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  • Open Access


    A Fully Coupled Finite Element Model of Landfill Gas Migration in a Partially Saturated Soil

    W. J. Ferguson1, B. Palananthakumar2

    CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.3, pp. 201-216, 2005, DOI:10.3970/cmes.2005.008.201

    Abstract Environmental and safety issues associated with landfill gas require the control of off-site migration. Mathematical modelling can assist in the understanding of the processes and mechanisms controlling gas migration from municipal waste disposal sites. This paper presents the development and application of a mathematical model that simulates landfill gas migration within a partially saturated soil. This model accounts for two-phase flow and incorporates multi-component (methane, carbon dioxide, dry air and moisture) transport in the gas and liquid phases together with concomitant heat migration. The governing system of fully coupled non-linear partial differential equations of the model have been derived from… More >

  • Open Access


    Eliminating Slivers in Three-Dimensional Finite Element Models

    R.H. Moore1, S. Saigal2

    CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.3, pp. 283-292, 2005, DOI:10.3970/cmes.2005.007.283

    Abstract An efficient method for treating slivers and other poorly shaped elements in finite element solutions is presented. A major difficulty for finite element analyses arises from the creation of slivers in automated mesh generation. Sliver shaped elements can degrade the accuracy of a solution and are difficult to remove from a mesh. The proposed method treats slivers by first merging them with neighboring elements to form polyhedra and next subdividing the polyhedra into well-shaped tetrahedral elements. The method does not require the cumbersome and expensive operations of addition or rearrangement of nodes. The validity and accuracy of the present method… More >

  • Open Access


    Intramyocardial Injections to De-Stiffen the Heart: A Subject-Specific in Silico Approach

    Yaghoub Dabiri1,3, Kevin L. Sack1,2, Semion Shaul1, Gabriel Acevedo-Bolton1, Jenny S. Choy3, Ghassan S. Kassab3, Julius M. Guccione1,*

    Molecular & Cellular Biomechanics, Vol.16, No.3, pp. 185-197, 2019, DOI:10.32604/mcb.2019.07364

    Abstract We hypothesized that minimally invasive injections of a softening agent at strategic locations in stiff myocardium could de-stiffen the left ventricle (LV) globally. Physics-based finite element models of the LV were created from LV echocardiography images and pressures recorded during experiments in four swine. Results confirmed animal models of LV softening by systemic agents. Regional de-stiffening of myocardium led to global de-stiffening of LV. The mathematical set up was used to design LV global de-stiffening by regional softening of myocardium. At an end diastolic pressure of 23 mmHg, when 8 ml of the free wall was covered by intramyocardial injections,… More >

  • Open Access


    Study of Biomechanical Response of Human Hand-Arm to Random Vibrations of Steering Wheel of Tractor

    G. Geethanjali, C. Sujatha

    Molecular & Cellular Biomechanics, Vol.10, No.4, pp. 303-317, 2013, DOI:10.3970/mcb.2013.010.303

    Abstract This paper reports a study on the biomechanical response of a human hand-arm model to random vibrations of the steering wheel of a tractor. An anatomically accurate bone-only hand-arm model from TurboSquidTM was used to obtain a finite element (FE) model to understand the Hand-arm vibration syndrome (HAVS), which is a neurological and vascular disorder caused by exposure of the human hand-arm to prolonged vibrations. Modal analysis has been done to find out the first few natural frequencies and mode shapes of the system. Coupling of degrees of freedom (DOF) had to be done in the FE idealization to do… More >

  • Open Access


    A Nonlinear Viscoelastic Finite Element Model of Polyethylene

    P.C. Chen∗,†, C.W. Colwell, D.D. D’Lima†,‡

    Molecular & Cellular Biomechanics, Vol.8, No.2, pp. 135-148, 2011, DOI:10.3970/mcb.2011.008.135

    Abstract A nonlinear viscoelastic finite element model of ultra-high molecular weight polyethylene (UHMWPE) was developed in this study. Eight cylindrical specimens were machined from ram extruded UHMWPE bar stock (GUR 1020) and tested under constant compression at 7% strain for 100 sec. The stress strain data during the initial ramp up to 7% strain was utilized to model the "instantaneous" stress-strain response using a Mooney-Rivlin material model. The viscoelastic behavior was modeled using the time-dependent relaxation in stress seen after the initial maximum stress was achieved using a stored energy formulation. A cylindrical model of similar dimensions was created using a… More >

  • Open Access


    Studies of Biaxial Mechanical Properties and Nonlinear Finite Element Modeling of Skin

