M-A Lavoie¹, A. Gakwaya¹, M. Nejad Ensan², D.G. Zimcik²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.4, pp. 111-118, 2007, DOI:10.3970/icces.2007.002.111

Abstract This paper reviews numerical methods that are currently available to simulate bird strike as well as the theory of the event. It also summarizes important parameters and provides guidelines as to how to set up the analysis and how to evaluate a model. The information provided is based on physical properties and available results regarding a bird and its behaviour upon impact. The simulations have been performed with LS-DYNA 970 but can be done in similar dynamic finite elements analysis codes. More >

I. Cerný ¹, V. Linhart¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.4, pp. 161-166, 2007, DOI:10.3970/icces.2007.001.161

Abstract Two different cases with the aim to show, how important the crack closure phenomenon can be in reality and can affect eventual crack growth behaviour by an unexpected way are described and discussed in the paper, namely: (i) a favourable effect of fretting oxidation crack closure in air which can disappear in oil environments, typical for many machinery applications and (ii) a favourable effect of crack closure occurring as a results of corrosion products in corrosive environments, which would normally increase crack growth rate by stress corrosion and corrosion fatigue mechanisms. More >

T. Nishioka¹, M.Kogame², T. Fujimoto¹, G. Okamoto¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.3, pp. 113-118, 2007, DOI:10.3970/icces.2007.001.113

Abstract In this study, we observed C.G.S. fringe pattern of dynamic fracture under impact load by an ultra high-speed CCD video camera, and stress intensity factors KI, KII are evaluated from the experimental measurements. From the evaluation of stress intensity factors, local mode I condition is observed during crack propagation. On the other hand, concentrated load is obtained by the experimental devices in this study. We suggest the least square method to estimate loading value based on the C.G.S. fringe pattern analyses. More >

C. Soutis¹, K. Diamanti¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.2, pp. 49-54, 2007, DOI:10.3970/icces.2007.001.049

Abstract A cost and time effective inspection strategy for in-service health monitoring of composites is demonstrated using the fundamental anti-symmetric A0 Lamb mode at frequencies of 15-20 kHz. In principle, this method involves analysis of the transmitted and/or reflected wave after interacting with the test-piece boundaries or discontinuities (defects). In the present work, the applicability of the technique to composite sandwich structures is explored. More >

Jun Zhang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.22, No.2, pp. 91-96, 2007, DOI:10.3970/cmes.2007.022.091

Abstract The most commonly used wavelets for image processing are the tensor-product of univariate wavelets, which have a disadvantage of giving a particular importance to the horizontal and vertical directions. In this paper, a new class of wavelet, non-separable wavelet, is investigated for image compression applications. The comparative results of image compression preprocessed with two different kinds of wavelet transform are presented: (1) non-separable wavelet transform; (2) tensor-product wavelet transform. The results of our experiments show that in the same vanishing moment, the non-separable wavelets perform better than the tensor-product wavelets in dealing with still images. More >

Chun Yang¹, Dalin Tang², Chun Yuan³, Thomas S. Hatsukami⁴, Jie Zheng⁵, Pamela K. Woodard⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.19, No.3, pp. 233-246, 2007, DOI:10.3970/cmes.2007.019.233

Abstract It has been recognized that fluid-structure interactions (FSI) play an important role in cardiovascular disease initiation and development. However, in vivo MRI multi-component FSI models for human carotid atherosclerotic plaques with bifurcation and quantitative comparisons of FSI models with fluid-only or structure-only models are currently lacking in the literature. A 3D non-Newtonian multi-component FSI model based on in vivo/ex vivo MRI images for human atherosclerotic plaques was introduced to investigate flow and plaque stress/strain behaviors which may be related to plaque progression and rupture. Both artery wall and plaque components were assumed to be hyperelastic,… More >

S. Ozaki¹, K. Hashiguchi², T. Okayasu², D.H. Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.18, No.2, pp. 101-120, 2007, DOI:10.3970/cmes.2007.018.101

Abstract In order to analyze precisely not only the elastoplastic deformation phenomenon of saturated particle assembly such as soils, grains, powdered and tablet medicines or three dimensional cellular materials, but also the frictional sliding phenomenon between saturated particle assembly and other bodies, a particle assembly-water coupled finite element program, that incorporates both the subloading surface and the subloading-friction models, is developed. Subsequently, simulations of the compaction behavior of saturated particle assembly under strain rate control are performed. It is revealed by the numerical experiment adopting the finite element program that the frictional sliding behavior of the contact boundary More >

M. Heshmatzadeh, G. E. Bridges¹

CMES-Computer Modeling in Engineering & Sciences, Vol.18, No.1, pp. 45-58, 2007, DOI:10.3970/cmes.2007.018.045

Abstract Cell Method, a Finite Formulation technique, is compared in detail with the Finite Element Method (FEM), a differential-based numerical technique. In the finite formulation technique, Poisson's equation is described starting from a topological foundation. The final set of algebraic equations resulting from the two approaches are compared in matrix form. The equivalence of the coefficient matrices is proven for a Voronoi dual mesh and linear shape functions in the FEM. The difference between the source (charge) vectors in the two approaches is described. It is shown that the use of linear shape functions in the More >

Y. Yan¹, K. Jules², M. Z. Saghir¹

FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.3, pp. 231-246, 2007, DOI:10.3970/fdmp.2007.003.231

Abstract Fluid science research including thermal diffusion in fluids benefits from the quiescent low-gravity environment provided by the International Space Station (ISS). However, residual gravities (or g-jitters) aboard the ISS impact the overall environment in which experiments are being performed. The impact of these residual gravities needs to be assessed to ensure that they are appropriately accounted for when results are being reported for experiments performed onboard the ISS. In this paper we study the thermal diffusion process in a ternary mixture of n-butane, dodecane and methane. Measured data from the Space Acceleration Measurement System (SAMS)… More >

V. Kozulić¹, H. Gotovac¹, B. Gotovac¹

CMC-Computers, Materials & Continua, Vol.6, No.2, pp. 51-70, 2007, DOI:10.3970/cmc.2007.006.051

Abstract In this paper, we present a multi-resolution adaptive algorithm for solving problems described by partial differential equations. The technique is based on the collocation method using Fup basis functions, which belong to a class of Rvachev's infinitely differentiable finite functions. As it is possible to calculate derivation values of Fup basis functions of high degree in a precise yet simple way, so it is possible to efficiently apply strong formulation procedures. The mesh free method developed in this work is named Adaptive Fup Collocation Method (AFCM). The distribution of collocation points within the observed area… More >