S. Okamoto¹, H. Noguchi²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.4, pp. 131-136, 2007, DOI:10.3970/icces.2007.002.131

Abstract This paper presents a control of walking robot by using inverse dynamics of link mechanisms, which has already been proposed and applied in several in-plane motions. In this method, FEM is used for the discretization of equations of motion. This method calculates nodal forces by evaluating equations of motion in a matrix form, and thus information from the entire system can be handled efficiently, and the torques input to each joint of link mechanisms to achieve required motion are calculated easily. This method is suitable to the feed-forward control of closed-loop or continuously link mechanisms. More >

Sanjeev Saxena¹, N. Ramakrishnan¹, B.K. Dutta², P. Rama Rao³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.4, pp. 147-152, 2007, DOI:10.3970/icces.2007.001.147

Abstract Several methods are in vogue to understand the process of crack initiation and propagation in ductile materials. In an attempt to achieve a unified understanding of these methods, a large deformation finite element analysis has been carried out. An attempt has been made to understand ductile fracture by numerically determining the ductile fracture toughness by three different methods viz. 1) Load-displacement method 2) Path-integral method 3) Stretch zone width method (SZW). In addition, an attempt has to be made to explore the possibility of using `characteristic distance'(lc) approach for establishing fracture toughness. The present study… More >

L. Wang¹, S. Zhang, W. M. Gao, X. Wang

CMES-Computer Modeling in Engineering & Sciences, Vol.20, No.1, pp. 11-20, 2007, DOI:10.3970/cmes.2007.020.011

Abstract In this paper, the penetration of a knife through a plain woven fabric is simulated with the finite element method to understand the process of stabbing and the mechanism of fiber breakage. The model focuses on the study of the deformation of individual yarns, and the effects of their material properties and fabric structure on the stabbing resistant force. The performance of the fabric is analyzed as a response of stabbing and the stress distributions in yarn transverse and longitudinal directions. An equation derived from energy and momentum conservations of the knife is proposed to More >

Q.W. Ma¹

CMES-Computer Modeling in Engineering & Sciences, Vol.18, No.3, pp. 223-234, 2007, DOI:10.3970/cmes.2007.018.223

Abstract Two methods have been recently developed by the author and his group: one called MLPG_R (Meshless Local Petrov-Galerkin method based on Rankine source solution) and the other called QALE-FEM (Quasi Arbitrary Lagrangian-Eulerian Finite Element Method). The former is a meshless method developed from a general MLPG (Meshless Local Petrov-Galerkin) method and is more computationally efficient than the general one when applied to modelling nonlinear water waves. The later is a mesh-based method similar to a conventional finite element method (FEM) when discretizing the governing equations but different from the conventional one in managing the mesh. 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 >

A. Frangi¹, L. Ghezzi, P. Faure-Ragani²

CMES-Computer Modeling in Engineering & Sciences, Vol.15, No.1, pp. 41-48, 2006, DOI:10.3970/cmes.2006.015.041

Abstract Three dimensional magneto-mechanical problems at low frequency are addressed by means of a coupled fast Boundary Element - Finite Element approach with total scalar potential and focusing especially on the issue of global force calculation on movable ferromagnetic parts. The differentiation of co-energy in this framework and the use of Maxwell tensor are critically discussed and the intrinsic links are put in evidence. Three examples of academic and industrial applications are employed for validation. More >

R. Springhetti¹, G. Novati¹, M. Margonari²

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.1, pp. 67-80, 2006, DOI:10.3970/cmes.2006.013.067

Abstract With reference to potential and elastostatic problems, a BEM-FEM coupling procedure, based on the symmetric Galerkin version of the BEM, is developed; the continuity conditions at the interface of the BE and FE subdomains are enforced in weak form; the global linear system is characterized by a symmetric coefficient matrix. The procedure is numerically tested with reference first to 2D potential problems and successively to 3D elastoplastic problems (with plastic strains confined to the FE subdomain). More >

Jin Ma, Hongbing Lu, Ranga Komanduri¹

CMES-Computer Modeling in Engineering & Sciences, Vol.12, No.3, pp. 213-228, 2006, DOI:10.3970/cmes.2006.012.213

Abstract The generalized interpolation material point (GIMP) method, recently developed using a C¹ continuous weighting function, has solved the numerical noise problem associated with material points just crossing the cell borders, so that it is suitable for simulation of relatively large deformation problems. However, this method typically uses a uniform mesh in computation when one level of material points is used, thus limiting its effectiveness in dealing with structures involving areas of high stress gradients. In this paper, a spatial refinement scheme of the structured grid for GIMP is presented for simulations with highly localized stress gradients.… More >

Masanori Kikuchi ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.2, pp. 49-60, 2006, DOI:10.3970/cmes.2006.011.049

Abstract Three kinds of fracture specimens are tested under different constraint conditions. By the SEM(Scanning Electron Microscope) observation, it is shown that the roughness of fracture surface is different from each other largely. This is the effect of constraint condition. The dimple fracture process is simulated by the finite element method using Gurson’s constitutive equation, and the crack tip stress fields are obtained. The distributions of stress triaxiality qualitatively agree with the experimental results. The J-R curves obtained also qualitatively agree with those of experiments, and the fracture surface roughness is well simulated. More >

G. Mishuris¹, A. Öchsner², G. Kuhn³

CMC-Computers, Materials & Continua, Vol.4, No.3, pp. 137-152, 2006, DOI:10.3970/cmc.2006.004.137

Abstract Nonclassical transmission conditions for dissimilar elastic structures with imperfect interfaces are investigated. The thin interface zone is assumed to be soft or stiff in comparison with the bonded materials and the transmission conditions for stiff interfaces are evaluated based on asymptotic analysis. The accuracy of the transmission conditions is clarified not only in terms of asymptotic estimate, but, which is especially important for users, also in values by accurate FEM calculations. The ranges of applicability of the conditions are discussed. More >