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Verification of a Two-Way Coupled Multiscale finite element code for Dynamic/Impact Problems

MECHANICS OF ADVANCED MATERIALS AND STRUCTURES 2013年第1期20卷 74-90页

作者： Souza, Flavio V. Allen, David H. MultiMech Res & Dev LLC Omaha NE USA Univ Texas Pan Amer Edinburg TX 78541 USA

Engineering applications are increasingly facing structural challenges. Restrictive economic constraints and more complex geometric design have led to the use of advanced materials, such as fiber-reinforced composites. The behavior of such materials is governed by their microstructure, thus demanding the use of multiscale approaches. The present article aims at the verification of a two-way coupled multiscale finite element code previously developed by the authors. A two-scale analytical solution for a functionally graded elastic material subject to dynamic loads is herein derived in order to verify the multiscale code. Comparisons to overkilled single scale finite element solutions are also presented.

关键词： multiscale modeling homogenization heterogeneous media verification finite element code

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The finite element code LEGAK-DK and Its Application to Numerical Analysis of Impact and Thermal Resistances of Air Transport Package in Hypothetical Accident Conditions

The Finite Element Code LEGAK-DK and Its Application to Nume...

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International Conference on Computational Science and Computational Intelligence (CSCI)

作者： Tsiberev, Kirill Spiridonov, Valentin Dyanov, Denis Kukanov, Sergey Russian Fed Nucl Ctr VNIIEF Dept Computat Math & Mech Sarov 607188 Russia

ISBN: (纸本)9781479930098

The paper presents the new finite element code LEGAK-DK for high performance computational developed in Russian Federal Nuclear Center VNIIEF and some numerical simulations results of the dynamic deformations of the air transport package, subjected to impacts at a high speed. Obtained residual deformed shapes are used to perform numerical analysis of the package's thermal condition in fire. These simulations allow estimating on how a thermal resistance of the package can be reduced after high speed impacts. Comparison of the results with the experimental data shows that they are in a good agreement.

关键词： Computational mechanics finite element code Simulations

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Toward performance portability of the Albany finite element analysis code using the Kokkos library

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INTERNATIONAL JOURNAL OF HIGH PERFORMANCE COMPUTING APPLICATIONS 2019年第2期33卷 332-352页

作者： Demeshko, Irina Watkins, Jerry Tezaur, Irina K. Guba, Oksana Spotz, William F. Salinger, Andrew G. Pawlowski, Roger P. Heroux, Michael A. Los Alamos Natl Lab Porting Albany Code Kokkos Los Alamos NM USA Sandia Natl Labs Extreme Scale Data Sci & Analyt Dept Livermore CA USA Sandia Natl Labs Ctr Comp Res POB 5800 Albuquerque NM 87185 USA Sandia Natl Labs Multiphys Applicat Dept POB 5800 Albuquerque NM 87185 USA Sandia Natl Labs POB 5800 Albuquerque NM 87185 USA

Performance portability on heterogeneous high-performance computing (HPC) systems is a major challenge faced today by code developers: parallel code needs to be executed correctly as well as with high performance on machines with different architectures, operating systems, and software libraries. The finite element method (FEM) is a popular and flexible method for discretizing partial differential equations arising in a wide variety of scientific, engineering, and industrial applications that require HPC. This article presents some preliminary results pertaining to our development of a performance portable implementation of the FEM-based Albany code. Performance portability is achieved using the Kokkos library. We present performance results for the Aeras global atmosphere dynamical core module in Albany. Numerical experiments show that our single code implementation gives reasonable performance across three multicore/many-core architectures: NVIDIA General Processing Units (GPU's), Intel Xeon Phis, and multicore CPUs.

关键词： Performance portability many-core programming finite element code climate simulations Kokkos library

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Maximization of the crushing energy absorption of cylindrical shells

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ADVANCES IN ENGINEERING SOFTWARE 2000年第6期31卷 425-432页

作者： Yamazaki, K Han, J Kanazawa Univ Dept Human & Mech Syst Engn Kanazawa Ishikawa 9208667 Japan

This paper concerns with the development of the crashworthiness maximization technique for tubular structures, and the application to the axial crushing problems of cylindrical tubes. In the program system presented in this study, an explicit finite element code, DYNA3D is adopted for simulating complicated crushing behavior of tubular structures. A series of aluminum cylindrical tubes are tested under axial impact condition for the experimental validation of the numerical solutions. Moreover, the response surface approximation technique is applied to construct an approximated design subproblem for optimization in the pre-assigned design space by using the technique of design-of-experiment. The approximated subproblem is then solved by the usual mathematical programming technique. These optimization processes are repeated until the given convergence conditions are satisfied. (C) 2000 Elsevier Science Ltd. All rights reserved.

