The elastic modulus of natural cellulose crystal was estimated by the molecular simulation technique. Values between 124 and 155 GPa were derived for the reasonable cellulose Iβ crystal model that were nearly equal to the observed value of 138 GPa. While the second-generation force fields were found to be superior to the first-generation ones for the optimization of cellulose structure, neither of these was good enough to achieve the structural optimization. They were, however, adequate for estimating the mechanical properties of cellulose, especially the second-generation force fields. The lateral (that is, intermolecular) interactions between cellulose chains were found to play an important role in the expression of the mechanical properties of cellulose crystal.
X-force Simulation Mechanical 2006
The bond stretching constant k i j \displaystyle k_ij can be determined from the experimental Infrared spectrum, Raman spectrum, or high-level quantum mechanical calculations. The constant k i j \displaystyle k_ij determines vibrational frequencies in molecular dynamics simulations. The stronger the bond is between atoms, the higher is the value of the force constant, and the higher the wavenumber (energy) in the IR/Raman spectrum. The vibration spectrum according to a given force constant can be computed from short MD trajectories (5 ps) with 1 fs time steps, calculation of the velocity autocorrelation function, and its Fourier transform.[6]
Force field parameterizations for simulations with maximum accuracy and transferability, e.g., IFF, follow a well-defined protocol.[5] The workflow may involve (1) retrieving an x-ray crystal structure or chemical formula, (2) defining atom types, (3) obtaining atomic charges, (4) assigning initial Lennard-Jones and bonded parameters, (5) computational tests of density and geometry relative to experimental reference data, (6) computational tests of energetic properties (surface energy,[18] hydration energy[19]) relative to experimental reference data, (7) secondary validation and refinement (thermal, mechanical, and diffusion properties).[20] Major iterative loops occur between steps (5) and (4), as well as between (6) and (4)/(3). The chemical interpretation of the parameters and reliable experimental reference data play a critical role.
HIV-1 protease flaps spontaneously open and reclose in molecular dynamics simulations Hornak, V., Okur, A., Rizzo, R. and Simmerling, C. Proceedings of the National Academy of Sciences of the United States of America, 2006, 103 (4), 915-920DOI: 10.1073/pnas.0508452103
Professor Miller is interested in solid mechanics and the mechanical behavior of metals, engineering alloys, composites and semiconductors. Research areas include crystal stress measurements, microplasticity, fatigue crack initiation, high temperature behavior of superalloys, mechanical behavior of silicon, design and implementation of new in situ experiments with synchrotron x-rays, multiscale model development and validation. Educational areas focus on mechanics of materials, material selection, x-ray diffraction, graduate solid mechanics, mechanics of composites, experimental methods and state variable modeling.Matthew Miller joined the Sibley School faculty in January, 1994 and is currently a full Professor. Miller received his B.S. in Mechanical Engineering from the Colorado School of Mines and his M.S. and Ph.D. from Georgia Tech. He was named the 1993 outstanding graduating Ph.D. in mechanical engineering and was inducted into the Georgia Tech. Council of Outstanding Young Engineering Alumni in 1995. Professor Miller spent a sabbatical leave at the Colorado School of Mines in 2000-2001, at the Advanced Photon Source (APS) at Argonne National Laboratory in 2007 and The Ohio State University in 2008. Professor Miller has developed in situ mechanical testing / synchrotron x-ray experiments at the Cornell High Energy Synchrotron Source (CHESS) and at the APS. In 2011, he co-organized a workshop at the APS to explore the synergy between high energy synchrotron x-ray diffraction experiments and high fidelity material behavior models. Miller is currently the Associate Director of CHESS and serves on the Section 1 Beamline Advisory Group at the APS. Professor Miller spent 6 years playing professional football before returning to obtain his engineering degrees. He played 4 years as an offensive lineman for the Cleveland Browns of the NFL and 2 years for the Denver Gold of the USFL.Professor Miller has received several teaching and advising awards at Cornell. He was a Lilly Teaching Fellow in 1995, he won the Dennis Shepherd Award as the Outstanding Teacher in the Sibley School in 1996. Miller won the James and Mary Tien Excellence in Teaching Award in 2004 and the James M. Marsha D. McCormick Award for Excellence in Advising First Year Students in 2006 - both awarded by the Cornell College of Engineering. Professor Miller won an NSF CAREER Award in 1997 and participated in the National Academy of Engineering Frontiers of Engineering in 1999. He won the ASM International Henry Marion Howe Award in 2009 for the Best Research Paper in Metallurgical and Materials Transactions in 2008. Professor Miller is on the Editorial Advisory Board of the International Journal of Fatigue and is on the Review Board for Integrating Materials and Manufacturing Innovation. In 2022, he was elected the Willis H. Carrier Professor in Engineering.
