinder forms and allows for increased storage capacity by occupying a non-convex envelope space. The second application problem is the design of an optimized propulsor intended to be produced using large-scale AM. This propulsor is optimized for inertial and hydrodynamic loads, and a parametric study of the effect of outer shell thickness is performed. © 2024 by The United States Government.

关键词： Shape optimization

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TOWARDS A multiphysics-BASED DIGITAL TWIN FOR PREDICTING AGING OF MULTIMATERIAL ADHESIVE STEP LAP JOINTS

TOWARDS A MULTIPHYSICS-BASED DIGITAL TWIN FOR PREDICTING AGI...

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ASME 2024 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, IDETC-CIE 2024

作者： Michopoulos, J.G. Apetre, N.A. Iliopoulos, A.P. Steuben, J.C. Computational Multiphysics Systems Laboratory Materials Science and Technology Division U.S. Naval Research Laboratory WashingtonDC20375 United States

ISBN: (纸本)9780791888346

We present the initial steps towards formulating a multiphysics-based digital twin for predicting aging for multi-material adhesive step lap joints (ASLJs) that accounts for mechanical and environmental generalized loading. Initially, we provide a definition of the digital twin context and the particular digital twin architecture considered associated with the data-driven digital twin flavor. Subsequently, focus is given to establishing and exercising a theoretical and computational framework accounting for the degradation of properties for materials participating in ASLJs due to environmentally-aided damage accumulation. A thermodynamics-based theory is derived as a first step. An initial computational implementation of it is developed and applied to two models of multi-material ASLJs involving a titanium Ti-6Al4V alloy and carbon epoxy composite adherent and an FM-300K adhesive. Several studies have been performed to identify the effect of parameters related to the choice of element order, mesh density, damage parameters and inclusion of damage models for the participating domains. Finally, the predictions obtained from the framework are compared with experimental results to establish the necessary validation for two environmental conditions of room and elevated temperatures at low ambient humidity. These results provide an initial insight into the characteristics of the aging degradation of ASLJ performance when both the adhesive and the composite material adherent are accumulating damage and contribute to aging of the respective materials. © 2024 by The United States Government.

关键词： Titanium alloys

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OBJECTIVE COLORMAPS FOR MINIMIZING INTERPRETATION BIAS IN SCIENCE AND ENGINEERING

OBJECTIVE COLORMAPS FOR MINIMIZING INTERPRETATION BIAS IN SC...

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ASME 2024 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, IDETC-CIE 2024

作者： Iliopoulos, A.P. Michopoulos, J.G. Steuben, J.C. Apetre, N. Birnbaum, A. Computational Multiphysics Systems Laboratory Materials Science and Technology Division U.S. Naval Research Laboratory WashingtonDC20375 United States

ISBN: (纸本)9780791888346

While working on the implementation of hygro-thermo-structural models for composite materials like those used in aircraft, we started noticing discontinuities in the fringe plots of the validation tests. This led us down a time-consuming path of debugging the implementation, that indicated that there were no problems with our numerical code. After further investigation we established the the issue emanated from the non-uniform nature of the colormap used to map the field variables. In researching the matter further we identified several contemporary attempts in establishing metric to judge the perceptual non-uniformity of colormaps. In this work we extend these attempts to encompass objective functions that allow for the automated generation of colormaps that minimize non-uniformity with the goal to reduce visual bias to the extent allowed by modern color theory and color standards. The objective functions are formulates on the basis of lightness, chromaticity, gamut completion, and desired color in both explicit and implict forms. We present several application examples and illustrate them based on typical benchmark data. We furthermore demonstrate the appearance of colormaps for the three types of color vision deficiency using simulated mapping. These studies are a precursor of refinement of the proposed framework towards more universal colormaps. © 2024 by The United States Government.

关键词： Aircraft materials

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GRADED MINIMAL SURFACE PERIODIC STRUCTURES FOR multiphysics METAMATERIAL APPLICATIONS

GRADED MINIMAL SURFACE PERIODIC STRUCTURES FOR MULTIPHYSICS ...

