Entity

Time filter

Source Type

Champaign, IL, United States

Buryachenko V.A.,University of Akron | Buryachenko V.A.,IllinoisRocstar, LLC
International Journal of Solids and Structures | Year: 2013

One considers a linear thermoelastic composite medium, which consists of a homogeneous matrix containing a statistically inhomogeneous random set of heterogeneities with various interface effects and subjected to essentially inhomogeneous loading by the fields of the stresses, temperature, and body forces (e.g.; for a centrifugal load). The general integral equations connecting the stress and strain fields in the point being considered and the surrounding points are obtained for the random and deterministic fields of inclusions. The method is based on a centering procedure of subtraction from both sides of a new initial integral equation their statistical averages obtained without any auxiliary assumptions such as the effective field hypothesis (EFH), which is implicitly exploited in the known centering methods. The new initial integral equation is presented in a general form of perturbations introduced by the heterogeneities and taking into account both the spring-layer model and coherent imperfect one. Some particular cases, asymptotic representations, and simplifications of proposed equations as well as a model example demonstrating the essence of two-step statistical average scheme are considered. General integral equations for the doubly and triply periodical structure composites are also obtained. © 2013 Elsevier Ltd. All rights reserved. Source


Buryachenko V.A.,University of Cagliari | Buryachenko V.A.,IllinoisRocstar, LLC
International Journal of Solids and Structures | Year: 2011

One considers a linear thermoelastic composite medium, which consists of a homogeneous matrix containing a statistically homogeneous random set of ellipsoidal uncoated or coated heterogeneities. It is assumed that the stress-strain constitutive relations of constituents are described by the nonlocal integral operators, whereas the equilibrium and compatibility equations remain unaltered as in classical local elasticity. The general integral equations connecting the stress and strain fields in the point being considered and the surrounding points are obtained. The method is based on a centering procedure of subtraction from both sides of a known initial integral equation their statistical averages obtained without any auxiliary assumptions such as, e.g.; effective field hypothesis implicitly exploited in the known centering methods. In a simplified case of using of the effective field hypothesis for analyzing composites with one sort of heterogeneities, one proves that the effective moduli explicitly depend on both the strain and stress concentrator factor for one heterogeneity inside the infinite matrix and does not directly depend on the elastic properties (local or nonlocal) of heterogeneities. In such a case, the Levin's (1967) formula in micromechanics of composites with locally elastic constituents is generalized to their nonlocal counterpart. A solution of a volume integral equation for one heterogeneity subjected to inhomogeneous remote loading inside an infinite matrix is proposed by the iteration method. The operator representation of this solution is incorporated into the new general integral equation of micromechanics without exploiting of basic hypotheses of classical micromechanics such as both the effective field hypothesis and "ellipsoidal symmetry" assumption. Quantitative estimations of results obtained by the abandonment of the effective field hypothesis are presented. © 2011 Elsevier Ltd. All rights reserved. Source


Buryachenko V.A.,University of Akron | Buryachenko V.A.,IllinoisRocstar, LLC
International Journal of Solids and Structures | Year: 2014

The basic feature of the peridynamic model considered is a continuum description of a material behavior as the integrated nonlocal force interactions between infinitesimal particles. In contrast to these classical theories, the peridynamic equation of motion introduced by Silling (2000) is free of any spatial derivatives of displacement. A heterogeneous bar of statistically homogeneous random structure of constituents with the peristatic mechanical properties is analyzed by the standard averaging tool of micromechanics. The applicability of local elasticity theory is demonstrated for description of effective elastic behavior of this bar. The approach proposed is based on numerical solution (for both the displacements and peristatic stresses) for one heterogeneity inside infinite homogeneous bar loaded by a pair of self-equilibrated concentrated remote forces. This solution is substituted into the general scheme of micromechanics of locally elastic media adapted for the considered case of 1D peristatic structures. A convergence of effective modulus estimations is demonstrated for both the peristatic composite bar and locally elastic bar. © 2014 Elsevier Ltd. All rights reserved. Source


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 124.98K | Year: 2014

Illinois Rocstar LLC proposes to develop and demonstrate the use of an integrated computational environment and infrastructure for electrochemical device design and simulation: ICED. This environment integrates the user's personal computational environment with high performance simulation applications for materials and processes. The current state of the art for electrochemical device design utilizes empirical or highly simplified models, homogeneous materials, and relies heavily on experimentation. ICED will enable device researchers to utilize advanced models implemented in state of the art simulation software, taking advantage of modern compute hardware, providing a truly predictive and exploratory research and design platform. To demonstrate the feasibility of the system, Illinois Rocstar will develop a detailed three-dimensional model for nanomaterial electrode performance, including modeling of the electrode microstructure, electron conduction, and ion transport in the solid and liquid phases. This model will be integrated into a device-scale simulation with existing simplified models of all device components. The model and simulation tool will be validated against experiments conducted by our SBIR partner, Xerion Advanced Battery Corp.


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 150.00K | Year: 2015

Problem Being Addressed: Lack of availability, usability, and the cost of development, ownership, and operation of high performance compute-ready simulation capabilities are significant barriers to utilization of modeling & simulation for American industry. Most open-source, free technologies are difficult to use and/or not validated to the extent needed for industrial application. Many commercial tools that are easy to use, are very expensive to own. Hardening of currently available research-quality simulation tools can can produce capabilities that are both easy to use and free. How This Problem is Being Addressed: The goal is to harden an ASC-developed multiphysics simulation application and distribute it under an open source license that allows unrestricted commercial use. Expert users from government, industry, and academia currently employ the code on modern large cluster platforms for a variety of multiphysics simulations. When completed, this project will produce the only open source massively parallel multiphysics application that is freely available, and which stands ready to utilize the nations modern high performance computing resources. Once hardened for ease of installation and use, the package will help lower the entry barriers to high performance computing-based modeling & simulation. Commercial Applications and Other Benefits:A freely available, open, and easily extensible massively parallel-ready multiphysics simulation capability for use by engineers and analysts from industry and other environments will be generated from this project. Such a capability will significantly reduce the barrier to entry for private sector entities endeavoring to utilize multiphysics simulations and incorporate them into design processes that leverage the nations extensive computing resources. To maintain competitiveness in the modern world marketplace, simulation applications must be designed for deployment in integrated environments and coupled models, simulating ever more complex interacting systems. The licensing model under which this application will be distributed facilitates its use and extension in any environment. The benefits include increased realism, decreased time-to-solution, increased manufacturing capability, reduced manufacturing cost, and a decrease in the product design cycle. The economic implications and range of commercial applications are large and promising. Modular high performance computing-ready simulation capabilities are the future of modeling & simulation for American industry, and a key to maintaining national competitiveness. Key Words: Multiphysics, graphical user interface, validation, modeling & simulation Summary for Members of Congress (13th Congressional District of Illinois): Establishing an infrastructure for high performance computing-aided modeling & simulation is key to the future of U.S. industrial competitiveness in the world marketplace. This project results in the nations first free, commercial-quality software to provide advanced, extensible multiphysics simulation capabilities and infrastructure to industry users.

Discover hidden collaborations