Symposia, Workshops, Conferences
http://hdl.handle.net/1813/305
2016-04-29T23:42:08ZPart 2: Possibilities for Transformational Change in the Next Century
http://hdl.handle.net/1813/43775
Part 2: Possibilities for Transformational Change in the Next Century
100
Years
of
Scholarship
at
Cornell
2015-09-25T00:00:00ZPart 1: Development Challenges Through a Sociological Lens
http://hdl.handle.net/1813/43774
Part 1: Development Challenges Through a Sociological Lens
100
Years
of
Scholarship
at
Cornell
2015-09-25T00:00:00Z(28) Resource: Anthony R. Ingraffea – Background Resources
http://hdl.handle.net/1813/38144
(28) Resource: Anthony R. Ingraffea – Background Resources
Cornell University
Computer Simulation and Physical Testing of Complex Fracturing Processes
A Symposium in Honor of Professor Emeritus Anthony R. Ingraffea
School of Civil and Environmental Engineering, Cornell University
September 27, 2014
2014-09-27T00:00:00Z(27) Resource: Anthony R. Ingraffea – Background, Publications, and Projects Related to Hydraulic Fracturing, Methane Emissions, and Gas Pipeline Safety (thru 2014)
http://hdl.handle.net/1813/38109
(27) Resource: Anthony R. Ingraffea – Background, Publications, and Projects Related to Hydraulic Fracturing, Methane Emissions, and Gas Pipeline Safety (thru 2014)
Ingraffea, Anthony R.
2014-09-27T00:00:00Z(29) Resource: Anthony R. Ingraffea – Curriculum Vitae
http://hdl.handle.net/1813/38108
(29) Resource: Anthony R. Ingraffea – Curriculum Vitae
Ingraffea, Anthony R.
2014-09-27T00:00:00Z(26) Resource: Anthony R. Ingraffea – A Brief Biography
http://hdl.handle.net/1813/38107
(26) Resource: Anthony R. Ingraffea – A Brief Biography
Cornell University
Anthony Ingraffea, known to most as “Tony,” retired on June 30, 2014. He enjoyed two years as a structural engineer with the Grumman Aerospace Corporation and two years as a county engineer with the Peace Corps in Venezuela before earning his doctorate at the University of Colorado in 1977. Since then, he has taught structural mechanics, structural engineering, and fracture mechanics at Cornell as a member of the School of Civil and Environmental Engineering.
2014-09-27T00:00:00Z(31) Resource: Anthony R. Ingraffea – Symposium Group Photo with Identifications
http://hdl.handle.net/1813/38106
(31) Resource: Anthony R. Ingraffea – Symposium Group Photo with Identifications
Cornell University
Computer Simulation and Physical Testing of Complex Fracturing Processes; A Symposium in Honor of Professor Emeritus Anthony R. Ingraffea; School of Civil and Environmental Engineering, Cornell University
2014-09-27T00:00:00Z(24) Toward High-Fidelity Multi-Scale Modeling of 3D Crack Evolution (slides)
http://hdl.handle.net/1813/38105
(24) Toward High-Fidelity Multi-Scale Modeling of 3D Crack Evolution (slides)
Spear, Ashley
In the ultimate quest to achieve predictive capabilities for crack evolution across multiple length scales, the final generation of Prof. Ingraffea’s graduate students stood on the shoulders of their predecessors, leveraging some of the most advanced materials-characterization and modeling techniques to capture crack geometries and environments with utmost fidelity. The first part of this talk highlights two novel, numerical toolsets that were developed to enable the prediction of 3D crack propagation at the structural or component length scale. The first toolset is one that uses material-state mapping along with FRANC3D-inspired adaptive remeshing to predict propagation of 3D cracks in ductile materials. The second toolset was developed to predict 3D crack-shape evolution by calculating local increments of crack extension, Δai, using energy-release-rate principles. The second part of the talk highlights novel characterization and modeling efforts that were carried out to understand (and eventually to predict) the formation and early propagation of 3D cracks at the microstructural length scale. In one effort, 3D characterization of fatigue-crack nucleation in a Ni-base superalloy microstructure was reconstructed using 3D crystal-plastic finite-element (CPFE) modeling. “Big data” concepts were utilized to discover quantitative correlations between the underlying microstructure and fatigue indicator parameters computed from the CPFE results. In another effort, the propagation of a microstructurally small fatigue crack in an aluminum alloy was characterized in 3D for the first time. The 3D measurements were converted to a 3D CPFE model that explicitly represented the history-dependent shape of the 3D fatigue crack as well as the surrounding grain structure. The talk concludes with important lessons learned in the Cornell Fracture Group and a look to the future.