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ASME 2024 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, IDETC-CIE 2024

作者： Apetre, N.A. Michopoulos, J.G. Iliopoulos, A.P. Steuben, J.C. Rodriguez, S.N. Graber, B.D. Kittur, M. Computational Multiphysics Systems Laboratory Materials Science and Technology Division U.S. Naval Research Laboratory WashingtonDC20375 United States Patuxent RiverMD20670 United States

ISBN: (纸本)9780791888346

The continuous progress of additive manufacturing techniques has enabled engineers and designers to build complex geometries at various length scales with minimal setup time, reduced need for skilled labor, and minimal material waste. One important subset of structures endowed with complex geometrical features is formed by periodic and non-periodic metamaterials that enable engineering applications where certain combinations of performance features are desirable. For example, these structures could be used in naval engineering applications where light-weight, large surface area, energy absorption, heat dissipation, and acoustic bandgaps are critical. Nevertheless, to deploy these complex geometry structures, their multiphysics response must be well understood and characterized. The current effort aims to describe an initial approach for designing and deploying graded triply periodic minimal surface (TPMS) architectures. The work focuses on three TPMS systems: (a) Neovius, (b) Schoen’s gyroid, and (c) Schoen’s F-RD made of Ti-6Al4V alloy. These three geometries are enhanced using variable wall thickness to obtain the so-called graded TPMS. Three problems are explored: (1) evaluation of the elastic equivalent material properties of various unit cells with graded thickness;(2) investigation of acoustics dispersion properties of three cells and (3) a thermo-structural response of a complex geometry made of twelve graded representative volume elements (RVE). Finite element results of the relevant thermo-structural partial differential equations for the case of a gyroid triply periodic cylindrical sandwich structure are presented. © 2024 by The United States Government.

关键词： Sandwich structures

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Generation of continuous toolpaths for additive manufacturing using implicit slicing 41

Generation of continuous toolpaths for additive manufacturin...

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41st Computers and Information in Engineering Conference, CIE 2021, Held as Part of the ASME 2021 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, IDETC-CIE 2021

作者： Steuben, J.C. Michopoulos, J.G. Iliopoulos, A.P. Computational Multiphysics Systems Laboratory Center of Materials Physics and Technology U.S. Naval Research Laboratory WashingtonDC20375 United States

ISBN: (纸本)9780791885376

The generation of toolpaths for additive manufacturing (AM), a process commonly known as "slicing," has a strong impact on the performance of both the associated hardware systems and the resulting objects. Available slicers invariably produce discontinuous toolpaths, featuring jumps or so-called "travel moves" during which the deposition of material or/and energy must be halted. For AM processes using slowly solidifying feedstock materials, such as thermosetting polymers or cementitious mixtures such as concrete, these toolpath discontinuities are highly undesirable due to the artifacts they generate. This renders existing slicers difficult to use in such applications, and presents a roadblock to the adoption of AM for such material systems. In the present work, this difficulty is addressed by the development of a simple geometric criterion for the existence of continuous toolpaths that are capable of producing a specified input geometry. This development is based on the principles of morphological geometric analysis and graph theory. It is shown that, for any geometric feature with a characteristic thickness at least twice the extrusion width, a continuous toolpath exists. Furthermore, a general-purpose algorithm for continuous toolpath generation, for arbitrarily shaped objects satisfying this criterion, is developed and demonstrated on a representative test problem. Finally, conclusions and the path forward for the usage of this approach with existing AM systems is explored. Copyright © 2021 by ASME and The United States Government

关键词： 3D printers

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Projection-based model-order reduction for unstructured meshes with graph autoencoders

arXiv

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arXiv 2024年

作者： Magargal, Liam K. Khodabakhshi, Parisa Rodriguez, Steven N. Jaworski, Justin W. Michopoulos, John G. Department of Mechanical Engineering and Mechanics Lehigh University BethlehemPA United States Computational Multiphysics Systems Laboratory U. S. Naval Research Laboratory WashingtonDC United States Kevin T. Crofton Department of Aerospace and Ocean Engineering Virginia Tech BlacksburgVA United States

This paper presents a graph autoencoder architecture capable of performing projection-based model-order reduction (PMOR) on advection-dominated flows modeled by unstructured meshes. The autoencoder is coupled with the time integration scheme from a traditional deep least-squares Petrov-Galerkin projection and provides the first deployment of a graph autoencoder into a PMOR framework. The presented graph autoencoder is constructed with a two-part process that consists of (1) generating a hierarchy of reduced graphs to emulate the compressive abilities of convolutional neural networks (CNNs) and (2) training a message passing operation at each step in the hierarchy of reduced graphs to emulate the filtering process of a CNN. The resulting framework provides improved flexibility over traditional CNN-based autoencoders because it is extendable to unstructured meshes. To highlight the capabilities of the proposed framework, which is named geometric deep least-squares Petrov-Galerkin (GD-LSPG), we benchmark the method on a one-dimensional Burgers’ equation problem with a structured mesh and demonstrate the flexibility of GD-LSPG by deploying it to a two-dimensional Euler equations model that uses an unstructured mesh. The proposed framework provides considerable improvement in accuracy for very low-dimensional latent spaces in comparison with traditional affine projections. Copyright © 2024, The Authors. All rights reserved.

