The simulation of high-rate deformation and failure of metals is has traditionally been performed... more The simulation of high-rate deformation and failure of metals is has traditionally been performed using Lagrangian finite element methods or Eulerian hydrocodes. Lagrangian mesh-based methods are limited by issues involving mesh entanglement under large deformation and considerable complexity in handling contact. On the other hand, Eulerian hydrocodes are prone to material diffusion. In the Material Point Method (MPM), the material state is defined on solid Lagrangian particles. The particles interact with other particles in the same body, with other solid bodies, or with fluids through a background mesh. Thus, some of the problems associated with finite element codes and hydrocodes are alleviated. Another attractive feature of the material point method is the ease with which large deformation, fully coupled, fluid-structure interaction problems can be handled. In this work, we present MPM simulations that involve large plastic deformations, contact, material failure and fragmentati...
A numerical algorithm for tightly coupled, high-deformation fluid-structure inter- action problem... more A numerical algorithm for tightly coupled, high-deformation fluid-structure inter- action problems is presented. The foundation of the method is the integration of a Lagrangian particle technique (the Material Point Method, or MPM) with a multi- material Eulerian code. In this approach, each material is described and evolves in its preferred reference frame (e.g., Lagrangian for solids, Eulerian for fluids). The MPM uses a background mesh to update particle states. By using the Eulerian multi-material mesh as the background mesh to update particle states, the solid materials have a dual representation in the Lagrangian and Eulerian frame. It is in this common reference frame that coupling interactions among materials are com- puted through momentum and energy exchange terms in the multi-field equations. The approach is outlined and results from a numerical order-of-accuracy study are presented. Simulation results are compared with known solutions for the stress distribution in a pre...
Protection of US Army vehicles and personnel against landmine and IED threats is an increasingly ... more Protection of US Army vehicles and personnel against landmine and IED threats is an increasingly important concern in the area of defense research. In this paper we describe the development of a Blast Computational Framework (BCF) that will provide an advanced modeling environment and a suite of tools for performing soil bound explosion simulations and their effects on vehicles and on the human occupants of the vehicles. The BCF will provide a virtual test-bed where disparate computational models can seamlessly interact with one another to provide a unified modeling solution for blast-vehicle-occupant scenarios. The BCF is being developed using state-of-the-art component-based software architecture and will provide a suite of integrated models consisting of both new and existing simulation tools. The enhanced simulation capabilities provided by the BCF will serve to better protect the crews of existing vehicles and to help design next-generation vehicles as well.
Abstract A tightly coupled fluid-structure interaction (FSI) solution technique incorporat- ing f... more Abstract A tightly coupled fluid-structure interaction (FSI) solution technique incorporat- ing fluid and solid mechanics, phase change and chemical reactions is presented. The continuum equations are solved with a cell-centered, multi-material ICE solu- tion method. This formulation is integrated with a Lagrangian, particle based, solid mechanics technique, known as the Material Point Method, as described by Kashiwa et al. [1] and Guilkey et al. [2]. The combined,method,can handle large deformations and phase change within a single grid, without the need of sepa- rate domains for fluids and solids, or the passing of boundary conditions. This paper discusses algorithmic issues involved in accounting for chemical reactions and phase transition among material phases (e.g., solid gas). Validation is pre- sented as are simulations showing large deformation,with phase change. These simulations were performed within a computational framework that contains tools for parallelization, perfor...
ABSTRACT A common theme in tissue engineering and cell and tissue biomechanics is how the mechani... more ABSTRACT A common theme in tissue engineering and cell and tissue biomechanics is how the mechanical properties of individual tissue components or embedded cellular structures influence the continuum mechanical behavior of a tissue or construct. Meshless methods provide a useful and convenient computational framework for answering these questions [1], allowing predictions of both the effective mechanical properties of constructs and the local stresses and strains at the level of the cell. Our research focuses on understanding the mechanics of angiogenic microvessels embedded in surrogate extracellular matrix (ECM) materials [1–4]. As a first step toward understanding the interface interactions between microvessels and the ECM, the objectives of this study were to use the material point method (MPM) to analyze models of surrogate microvessels embedded in collagen gel and investigate the effects of microvessel volume fraction and interface conditions between the surrogate vessels and the collagen gel.