FIGURE 22. Application prospect of the simulation method proposed in this paper: (A) simulation of mechanical compaction with particle breakage considering various geological factors, (B) fluid flow simulation with Avizo 9.0, and (C) 3D visualization effect of the model and 2D slice images.
Citation: Jia T, Zhang L, Chen C, Wang Z, Yan Y and Li J (2023) Numerical simulation of mechanical compaction and pore evolution of sandstone considering particle breakage. Front. Earth Sci. 10:1038038. doi: 10.3389/feart.2022.1038038
FAJRI research objective is to advance the science and technology, develop, and to disseminate new knowledge of material joining for load-bearing structural and mechanical joint systems that may be made of similar and/or mixed materials. This includes metals, composites, polymers, and plastics that are joined by mechanical fastening, adhesive bonding, welding, riveting, hybrid or other advanced joining methods.FAJRI Research PhilosophyIn its material joining research, FAJRI follows a systems approach that would simultaneously investigate the relative significance of single and multiple variable interactions, which would affect the overall system performance and reliability. Those variables are divided into six groups that belong to: 1) the joint, 2) the joining element, 3) the joining tool, 4) process control method, 5) in-service loads, and 6) environmental effects.FAJRI Research MethodologyA combination of analytical and mathematical modeling, numerical and computer simulation, experimental testing and validation methods are used.FAJRI Facility and Test EquipmentFAJRI dedicated lab space and graduate student office occupy a 4,000 sq. ft secure suite on the second floor of Dodge Hall on the main campus of Oakland University. Dedicated FAJRI equipment include MTS fatigue testing system with high temperature chamber and grip rating (100kN), 5-spindle DC-nut runner with controls, Junker machine for Vibration loosening, two Torque-tension-angle research systems (up to 1,000 ft-lb), Wyko optical profiler for surface roughness measurement, Dynamic Mechanical Analyzer (DMA), Environmental Chamber with controls, Cyclic salt-fog corrosion chamber, Autoclave with Process Controls for film adhesive bonding, Vibration-isolation table, NDE equipment (ultrasonic and optical), FEA software and computer work stations, secure storage space and conference room facility for ITAR projects, ...etc. Several specialty labs in various engineering and science departments also support FAJRI research; this includes the Optics and NDE lab, Chemistry labs, and a well-equipped machining center for test fixture design and sample manufacturing.NSF Initiative for Composite Joining Research at OU _ID=1822028Dr. Nassar and his interdisciplinary research team at Oakland, in partnership with their counter parts at Georgia Institute of Technology (GT), and The University of Tennessee-Knoxville (UTK)], have been recently awarded respective NSF Planning grants to develop a full proposal for Phase 1 ($4.5 million) of an IUCRC (Industry-University Cooperative Research Center). The three-phase ($13.5m total) NSF initiative would establish three closely coordinated sites for a new research centers for Digital Composite Joining and Repair (D-CJAR) at OU, GT, and UTK. A research team of 30 faculty experts, from the three partnering universities, would lead the research at the three respective D-CJAR sites, in close partnership with interested industry and other government research agencies. An NSF-led Planning meeting between respective academic and industrial partners is scheduled at Georgia Tech during the first quarter of 2019 for the 3-partnering universities to plan NSF proposal for Phase 1. NSF requires the formation of an Industrial Advisory Board (IAB) at each of the three D-CJAR sites to select and fund research projects. The OU site of D-CJAR would have an automotive/ground vehicle thrust, while the GT and UTK sites would respectively have Aerospace, and Energy/infrastructure thrusts. Subsequent to review, and hopeful award, by NSF, the start date for the 3 D-CJAR sites would be during the last quarter of 2019. 2ff7e9595c
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