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3 Technological Barriers: Computational, Experimental, and Integration Needs for ICME
Pages 67-101

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From page 67...
... However, there remain significant technical barriers to the widespread adoption of ICME capabilities. In this chapter the committee discusses many of those challenges, focusing not only on modeling tools but also on the materials databases and experimental tools needed to make ICME a reality for a broad spectrum of materials applications.
From page 68...
... Current computational materials methods range from the specialized materials modeling methods that are used in fundamen tal research to the full-scale materials processing tools at manufacturing facilities. Researchers in materials science, mechanics, physics, and chemistry explore mate rials processing–structure–property relationships as a natural part of the research process.
From page 69...
... Consider length scales from 1 angstrom to 100 microns. At the smallest scales scientists use electronic structure methods to predict bonding, magnetic moments, and transport properties of atoms in different configurations.
From page 70...
... electronic structure, diagrams, phase fractions, Fact Sage calorimetry data, free- multicomponent phase energy functions fit to diagram, free energies materials databases Microstructural Free-energy and kinetic Solidification and dendritic OpenPF, MICRESS, evolution methods databases (atom structure, microstructure DICTRA, 3DGG, Rex3D (phase-field, front- mobilities) , interface and during processing, tracking methods, Potts grain boundary energies, deployment, and evolution models)
From page 71...
... Thermodynamic methods range from first-principle predictions of phase diagrams to complex database integration methods using existing tabulated data to produce phase diagrams and kinetics data. These methods are being developed by the CALculation of PHAse Diagram (CALPHAD)
From page 72...
... Saunders and A.P. Miodownik, CALPHAD -- Calculation of Phase Diagrams, A Comprehensive Guide, Oxford, England: Elsevier (1998)
From page 73...
... The enabling factors that led to the CALPHAD capability of today will also be critical enablers for the development of a widespread ICME capability in the future. mechanical and mesoscale property models include solid mechanics and FEA methods that use experimentally derived models of materials behavior to explore microstructural influences on properties.
From page 74...
... While still an unsolved problem, projects like those sponsored by Eclipse are focused on the creation of open development platforms to make such computational linkages easier. Each class of methods in Table 3.1 has its own needs and challenges, among them the following: • Extensions of atomistic simulations to longer times through the use, for example, of accelerated dynamics methods and to broader classes of mate rials systems through the development and validation of force fields for application to heterogeneous/mixed materials, especially at the interfaces between material types (for example, metal-ceramic) ; • Development of spatially hierarchical microstructural evolution methods for concurrently modeling microstructural features across length scales; • Advances in crystal plasticity finite element methods to include the effects of local heterogeneities in the microstructure; • Methods for modeling the spatial and temporal scales between dislocation dynamics and continuum level (for instance, finite element methods)
From page 75...
... Thus the computational capabilities required to model materials behavior for ICME are becoming increasingly available to the practicing materials engineer. The prognosis is for continued improvements in hardware capabilities.
From page 76...
... Low-level fault detection is just entering compilers and parallel computing middle ware such as message-passing interface (MPI) , but no broadly available materials simulation tools currently take advantage of these capabilities or provide their own fault detection to improve their reliability.
From page 77...
...  SinceICME is best practiced with complementary experimental and theoretical approaches, the validation of computational methods to fill gaps in theoretical understanding is critical to building a robust ICME approach. Validation is discussed in the section "Role of Experimentation in Com putational Materials Science and ICME."
From page 78...
... process and for more efficient develop ment of future ICME tools. Visualization The ability to visualize the output of complex analysis is crucial to understand ing design challenges of today and tomorrow.
From page 79...
... Role of Experimentation in Computational Materials Science and ICME Experimental Calibration and Validation One of the important lessons of earlier ICME efforts is the profound impor tance of experimental results for calibrating and validating computational meth ods and filling gaps in theoretical understanding. In fact ICME is best practiced with complementary experimental and theoretical approaches.
From page 80...
... Three-Dimensional Microstructural Characterization Structure–property models for materials are at the core of any ICME imple mentation. Virtually all engineering materials contain structural features at the micro- or nanoscale that strongly influence properties.
From page 81...
... By their nature, engineering materials are not amenable to many of the imaging modes utilized in the medical field. Except for special cases like synchrotron radiation, where large volumes of material are transparent to the imaging radiation, engineering materials must often be physically sectioned to acquire two-dimensional imaging "slices." Recent interesting serial sectioning approaches include automated robotic
From page 82...
... Rapid, Targeted Experimentation As described above, the availability of experimental data to fill gaps in theoreti cal understanding, calibrate models, and validate ICME results is a key prerequisite for widespread ICME utilization. While experimental evaluation of new materials and evaluation of the influence of new processing approaches have been the corner stone of materials development, such evaluation is slow and often very expensive, so that a more rapid approach to experimental exploration is needed.
From page 83...
... , aspects of binary and ternary phase diagrams can be explored with the use of a single sample, reducing by a factor of 20 to 100 the required number of samples that must be processed to obtain this fundamental information. Among the new techniques for probling properties in small volumes are local laser-based probes for thermal and electrical conductiv ity, nanoindentors, and new electron backscattered scanning electron microscopy (SEM)
From page 84...
... for rapid mapping of the Ni-Fe-Mo phase diagram and for studying the alloying effect of Mo addition to IN706. The phase diagram is plotted using atomic percent axes with numbering of the scales removed for simplicity.
From page 85...