Contact between deformable bodies is a dif- cult problem in the analysis of engineering systems. ... more Contact between deformable bodies is a dif- cult problem in the analysis of engineering systems. A new approach to contact has been implemented us- ing the Material Point Method for solid mechanics, Bar- denhagen, Brackbill, and Sulsky (2000a). Here two im- provements to the algorithm are described. The rst is to include the normal traction in the contact logic to
Journal of the Mechanics and Physics of Solids, 2005
ABSTRACT Foamed materials are increasingly finding application in engineering systems on account ... more ABSTRACT Foamed materials are increasingly finding application in engineering systems on account of their unique properties. The basic mechanics which gives rise to these properties is well established, they are the result of collapsing the foam microstructure. Despite a basic understanding, the relationship between the details of foam microstructure and foam bulk response is generally unknown. With continued advances in computational power, many researchers have turned to numerical simulation to gain insight into the relationship between foam microstructure and bulk properties. However, numerical simulation of foam microscale deformation is a very challenging computational task and, to date, simulations over the full range of bulk deformations in which these materials operate have not been reported. Here a particle technique is demonstrated to be well-suited for this computational challenge, permitting simulation of the compression of foam microstructures to full densification. Computations on idealized foam microstructures are in agreement with engineering guidelines and various experimental results. Dependencies on degree of microstructure regularity and material properties are demonstrated. A surprising amount of porosity is found in fully-densified foams. The presence of residual porosity can strongly influence dynamic material response and hence needs to be accounted for in bulk (average) constitutive models of these materials.
Page 1. ORIGINAL ARTICLE A component-based parallel infrastructure for the simulation of fluidst... more Page 1. ORIGINAL ARTICLE A component-based parallel infrastructure for the simulation of fluidstructure interaction Steven G. Parker Æ James Guilkey Æ Todd Harman Received: 19 April 2005 / Accepted: 1 February 2006 ...
Biomechanics and modeling in mechanobiology, Jan 28, 2014
During angiogenesis, sprouting microvessels interact with the extracellular matrix (ECM) by degra... more During angiogenesis, sprouting microvessels interact with the extracellular matrix (ECM) by degrading and reorganizing the matrix, applying traction forces, and producing deformation. Morphometric features of the resulting microvascular network are affected by the interaction between the matrix and angiogenic microvessels. The objective of this study was to develop a continuous-discrete modeling approach to simulate mechanical interactions between growing neovessels and the deformation of the matrix in vitro. This was accomplished by coupling an existing angiogenesis growth model which uses properties of the ECM to regulate angiogenic growth with the nonlinear finite element software FEBio ( www.febio.org ). FEBio solves for the deformation and remodeling of the matrix caused by active stress generated by neovessel sprouts, and this deformation was used to update the ECM into the current configuration. After mesh resolution and parameter sensitivity studies, the model was used to ac...
Studies in health technology and informatics, 2005
The objective of this research was to develop realistic computational models for soft tissues sub... more The objective of this research was to develop realistic computational models for soft tissues subjected to finite deformation and failure, and to test these models in the context of numerical simulations of penetrating trauma injuries. A transversely isotropic hyperelastic model with strain-based failure criteria was used to represent the behavior of anisotropic soft tissue. The constitutive model was implemented into an existing numerical code based on the Material Point Method (MPM). The penetration of a low-speed bullet through a myocardium material slab was simulated and several wounding scenarios were analyzed and compared. The material symmetry, the type of contact modeled between the bullet and the soft tissue and the bullet speed were shown to have a significant influence on the wound profile.
