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  • Open Access

    ARTICLE

    Simulation of Dynamic Failure Evolution in Brittle Solids without Using Nonlocal Terms in the Strain-Stress Space

    Z. Chen1, W. Hu1, E.P. Chen2

    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.4, pp. 57-62, 2000, DOI:10.3970/cmes.2000.001.509

    Abstract To simulate the dynamic failure evolution without using nonlocal terms in the strain-stress space, a damage diffusion equation is formulated with the use of a combined damage/plasticity model that was primarily applied to the case of rock fragmentation. A vectorized model solver is developed for large-scale simulation. Two-dimensional sample problems are considered to illustrate the features of the proposed solution procedure. It appears that the proposed approach is effective in simulating the evolution of localization, with parallel computing, in a single computational domain involving different lower-order governing differential equations. More >

  • Open Access

    ARTICLE

    A Spectral Scheme to Simulate Dynamic Fracture Problems in Composites

    Changyu Hwang1, Philippe H. Geubelle2

    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.4, pp. 45-56, 2000, DOI:10.3970/cmes.2000.001.497

    Abstract This paper presents the formulation and numerical implementation of a spectral scheme specially developed to simulate dynamic fracture events in unidirectional and cross-ply fiber-reinforced composites. The formulation is based on the spectral representation of the transversely isotropic elastodynamic relations between the traction stresses along the fracture plane and the resulting displacements. Example problems involving stationary or dynamically propagating cracks in fiber-reinforced composites are investigated and compared with reference solutions available in the literature and/or experimental observations. More >

  • Open Access

    ARTICLE

    A 3-D Boundary Element Method for Dynamic Analysis of Anisotropic Elastic Solids1

    M. Kögl, L. Gaul2

    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.4, pp. 27-44, 2000, DOI:10.3970/cmes.2000.001.479

    Abstract A Boundary Element formulation is presented for the solution of three-dimensional problems of anisotropic elastodynamics. Due to the complexity of the dynamic fundamental solutions for anisotropic materials and the resulting high computational costs, the approach at hand uses the fundamental solution of the static operator. This leads to a domain integral in the representation formula which contains the inertia term. The domain integral can be transformed to the boundary using the Dual Reciprocity Method. This results in a system of ordinary differential equations in time with time-independent matrices. Several general questions concerning the anisotropic solutions, More >

  • Open Access

    ARTICLE

    BEM / FEM Comparison Studies for the Inelastic Dynamic Analysis of Thick Plates on Elastic Foundation

    C.P . Providakis1

    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.3, pp. 123-130, 2000, DOI:10.3970/cmes.2000.001.425

    Abstract Boundary and Finite Element methodologies for the determination of the inelastic response of thick plates resting on Winkler-type elastic foundations are compared and critically discussed. For comparison reasons the domain/boundary element and the finite element methodology use isoparametric elements of the same accuracy level. After a discretizaton of the integral equations of motion in both methodologies an efficient step-by-step time integration algorithm is used to solve the resulting matrix equations. Comparison studies are shown for impacted elastoplastic thick plates with smooth boundaries and supported on different Winkler-type foundations. The numerical results reveal that boundary element More >

  • Open Access

    ARTICLE

    A Numerical Variational Approach for Rotor-Propeller Aerodynamics in Axial Flight

    F. Simonetti1, R. M. Ardito Marretta2

    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.3, pp. 81-90, 2000, DOI:10.3970/cmes.2000.001.383

    Abstract Advanced propellers are being developed to improve the performance and fuel economy of future transport aircraft. To study them, various aerodynamic prediction models and systems (from theory to experiment) have been developed via several approaches (Free Wake Analysis, helicoidal source methods, scale model tests). This study focuses on the development of an efficient numerical method to predict the behaviour of rotor or propeller in forward flight. Based on a variational approach, the present numerical technique allows a significant reduction of computer resources used in the calculation of instantaneous velocities to determine the wake geometry and More >