关键词： structural optimization crushing energy absorption response surface approach design of experiment finite element code

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AN ECCENTRICALLY STIFFENED SHELL element MODEL WITH GEOMETRICALLY NONLINEAR CAPABILITY

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ENGINEERING COMPUTATIONS 1995年第5期12卷 451-467页

作者： JIANG, L CHERNUKA, MW Martec Limited 1888 Brunswick StreetSuite 400 Halifax Nova Scotia B3J 3J8 Canada Martec Limited 1888 Brunswick Street Suite 400Halifax Nova Scotia B3J 3J8 Canada

A stiffened shell element is presented for geometrically non-linear analysis of eccentrically stiffened shell structures. Modelling with this element is more accurate than with the traditional equivalent orthotropic plate element or with lumping stiffeners. In addition, mesh generation is easier than with the conventional finite element approach where the shell and beam elements are combined explicitly to represent stiffened structures. In the present non-linear finite element procedure, the tangent stiffness matrix is derived using the updated Lagrangian formulation and the element strains, stresses, and internal force vectors are updated employing a corotational approach. The non-vectorial characteristic of large rotations is taken into account. This stiffened shell element formulation is ideally suited for implementation into existing linear finite element programs and its accuracy and effectiveness have been demonstrated in several numerical examples.

关键词： STIFFENED SHELL element finite element code VAST

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Real-Time Collision Mitigation Strategies for Autonomous Vehicles

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IEEE TRANSACTIONS ON INTELLIGENT TRANSPORTATION SYSTEMS 2024年第10期25卷 13483-13493页

作者： Bosia, Leonardo Manganotto, Luca Anghileri, Marco Dolci, Stefano Astori, Paolo Kan, Cing-Dao Politecn Milan Dept Aerosp Sci & Technol DAER I-20133 Milan Italy George Mason Univ Ctr Collis & Safety Anal Fairfax VA 22030 USA

Autonomous vehicles (AVs) offer a promising solution to mitigate human errors and, consequently, reduce the number of road traffic fatalities. While AVs may significantly reduce the number of collisions in the future, they will not be able to completely eliminate it, as certain accidents cannot be avoided due to the physical limitations of the vehicle, and the boundary conditions imposed by the environment. This paper presents an initial investigation into a novel methodology that aims to mitigate the consequences of unavoidable accidents by determining the vehicle trajectory that minimizes injuries to the occupants of the AV in real-time. This result is achieved using a multibody (MBD) crash simulation software to simulate all the possible impacts and determine the one with the lower severity. The approach used is hybrid: the AV can run simulations in real-time as well as access a database where pre-simulated crash results are stored. The maximum computational time required by the software to perform an impact simulation was 80 milliseconds, comfortably within the total time allowable for the AV to detect the unavoidable accident and implement corrective actions, determined to be 0.3 seconds for the scenarios considered. The results of the multibody code were compared with a finite element code, and among the severity indices considered, the Theoretical Head Impact Velocity index has the highest correlation coefficient between the two software. Overall, the proposed methodology demonstrated potentiality both in terms of results and feasibility and could have significant implications for the development of safer self-driving cars.

关键词： Autonomous vehicles multibody code severity indices finite element code simulation time reaction time multibody crash real time crash simulation unavoidable impacts

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Thermal shock problem of a three-layered functionally graded zirconia/titanium alloy strip based on a unified generalized thermoelasticity theory

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JOURNAL OF THERMAL STRESSES 2017年第5期40卷 583-602页

作者： Nikolarakis, Antonios M. Theotokoglou, Efstathios E. Natl Tech Univ Athens Sch Appl Math & Phys Sci Dept Mech Lab Testing & Mat Theocaris BldgZografou Campus GR-15773 Athens Greece

The one-dimensional thermoelastic analysis of a three-layered ceramic/metal functionally graded strip under thermal loading is considered, utilizing classical and generalized coupled thermoelasticity theories. A finite element code is developed for the numerical study of the transient fields of displacement, temperature change, and stress. The code is verified through the analytical and the numerical results available in the literature. The applications presented imply that the classical coupled thermoelasticity theory offers unsatisfactory description of the thermomechanical response of a solid under fast transient thermal loading. Instead, generalized thermoelasticity theories such as the Lord-Shulman theory or the Green-Lindsay theory should be used.