The simulation of high-rate deformation and failure of metals is has traditionally been performed... more The simulation of high-rate deformation and failure of metals is has traditionally been performed using Lagrangian finite element methods or Eulerian hydrocodes. Lagrangian mesh-based methods are limited by issues involving mesh entanglement under large deformation and considerable complexity in handling contact. On the other hand, Eulerian hydrocodes are prone to material diffusion. In the Material Point Method (MPM), the material state is defined on solid Lagrangian particles. The particles interact with other particles in the same body, with other solid bodies, or with fluids through a background mesh. Thus, some of the problems associated with finite element codes and hydrocodes are alleviated. Another attractive feature of the material point method is the ease with which large deformation, fully coupled, fluid-structure interaction problems can be handled. In this work, we present MPM simulations that involve large plastic deformations, contact, material failure and fragmentati...
A numerical algorithm for tightly coupled, high-deformation fluid-structure inter- action problem... more A numerical algorithm for tightly coupled, high-deformation fluid-structure inter- action problems is presented. The foundation of the method is the integration of a Lagrangian particle technique (the Material Point Method, or MPM) with a multi- material Eulerian code. In this approach, each material is described and evolves in its preferred reference frame (e.g., Lagrangian for solids, Eulerian for fluids). The MPM uses a background mesh to update particle states. By using the Eulerian multi-material mesh as the background mesh to update particle states, the solid materials have a dual representation in the Lagrangian and Eulerian frame. It is in this common reference frame that coupling interactions among materials are com- puted through momentum and energy exchange terms in the multi-field equations. The approach is outlined and results from a numerical order-of-accuracy study are presented. Simulation results are compared with known solutions for the stress distribution in a pre...
Protection of US Army vehicles and personnel against landmine and IED threats is an increasingly ... more Protection of US Army vehicles and personnel against landmine and IED threats is an increasingly important concern in the area of defense research. In this paper we describe the development of a Blast Computational Framework (BCF) that will provide an advanced modeling environment and a suite of tools for performing soil bound explosion simulations and their effects on vehicles and on the human occupants of the vehicles. The BCF will provide a virtual test-bed where disparate computational models can seamlessly interact with one another to provide a unified modeling solution for blast-vehicle-occupant scenarios. The BCF is being developed using state-of-the-art component-based software architecture and will provide a suite of integrated models consisting of both new and existing simulation tools. The enhanced simulation capabilities provided by the BCF will serve to better protect the crews of existing vehicles and to help design next-generation vehicles as well.
Abstract A tightly coupled fluid-structure interaction (FSI) solution technique incorporat- ing f... more Abstract A tightly coupled fluid-structure interaction (FSI) solution technique incorporat- ing fluid and solid mechanics, phase change and chemical reactions is presented. The continuum equations are solved with a cell-centered, multi-material ICE solu- tion method. This formulation is integrated with a Lagrangian, particle based, solid mechanics technique, known as the Material Point Method, as described by Kashiwa et al. [1] and Guilkey et al. [2]. The combined,method,can handle large deformations and phase change within a single grid, without the need of sepa- rate domains for fluids and solids, or the passing of boundary conditions. This paper discusses algorithmic issues involved in accounting for chemical reactions and phase transition among material phases (e.g., solid gas). Validation is pre- sented as are simulations showing large deformation,with phase change. These simulations were performed within a computational framework that contains tools for parallelization, perfor...
ABSTRACT A common theme in tissue engineering and cell and tissue biomechanics is how the mechani... more ABSTRACT A common theme in tissue engineering and cell and tissue biomechanics is how the mechanical properties of individual tissue components or embedded cellular structures influence the continuum mechanical behavior of a tissue or construct. Meshless methods provide a useful and convenient computational framework for answering these questions [1], allowing predictions of both the effective mechanical properties of constructs and the local stresses and strains at the level of the cell. Our research focuses on understanding the mechanics of angiogenic microvessels embedded in surrogate extracellular matrix (ECM) materials [1–4]. As a first step toward understanding the interface interactions between microvessels and the ECM, the objectives of this study were to use the material point method (MPM) to analyze models of surrogate microvessels embedded in collagen gel and investigate the effects of microvessel volume fraction and interface conditions between the surrogate vessels and the collagen gel.
