A multiscale damage-plasticity model for compaction band and fractures in anisotropic fluid-infiltrating porous media Abstract: Many engineering applications, such as geological disposal of nuclear waste, require reliable predictions on the hydro-mechanical responses of porous media exposed to extreme environments. This presentation will discuss the relevant modeling techniques designed specific for porous media subjected to such harsh environments. In particular, we will provide an overview of (1) the variational eigen-deformation techniques used to model brittle fracture and compaction bands, (2) the usage of adaptive nonlocal multiscale techniques to link grain-scale simulations to macroscopic predictions and hence bypass the usage of any macroscopic phenomenological law, and the coupling of crystal plasticity and multi-phase-field model designed to replicate the thermal- and rate-dependent damage-plasticity of crystalline rock. Special emphasis is placed on how formation and propagation of flow barrier formed by array of compaction bands and the flow conduit formed by fractures interact and affected the macroscopic hydro-mechanical behavior of brittle porous media. (hosted by Prof. Robert Zimmerman)
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Coupled phase-field and plasticity modeling of geological materials: from brittle fracture to ductile flow Author: Jinhyun Choo, WaiChing Sun Accepted Date: Oct 4th, 2017 Abstract: The failure behavior of geological materials depends heavily on confining pressure and strain rate. Under a relatively low confining pressure, these materials tend to fail by brittle, localized fracture, but as the confining pressure increases, they show a growing propensity for ductile, diffuse failure accompanying plastic flow. Furthermore, the rate of deformation often exerts control on the brittleness. Here we develop a theoretical and computational modeling framework that encapsulates this variety of failure modes and their brittle-ductile transition. e framework couples a pressure-sensitive plasticity model with a phase-field approach to fracture which can simulate complex fracture propagation without tracking its geometry. We derive a phase-field formulation for fracture in elastic-plastic materials as a balance law of microforce, in a new way that honors the dissipative nature of the fracturing processes. For physically meaningful and numerically robust incorporation of plasticity into the phase-field model, we introduce several new ideas including the use of phase-field effective stress for plasticity, and the dilative/compactive split and rate-dependent storage of plastic work. We construct a particular class of the framework by employing a Drucker–Prager plasticity model with a compression cap, and demonstrate that the proposed framework can capture brittle fracture, ductile flow, and their transition due to confining pressure and strain rate. [PDF] Our team member and PhD student SeonHong Na passed his PhD candidacy exam. His PhD proposal entitled "Multiscale thermo-hydro-mechanical-chemical (THMC) coupling effects for fluid-infiltrating dual-porosity crystalline rock: theory, implementation, and validation" is examined by the committee consisted of Professor Jacob Fish, Professor Hoe Ling, Professor Jeffery Kysar. We thank all the committee members for their insightful questions, comments and time. Congratulations for this well-deserved achievement, SeonHong! Good luck for your final PhD defense! It is my great pleasure to announce that our postdoc research scientist, Dr. Jinhyun Choo has accepted a tenure-track position as assistant professor at the University of Hong Kong. Jinhyun joined our research group as a postdoctoral research scientist in Fall 2016 after finishing his PhD under the tutelage of Professor Ronaldo Borja at Stanford University. During his productive tenure at Columbia, we have submitted three journal articles with Jinhyun, of which one is accepted. He is the first author of the other two works on modeling brittle-ductile transition and on chemoporomechanics of brittle porous materials. Prior to Stanford and Columbia, he obtained his B.S. and M.S. degrees from Seoul National University, and worked at an engineering firm and a government funded research institute in Korea. He is the recipient of several prestigious awards including a Fulbright Scholarship and a Charles H. Leavell Fellowship for research on sustainable built environment. For more information, please visit his website: http://jinhyunchoo.com/ His work with us are listed below.