2014-09-27T00:00:00Z(22) X-Ray Micro Computed Tomography Based Study of the Effects of Copper-Rich Segregation Structures on Microstructurally-Small Fatigue-Crack Propagation in Al-Cu Alloys (slides)
http://hdl.handle.net/1813/38104
(22) X-Ray Micro Computed Tomography Based Study of the Effects of Copper-Rich Segregation Structures on Microstructurally-Small Fatigue-Crack Propagation in Al-Cu Alloys (slides)
Hochhalter, Jacob
Microstructural features significantly influence fatigue crack growth, particularly during the early stages of initiation and growth, which can account for the majority of life. In the present study, high-resolution X-Ray micro computed tomography (uCT) is used to study the influence that individual copper-rich segregation (CRS) structures have on microstructurally-small fatigue-crack (MSFC) propagation. Several single-crystal specimens of Al-Cu are fabricated and heat-treated to produce specific CRS structures, where their density and distribution are varied. By observing the crack propagation path and interaction with the CRS structures periodically using X-Ray uCT, the mechanisms governing how such features influence the early stages of crack growth are examined. With the capability to control the density and distribution of the copper segregation structures relative to loading direction, design of optimal copper segregation structures to decelerate MSFC growth rates by producing tortuous crack paths to maximize closure is proposed.
2014-09-27T00:00:00Z(20) Methane Emissions Make Shale Gas a Bridge to Nowhere (slides)
http://hdl.handle.net/1813/38103
(20) Methane Emissions Make Shale Gas a Bridge to Nowhere (slides)
Howarth, Robert
Only in the past decade of so have two technologies (high-volume hydraulic fracturing and precision directional drilling) combined to allow extracting natural gas from shale, and half of all shale gas ever developed has been produced only in the past 3-4 years. Consequently, the scientific study of the environmental consequences is also quite new. Nonetheless, these consequences are large and diverse, including contaminating groundwater and surface waters and polluting the air. One of the greatest concerns is with the climatic effects: shale gas is widely promoted as a bridge fuel that allows society to continue to rely on fossil fuels while reducing greenhouse gas emissions. However, my research with Prof. Ingraffea indicates that when emissions of methane as well as carbon dioxide are considered, shale gas has perhaps the largest greenhouse gas footprint of any fossil fuel. Even before the shale gas boom, the natural gas industry was the largest source of methane pollution in the US and one of the two largest sources globally (together with animal agriculture). Without large reductions in emissions of both methane and carbon dioxide, the average temperature of the Earth will reach 1.5°C to 2°C above the 20th Century baseline within the next few decades, creating a risk of runaway feedbacks in the climate system leading to even more rapid warming and climate disruption. To reduce this risk, society should move away from all fossil fuels – but particularly shale gas – as rapidly as possible.
2014-09-27T00:00:00Z(18) On the Virtual Crack Extension for Calculating the Energy Release Rate and Its (slides)
http://hdl.handle.net/1813/38102
(18) On the Virtual Crack Extension for Calculating the Energy Release Rate and Its (slides)
Hwang, Changyu
This presentation introduces a numerical method for calculating the energy release rates and their higher order derivatives for a multiply cracked body under general mixed-node conditions in two and three dimensions. This work generalizes the analytical virtual crack extension method for linear elastic fracture mechanics presented by Lin and Abel, who introduced the direct integral forms of the energy release rate and its derivatives for a structure containing a two dimensional single crack. Here Lin and Abel’s method is generalized and derivations are provided for verification of the following: extension to the general case of a system of interacting cracks in two dimensions, extension to the axisymmetric case, extension to three-dimensional crack with an arbitrarily curved front under general mixed-mode loading conditions, inclusion of non-uniform crack-face pressure and thermal loading, and an evaluation of the second order derivative of the energy release rate. The method provides the direct integral forms of stiffness derivatives, and thus there is no need for the analyst to specify a finite length of virtual crack extension. The salient feature of this method is that the energy release rates and their higher derivatives for multiple cracks in two and three dimensions can be computed in a single analysis. It is shown that the number of rings of elements surrounding the crack tip that are involved in the mesh perturbation due to the virtual crack extension has an effect on the solution accuracy.
2014-09-27T00:00:00Z(16) Multiscale Materials Modeling (slides)
http://hdl.handle.net/1813/38101
(16) Multiscale Materials Modeling (slides)
Chen, Chuin-Shan David
Fracturing processes occur at different materials length scales and naturally call for multiscale modeling. In this talk, I will present my journey on multiscale materials modeling, descended from my Ph.D. and Postdoc research association with Professor Anthony R. Ingraffea. Two critical length scales and modeling techniques will be addressed: one at the dislocation level and the other at the materials grain level. At the dislocation level, I will emphasize on the large-scale atomistic simulation: a new paradigm to study mechanics of materials in which mechanisms and properties are emerged directly from the fundamental evolution of atoms. At the grain level, a micromechanics model to simulate inter-granular fracture will be addressed.
2014-09-27T00:00:00Z(14) 3D Characterization and Modeling of Fatigue Cracks (slides)
http://hdl.handle.net/1813/38100
(14) 3D Characterization and Modeling of Fatigue Cracks (slides)
Rollett, Anthony D.