Contact between deformable bodies is a dif- cult problem in the analysis of engineering systems. ... more Contact between deformable bodies is a dif- cult problem in the analysis of engineering systems. A new approach to contact has been implemented us- ing the Material Point Method for solid mechanics, Bar- denhagen, Brackbill, and Sulsky (2000a). Here two im- provements to the algorithm are described. The rst is to include the normal traction in the contact logic to
Journal of the Mechanics and Physics of Solids, 2005
ABSTRACT Foamed materials are increasingly finding application in engineering systems on account ... more ABSTRACT Foamed materials are increasingly finding application in engineering systems on account of their unique properties. The basic mechanics which gives rise to these properties is well established, they are the result of collapsing the foam microstructure. Despite a basic understanding, the relationship between the details of foam microstructure and foam bulk response is generally unknown. With continued advances in computational power, many researchers have turned to numerical simulation to gain insight into the relationship between foam microstructure and bulk properties. However, numerical simulation of foam microscale deformation is a very challenging computational task and, to date, simulations over the full range of bulk deformations in which these materials operate have not been reported. Here a particle technique is demonstrated to be well-suited for this computational challenge, permitting simulation of the compression of foam microstructures to full densification. Computations on idealized foam microstructures are in agreement with engineering guidelines and various experimental results. Dependencies on degree of microstructure regularity and material properties are demonstrated. A surprising amount of porosity is found in fully-densified foams. The presence of residual porosity can strongly influence dynamic material response and hence needs to be accounted for in bulk (average) constitutive models of these materials.
Page 1. ORIGINAL ARTICLE A component-based parallel infrastructure for the simulation of fluidst... more Page 1. ORIGINAL ARTICLE A component-based parallel infrastructure for the simulation of fluidstructure interaction Steven G. Parker Æ James Guilkey Æ Todd Harman Received: 19 April 2005 / Accepted: 1 February 2006 ...
Biomechanics and modeling in mechanobiology, Jan 28, 2014
During angiogenesis, sprouting microvessels interact with the extracellular matrix (ECM) by degra... more During angiogenesis, sprouting microvessels interact with the extracellular matrix (ECM) by degrading and reorganizing the matrix, applying traction forces, and producing deformation. Morphometric features of the resulting microvascular network are affected by the interaction between the matrix and angiogenic microvessels. The objective of this study was to develop a continuous-discrete modeling approach to simulate mechanical interactions between growing neovessels and the deformation of the matrix in vitro. This was accomplished by coupling an existing angiogenesis growth model which uses properties of the ECM to regulate angiogenic growth with the nonlinear finite element software FEBio ( www.febio.org ). FEBio solves for the deformation and remodeling of the matrix caused by active stress generated by neovessel sprouts, and this deformation was used to update the ECM into the current configuration. After mesh resolution and parameter sensitivity studies, the model was used to ac...
Studies in health technology and informatics, 2005
The objective of this research was to develop realistic computational models for soft tissues sub... more The objective of this research was to develop realistic computational models for soft tissues subjected to finite deformation and failure, and to test these models in the context of numerical simulations of penetrating trauma injuries. A transversely isotropic hyperelastic model with strain-based failure criteria was used to represent the behavior of anisotropic soft tissue. The constitutive model was implemented into an existing numerical code based on the Material Point Method (MPM). The penetration of a low-speed bullet through a myocardium material slab was simulated and several wounding scenarios were analyzed and compared. The material symmetry, the type of contact modeled between the bullet and the soft tissue and the bullet speed were shown to have a significant influence on the wound profile.
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Papers by James Guilkey