Lu Wang, Guangyan Liu, Yanan Yi, Shaopeng Ma^*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.21, No.2, pp. 31-31, 2019, DOI:10.32604/icces.2019.04974

Abstract Nuclear graphite is a key material in high temperature gas-cooled reactors. The evaluation of its damage evolution is of great importance for safety assessment of nuclear graphite structures. However, the damage properties of nuclear graphite are difficult to characterize by the traditional testing approaches, i.e., uniaxial tension and compression tests due to the inconvenience of conducting uniaxial tension/compression tests. In this paper, an inverse method was developed to identify the damage parameters of a nuclear graphite material IG11. The method is based on the non-contact digital image correlation and finite element model updating techniques, and damage-induced nonlinear stress-strain curves for… More >

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 >

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 >

Yaghoub Dabiri^1,3, Kevin L. Sack^1,2, Semion Shaul¹, Gabriel Acevedo-Bolton¹, Jenny S. Choy³, Ghassan S. Kassab³, Julius M. Guccione^1,*

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 >

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 >

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 >

Xituan Shang^*, Michael R. T. Yen^1,†, 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 >

Morakot Likhitpanichkul¹, X. Edward Guo², Van C. Mow^1,3

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 >

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 (R_Fos) and height is about 2R_Fos. 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 R_Fos. 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 >

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 >