Enormous strides have been made in quantifying the growth of fatigue cracks over the years and incorporating that understanding in predictions of component lifetime. Nevertheless, it is clear that the behavior of short cracks is less well quantified, where short is relative to the length scale(s) found in materials microstructure, e.g. grain size. Ultimately, materials science seeks to predict the location and growth of fatigue cracks in order to design materials microstructure to maximize fatigue lifetime. Towards that end, it is interesting to study the relationship between cracks and microstructure near the initiation point. Short fatigue cracks in nickel-based superalloys have been characterized using conventional SEM and orientation mapping. 3D characterization used High Energy Diffraction Microscopy (HEDM), and computed tomography (CT) to map out the crack positions within their embedding grain structure. The main finding is that cracks develop most readily along long twin boundaries with high resolved shear stress on the slip systems parallel to the twin plane. Also, both halves of a different superalloy, fully fractured sample have been fully characterized in 3D using the same tools. The HEDM and CT were performed with high energy x-rays on beamline 1ID at the Advanced Photon Source (APS). The 3D orientation maps are used as input to computations of the full field stress-strain response. The fracture surface is analyzed with respect to local orientation and inter- versus trans-granular character. The likely origins of fatigue crack initiation in these cases are discussed.
2014-09-27T00:00:00Z(12) A Short History of Crack Growth Simulation Software Developed at Cornell University (slides)
http://hdl.handle.net/1813/38099
(12) A Short History of Crack Growth Simulation Software Developed at Cornell University (slides)
Wawrzynek, Paul
During his 37 years at Cornell University, Dr. Anthony Ingraffea has inspired his graduate students to create a series of computer programs for simulating fracture propagation for a wide variety of engineering materials and applications. Each of these programs represented the most advanced and capable fracture simulation programs of their time. On the occasion of his retirement, this talk will review this sequence of programs and highlight their features and the insights they brought to the small, yet important, area of computational mechanics.
2014-09-27T00:00:00Z(10) Non-manifold Geometric Modeling as a Framework for Computational Mechanics (slides)
http://hdl.handle.net/1813/38098
(10) Non-manifold Geometric Modeling as a Framework for Computational Mechanics (slides)
Martha, Luiz Fernando
Geometric modeling is an area of computer graphics that deals with creation, manipulation, maintenance, and analysis of representations of geometric forms of two and three-dimensional objects. It is applied in several fields, such as movie production, design of industrial mechanical parts, scientific visualization, and reproduction of objects for analysis in engineering. Historically, geometric modeling has evolved from wireframe modeling to surface modeling, solid modeling, and non-manifold modeling. Non-manifold geometric modeling allows the representation of multiregion objects, of internal or dangling structures, and of lower dimensions degenerated parts. Many application areas of geometric modeling take advantage of the additional features of non-manifold representation. In computational mechanics, for example, it is common the analysis of idealized structures such as shells combined with solids and beams. Another application is the representation of heterogeneous objects with regions with common volumes, coincident faces, internal structures, and solids consisting of different materials. This lecture illustrates the use of topological data structures for non-manifold representations as a framework for numerical simulations in computational mechanics. The main focus here is on the development of strategies for mesh generation for modeling heterogeneous objects such as subsurface geological models.
2014-09-27T00:00:00Z(30) Resource: Anthony R. Ingraffea – Directory with Abstracts and URLs
http://hdl.handle.net/1813/38097
(30) Resource: Anthony R. Ingraffea – Directory with Abstracts and URLs
Cornell University
Computer Simulation and Physical Testing of
Complex Fracturing Processes; A Symposium in Honor of Professor Emeritus Anthony R. Ingraffea; School of Civil and Environmental Engineering, Cornell University; September 27, 2014
2014-09-27T00:00:00Z(08) Working with Tony is everything it's cracked up to be (slides)
http://hdl.handle.net/1813/38096
(08) Working with Tony is everything it's cracked up to be (slides)
Pingali, Keshav
Back in 2000, NSF awarded a consortium of universities, led by Cornell, one of the first large Information Technology Research (ITR) grants for a project titled "Adaptive Software for Field-driven Simulations." As the Computer Science PI of this multi-disciplinary, multi-institutional project, I knew nothing about partial differential equations, finiteelements, Delaunay mesh generation, h- and p-refinement, or singularities at crack-tips, and I knew even less about how to inspire and lead large teams of researchers. Over the next 5 years and at the cost of 10 million dollars to US taxpayers, I learned these things (and fly-fishing) from Tony Ingraffea. The experience literally changed my life. I will try to convince you that it was for the better.