Author List: S. Na, W.C. Sun, H. Yoon, M. Ingraham Abstract: For assessing energy-related activities in the subsurface, it is important to investigate the impact of the spatial variability and anisotropy on the geomechanical behavior of shale. The Brazilian test, an indirect tensile-splitting method is performed in this work, and the evolution of strain field is obtained using digital image correlation. Experimental results show the significant impact of local heterogeneity and lamination on the crack pattern characteristics. For numerical simulations, a phase field method is used to simulate the brittle fracture behavior under various Brazilian test conditions. In this study, shale is assumed to consist of two constituents including the stiff and soft layers to which the same toughness but different elastic moduli are assigned. Microstructural heterogeneity is simplified to represent mesoscale (e.g., millimeter scale) features such as layer orientation, thickness, volume fraction, and defects. The effect of these structural attributes on the onset, propagation, and coalescence of cracks is explored. The simulation results show that spatial heterogeneity and material anisotropy highly affect crack patterns and effective fracture toughness, and the elastic contrast of two constituents significantly alters the effective toughness. However, the complex crack patterns observed in the experiments cannot completely be accounted for by either an isotropic or transversely isotropic effective medium approach. This implies that cracks developed in the layered system may coalesce in complicated ways depending on the local heterogeneity, and the interaction mechanisms between the cracks using two-constituent systems may explain the wide range of effective toughness of shale reported in the literature. [URL] MR004: Data-driven and theoretical approaches for modeling, prediction, analysis of thermo-hydro-mechanical behaviors of frozen soil and rocks
Submit an Abstract to this Session Session ID#: 27208 Session Description: Frozen soil and rocks are integrated parts of the Earth’s climate system. The timing, duration, thickness and distribution of frozen geomaterialsare dominated by heat exchanges between the environment and the land surface and the multiphysical coupling effects. During freezing and thawing cycles, microscopic mechanisms such as cryo-suction, thermal and hydraulic convection-diffusion, micro-cracks, enhanced particle interlocking and ice strengthening may have a profound effect on the land surfaces at the field scale. Yet, incorporating these complex micro-mechanical coupling effects for applications to earth system modeling remains difficult. This AGU session seeks contributions that innovate new techniques in (1) experimental and field works across length scales (e.g. micro-CT imaging, Lidar scan); (2) numerical modeling of frozen geomaterials, and (3) emerging technologies in data generation, collection and interpretation, such as climate-controlled experimental tests, data-driven machine learning and other approaches that improve the forward prediction and understanding of frozen geomaterials. Primary Convener: WaiChing Sun, Columbia University, Civil Engineering and Engineering Mechanics, New York, NY, United States Conveners: Seth Saltiel, Lawrence Berkeley National Laboratory, Berkeley, CA, United States and Jonathan Blair Ajo Franklin, Lawrence Berkeley National Laboratory, Geophysics, Berkeley, CA, United States Cross-Listed:
Index Terms: 0702 Permafrost [CRYOSPHERE] 0704 Seasonally frozen ground [CRYOSPHERE] 0798 Modeling [CRYOSPHERE] 3902 Creep and deformation [MINERAL PHYSICS] It is my honor to report that our team member PhD student SeonHong Na is selected as the recipient of two awards in the CEEM department annual dinner. The Dongju Lee memorial award is given in recognition of SeonHong's superior achievement and in honor of the integrity, curiosity and creativity. The Dongju Lee Memorial Award and Memorial Lecture were established with a generous contribution from the Lee Family. Congrats SeonHong! Presentation 1: 6/5 9:30am to 9:50am Room: Salon B MS 61 Computational Geomehanics A critical assessment on phase field and eigen-erosion modeling of fractures in anisotropic fluid-infiltrating porous medias. WaiChing Sun, SeonHong Na, Kun Wang, Jinhyun Choo, Eric Bryant The onset and propagation of the cracks and compaction bands, and the interactions between them in the host matrix, are important