... fabricated in a focused ion beam system. They are com pressed with a nanoindentor tip to obtain stress-strain data (b)
From page 86...
... 86 I n t e g r at e d C o m p u tat i o na l M at e r i a l s E n g i n e e r i n g Periodic Experimental Experimental Table Database Database Analysis Code ab initio, DFT codes Crystal Atomic Structure Potentials Backed out from CALPHAD Backed out from MD codes Gibbs Free- Diffusion Energy Constants Functions Optimization Software CALPHAD codes Diffusion codes Phase TTT, CCT Diagrams Diagrams Deterministic or Analytical Methods + FEA Microstructures Deterministic or Analytical Methods Mechanical, Physical, Electronic, Magnetic Properties Lifingcodes + FEA Component Life FIGURE 3-5 Integrating databases and computational materials science tools. DFT, density functional theory; MD, molecular dynamics; TTT, time–temperature transformation curve; and CCT, continuous cooling transformation curves.
From page 87...
... Such is the case for the materials thermodynamics and phase diagrams (CALPHAD: CALculation of PHAse Diagram) community, which constructs databases from literature data and unpublished academic and industrial studies and then sells them as part of a thermodynamic modeling package.
From page 88...
... Requirements for ICME Databases Those who have built large scientific databases in the biology and physics communities emphasize two design principles.21,22 First, useful databases must start with a taxonomy of the field that is comprehensive and able to accommodate change. The fundamental problem with materials databases is that their structure, or schema, is generally focused narrowly on the immediate problem of the user base and is not easily expandable.
From page 89...
... However, to maintain their competitive advantage, OEMs may decide to maintain proprietary databases for their core technologies. Ideally, ICME software should be able to seamlessly integrate multiple proprietary and public data sources as inputs to materials and system integration tools in order to optimize over all the available data.
From page 90...
... Materials informatics, a promising new development in materials research, offers a way to meet that challenge. Materials informatics employs creating databases and advanced data mining and analysis methods to seek patterns of behavior from large, complex data sets, with the goal of identifying new physical relationships between chemistry, structure, and properties.
From page 91...
... To be more specific, consider the hybrid data mining and simulation technique of Fischer et al. for determining lowest-energy intermetallic structures and con structing their phase diagrams.24 A database holds the structures and free energies of a large number of binary and ternary intermetallic systems.
From page 92...
... Integration Tools: The Technological "I" in ICME Technical tools for integrating materials knowledge are of obvious importance for ICME. Integration tools are the glue that binds software applications and databases into an integrated, cohesive, systemwide design tool that can be used by many contributors to the design effort.
From page 93...
... Knowledge from disparate sources and domains (for example, thermodynamic models, models for simulating manufacturing processes, microstructural evolution models, and property models) is required to fully assess the influence of the manufacturing process on the properties of the materials that make up a manufactured product.
From page 94...
... Commercial Integration Tools Commercial integration software tools are available that are designed to link a variety of disparate software applications into an integrated package, which can then be used to optimize some underlying process. As a result of these efforts, de facto standards are emerging for "wrapping" models, running parallel parametric simulations, applying sensitivity analysis, and reducing the complexity (order)
From page 95...
... Accessed February 2008. 28 Alex Van der Velden, Engineous, "Use of process integration and design optimization tools for product design incorporating materials as a design variable," Presentation to the committee on March 14, 2007.
From page 96...
... Accessed February 2008. 32 Alex Van der Velden, Engineous, "Use of process integration and design optimization tools for product design incorporating materials as a design variable," Presentation to the committee on March 14, 2007.
From page 97...
... Once applications are linked into a common framework, the next logical step is to perform multidisciplinary, systemwide design and optimization. Design trade-offs can be made, and the result ing behavior can be propagated throughout the entire design work flow to obtain globally optimal solutions.
From page 98...
... The committee proposes the following definition for the term "ICME cyberinfrastructure:" The Internet-based collaborative materials science and engineering research and development environments that support advanced data acquisition, data and model storage, data and model management, data and model mining, data and model visualization, and other computing and information processing services required to develop an integrated computational materials engineering capability. A key element of the ICME cyberinfrastructure will be individual collabora tive ICME Web sites and information repositories that are established for specific purposes by a variety of organizations but linked in some fashion to a broader network that represents the ICME cyberinfrastructure.
From page 99...
... The goal of a balanced, well-designed ICME cyberinfrastructure is to give scientists and engineers the means to do a number of things: • Link applications codes -- for example, UniGraphics, PrecipiCalc, and ANSYS; • Develop models that accurately predict multiscale material behaviors; • Store and retrieve analytical and experimental data in common databases; • Provide a repository for material models; • Execute computational code anywhere computational resources are available; • Visualize large-scale data; • Enable local or geographically disperse collaborative research; and • Measure the uncertainty in a given design and the contributions of indi vidual design parameters or sources. The desired future state is one in which a government-sponsored cyberinfra structure composed of a variety of special-purpose Web sites is widely used for collaboration between researchers here and abroad.
From page 100...
... Without proper secu rity, corporate and government security policies will impede the development of systemwide design environments. Summary Although existing computational materials science capabilities are impressive, they have not had a significant impact on materials engineering.
From page 101...
... Physically based models and simulation tools have pro gressed to the point where ICME is now feasible for certain applications, though much development and validation remain to be done if ICME is to be more broadly adopted. The widespread adoption of ICME approaches will require significant development of models, integration tools, new experimental methods, and major efforts in calibration of models for specific materials systems and validation.


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