2014-11-03T00:00:00Z(06) Thunderhead Engineering – Continuing the Rand Hall Ethos (slides)
http://hdl.handle.net/1813/38095
(06) Thunderhead Engineering – Continuing the Rand Hall Ethos (slides)
Swenson, Daniel
Tony Ingraffea inspired us. In me, he reinforced the love of programming and amazement at the ability of applied mathematics to represent the real world. At some level, we all want people to recognize and appreciate what we are doing. If you are developing fundamental engineering concepts, you write papers and pursue research. If you are writing software, you want people to use and apply your programs. Thunderhead Engineering grew out of that desire. As a result of research we were doing at Kansas State, Brian Hardeman and I decided that we wanted to commercialize some of our work. In 1998, we were fortunate to obtain a Small Business Innovative Research that supported development of our first product, PetraSim, a user interface for the TOUGH2 code from Lawrence Berkeley National Laboratory. TOUGH2 solves the problem of multi-phase flow in porous media. The development we did for PetraSim has made it possible for us to develop two more products, PyroSim -- that model fires in buildings, and Pathfinder -- that models emergency evacuation. At this time we are completely self-sustaining from software sales and have six fulltime employees. I will discuss how a company can be a long-term approach to ensuring that the work you start will be continued and some of the challenges we face as we look to the future.
2014-09-27T00:00:00Z(04) State-Based Peridynamic Lattice Modeling of Reinforced Concrete Structures (slides)
http://hdl.handle.net/1813/38094
(04) State-Based Peridynamic Lattice Modeling of Reinforced Concrete Structures (slides)
Gerstle, Walter
Continuum peridynamics provides an alternative to continuum mechanics. However, peridynamics is more general because it allows cracks to emerge. However, peridynamics requires further discretization to be implemented on a computer. Peridynamics assumes the material space is a continuous Cartesian real space. In contrast, in this paper we assume the material space is a discrete Cartesian integer space, defining a regular lattice of material particles, and proceed to develop the state-based peridynamic lattice model (SPLM). With the SPLM, the forces between neighboring particles are characterized by the force state, T, and the stretches between particles are characterized by the deformation state, Y. The material model arises from a peridynamic function relating the force state to the deformation state. With the SPLM, continuous deformations, elasticity, damage, plasticity, cracks, and fragments can be simulated in a coherent and simple manner. With the ongoing increase in computational storage capacity and processing power, the SPLM becomes increasingly competitive with more traditional continuum approaches like the finite element method.
2014-09-27T00:00:00Z(02) A Concrete Damage Plasticity Model For Ancient Roman Pozzolanic Concrete Vaulted (slides)
http://hdl.handle.net/1813/38093
(02) A Concrete Damage Plasticity Model For Ancient Roman Pozzolanic Concrete Vaulted (slides)
Perucchio, Renato
The invention of pozzolanic concrete (opus caementicium) provided ancient Roman engineers with an extraordinarily versatile and durable building material, which made possible the construction of some of the largest and most complex vaulted structures built in antiquity. In 2010, in collaboration with Ingraffea, we conducted an experimental study on Mode-I fracture properties of reproduced Imperial Roman pozzolanic mortar using an ad-hoc arc shaped bending test. In the present study we use these data in conjunction with post-critical compressive response data available from the literature to construct a non-linear damage plasticity formulation for opus caementicium suitable for 3D implementation in Abaqus Explicit. We use this FE formulation to evaluate how the structural design of the vault supporting system of Diocletian’s Frigidarium (298-306 AD), consisting of flanking shear walls and monolithic granite columns, affects the development and propagation of fractures and ultimately the static and seismic stability of the vault.
2014-09-27T00:00:00Z(21) X-Ray Micro Computed Tomography Based Study of the Effects of Copper-Rich Segregation Structures on Microstructurally-Small Fatigue-Crack Propagation in Al-Cu Alloys
http://hdl.handle.net/1813/38091
(21) X-Ray Micro Computed Tomography Based Study of the Effects of Copper-Rich Segregation Structures on Microstructurally-Small Fatigue-Crack Propagation in Al-Cu Alloys
Hochhalter, Jacob
Microstructural features significantly influence fatigue crack growth, particularly during the early stages of initiation
and growth, which can account for the majority of life. In the present study, high-resolution X-Ray micro computed
tomography (uCT) is used to study the influence that individual copper-rich segregation (CRS) structures have on
microstructurally-small fatigue-crack (MSFC) propagation. Several single-crystal specimens of Al-Cu are fabricated and
heat-treated to produce specific CRS structures, where their density and distribution are varied. By observing the crack
propagation path and interaction with the CRS structures periodically using X-Ray uCT, the mechanisms governing
how such features influence the early stages of crack growth are examined. With the capability to control the density
and distribution of the copper segregation structures relative to loading direction, design of optimal copper segregation
structures to decelerate MSFC growth rates by producing tortuous crack paths to maximize closure is proposed.
Jacob Hochhalter, PhD ‘10; Materials Research Engineer, Durability and Damage Tolerance Branch, NASA Langley
Research Center
2014-09-27T00:00:00Z(25) Closing Remarks
http://hdl.handle.net/1813/38090
(25) Closing Remarks
Abel, John F.
2014-09-27T00:00:00Z(00) Welcome Remarks
http://hdl.handle.net/1813/38089
(00) Welcome Remarks
Liu, Phillip L.
