Kazuhiko Kakuda¹, Tsuyoki Nagashima¹, Yuki Hayashi¹, Shunsuke Obara¹, Jun Toyotani¹, Nobuya Katsurada², Shunji Higuchisup>2, Shohei Matsuda²

CMES-Computer Modeling in Engineering & Sciences, Vol.88, No.1, pp. 17-28, 2012, DOI:10.3970/cmes.2012.088.017

Abstract An acceleration of the particle-based incompressible fluid flow simulations on GPU using CUDA is presented. The particle method is based on the MPS (Moving Particle Semi-implicit) scheme using logarithmic-type weighting function to stabilize the spurious oscillatory solutions for the pressure fields which are governed by Poisson equation. The standard MPS scheme is widely utilized as a particle strategy for the free surface flow, the problem of moving boundary, multi-physics/multi-scale ones, and so forth. Numerical results demonstrate the workability and the validity of the present approach through dam-breaking flow problem. More >

Jiawei Xiang^1,2, Yanxue Wang³, Zhansi Jiang³, Jiangqi, Long¹, Guang Ma¹

CMES-Computer Modeling in Engineering & Sciences, Vol.88, No.1, pp. 1-16, 2012, DOI:10.3970/cmes.2012.088.001

Abstract Two-dimensional wavelet-based numerical approximation using Hermite cubic spline wavelet on the interval (HCSWI) is proposed to solve stress intensity factors (SIFs) of plate structures. The good localization property of wavelets is used to approximate displacement fields by multi-scale bases of HCSWI. Example computations are performed for plates with a central crack and double edge cracks. The numerical results prove that, compared with the conventional finite element method and the analytical solutions, the new procedure are efficient in both its accuracy and its reduction of degree of freedoms (DOFs). More >

MC. Ho Ba Tho¹, PE Mazeran², K El Kirat¹, S.F. Bensamoun¹

CMES-Computer Modeling in Engineering & Sciences, Vol.87, No.6, pp. 557-578, 2012, DOI:10.3970/cmes.2012.087.557

Abstract Mechanical properties of cortical human bone have been investigated for more than four decades. Numerous experimental investigations on bone characterization were performed ; mechanical, vibrational, acoustical testing and morphological, physico-chemical investigations. Due to the techniques, different levels of investigation were performed and subsequently quantitative parameters are concerning different level of structure of bone (organ, tissue,... ). According to our knowledge, few investigations were performed simultaneously on mechanical, morphological and physico-chemical properties of bone. The objectives of the present study were to investigate the influence of multiscale structural characteristics of the bone tissue on its mechanical behavior and to provide some… More >

R. Khanna^1,2, D. R. Katti¹, K. S. Katti¹

CMES-Computer Modeling in Engineering & Sciences, Vol.87, No.6, pp. 530-556, 2012, DOI:10.3970/cmes.2012.087.530

Abstract Here we report a new in situ nanoindentation technique developed to evaluate the composite mechanical behavior of cell-biomaterial construct under physiological conditions over the time scale of bone nodule generation. Using this technique, mechanical behavior of osteoblast cell-substrate interfaces on tissue engineered materials (chitosan-polygalacturonic acid-nanohydroxyapatite (CPH) films) is investigated. Mechanical behavior of cells in the elastic regime over the time scale of cell adhesion (1 day), proliferation (4 days), development (8 days) and maturation (22 days) of bone nodules is evaluated. Our results indicate that the elastic properties of flat cells are higher (indicating stiffer response, after 4 days, as… More >

K.W. Luczynski¹, A. Dejaco¹, O. Lahayne¹, J. Jaroszewicz², W.Swieszkowski², C. Hellmich¹

CMES-Computer Modeling in Engineering & Sciences, Vol.87, No.6, pp. 505-529, 2012, DOI:10.3970/cmes.2012.087.505

Abstract A 71 volume-% macroporous tissue engineering scaffold made of poly-l-lactide (PLLA) with 10 mass-% of pseudo-spherical tri-calcium phosphate (TCP) inclusions (exhibiting diameters in the range of several nanometers) was microCT-scanned. The corresponding stack of images was converted into regular Finite Element (FE) models consisting of around 100,000 to 1,000,000 finite elements. Therefore, the attenuation-related, voxel-specific grey values were converted into TCP-contents, and the latter, together with nanoindentation tests,entered a homogenization scheme of the Mori-Tanaka type, as to deliver voxel-specific (and hence, finite element-specific) elastic properties. These FE models were uniaxially loaded, giving access to the macroscopic Young's modulus of the… More >