for numerous engineering applications, such as hydraulic fracture and CO2 storage. A simple way to capture the formation, propagation and coalescence of crack is to incorporate the generalized Griffith theory into a variational framework. Depending on how the regularized Griffith energy functional is formulated, the resultant model may either use a phase field or a binary indicator to represent cracks. This work compares the two theories and their corresponding numerical implementations. In particular, we show that that that the eigen-fracture and operator-split phase field model can be implemented in an almost identical code design. We then extend the formulation to incorporate the hydro-mechanical coupling effect and show the importance of the hydraulic dissipation to the resultant crack pattern of the porous media through numerical examples. Further improvement of the model, such as the incorporation of the anisotropic fracture energy and the generalization for capturing compaction band as Mode I anti-crack are also highlighted. Presentation 2: 6/6 3:55pm-4:15pm Data-driven discrete-continuum method for partially saturated porous media Kun Wang, WaiChing Sun We presents a hybrid data-driven approach to model multi-physical process in fluid-infiltrating porous media across length scales. Unlike single-physical problems where data-driven model is often used as a replacement of solid constitutive law, a hydro-mechanical problem often leads to more complex hierarchical relations among physical quantities which complicates the design of the data-driven solver. In the case when artificial neural network is used, additional issues may arise when constraints and rules, such as material frame indifference, cannot be explicitly enforced without artificially expanding the training dataset. In this work, we introduce a component-based strategy in which a multiphysical computational model are viewed as a directed graph, a network consisting of inter-connected vertrices representing physical quantities. This strategy enables modelers to couple data-driven model with conventional mathematical expression methods by considering different hierarchical relations among data. Depending on the availability of data, hybridization of data-driven and mathematical models may take different form. To enforce material frame indifference efficiently, we employ spectral decomposition to handle the invariant and spin terms via Lie algebra. Invited Presentation in Spent Fuel Waste Storage Technology Annual Meeting, Las Vegas 5/24/20175/23/2017 Computational thermo-hydro-mechanics of crystalline rock salt for nuclear waste disposal
SeonHong Na, WaiChing Sun Abstract Rock salt is one of the major materials used for nuclear waste disposal. The desired characteristics of rock salt, i.e. the high thermal conductivity, low permeability and self-healing is highly related to the crystalline microstructure. Conventionally, this microstructural effect is often incorporated phenomenologically in macroscopic models. Nevertheless, Rock salt is a crystalline material of which the thermo-mechanical behavior is dictated by the nature of crystal lattice and mcriomechanics the slip system. This paper present a model proposed to examine these fundamental mechanisms at the grain scale level. We employ the single-crystal plasticity framework on salt and idealized it as an FCC crystal lattice with a pair of Na+ and Cl- ions as basis. Utilizing an viso-elasto-plastic framework, we capture the existence of elastic region in the stress space and the sequence of slip system activation of salt under different temperature ranges. To capture the intragranular fracture, we introduce an anisotropic phase-field based model to capture the anisotropy of critical energy release rate of a single crystal. Numerical examples demonstrated that the proposed model is able to capture the brittle-ductile transition under various of loading rate, temperature and confining pressure. Abstract: A combined phase field and crystal plasticity approach for capturing thermo-mechanical behavior of polycrystalline rock salt SeonHong Na, WaiChing Sun Department of Civil Engineering and Engineering Mechanics, Fu Foundation School of Engineering and Applied Science, Columbia University, New York Rock salt or halite is one of the major materials used for nuclear waste disposal. The desired characteristics of rock salt, i.e. the high thermal conductivity, low permeability and self-healing are highly