2014-09-27T00:00:00Z(23) Toward High-Fidelity Multi-Scale Modeling of 3D Crack Evolution
http://hdl.handle.net/1813/38088
(23) Toward High-Fidelity Multi-Scale Modeling of 3D Crack Evolution
Spear, Ashley
In the ultimate quest to achieve predictive capabilities for crack evolution across multiple length scales, the final
generation of Prof. Ingraffea’s graduate students stood on the shoulders of their predecessors, leveraging some of the
most advanced materials-characterization and modeling techniques to capture crack geometries and environments with
utmost fidelity. The first part of this talk highlights two novel, numerical toolsets that were developed to enable the
prediction of 3D crack propagation at the structural or component length scale. The first toolset is one that uses
material-state mapping along with FRANC3D-inspired adaptive remeshing to predict propagation of 3D cracks in
ductile materials. The second toolset was developed to predict 3D crack-shape evolution by calculating local
increments of crack extension, Δai, using energy-release-rate principles. The second part of the talk highlights novel
characterization and modeling efforts that were carried out to understand (and eventually to predict) the formation and
early propagation of 3D cracks at the microstructural length scale. In one effort, 3D characterization of fatigue-crack
nucleation in a Ni-base superalloy microstructure was reconstructed using 3D crystal-plastic finite-element (CPFE)
modeling. “Big data” concepts were utilized to discover quantitative correlations between the underlying
microstructure and fatigue indicator parameters computed from the CPFE results. In another effort, the propagation of
a microstructurally small fatigue crack in an aluminum alloy was characterized in 3D for the first time. The 3D
measurements were converted to a 3D CPFE model that explicitly represented the history-dependent shape of the 3D
fatigue crack as well as the surrounding grain structure. The talk concludes with important lessons learned in the
Cornell Fracture Group and a look to the future.
Ashley Spear, PhD ‘14; Assistant Professor of Mechanical Engineering, Multiscale Mechanics and Materials
Laboratory, University of Utah
2014-09-27T00:00:00Z(13) 3D Characterization and Modeling of Fatigue Cracks
http://hdl.handle.net/1813/37993
(13) 3D Characterization and Modeling of Fatigue Cracks
Rollett, Anthony D.
Enormous strides have been made in quantifying the growth of fatigue cracks over the years and incorporating that
understanding in predictions of component lifetime. Nevertheless, it is clear that the behavior of short cracks is less
well quantified, where short is relative to the length scale(s) found in materials microstructure, e.g. grain size.
Ultimately, materials science seeks to predict the location and growth of fatigue cracks in order to design materials
microstructure to maximize fatigue lifetime. Towards that end, it is interesting to study the relationship between cracks
and microstructure near the initiation point. Short fatigue cracks in nickel-based superalloys have been characterized
using conventional SEM and orientation mapping. 3D characterization used High Energy Diffraction Microscopy
(HEDM), and computed tomography (CT) to map out the crack positions within their embedding grain structure. The
main finding is that cracks develop most readily along long twin boundaries with high resolved shear stress on the slip
systems parallel to the twin plane. Also, both halves of a different superalloy, fully fractured sample have been fully
characterized in 3D using the same tools. The HEDM and CT were performed with high energy x-rays on beamline 1ID
at the Advanced Photon Source (APS). The 3D orientation maps are used as input to computations of the full field
stress-strain response. The fracture surface is analyzed with respect to local orientation and inter- versus trans-granular
character. The likely origins of fatigue crack initiation in these cases are discussed.
Anthony D. Rollett
- Professor of Material Science and Engineering, Carnegie Mellon University
2014-09-27T00:00:00Z(11) A Short History of Crack Growth Simulation Software Developed at Cornell University
http://hdl.handle.net/1813/37991
(11) A Short History of Crack Growth Simulation Software Developed at Cornell University
Wawrzynek, Paul
During his 37 years at Cornell University, Dr. Anthony Ingraffea has inspired his graduate students to create a series of
computer programs for simulating fracture propagation for a wide variety of engineering materials and
applications. Each of these programs represented the most advanced and capable fracture simulation programs of their
time. On the occasion of his retirement, this talk will review this sequence of programs and highlight their features and
the insights they brought to the small, yet important, area of computational mechanics.
Paul Wawrzynek, PhD ‘91; Senior Research Associate, Cornell Fracture Group; Chief Technology Officer, Fracture Analysis Consultants, Inc.
