The NEAMS program aims to develop an integrated multi-physics simulation capability "pellet-to-pl... more The NEAMS program aims to develop an integrated multi-physics simulation capability "pellet-to-plant" for the design and analysis of future generations of nuclear power plants. In particular, the Reactor Product Line code suite's multi-resolution hierarchy is being designed to ultimately span the full range of length and time scales present in relevant reactor design and safety analyses, as well as scale from desktop to petaflop computing platforms. Flow-induced vibration (FIV) is widespread problem in energy systems because they rely on fluid movement for energy conversion. Vibrating structures may be damaged as fatigue or wear occurs. Given the importance of reliable components in the nuclear industry, flow-induced vibration has long been a major concern in safety and operation of nuclear reactors. In particular, nuclear fuel rods and steam generators have been known to suffer from flow-induced vibration and related failures. Advanced reactors, such as integral Pressurized Water Reactors (PWRs) considered for Small Modular Reactors (SMR), often rely on innovative component designs to meet cost and safety targets. One component that is the subject of advanced designs is the steam generator, some designs of which forego the usual shell-and-tube architecture in order to fit within the primary vessel. A significant amount of data exists on flow-induced vibration in shell-and-tube heat exchangers, and heuristic methods are available to predict FIV based on a set of given assumptions. In contrast, advanced designs have far less data available. Advanced modeling and simulation based on coupled structural and fluid simulations have the potential to predict flow-induced vibration in a variety of designs, reducing the need for expensive experimental programs, especially at the conceptual design stage.
This report provides the NIKE3D user's manual update summary for changes made from version 3.0.0 ... more This report provides the NIKE3D user's manual update summary for changes made from version 3.0.0 April 24, 1995 to version 3.3.6 March 24,2000. The updates are excerpted directly from the code printed output file (hence the Courier font and formatting), are presented in chronological order and delineated by NIKE3D version number. NIKE3D is a fully implicit three-dimensional finite element code for analyzing the finite strain static and dynamic response of inelastic solids, shells, and beams. Spatial discretization is achieved by the use of 8-node solid elements, 2-node truss and beam elements, and 4-node membrane and shell elements. Thirty constitutive models are available for representing a wide range of elastic, plastic, viscous, and thermally dependent material behavior. Contact-impact algorithms permit gaps, frictional sliding, and mesh discontinuities along material interfaces. Several nonlinear solution strategies are available, including Full-, Modified-, and Quasi-Newton methods. The resulting system of simultaneous linear equations is either solved iteratively by an element-by-element method, or directly by a direct factorization method.
To meet the simulation needs of the GNEP program, LLNL is leveraging a suite of high-performance ... more To meet the simulation needs of the GNEP program, LLNL is leveraging a suite of high-performance codes to be used in the development of a multi-physics tool for modeling nuclear reactor cores. The Osiris code project, which began last summer, is employing modern computational science techniques in the development of the individual physics modules and the coupling framework. Initial development is focused on coupling thermal-hydraulics and neutral-particle transport, while later phases of the project will add thermal-structural mechanics and isotope depletion. Osiris will be applicable to the design of existing and future reactor systems through the use of first-principles, coupled physics models with fine-scale spatial resolution in three dimensions and fine-scale particle-energy resolution. Our intent is to replace an existing set of legacy, serial codes which require significant approximations and assumptions, with an integrated, coupled code that permits the design of a reactor core using a first-principles physics approach on a wide range of computing platforms, including the world's most powerful parallel computers. A key research activity of this effort deals with the efficient and scalable coupling of physics modules which utilize rather disparate mesh topologies. Our approach allows each code module to use a mesh topology and resolution that is optimal for the physics being solved, and employs a mesh-mapping and data-transfer module to effect the coupling. Additional research is planned in the area of scalable, parallel thermal-hydraulics, high-spatial-accuracy depletion and coupled-physics simulation using Monte Carlo transport.
Modeling of selective laser melting requires consideration of both heat transfer and solid mechan... more Modeling of selective laser melting requires consideration of both heat transfer and solid mechanics. The present work describes continuum modeling of SLM as envisioned for eventually supporting part-scale modeling of this fabrication process to determine end-state information such as residual stress and distortion. The determination of the evolving temperatures is dependent on the state of the material (powder or solid), the specified heating, the value of each of the constitutive parameters, and the configuration. Similarly, the current mechanical configuration is dependent on the temperatures, the powder-solid state, and the values of the constitutive parameters. A multi-mechanics formulation is required to properly describe such problems. The current report describes the problem formulation, numerical method, and constitutive parameters necessary to solve such a problem. Additionally, various verification and example problems are presented to illustrate the Diablo implementation.