关键词： finite element code functionally graded materials generalized thermoelasticity thermal shock loading

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Constitutive relations in 3-D for a wide range of strain rates and temperatures - Application to mild steels

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INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES 2007年第17期44卷 5611-5634页

作者： Rusinek, A. Zaera, R. Klepaczko, J. R. Univ Metz CNRS Lab Phys & Mech Mat UMR 75 54 F-57045 Metz France Univ Carlos III Madrid Dept Continum Mech & Struct Anal Madrid 28911 Spain

An original phenomenological thermo-visco-plastic model is reported that encompasses strain hardening, strain rate and temperature sensitivity. The model is based to some extent on the concept of physical modeling proposed earlier by Klepaczko [Klepaczko, JR. 1975. Thermally activated flow and strain rate history effects for some polycrystalline FCC metals. Mater. Sci. Engng. 18, 121-135], and also by different authors, for example: [Becker, R. 1925. Uber die plastizitat amorpher und kristalliner fester korper. Z. Physik 26, 919-925;Seeger, A., 1957. Dislocations and Mechanical Properties of Crystals, Wiley, New York;Conrad, H., 1964. Thermally activated deformation of metals J. Metals 16, 582;Gilman, J.J. 1968. Dislocation dynamics and response of materials to impact Appl. Mech. Rev. 21, 767-783;Gibbs, G.B., 1969. Thermodynamic analysis of dislocation glide controlled by dispersed local obstacles. Mater. Sci. Engng. 4, 313-328;Kocks, U.F., Argon, A.S., Ashby, M.F., 1975. Thermodynamics and kinetics of slip. In: Progress in Materials Science, vol. 19. Pergamon Press, New York, p. 19;Kocks, U.F. 1976. Laws for work-hardening and low-temperature creep. J. Eng. Mater. Technol. 98, 76-85, and later by many others. The thermo-visco-plastic formulation, called RK and applied in this paper, has been verified experimentally for strain rates of 10(-4) s(-1) <= epsilon(p) <= 5 x 103 s(-1) and temperatures 213 K <=, T <= 393 K, it covers the range of dynamic loadings observed during crash tests and other impact problems. In order to implement the RK constitutive relation, a thermo-visco-plastic algorithm based on the J(2) theory of plasticity is constructed. The type of algorithm is a return mapping one that introduces the consistency condition (f = a sigma- sigma(y) = 0), without the overstress state proposed by Perzyna [Perzyna, P. 1966. Fundamental problems in viscoplasticity. Advances in Applied Mechanics, vol. 9. Academic Press, New York, pp. 243-377], The coupling of the

关键词： mild steel RK constitutive relation thermo-visco-plasticity consistent algorithm dynamic plasticity numerical simulations finite element code

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Coupled dynamic elastic-plastic analysis of earth structures

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SOIL DYNAMICS AND EARTHQUAKE ENGINEERING 2003年第6期23卷 435-454页

作者： Zerfa, FZ Loret, B Inst Mecan Grenoble Lab Sols Solides Struct F-38041 Grenoble France

A fully coupled finite element code based on mixture theory is developed. Prevost's multi-surface constitutive model is tailored to three-dimensional loads and used to predict effective stresses. A new viscous boundary is implemented to avoid wave reflections towards the structure. In contrast to traditional methods, this boundary is able to absorb the two dilatational waves and the shear wave. Two soil deposits and two dams, with different slopes, composed by loose and dense sands have been subjected to the Pacoima accelerogram. Results show how the liquefaction propagates in the soil deposits and earth dams. The importance of the coupling between dilatancy-contractancy and filtration is highlighted by a parametric investigation. Phenomena such as liquefaction and cyclic mobility are reproduced, indicating the robustness of the constitutive model and finite element simulations. As an outcome of the parametric analysis, the seismic stability of dams cannot be improved by decreasing the upstream or downstream slopes. (C) 2003 Elsevier Ltd. All rights reserved.

关键词： elastic-plastic analysis finite element code Prevost's multi-surface constitutive model liquefaction

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Protection effectiveness of an oblique plate against a long rod

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INTERNATIONAL JOURNAL OF IMPACT ENGINEERING 2006年第1-12期33卷 872-879页

作者： Yoo, Y. H. Lee, M. Sejong Univ Dept Mech Engn Seoul 143747 South Korea Agcy Def Dev Taejon 305600 South Korea

Protection effectiveness of an oblique metallic plate against a long rod projectile has been evaluated through a three-dimensional dynamic finite element computer program. The parameters considered in the simulations are the impact velocity, oblique plate thickness, gap distance between oblique plate and witness block, and obliquity. It was found that protection performance of an oblique plate was maximized in case that the ratio of line-of-sight (LOS) plate thickness to projectile diameter is around 2.0. This result may be used as a guide for the design of obliquely spaced armour structures against long rod projectiles. (C) 2006 Elsevier Ltd. All rights reserved.

关键词： protection effectiveness obliquity advantage long rod finite element code

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