2014-09-27T00:00:00Z(19) Methane Emissions Make Shale Gas a Bridge to Nowhere
http://hdl.handle.net/1813/37990
(19) Methane Emissions Make Shale Gas a Bridge to Nowhere
Howarth, Robert
Only in the past decade of so have two technologies (high-volume hydraulic fracturing and precision directional
drilling) combined to allow extracting natural gas from shale, and half of all shale gas ever developed has been
produced only in the past 3-4 years. Consequently, the scientific study of the environmental consequences is also quite
new. Nonetheless, these consequences are large and diverse, including contaminating groundwater and surface waters
and polluting the air. One of the greatest concerns is with the climatic effects: shale gas is widely promoted as a bridge
fuel that allows society to continue to rely on fossil fuels while reducing greenhouse gas emissions. However, my
research with Prof. Ingraffea indicates that when emissions of methane as well as carbon dioxide are considered, shale
gas has perhaps the largest greenhouse gas footprint of any fossil fuel. Even before the shale gas boom, the natural gas
industry was the largest source of methane pollution in the US and one of the two largest sources globally (together
with animal agriculture). Without large reductions in emissions of both methane and carbon dioxide, the average
temperature of the Earth will reach 1.5°C to 2°C above the 20th Century baseline within the next few decades, creating a
risk of runaway feedbacks in the climate system leading to even more rapid warming and climate disruption. To
reduce this risk, society should move away from all fossil fuels – but particularly shale gas – as rapidly as possible.
Robert Howarth
2014-09-27T00:00:00Z(17) On the Virtual Crack Extension for Calculating the Energy Release Rate and Its Derivatives
http://hdl.handle.net/1813/37989
(17) On the Virtual Crack Extension for Calculating the Energy Release Rate and Its Derivatives
Hwang, Changyu
This presentation introduces a numerical method for calculating the energy release rates and their higher order
derivatives for a multiply cracked body under general mixed-node conditions in two and three dimensions. This work
generalizes the analytical virtual crack extension method for linear elastic fracture mechanics presented by Lin and
Abel, who introduced the direct integral forms of the energy release rate and its derivatives for a structure containing a
two dimensional single crack. Here Lin and Abel’s method is generalized and derivations are provided for verification
of the following: extension to the general case of a system of interacting cracks in two dimensions, extension to the
axisymmetric case, extension to three-dimensional crack with an arbitrarily curved front under general mixed-mode
loading conditions, inclusion of non-uniform crack-face pressure and thermal loading, and an evaluation of the second
order derivative of the energy release rate. The method provides the direct integral forms of stiffness derivatives, and
thus there is no need for the analyst to specify a finite length of virtual crack extension. The salient feature of this
method is that the energy release rates and their higher derivatives for multiple cracks in two and three dimensions can
be computed in a single analysis. It is shown that the number of rings of elements surrounding the crack tip that are
involved in the mesh perturbation due to the virtual crack extension has an effect on the solution accuracy.
Changyu Hwang, PhD ‘99; Professor/Dean for Research Affairs/President of University-Industry Foundation, Seoul
Venture University, South Korea
2014-09-27T00:00:00Z(15) Multiscale Materials Modeling
http://hdl.handle.net/1813/37983
(15) Multiscale Materials Modeling
Chen, Chuin-Shan David
Fracturing processes occur at different materials length scales and naturally call for multiscale modeling. In this talk, I
will present my journey on multiscale materials modeling, descended from my Ph.D. and Postdoc research association
with Professor Anthony R. Ingraffea. Two critical length scales and modeling techniques will be addressed: one at the
dislocation level and the other at the materials grain level. At the dislocation level, I will emphasize on the large-scale
atomistic simulation: a new paradigm to study mechanics of materials in which mechanisms and properties are
emerged directly from the fundamental evolution of atoms. At the grain level, a micromechanics model to simulate
inter-granular fracture will be addressed.
Chuin-Shan David Chen, PhD ‘99; Professor of Computer-Aided Engineering, Department of Civil Engineering, National
Taiwan University
2014-09-27T00:00:00Z(09) Non-manifold Geometric Modeling as a Framework for Computational Mechanics
http://hdl.handle.net/1813/37961
(09) Non-manifold Geometric Modeling as a Framework for Computational Mechanics
Martha, Luiz Fernando
Geometric modeling is an area of computer graphics that deals with creation, manipulation, maintenance, and analysis
of representations of geometric forms of two and three-dimensional objects. It is applied in several fields, such as
movie production, design of industrial mechanical parts, scientific visualization, and reproduction of objects for
analysis in engineering. Historically, geometric modeling has evolved from wireframe modeling to surface modeling,
solid modeling, and non-manifold modeling. Non-manifold geometric modeling allows the representation of multiregion
objects, of internal or dangling structures, and of lower dimensions degenerated parts. Many application areas
of geometric modeling take advantage of the additional features of non-manifold representation. In computational
mechanics, for example, it is common the analysis of idealized structures such as shells combined with solids and
beams. Another application is the representation of heterogeneous objects with regions with common volumes,
coincident faces, internal structures, and solids consisting of different materials. This lecture illustrates the use of
topological data structures for non-manifold representations as a framework for numerical simulations in
computational mechanics. The main focus here is on the development of strategies for mesh generation for modeling
heterogeneous objects such as subsurface geological models.