The NEAMS Reactor Product Line effort aims to develop an integrated multi-physics simulation capa... more The NEAMS Reactor Product Line effort aims to develop an integrated multi-physics simulation capability for the design and analysis of future generations of nuclear power plants. The Reactor Product Line code suite's multi-resolution hierarchy is being designed to ultimately span the full range of length and time scales present in relevant reactor design and safety analyses, as well as scale from desktop to petaflop computing platforms.
Selective laser melting (SLM) is an additive manufacturing process in which multiple, successive ... more Selective laser melting (SLM) is an additive manufacturing process in which multiple, successive layers of metal powders are heated via laser in order to build a part. Modeling of SLM requires consideration of the complex interaction between heat transfer and solid mechanics. The present work describes the authors initial efforts to validate their first generation model, as described in Hodge, et al. [1]. In particular, the comparison of model-generated solid mechanics results, including both deformation and stresses, is presented. Additionally, results of various perturbations of the process parameters and modeling strategies are discussed.
Scan pattern dependent (multi-track) residual stress buildup over multiple layers in the powder b... more Scan pattern dependent (multi-track) residual stress buildup over multiple layers in the powder bed fusion process is governed by coupled thermo-mechanics. The high computational cost associated with these simulations has resulted in the general adoption of approximate computational methods. The numerical or thermo-mechanical accuracy of assumptions made in these computational methods is not fully characterized. If benchmark multi-track simulations for small size multi-layer parts are available, including temperatures, strain fields and deformation results, it will be possible to scientifically develop new approximation schemes or modify existing ones to improve their accuracy. Present work develops a suggestive benchmark using full multi-track thermomechanical simulations, with comparison to various approximate methods. The target configurations are simple prismatic geometries with 30 layers and up to 120 mm3 volume, illustrating the influence of domain size on the approximate resu...
The NEAMS program aims to develop an integrated multi-physics simulation capability "pellet-to-pl... more The NEAMS program aims to develop an integrated multi-physics simulation capability "pellet-to-plant" for the design and analysis of future generations of nuclear power plants. In particular, the Reactor Product Line code suite's multi-resolution hierarchy is being designed to ultimately span the full range of length and time scales present in relevant reactor design and safety analyses, as well as scale from desktop to petaflop computing platforms. Flow-induced vibration (FIV) is widespread problem in energy systems because they rely on fluid movement for energy conversion. Vibrating structures may be damaged as fatigue or wear occurs. Given the importance of reliable components in the nuclear industry, flow-induced vibration has long been a major concern in safety and operation of nuclear reactors. In particular, nuclear fuel rods and steam generators have been known to suffer from flow-induced vibration and related failures. Advanced reactors, such as integral Pressurized Water Reactors (PWRs) considered for Small Modular Reactors (SMR), often rely on innovative component designs to meet cost and safety targets. One component that is the subject of advanced designs is the steam generator, some designs of which forego the usual shell-and-tube architecture in order to fit within the primary vessel. A significant amount of data exists on flow-induced vibration in shell-and-tube heat exchangers, and heuristic methods are available to predict FIV based on a set of given assumptions. In contrast, advanced designs have far less data available. Advanced modeling and simulation based on coupled structural and fluid simulations have the potential to predict flow-induced vibration in a variety of designs, reducing the need for expensive experimental programs, especially at the conceptual design stage.
This report provides the NIKE3D user's manual update summary for changes made from version 3.0.0 ... more This report provides the NIKE3D user's manual update summary for changes made from version 3.0.0 April 24, 1995 to version 3.3.6 March 24,2000. The updates are excerpted directly from the code printed output file (hence the Courier font and formatting), are presented in chronological order and delineated by NIKE3D version number. NIKE3D is a fully implicit three-dimensional finite element code for analyzing the finite strain static and dynamic response of inelastic solids, shells, and beams. Spatial discretization is achieved by the use of 8-node solid elements, 2-node truss and beam elements, and 4-node membrane and shell elements. Thirty constitutive models are available for representing a wide range of elastic, plastic, viscous, and thermally dependent material behavior. Contact-impact algorithms permit gaps, frictional sliding, and mesh discontinuities along material interfaces. Several nonlinear solution strategies are available, including Full-, Modified-, and Quasi-Newton methods. The resulting system of simultaneous linear equations is either solved iteratively by an element-by-element method, or directly by a direct factorization method.
