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A Symposium in Honor of Professor Emeritus Anthony R. Ingraffea

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A Symposium in Honor of Professor Emeritus Anthony R. Ingraffea
Computer Simulation and Physical Testing of Complex Fracturing Processes
School of Civil and Environmental Engineering, Cornell University, September 27, 2014

Ingraffea Symposium Directory with Abstracts and URLs.pdf
Ingraffea Symposium Background Resources

Session 1: John Abel, Session Chair
Welcome Remarks by Phillip L. Liu and John Abel
- A Concrete Damage Plasticity Model For Ancient Roman Pozzolanic Concrete Vaulted Structures by Renato Perucchio
- State-Based Peridynamic Lattice Modeling of Reinforced Concrete Structures by Walter Gerstle
- Thunderhead Engineering – Continuing the Rand Hall Ethos by Daniel Swenson

Session 2: Bruce Carter, Session Chair
- Working with Tony is everything it's cracked up to be by Keshav Pingali
- Non-manifold Geometric Modeling as a Framework for Computational Mechanics Simulations by Luiz Fernando Martha
- A Short History of Crack Growth Simulation Software Developed at Cornell University by Paul Wawrzynek

Session 3: Paul Wawrzynek, Session Chair
- 3D Characterization and Modeling of Fatigue Cracks by Anthony D. Rollett
- Multiscale Materials Modeling by Chuin-Shan David Chen
- On the Virtual Crack Extension for Calculating the Energy Release Rate and Its Derivatives by Changyu Hwang

Session 4: Derek Warner, Session Chair
- Methane Emissions Make Shale Gas a Bridge to Nowhere by Robert Howarth
- 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 by Jacob Hochhalter
- Toward High-Fidelity Multi-Scale Modeling of 3D Crack Evolution by Ashley Spear
Closing Remarks by John F. Abel

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    (28) Resource: Anthony R. Ingraffea – Background Resources
    Cornell University (The Internet-First University Press, 2014-09-27)
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    (29) Resource: Anthony R. Ingraffea – Curriculum Vitae
    Ingraffea, Anthony R. (2014-09-27)
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    (26) Resource: Anthony R. Ingraffea – A Brief Biography
    Cornell University (The Internet-First University Press, 2014-09-27)
    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.
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    (31) Resource: Anthony R. Ingraffea – Symposium Group Photo with Identifications
    Cornell University (The Internet-First University Press, 2014-09-27)
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    (24) Toward High-Fidelity Multi-Scale Modeling of 3D Crack Evolution (slides)
    Spear, Ashley (The Internet-First University Press, 2014-09-27)
    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.
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    (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 (The Internet-First University Press, 2014-09-27)
    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.
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    (20) Methane Emissions Make Shale Gas a Bridge to Nowhere (slides)
    Howarth, Robert (The Internet-First University Press, 2014-09-27)
    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.
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    (18) On the Virtual Crack Extension for Calculating the Energy Release Rate and Its (slides)
    Hwang, Changyu (The Internet-First University Press, 2014-09-27)
    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.
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    (16) Multiscale Materials Modeling (slides)
    Chen, Chuin-Shan David (The Internet-First University Press, 2014-09-27)
    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.