Luiz Fernando Martha, PhD ‘89; Professor of Civil Engineering, Pontifical Catholic University of Rio de Janeiro (PUC-Rio),
Brazil; Member and Manager, Computer Graphics Technology Group (Tecgraf), PUC-Rio
2014-09-27T00:00:00Z(07) Working with Tony is everything it's cracked up to be
http://hdl.handle.net/1813/37959
(07) Working with Tony is everything it's cracked up to be
Pingali, Keshav
Back in 2000, NSF awarded a consortium of universities, led by Cornell, one of the first large Information Technology
Research (ITR) grants for a project titled "Adaptive Software for Field-driven Simulations." As the Computer Science PI
of this multi-disciplinary, multi-institutional project, I knew nothing about partial differential equations, finiteelements,
Delaunay mesh generation, h- and p-refinement, or singularities at crack-tips, and I knew even less about
how to inspire and lead large teams of researchers. Over the next 5 years and at the cost of 10 million dollars to US
taxpayers, I learned these things (and fly-fishing) from Tony Ingraffea. The experience literally changed my life. I will
try to convince you that it was for the better.
Keshav Pingali; Professor, Department of Computer Science, University of Texas at Austin; The W.A. "Tex" Moncrief Chair of Computing, Institute for Computational Engineering
and Sciences (ICES), UT Austin; Formerly on the faculty of the Department of Computer Science at Cornell from 1986 to
2006, where he held the India Chair of Computer Science
2014-09-27T00:00:00Z(05) Thunderhead Engineering – Continuing the Rand Hall Ethos
http://hdl.handle.net/1813/37958
(05) Thunderhead Engineering – Continuing the Rand Hall Ethos
Swenson, Daniel
Tony Ingraffea inspired us. In me, he reinforced the love of programming and amazement at the ability of applied
mathematics to represent the real world. At some level, we all want people to recognize and appreciate what we are
doing. If you are developing fundamental engineering concepts, you write papers and pursue research. If you are
writing software, you want people to use and apply your programs. Thunderhead Engineering grew out of that desire.
As a result of research we were doing at Kansas State, Brian Hardeman and I decided that we wanted to commercialize
some of our work. In 1998, we were fortunate to obtain a Small Business Innovative Research that supported
development of our first product, PetraSim, a user interface for the TOUGH2 code from Lawrence Berkeley National
Laboratory. TOUGH2 solves the problem of multi-phase flow in porous media. The development we did for PetraSim
has made it possible for us to develop two more products, PyroSim -- that model fires in buildings, and Pathfinder --
that models emergency evacuation. At this time we are completely self-sustaining from software sales and have six fulltime
employees. I will discuss how a company can be a long-term approach to ensuring that the work you start will be
continued and some of the challenges we face as we look to the future.
Daniel Swenson, PhD ‘86; Principal, Thunderhead Engineering (www.thunderhead.com); Professor Emeritus of Mechanical and Nuclear Engineering, Kansas State University
2014-09-27T00:00:00Z(03) State-Based Peridynamic Lattice Modeling of Reinforced Concrete Structures
http://hdl.handle.net/1813/37956
(03) State-Based Peridynamic Lattice Modeling of Reinforced Concrete Structures
Gerstle, Walter
Continuum peridynamics provides an alternative to continuum mechanics. However, peridynamics is more general
because it allows cracks to emerge. However, peridynamics requires further discretization to be implemented on a
computer. Peridynamics assumes the material space is a continuous Cartesian real space. In contrast, in this paper we
assume the material space is a discrete Cartesian integer space, defining a regular lattice of material particles, and
proceed to develop the state-based peridynamic lattice model (SPLM). With the SPLM, the forces between neighboring
particles are characterized by the force state, T, and the stretches between particles are characterized by the deformation
state, Y. The material model arises from a peridynamic function relating the force state to the deformation state. With
the SPLM, continuous deformations, elasticity, damage, plasticity, cracks, and fragments can be simulated in a coherent
and simple manner. With the ongoing increase in computational storage capacity and processing power, the SPLM
becomes increasingly competitive with more traditional continuum approaches like the finite element method.
Walter Gerstle, PhD ‘86,
Professor of Civil Engineering, University of New Mexico; A Symposium in Honor of Professor Emeritus Anthony R. Ingraffea:
Computer Simulation and Physical Testing of Complex Fracturing Processes
2014-09-27T00:00:00Z(01) A Concrete Damage Plasticity Model For Ancient Roman Pozzolanic Concrete Vaulted
http://hdl.handle.net/1813/37955
(01) A Concrete Damage Plasticity Model For Ancient Roman Pozzolanic Concrete Vaulted
Perucchio, Renato
The invention of pozzolanic concrete (opus caementicium) provided ancient Roman engineers with an extraordinarily
versatile and durable building material, which made possible the construction of some of the largest and most complex
vaulted structures built in antiquity. In 2010, in collaboration with Ingraffea, we conducted an experimental study on
Mode-I fracture properties of reproduced Imperial Roman pozzolanic mortar using an ad-hoc arc shaped bending test.
In the present study we use these data in conjunction with post-critical compressive response data available from the
literature to construct a non-linear damage plasticity formulation for opus caementicium suitable for 3D implementation
in Abaqus Explicit. We use this FE formulation to evaluate how the structural design of the vault supporting system of
Diocletian’s Frigidarium (298-306 AD), consisting of flanking shear walls and monolithic granite columns, affects the
development and propagation of fractures and ultimately the static and seismic stability of the vault.