To meet the simulation needs of the GNEP program, LLNL is leveraging a suite of high-performance ... more To meet the simulation needs of the GNEP program, LLNL is leveraging a suite of high-performance codes to be used in the development of a multi-physics tool for modeling nuclear reactor cores. The Osiris code project, which began last summer, is employing modern computational science techniques in the development of the individual physics modules and the coupling framework. Initial development is focused on coupling thermal-hydraulics and neutral-particle transport, while later phases of the project will add thermal-structural mechanics and isotope depletion. Osiris will be applicable to the design of existing and future reactor systems through the use of first-principles, coupled physics models with fine-scale spatial resolution in three dimensions and fine-scale particle-energy resolution. Our intent is to replace an existing set of legacy, serial codes which require significant approximations and assumptions, with an integrated, coupled code that permits the design of a reactor core using a first-principles physics approach on a wide range of computing platforms, including the world's most powerful parallel computers. A key research activity of this effort deals with the efficient and scalable coupling of physics modules which utilize rather disparate mesh topologies. Our approach allows each code module to use a mesh topology and resolution that is optimal for the physics being solved, and employs a mesh-mapping and data-transfer module to effect the coupling. Additional research is planned in the area of scalable, parallel thermal-hydraulics, high-spatial-accuracy depletion and coupled-physics simulation using Monte Carlo transport.
Modeling of selective laser melting requires consideration of both heat transfer and solid mechan... more Modeling of selective laser melting requires consideration of both heat transfer and solid mechanics. The present work describes continuum modeling of SLM as envisioned for eventually supporting part-scale modeling of this fabrication process to determine end-state information such as residual stress and distortion. The determination of the evolving temperatures is dependent on the state of the material (powder or solid), the specified heating, the value of each of the constitutive parameters, and the configuration. Similarly, the current mechanical configuration is dependent on the temperatures, the powder-solid state, and the values of the constitutive parameters. A multi-mechanics formulation is required to properly describe such problems. The current report describes the problem formulation, numerical method, and constitutive parameters necessary to solve such a problem. Additionally, various verification and example problems are presented to illustrate the Diablo implementation.
The NEAMS Reactor Product Line effort aims to develop an integrated multi-physics simulation capa... more The NEAMS Reactor Product Line effort aims to develop an integrated multi-physics simulation capability for the design and analysis of future generations of nuclear power plants. The Reactor Product Line code suite's multi-resolution hierarchy is being designed to ultimately span the full range of length and time scales present in relevant reactor design and safety analyses, as well as scale from desktop to petaflop computing platforms.
Selective laser melting (SLM) is an additive manufacturing process in which multiple, successive ... more Selective laser melting (SLM) is an additive manufacturing process in which multiple, successive layers of metal powders are heated via laser in order to build a part. Modeling of SLM requires consideration of the complex interaction between heat transfer and solid mechanics. The present work describes the authors initial efforts to validate their first generation model, as described in Hodge, et al. [1]. In particular, the comparison of model-generated solid mechanics results, including both deformation and stresses, is presented. Additionally, results of various perturbations of the process parameters and modeling strategies are discussed.
Scan pattern dependent (multi-track) residual stress buildup over multiple layers in the powder b... more Scan pattern dependent (multi-track) residual stress buildup over multiple layers in the powder bed fusion process is governed by coupled thermo-mechanics. The high computational cost associated with these simulations has resulted in the general adoption of approximate computational methods. The numerical or thermo-mechanical accuracy of assumptions made in these computational methods is not fully characterized. If benchmark multi-track simulations for small size multi-layer parts are available, including temperatures, strain fields and deformation results, it will be possible to scientifically develop new approximation schemes or modify existing ones to improve their accuracy. Present work develops a suggestive benchmark using full multi-track thermomechanical simulations, with comparison to various approximate methods. The target configurations are simple prismatic geometries with 30 layers and up to 120 mm3 volume, illustrating the influence of domain size on the approximate resu...
Uploads
Papers by Robert Ferencz