G. Mattei^1,2, A. Tirella^1,2, A. Ahluwalia^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.87, No.6, pp. 483-504, 2012, DOI:10.3970/cmes.2012.087.483

Abstract Biological function is intricately linked with structure. Many biological structures are characterised by functional spatially distributed gradients in which each layer has one or more specific functions to perform. Reproducing such structures is challenging, and usually an experimental trial-and-error approach is used. In this paper we investigate how the gravitational sedimentation of discrete solid particles (secondary phase) within a primary fluid phase with a time-varying dynamic viscosity can be used for the realisation of stable and reproducible continuous functionally graded materials (FGMs). Computational models were used to simulate the distribution of a particle phase in a fluid domain. Firstly a… More >

F. Maceri¹, M. Marino¹, G. Vairo¹

CMES-Computer Modeling in Engineering & Sciences, Vol.87, No.5, pp. 461-482, 2012, DOI:10.3970/cmes.2012.087.461

Abstract The mechanical behavior of biopolymer mo -le -cu -les is herein addressed and a novel predictive model for their elasto-damage response is proposed. Both entropic and energetic elastic mechanisms are accounted for, and coupled by consistent equilibrium conditions. Moreover, through non-smooth mechanics arguments, molecular damage is modeled accounting for failure due to both mechanical and non-mechanical damage sources. The model is applied to collagen molecules and an excellent agreement with available experimental tests and atomistic computations is shown. The proposed predictive theory can be usefully integrated in hierarchical models of biological structures towards a multiscale continuum approach. More >

Taffetani M.¹, Bertarelli E.^1,2, Gottardi R.^3,4, Raiteri R.⁵, Vena P.^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.87, No.5, pp. 433-460, 2012, DOI:10.3970/cmes.2012.087.433

Abstract Dynamic nanoindentation is a novel nanomechanical testing that is being increasingly used to characterize the frequency response of viscoelastic materials and of soft hydrated biological tissues at the micrometric and nanometric length scales. This technique is able to provide more information than those obtained by simple indentation; however, its interpretation is still an open issue for complex materials such as the case of anisotropic biological tissues that generally have a high water content. This work presents a numerical model to characterize the frequency response of poro-elastic tissues subjected to harmonic indentation loading with particular regard to the effect of geometrical… More >

J.A. García^1,2, J.M. Peña¹, S. McHugh², A. Jérusalem^2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.87, No.5, pp. 411-432, 2012, DOI:10.3970/cmes.2012.087.411

Abstract Neuronal growth is a complex process involving many intra- and extracellular mechanisms which are collaborating conjointly to participate to the development of the nervous system. More particularly, the early neocortical development involves the creation of a multilayered structure constituted by neuronal growth (driven by axonal or dendritic guidance cues) as well as cell migration. The underlying mechanisms of such structural lamination not only implies important biochemical changes at the intracellular level through axonal microtubule (de)polymerization and growth cone advance, but also through the directly dependent stress/stretch coupling mechanisms driving them. Efforts have recently focused on modeling approaches aimed at accounting… More >

V. Sansalone^1,∗, V. Bousson², S. Naili¹, C. Bergot², F. Peyrin³, J.D. Laredo², G. Haïat¹

CMES-Computer Modeling in Engineering & Sciences, Vol.87, No.5, pp. 387-410, 2012, DOI:10.3970/cmes.2012.087.387

Abstract This paper investigates the effects of the heterogeneous distribution of the Haversian Porosity (HP) and Tissue Mineral Density (TMD) on the elastic coefficients of bone in the human femoral neck. A bone specimen from the inferior femoral neck was obtained from a patient undergoing standard hemiarthroplasty. The specimen was imaged using 3-D synchrotron micro-computed tomography (voxel size of 10.13 mm), leading to the determination of the anatomical distributions of HP and TMD. These experimental data were used to estimate the elastic coefficients of the bone using a three-step homogenization model based on continuum micromechanics: (i) At the tissue scale (characteristic… More >