related to the crystalline microstructure. Conventionally, this microstructural effect is often incorporated phenomenologically in macroscopic models. Nevertheless, effort to directly simulate the interplays among micro-mechanical mechanisms, such as micro-cracking, inelastic dilatancy, grain boundary sliding and dislocation creeping, which may bring more reliable and robust forward predictions for the long-term thermo-mechanical behavior of salt, are lacking. The goal of this research is to fulfill this knowledge gap. In particular, we first formulate a computational framework that may predict multi-slip system crystal plasticity of single crystal in rate-independent and rate-dependent regimes. Using this as a starting point, we introduce an anisotropic phase-field based model in which displacement and temperature jumps are regularized to model the grain boundary where the temperature-dependent plastic flow is parallel to the ground boundaries. The texture of the polycrystalline salt is assumed to be random by assigning different sets of orientations to each grain. The grain boundary is approximated using the crystal plasticity constitutive model with single slip system to include the inelastic behavior, while the fracture response is captured via the evolving phase field. Numerical examples demonstrate that the proposed model is able to capture the brittle-ductile transition under various of loading rate, temperature and confining pressure with a minimal set of material parameters. Keywords: salt, halite, crystal plasticity, slip system, thermo-mechanical analysis, constitutive model
Two of our CMAME papers published last year, "A unified variational eigen-erosion framework for interacting brittle fractures and compaction bands in fluid-infiltrating porous media" and "Computational thermo-hydro-mechanics for multiphase freezing and thawing porous media in the finite deformation range" are among the most downloaded articles in Computer Methods in Applied Mechanics and Engineering. [URL] [PDF]
It is my great pleasure to announce that our former PhD student of the research group, Dr. Yang Liu has accepted a tenure-track position as assistant professor of mechanical and Industrial Engineering at Northeastern University. Yang currently works as a postdoctoral scholar at the Institute For Soldier Nanotechnologies of MIT. She is the first PhD graduate of our research group. In 2015, she won the best paper competition among students from more than 100 minisymposia at USNCCM San Diego. She has published the following two journal articles during her tenure in our group.
Congratulations Yang for this wonderful accomplishment! A hierarchical sequential ALE poromechanics model for tire-soil-water interaction on fluid-infiltrated roads
Authors: Ines Wollny, WaiChing Sun, Michael Kaliske This paper introduces a hierarchical sequential arbitrary Lagrangian-Eulerian (ALE) model for predicting the tire-soil-water interaction at finite deformation. Using the ALE framework, the interaction between a rolling pneumatic tire and the fluid infiltrated soil underneath will be captured numerically. The road is assumed to be a fully saturated two-phase porous medium. The constitutive response of the tire and the solid skeleton of the porous medium are idealized as hyperelastic. Meanwhile, the interaction between tire, soil and water will be simulated via a hierarchical operator-split algorithm. A salient feature of the proposed framework is the steady state rolling framework. While the finite element mesh of the soil is fixed to a reference frame and moves with the tire, the solid and fluid constituents of the soil are flowing through the mesh in the ALE model according to the rolling speed of the tire. This treatment leads to an elegant and computationally efficient formulation to investigate the tire-soil-water interaction both close to the contact and in the far field. The presented ALE model for tire-soil-water interaction provides the essential basis for future applications e.g. to a path-dependent frictional-cohesive response of the consolidating soil and unsaturated soil, respectively. [URL] Our paper "A stabilized finite element formulation for monolithic thermo-hydro-mechanical simulations at finite strain" published in IJNME at 2015 is the top 5 most cited papers from 2015 to 2016. The paper can be downloaded via the Wiley Online Library [URL]. Dates and Location: August 29-31, Copenhagen/Lyngby, Denmark Webpage: http://www.conferencemanager.dk/mcacm Overview and Objectives: Complex materials play an essential role in many applications, ranging from turbine blades, car chassis, computer and cell phone cases, battery systems, stretchable and wearable electronics, to biomedical applications. Those materials often operate and must maintain their high performance in harsh environments. The advancement of computationalmethods at multiple scales opens new possibilities for the design of such complex materials and the optimization of their intrinsic properties under extreme events. The bridging of different length and time scales though still represents an area of active research with many unresolved challenges. For example, material degradation is considered as a typical multiscale process, controlled by nanoscale defects, highly affecting the macroscopic material response. The confirmed presenters include Jose E. Andrade (Caltech), Ronaldo I. Borja (Stanford), JS Chen (UC San Diego), William Curtin (EPFL), Jacob Fish (Columbia), Somnath Ghosh (Johns Hopkins), Ellen Kuhl (Stanford), Lars P. Mikkelsen (TU Denmark ), Christian Frithiof Niordson (TU Denmark), Stefanie Reese (RWTH Aachen), Siegfried Schmauder (Stuttgart), Jörg Schröder (Universität Duisburg-Essen), Mads Peter Sørensen (TU Denmark) and others. Symposium Topics include but are not limited to • Multiscale modeling of materials • Multiphysics modeling of materials • Computational materials science • Micromechanics of materials • Scale bridging and homogenization • Materials under extreme environments • Hierarchical materials • Nanomaterials • Biological and natural materials • Geomaterials Computational thermo-hydro-mechanics for multiphase freezing and thawing porous media in the finite deformation range SeonHong Na, WaiChing Sun Abstract A stabilized thermo-hydro-mechanical (THM) finite element model is introduced to investigate the freeze-thaw action of frozen porous media in the finite deformation range. By applying mixture theory, frozen soil is idealized as a composite consisting of three phases, i.e., solid grain, unfrozen water and ice crystal. A generalized hardening rule at finite strain is adopted to replicate how the elasto-plastic responses and critical state evolve under the influence of phase transitions and heat transfer. The enhanced particle interlocking and ice strengthening during the freezing processes and the thawing-induced consolidation at the geometrical nonlinear regimes are both replicated in numerical examples. The numerical issues due to lack of two-fold inf-sup condition and ill-conditioning of the system of equations are addressed. Numerical examples for engineering applications at cold region are analyzed via the proposed model to predict the impacts of changing climate on infrastructure at cold regions. [DRAFT] A unified variational eigen-erosion framework for interacting brittle fractures and compaction bands in fluid-infiltrating porous media Kun, Wang WaiChing Sun Abstract The onset and propagation of the cracks and compaction bands, and the interactions between them in the host matrix, are important for numerous engineering applications, such as hydraulic fracture and CO2 storage. While crack may become flow conduit that leads to leakage, formation of compaction band often accompanies significant porosity reduction that prevents fluid to flow through. The objective of this paper is to present a new unified framework that predicts both the onset, propagation and interactions among cracks and compaction bands via an eigen-deformation approach. By extending the generalized Griffith's theory, we formulate a unified nonlocal scheme that is capable to predict the fluid-driven fracture and compression-driven anti-crack growth while incorporating the cubic law to replicate the induced anisotropic permeability changes triggered by crack and anti-crack growth. A set of numerical experiments are used to demonstrate the robustness and efficiency of the proposed model. [DRAFT] H51C-1492 Phase field modeling of crack propagations in fluid-saturated porous media with anisotropic surface energy
