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  • Open Access

    ARTICLE

    Viscous Equations of Fluid Film Dynamics

    Pavel Grinfeld1

    CMC-Computers, Materials & Continua, Vol.19, No.3, pp. 239-254, 2010, DOI:10.3970/cmc.2010.019.239

    Abstract We model viscosity in the framework of the exact nonlinear equations of fluid film dynamics. The proposed approach yields monotonic dissipation of energy and guarantees that viscous forces are not engaged when the film undergoes rigid motion. With the addition of viscosity, the governing system has all the essential elements - inertia, surface tension, interaction with the ambient medium, influence of external fields and, now, viscosity - for accurate prediction and interpretation of experimental observations. The fluid film is modelled as a two-dimensional manifold. The film's thickness is represented by a surface density function. The resulting system is the fluid… More >

  • Open Access

    ARTICLE

    Dynamic Properties of Cortical Bone Tissue: Izod Tests and Numerical Study

    Adel A. Abdel-Wahab1, Angelo Maligno1, Vadim V. Silberschmidt1

    CMC-Computers, Materials & Continua, Vol.19, No.3, pp. 217-238, 2010, DOI:10.3970/cmc.2010.019.217

    Abstract Bone is the principal structural component of a skeleton: it assists the load-bearing framework of a living body. Structural integrity of this component is important; understanding of its mechanical behaviour up to failure is necessary for prevention and diagnostic of trauma. In dynamic events such as traumatic falls, involvement in car crash and sports injuries, bone can be exposed to loads exceeding its structural strength and/or fracture toughness. By developing adequate numerical models to predict and describe its deformation and fracture behaviour up to fracture, a detailed study of reasons for, and ways to prevent or treatment methods of, bone… More >

  • Open Access

    ARTICLE

    Effects of Loading Conditions on Deformation Process in Indentation

    M. Demiral, A. Roy, V. V. Silberschmidt1

    CMC-Computers, Materials & Continua, Vol.19, No.2, pp. 199-216, 2010, DOI:10.3970/cmc.2010.019.199

    Abstract Static indentation experiments are typically performed to characterize the mechanical properties of a material of interest by a rigid indenter of known geometry to various depths. In contrast, dynamic indentation of materials has not been fully studied. Evaluating material performance under dynamic loading conditions is a challenge and we demonstrate that various modelling schemes may be appropriate for different flavours of dynamic indentation. In order to compare underlying thermo-mechanics and deformation processes in a static and dynamic indentation process, indentation of a rigid indenter into a workpiece to a fixed chosen penetration is extensively studied. A nonlinear strain rate and… More >

  • Open Access

    ARTICLE

    Ionic Polymer Metal Composite Flapping Actuator Mimicking Dragonflies

    Sujoy Mukherjee1, Ranjan Ganguli1,2

    CMC-Computers, Materials & Continua, Vol.19, No.2, pp. 105-134, 2010, DOI:10.3970/cmc.2010.019.105

    Abstract In this study, variational principle is used for dynamic modeling of an Ionic Polymer Metal Composite (IPMC) flapping wing. The IPMC is an Electro-active Polymer (EAP) which is emerging as a useful smart material for `artificial muscle' applications. Dynamic characteristics of IPMC flapping wings having the same size as the actual wings of three different dragonfly species Aeshna Multicolor, Anax Parthenope Julius and Sympetrum Frequens are analyzed using numerical simulations. An unsteady aerodynamic model is used to obtain the aerodynamic forces. A comparative study of the performances of three IPMC flapping wings is conducted. Among the three species, it is… More >

  • Open Access

    ARTICLE

    The Molecular Dynamic Finite Element Method (MDFEM)

    Lutz Nasdala1 , Andreas Kempe1 and Raimund Rolfes1

    CMC-Computers, Materials & Continua, Vol.19, No.1, pp. 57-104, 2010, DOI:10.3970/cmc.2010.019.057

    Abstract In order to understand the underlying mechanisms of inelastic material behavior and nonlinear surface interactions, which can be observed on macroscale as damping, softening, fracture, delamination, frictional contact etc., it is necessary to examine the molecular scale. Force fields can be applied to simulate the rearrangement of chemical and physical bonds. However, a simulation of the atomic interactions is very costly so that classical molecular dynamics (MD) is restricted to structures containing a low number of atoms such as carbon nanotubes. The objective of this paper is to show how MD simulations can be integrated into the finite element method… More >