  • Open Access

    ARTICLE

    Dynamics of Machinery 2D Elastic Casing, with Central Hole, Subject to an In-Plane Deflection-Dependent Rotating Load

    F. M. A. El-Saeidy1

    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.3, pp. 33-42, 2000, DOI:10.3970/cmes.2000.001.335

    Abstract In rotating radial ball bearings supported on elastic casings with the bearing outer ring lightly fitted into the housing, the force due to the ball elastic contact is indeed a rotating load rolling over the housing. For accurate estimation of the dynamic deformations of the casing annulus (hole), which in turn affect the bearing tolerances and hence the magnitudes of the generated forces, effect of the load rotation (motion) should be considered. Considering the integral casing and the outer ring to be a plate, an isoparametric plane stress finite-element (FE) based analytical procedure is presented… More >

  • Open Access

    ARTICLE

    A Boundary-only Solution to Dynamic Analysis of Non-homogeneous Elastic Membranes

    J.T. Katsikadelis1, M.S. Nerantzaki1

    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.3, pp. 1-9, 2000, DOI:10.3970/cmes.2000.001.303

    Abstract A boundary-only method is presented for the solution of the vibration problem of non-homogeneous membranes. Both free and forced vibrations are considered. The presented method is based on the Analog Equation Method (AEM). According to this method the second order partial differential equation with variable coefficients of hyperbolic type, which governs the dynamic response of the membrane, is substituted by a Poisson's equation describing a quasi-static problem for the homogeneous membrane subjected to a fictitious time dependent load. The fictitious load is established using BEM. Several numerical examples are presented which illustrate the efficiency and More >

  • Open Access

    ARTICLE

    Static and Dynamic Analysis of Shell Panels Using the Analog Equation Method

    A.J. Yiotis1, J.T. Katsikadelis1

    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.2, pp. 95-104, 2000, DOI:10.3970/cmes.2000.001.255

    Abstract The Analog Equation Method is applied to the static and dynamic analysis of thin cylindrical shell panels. The Fl\"{u}gge theory is adopted. The three displacement components are established by solving two membrane and one plate bending problems under the same boundary conditions subjected to "appropriate'' (equivalent) fictitious loads. Numerical results are presented which illustrate the efficiency and the accuracy of the proposed method. More >

  • Open Access

    ARTICLE

    Non-Linear Rigid Body Dynamics: Energy and Momentum Conserving Algorithm

    Fernando A. Rochinha1, Rubens Sampaio2

    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.2, pp. 7-18, 2000, DOI:10.3970/cmes.2000.001.167

    Abstract The dynamics of flexible systems, such as robot manipulators, mechanical chains or cables, is becoming increasingly important in engineering. The main question arising from the numerical modelling of large overall motions of multibody systems is an appropriate treatment for the large rotations. In the present work an alternative approach is proposed leading to a time-stepping numerical algorithm which achieves stable solutions combined with high precision. In particular, in order to check the performance of the proposed approach, two examples having preserved constants of the motion are presented. More >

  • Open Access

    ARTICLE

    Accurate Modelling and Simulation of Thermomechanical Microsystem Dynamics

    S. Taschini1, J. Müller2, A. Greiner2, M. Emmenegger1, H. Baltes1, J.G. Korvink2

    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 31-44, 2000, DOI:10.3970/cmes.2000.001.031

    Abstract We present three techniques to accurately model the thermomechanical response of microsystem components: a new, accurate and stable Kirchhoff-Love multi-layered plate model implemented as an Argyris finite element, a model for the amplitude fluctuations of vibrational modes in micro-mechanical structures within a gaseous environment, and the consistent refinement of a finite element mesh in order to maximize the computational accuracy for a given mesh size. We have implemented these techniques in our in-house MEMS finite element program and accompanying Monte Carlo simulator. We demonstrate our approach to dynamic modeling by computing the thermomechanical response of More >

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