Renato Perucchio, PhD ‘84
Professor of Mechanical Engineering and of Biomedical Engineering; Director of Program
in Archaeology, Technology and Historical Structures; University of Rochester; A Symposium in Honor of Professor Emeritus Anthony R. Ingraffea:
Computer Simulation and Physical Testing of Complex Fracturing Processes
2014-09-27T00:00:00Z8 Roger Spanswick – Reflections
http://hdl.handle.net/1813/37310
8 Roger Spanswick – Reflections
Spanswick, Andrew; Spanswick, Helen; Spanswick, Robert
This video is about Reflections and open microphone.
2014-06-02T00:00:00ZRoger Spanswick Symposium Announcement
http://hdl.handle.net/1813/37306
Roger Spanswick Symposium Announcement
2014-06-02T00:00:00ZRoger Spanswick Symposium Program
http://hdl.handle.net/1813/37305
Roger Spanswick Symposium Program
2014-06-02T00:00:00Z7 Roger Spanswick – Friend
http://hdl.handle.net/1813/37303
7 Roger Spanswick – Friend
Wilson, Allison; Leopold, Lynn; Campbell, Rochelle
This video is about Roger Spanswick as Friend.
2014-06-02T00:00:00Z6 Roger Spanswick – Sage
http://hdl.handle.net/1813/37302
6 Roger Spanswick – Sage
Wayn, Randy; Walker, Larry; Minorsky, Peter
This video is about Roger Spanswick - Sage.
2014-06-02T00:00:00Z5 Roger Spanswick - Teaching
http://hdl.handle.net/1813/37301
5 Roger Spanswick - Teaching
Williams, Steve; Kass, Lee
This video is about Roger Spanswick's Teaching.
2014-06-02T00:00:00Z4 Roger Spanswick – Outreach
http://hdl.handle.net/1813/37300
4 Roger Spanswick – Outreach
DuPont, Frances; O’Neill, Sharman; Perlin, David
This video is about Roger Spanswick Outreach Project.
2014-06-02T00:00:00Z3 Roger Spanswick – Mentor
http://hdl.handle.net/1813/37299
3 Roger Spanswick – Mentor
Zhou, Dennis; Sun, Chris; Ellis, Erle
This video is about Roger Spanswick – The Mentor.
2014-06-02T00:00:00Z2 Roger Spanswick - Scientist
http://hdl.handle.net/1813/37298
2 Roger Spanswick - Scientist
Cornish, Katrina; Hay, Jordan; Keifer, David
This video is about Roger Spanswick as the Scientist.
2014-06-02T00:00:00Z1 Roger Spanswick – Brief History
http://hdl.handle.net/1813/37297
1 Roger Spanswick – Brief History
Davies, Peter
This video is a brief biography for Roger Spanswick.
2014-06-02T00:00:00Z0 Roger Spanswick – Meet the Presenters
http://hdl.handle.net/1813/37296
0 Roger Spanswick – Meet the Presenters
Davies, Peter
This video is about Meet the Speakers.
2014-06-02T00:00:00ZNAE Regional Symposium at Cornell 2012 Session_2
http://hdl.handle.net/1813/36267
NAE Regional Symposium at Cornell 2012 Session_2
This video is about the National Academy of Engineering Symposium on Sustainability held at Cornell University in 2012 Session 2.
2012-05-16T00:00:00ZNAE Regional Symposium at Cornell 2012 Session_1
http://hdl.handle.net/1813/36265
NAE Regional Symposium at Cornell 2012 Session_1
This video is about the National Academy of Engineering Symposium of May 16, 2012 on Sustainability.
2012-05-16T00:00:00Z08_Plant Biology in the Next 100 Years
http://hdl.handle.net/1813/33666
08_Plant Biology in the Next 100 Years
Roeder, Adrienne
Dr. Adrienne Roeder reviewed the many changes that have occurred since the University was first founded, and made the important point that “If we can predict the scientific developments in the next 100 years, we have failed our task” as scientists.
2013-06-29T00:00:00Z06_The Early Integrated History of the Four Cornell Herbaria
http://hdl.handle.net/1813/33665
06_The Early Integrated History of the Four Cornell Herbaria
Dirig, Robert
Mr. Robert Dirig discussed the history of Cornell University’s four major herbaria, which include collections of vascular plants, algae, fungi, and lichens, and showed how these herbaria contributed to the University’s prestige.
2013-06-29T00:00:00Z07_The Tompkins County Flora: A new life for a cherished collection
http://hdl.handle.net/1813/33664
07_The Tompkins County Flora: A new life for a cherished collection
Nixon, Kevin C.
Dr. Kevin C. Nixon developed the theme of how herbaria influence (and will continue to influence) both basic and applied research.
2013-06-29T00:00:00Z