  • Open Access

    ARTICLE

    Interface Effect on the Dynamic Stress around an Elliptical Nano-Inhomogeneity Subjected to Anti-Plane Shear Waves

    Xue-Qian Fang1,2, Xiao-Hua Wang1, Le-Le Zhang3

    CMC-Computers, Materials & Continua, Vol.16, No.3, pp. 229-246, 2010, DOI:10.3970/cmc.2010.016.229

    Abstract In the design of advanced micro- and nanosized materials and devices containing inclusions, the effects of surfaces/interfaces on the stress concentration become prominent. In this paper, based on the surface/interface elasticity theory, a two-dimensional problem of an elliptical nano-inhomogeneity under anti-plane shear waves is considered. The conformal mapping method is then applied to solve the formulated boundary value problem. The analytical solutions of displacement fields are expressed by employing wave function expansion method, the expanded mode coefficients are determined by satisfying the boundary conditions at the interfaces of the nano-inhomogeneity. Analyses show that the effect of the interfacial properties on… More >

  • Open Access

    ARTICLE

    Lattice Dynamics and Second and Third Order Elastic Constants of Iron at Elevated Pressures

    Hieu H. Pham1, Tahir Ça ˇgın1

    CMC-Computers, Materials & Continua, Vol.16, No.2, pp. 175-194, 2010, DOI:10.3970/cmc.2010.016.175

    Abstract We analyze the lattice dynamics of Fe in different crystal phases (bcc, fcc and hcp) by using density-functional theory. The study on equations of states indicates that bcc Fe is more stable than fcc and hcp Fe at low pressures. However, dynamical instabilities in lattice vibrations of bcc Fe predict a phase transformation from bcc to hcp at higher pressures. We reported a complete set of second-order and third-order elastic constants of Fe in these three phases. We observed a linear variation in the values of second order elastic constant as a function of increased pressures. The phonon spectra were… More >

  • Open Access

    ARTICLE

    A Molecular Dynamics Study of Irradiation Induced Cascades in Iron Containing Hydrogen

    E. Hayward1, C. Deo1

    CMC-Computers, Materials & Continua, Vol.16, No.2, pp. 101-116, 2010, DOI:10.3970/cmc.2010.016.101

    Abstract Damage cascades representative of those that would be induced by neutron irradiation have been simulated in systems of pure iron and iron containing 0.01 at.% hydrogen. Results from molecular dynamics simulations using three different embedded-atom method (EAM) type potentials are compared for primary knock-on atom energies of 5, 10, and 20 keV to assess the effect of hydrogen on the primary damage state. We examine the influence of hydrogen on the primary damage state due to a single radiation cascade. These results can serve as an atomistic database for methods and simulations for long time scale evolution of radiation damage. More >

  • Open Access

    ARTICLE

    Molecular Dynamics Study of Dynamic Responses of Glassy Silica under Shock Impact

    Luming Shen1

    CMC-Computers, Materials & Continua, Vol.15, No.3, pp. 241-260, 2010, DOI:10.3970/cmc.2010.015.241

    Abstract In this study, molecular dynamics (MD) simulations are performed to form glassy silica from meltedb-cristobalite using cooling rates of 2, 20 and 200 K/ps. The resulting glassy silica samples are then shocked at particle velocities ranging from 0.3 to 11 km/s in the MD simulations. The effect of the cooling rate on the shock wave velocity is observed for particle velocities below 2 km/s. Moreover, the simulated pressure and density of the shocked glassy silica increase as the cooling rate increases. As compared with the experimental data, the MD simulation can approximately identify the initiation of densification and predict the… More >

  • Open Access

    ARTICLE

    Meshless Local Petrov-Galerkin (MLPG) Method for Laminate Plates under Dynamic Loading

    J. Sladek1, V. Sladek1, P. Stanak1, Ch. Zhang2

    CMC-Computers, Materials & Continua, Vol.15, No.1, pp. 1-26, 2010, DOI:10.3970/cmc.2010.015.001

    Abstract A meshless local Petrov-Galerkin (MLPG) method is applied to solve laminate plate problems described by the Reissner-Mindlin theory. Both stationary and transient dynamic loads are analyzed here. The bending moment and the shear force expressions are obtained by integration through the laminated plate for the considered constitutive equations in each lamina. The Reissner-Mindlin theory reduces the original three-dimensional (3-D) thick plate problem to a two-dimensional (2-D) problem. Nodal points are randomly distributed over the mean surface of the considered plate. Each node is the center of a circle surrounding this node. The weak-form on small subdomains with a Heaviside step… More >

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