SeonHong Na1, WaiChing Sun1, Hongkyu Yoon2 and Jinhyun Choo3, (1)Columbia University, Department of Civil Engineering and Engineering Mechanics, New York, NY, United States, (2)Sandia National Lab, Albuquerque, NM, United States, (3)Stanford University, Stanford, CA, United States Moscone South - Poster Hall H51C-1490 A discontinuous finite element approach to cracking in coupled poro-elastic fluid flow models Cian R Wilson1, Marc W Spiegelman1, Owen Evans1, Ole Ivar Ulven2 and WaiChing Sun3, (1)Columbia University of New York, Palisades, NY, United States, (2)University of Oslo, Oslo, Norway, (3)Columbia University, Department of Civil Engineering and Engineering Mechanics, New York, NY, United States Moscone South - Poster Hall H51C-1474 A unified variational eigen-deformation model for simulating compaction band and fracture propagation in fluid-infiltrating porous media WaiChing Sun and Kun Wang, Columbia University, Department of Civil Engineering and Engineering Mechanics, New York, NY, United States Moscone South - Poster Hall H54C-05 Fluid-induced Rock Transformation Modeled via a Two-way Coupled Hydromechanical DEM-network Model Ole Ivar Ulven, University of Oslo, Oslo, Norway and WaiChing Sun, Columbia University, Department of Civil Engineering and Engineering Mechanics, New York, NY, United States Moscone West - 3020 FRIDAY, 16 DECEMBER 2016 08:00 - 12:20 13:40 - 15:40 16:00 - 18:00 17:00 - 17:15 Our manuscript (co-authored by former student Zhijun Cai and postdoc scholar Dr. Jinhyun Choo) has been accepted by International Journal of Numerical Method in Engineering (see PDF). The abstract is listed below:
Mixed Arlequin method for multiscale poromechanics problems An Arlequin poromechanics model is introduced to simulate the hydro-mechanical coupling effects of fluid-infiltrated porous media across different spatial scales within a concurrent computational framework. A two-field poromechanics problem is first recast as the two-fold saddle point of an incremental energy functional. We then introduce Lagrange multipliers and compatibility energy functionals to enforce the weak compatibility of hydro-mechanical responses in the overlapped domain. To examine the numerical stability of this hydro-mechanical Arlequin model, we derive a necessary condition for stability, the two-fold inf--sup condition for multi-field problems, and establish a modified inf--sup test formulated in the product space of the solution field. We verify the implementation of the Arlequin poromechanics model through benchmark problems covering the entire range of drainage conditions. Through these numerical examples, we demonstrate the performance, robustness, and numerical stability of the Arlequin poromechanics model. A special issue on computational poromechanics edited by Dr. Sun has been published in International Journal for Multiscale Computational Engineering. Detailed information can be found at
http://www.dl.begellhouse.com/journals/61fd1b191cf7e96f,2b8c00292c2d9c29.html The table of content is listed below. Table of Contents: PREFACE: COMPUTATIONAL POROMECHANICS WaiChing Sun pages v-vi DOI: 10.1615/IntJMultCompEng.2016018596 GENERAL FORMULATION OF A POROMECHANICAL COHESIVE SURFACE ELEMENT WITH ELASTOPLASTICITY FOR MODELING INTERFACES IN FLUID-SATURATED GEOMATERIALS Richard A. Regueiro, Zheng Duan, Wei Wang, John D. Sweetser, Erik W. Jensen pages 323-347 DOI: 10.1615/IntJMultCompEng.2016018962 SIMULATING FRAGMENTATION AND FLUID-INDUCED FRACTURE IN DISORDERED MEDIA USING RANDOM FINITE-ELEMENT MESHES Joseph E. Bishop, Mario J. Martinez, Pania Newell pages 349-366 DOI: 10.1615/IntJMultCompEng.2016016908 MULTISCALE MODEL FOR DAMAGE-FLUID FLOW IN FRACTURED POROUS MEDIA Richard Wan, Mahdad Eghbalian pages 367-387 DOI: 10.1615/IntJMultCompEng.2016016951 IDENTIFYING MATERIAL PARAMETERS FOR A MICRO-POLAR PLASTICITY MODEL VIA X-RAY MICRO-COMPUTED TOMOGRAPHIC (CT) IMAGES: LESSONS LEARNED FROM THE CURVE-FITTING EXERCISES Kun Wang, WaiChing Sun, Simon Salager, SeonHong Na, Ghonwa Khaddour pages 389-413 DOI: 10.1615/IntJMultCompEng.2016016841 ALBANY: USING COMPONENT-BASED DESIGN TO DEVELOP A FLEXIBLE, GENERIC MULTIPHYSICS ANALYSIS CODE Andrew G. Salinger, Roscoe A. Bartlett, Andrew M. Bradley, Qiushi Chen, Irina P. Demeshko, Xujiao Gao, Glen A. Hansen, Alejandro Mota, Richard P. Muller, Erik Nielsen, Jakob T. Ostien, Roger P. Pawlowski, Mauro Perego, Eric T. Phipps, WaiChing Sun, Irina K. Tezaur pages 415-438 DOI: 10.1615/IntJMultCompEng.2016017040 Data-driven multiscale poromechanics model for cold region applications