关键词： Least squares approximations

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Multiscale tomographic wave-matter interaction modeling to enable artifact-free material defect reconstruction

Multiscale tomographic wave-matter interaction modeling to e...

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ASME 2020 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, IDETC-CIE 2020

作者： Steuben, J.C. Michopoulos, J.G. Iliopoulos, A.P. Graber, B.D. Birnbaum, A.J. Computational Multiphysics Systems Laboratory Center of Materials Physics and Technology U.S. Naval Research Laboratory WashingtonDC20375 United States

ISBN: (纸本)9780791883983

The fabrication and subsequent in-service excitation of materials/structures invariably generates significant defects including cracks, voids and inclusions, spanning many length scales. The various technologies available for detecting and qualitatively describing such defects suffer from the introduction of various degrees inaccuracy when it comes to the quantification of defect geometry. This can have an adverse impact on modeling and understanding how the material/part/structure performance is effected by these defects. The main cause of this shortcoming is that aspects of the physical processes used to interrogate the material system, using monochromatic or polychromatic waves such as X-ray, mm-wave, or ultrasound, are not taken into account. These waves interact with the multiscale defect ensemble in a complex fashion that inevitably produces spurious "artifacts" in the resulting data, which cannot be removed via conventional data post-processing. These artifacts then introduce unacceptable levels of error when reconstructing defect geometry and computing the remaining lifespan of defect-bearing materials/structures. The present work introduces preliminary efforts towards a multiscale modeling and simulation framework for capturing the interactions of waves (such as X-rays) with materials bearing defect ensembles. It is shown that conventional approaches such as ray tracing are not adequate, and a more robust solution to the relevant wave equations utilizing the Finite Element discretization is employed. A general parameterization of defect geometries based on superquadratic functions is also introduced, and the interactions of defects modeled in this fashion with X-rays are investigated. It is also shown that this combination of parameterization and modeling techniques allows the recovery of true, artifact-free defect geometry utilizing classical inverse methods. The methodology is demonstrated using synthetic tomographic data, and the path forward to a more c

关键词： Wave equations

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Determination of the Thermal Conductivity of Gas-Hydrate-Containing Porous Media using Discrete Geometric Analogues

Determination of the Thermal Conductivity of Gas-Hydrate-Con...

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2022 IEEE International Multi-Conference on Engineering, Computer and Information Sciences, SIBIRCON 2022

作者： Markov, Sergey I. Shurina, Ella P. Itkina, Natalya B. Trofimuk Institute of Petroleum Geology and Geophysics SB RAS Lab. of Math. Modeling of Multiphysics Phenomena in Native and Artif. Multiscale Heterogeneous Media Department of Computer Technologies Novosibirsk State Technical University Novosibirsk Russia Laboratory of Analysis and Optimization of Nonlinear Systems Institute of Computational Technologies Novosibirsk State Technical University SB RAS Department of Computer Technologies Novosibirsk Russia

ISBN: (纸本)9781665464802

This work deals with the problem of reconstructing the thermal conductivity coefficient of ice-gas-hydrate rocks. It is proposed to use the results of direct mathematical simulation of heat transfer processes in a heterogeneous porous medium with different phase composition, and the principles of energy conservation law. The results of high-resolution X-ray tomography are applied to construct a digital model of the gas-hydrate-containing medium using machine learning procedure and special thresholding methods. A discrete geometrical model of the digital model is constructed by methods based on adapted symplectic partitions. In contrast to existing solutions to the above problem, our approach is not based on the application of phenomenological reduced models. We apply continuum models of the medium under study, and the heat transfer process. This approach makes it possible to obtain physically relevant results for determining the thermal conductivity coefficient of a heterogeneous medium using its digital analogue. The influence of the phase composition and contrast of the thermal characteristics on the value of thermal conductivity coefficient of ice-gas-hydrate-containing samples is presented. © 2022 IEEE.

关键词： Porous materials

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