    Xituan Shang*, Michael R. T. Yen1,†, M. Waleed Gaber

    Molecular & Cellular Biomechanics, Vol.7, No.2, pp. 93-104, 2010, DOI:10.3970/mcb.2010.007.093

    Abstract The objective of this research is to conduct mechanical property studies of skin from two individual but potentially connected aspects. One is to determine the mechanical properties of the skin experimentally by biaxial tests, and the other is to use the finite element method to model the skin properties. Dynamic biaxial tests were performed on 16 pieces of abdominal skin specimen from rats. Typical biaxial stress-strain responses show that skin possesses anisotropy, nonlinearity and hysteresis. To describe the stress-strain relationship in forms of strain energy function, the material constants of each specimen were obtained and the results show a high… More >

  • Open Access


    The Effect of Matrix Tension-Compression Nonlinearity and Fixed Negative Charges on Chondrocyte Responses in Cartilage

    Morakot Likhitpanichkul1, X. Edward Guo2, Van C. Mow1,3

    Molecular & Cellular Biomechanics, Vol.2, No.4, pp. 191-204, 2005, DOI:10.3970/mcb.2005.002.191

    Abstract Thorough analyses of the mechano-electrochemical interaction between articular cartilage matrix and the chondrocytes are crucial to understanding of the signal transduction mechanisms that modulate the cell metabolic activities and biosynthesis. Attempts have been made to model the chondrocytes embedded in the collagen-proteoglycan extracellular matrix to determine the distribution of local stress-strain field, fluid pressure and the time-dependent deformation of the cell. To date, these models still have not taken into account a remarkable characteristic of the cartilage extracellular matrix given rise from organization of the collagen fiber architecture, now known as the tension-compression nonlinearity (TCN) of the tissue, as well… More >

  • Open Access


    Stress Concentrations Caused by Embedded Optical Fiber Sensors in Composite Laminates

    Kunigal Shivakumar1, Anil Bhargava2

    CMC-Computers, Materials & Continua, Vol.1, No.2, pp. 173-190, 2004, DOI:10.3970/cmc.2004.001.173

    Abstract The fiber optic sensor (FOS) embedded perpendicular to reinforcing fibers causes an `Eye' shaped defect. The length is about 16 times fiber optic radius (RFos) and height is about 2RFos. The eye contains fiber optics in the center surrounded by an elongated resin pocket. Embedding FOS causes geometric distortion of the reinforcing fiber over a height equal to 6 to 8 RFos. This defect causes severe stress concentration at the root of the resin pocket, the interface (in the composite) between the optical fiber and the composite, and at 90° to load direction in the composite. The stress concentration was… More >

  • Open Access


    Generic Linking of Finite Element Models for Non-Linear Static and Global Dynamic Analyses of Aircraft Structures

    A.J. de Wit1, D. Akçay Perdahcıoğlu2, T. Ludwig3, W.M. van den Brink1, A. de Boer2

    CMC-Computers, Materials & Continua, Vol.32, No.3, pp. 201-218, 2012, DOI:10.3970/cmc.2012.032.201

    Abstract Depending on the type of analysis, Finite Element (FE) models of different fidelity are necessary. Creating these models manually is a labor intensive task. This paper discusses two approaches for generating FE models of different fidelity from a single reference FE model. The models are created with a single modelling and meshing toolkit. These different fidelity models are created for use with global-local non-linear static analysis and for use with dynamic linear sub-structuring reduction method. Efficiency of the developed approaches is demonstrated via non-linear static and modal analysis of a carbon-fiber stiffened panel. More >

  • Open Access


    Determination of the Normal Contact Stiffness and Integration Time Step for the Finite Element Modeling of Bristle-Surface Interaction

    Libardo V. Vanegas-Useche1, Magd M. Abdel-Wahab2,3,4,*, Graham A. Parker5

    CMC-Computers, Materials & Continua, Vol.56, No.1, pp. 169-184, 2018, DOI: 10.3970/cmc.2018.01827

    Abstract In finite element modeling of impact, it is necessary to define appropriate values of the normal contact stiffness, Kn, and the Integration Time Step (ITS). Because impacts are usually of very short duration, very small ITSs are required. Moreover, the selection of a suitable value of Kn is a critical issue, as the impact behavior depends dramatically on this parameter. In this work, a number of experimental tests and finite element analyses have been performed in order to obtain an appropriate value of Kn for the interaction between a bristle of a gutter brush for road sweeping and a concrete… More >

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