WaiChing Sun, Columbia University Abstract: The hydro-mechanical responses of geological materials, such as soil and rock are strongly influenced by the environmental they subjected to. In cold region, the ice crystals in the void space may introduce many interesting multi-physical behaviors, such as creeping, thermal-induced hardening/softening and freeze-thaw action responsible for sharing the earth surface features and the mobility of vehicles. This talk focuses on the multiscale modeling techniques for predicting those thermos-hydro-mechanical behaviors developed by my research team and supported by the ARO Earth Materials and Process program. In particular, we will discuss (1) a finite strain finite element model that captures the freeze-thaw action of frozen soil, (2) multiscale techniques used to link grain-scale simulations to macroscopic micro-polar continua models, and (3) a new class of constitutive-law-free model that enables predictions made directly from experimental or simulated data based on spectral decomposition. Spurious pathological predictions by previous DEM-FEM models are examined and the remedies are proposed. Preliminary validation with experiments for the temperature- and rate-dependent behavior of frozen soil will also be discussed. Bio: WaiChing Sun is an assistant professor in the Department of Civil Engineering and Engineering Mechanics at Columbia University, New York. From 2011 to 2013, he served as a senior member of technical staff at Sandia National Laboratories. Professor Sun works in the fields of theoretical and computational poromechanics with a special emphasis on geomechanical applications. His research includes multiscale modeling porous media, multiscale verification and validation with CT images, digital rock and granular physics, applications of mathematical tools, such as graph theory, Lie algebra for modern engineering problems. He has published more than 40 peer-reviewed articles. He received the Dresden Fellowship in 2016, US AFOSR Young Investigator Program Award in 2016, US Army Young Investigator Program Award in 2015, and the Caterpillar Best Paper Prize in 2013. Dr. Sun holds BS degree from UC Davis (2005), MS degrees from Stanford (2007) and Princeton (2008) and PhD degrees from Northwestern (2011). Our proposal titled "Modeling the High-rate Responses of Wetted Granular Materials Across Scales and the Third-party Replicable Validation Exercises Utilizing 3D Printers" is selected to receive the 2017 AFOSR Young Investigator Award. The YIP is open to scientists and engineers at research institutions across the United States who received Ph.D. or equivalent degrees in the last five years and who show exceptional ability and promise for conducting basic research.The objective of this program is to foster creative basic research in science and engineering, enhance early career development of outstanding young investigators, and increase opportunities for the young investigators to recognize the Air Force mission and the related challenges in science and engineering.
The press release can be found in the URL below: http://www.wpafb.af.mil/News/Article-Display/Article/969772/afosr-awards-grants-to-58-scientists-and-engineers-through-its-young-investigat We will have two oral-presentations for the upcoming SES Meeting at University of Maryland:
Presentation 1: D8-4: Computational Mechanics of Materials and Structures: Room 0102 10:00am to 10:20am Computational thermo-hydro-mechanics for multiphase frozen soil with unfrozen water flow in the finite deformation range -- SeonHong Na & WaiChing Sun Presentation 2: D9-6 Friction, Fracture and damage: Room 0101 1:20pm-1:40pm A binary eigen-deformation model for propagating fractures and shear failure in fluid-infiltrating porous media -- Kun Wang & WaiChing Sun 2nd year graduate student SeonHong Na in our research group has awarded 2nd place in the Student Paper Competition in Inelasticity and Multiscale Behavior Committee at Engineering Mechanics Institute Conference at Vanderbilt University, Nashville, TN. His work is on computational cryo-mechanics of frozen soil at finite deformation range. The committee has first chosen 5 finalists among all student paper submitted to the committee. The selected finalists are then given the opportunity to present in front of the judge and the top three papers are selected. SeonHong Na's work is selected by the judge as the top three papers among all of the submitted work to the Inelasticity and Multiscale Behavior Committee. Previously, former student of the research group Dr Yang Liu (now at MIT) has also won the Best Poster Competition at USNCCM San Diego.
Congratulations SeonHong for this wonderful achievement! |
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