Shueei-Muh Lin¹

CMES-Computer Modeling in Engineering & Sciences, Vol.52, No.1, pp. 105-124, 2009, DOI:10.3970/cmes.2009.052.105

Abstract In this study, the mathematical model of a non-constant rotating beam is established. It is an in-plane moving mass problem. Due to the effect of non-constant rotation, this model is composed of a governing differential equation with time-dependent coefficients and forcing term and three homogenous boundary conditions and one non-homogeneous boundary condition with time-dependent coefficients and forcing term. It is basically different to the system with constant rotation speed [Lin, 2008] and the linear moving beam system [Lin, 2009]. Obviously, a moving mass problem with time-dependent coefficients and forcing term is very complicated. A new… More >

Yongchang Cai^1,2, J.K. Paik³, Satya N. Atluri³

CMES-Computer Modeling in Engineering & Sciences, Vol.53, No.2, pp. 123-152, 2009, DOI:10.3970/cmes.2009.053.123

Abstract This paper presents a simple finite element method, based on simple mechanics and physical clarity, for geometrically nonlinear large rotation analyses of space frames consisting of members of arbitrary cross-section. A co-rotational reference frame, involving the axes of each finitely rotated beam finite-element, is used as the Updated Lagrangian reference frame for the respective element. A von Karman type nonlinear theory of deformation is employed in the co-rotational reference frame of each beam element, to account for bending, stretching, and torsion of each element. An assumed displacement approach is used to derive an explicit expression… More >

Yi W. Wan¹, Huan J. Keh²

CMES-Computer Modeling in Engineering & Sciences, Vol.53, No.1, pp. 73-94, 2009, DOI:10.3970/cmes.2009.053.073

Abstract The problem of the rotation of a rigid particle of revolution about its axis in a viscous fluid is studied theoretically in the steady limit of low Reynolds number. The fluid is allowed to slip at the surface of the particle. A singularity method based on the principle of distribution of a set of spherical singularities along the axis of revolution within a prolate particle or on the fundamental plane within an oblate particle is used to find the general solution for the fluid velocity field that satisfies the boundary condition at infinity. The slip… More >

Chein-Shan Liu¹, Weichung Yeih², Satya N. Atluri³

CMES-Computer Modeling in Engineering & Sciences, Vol.44, No.3, pp. 281-312, 2009, DOI:10.3970/cmes.2009.044.281

Abstract Here we develop a general purpose pre/post conditionerT, to solve an ill-posed system of linear equations,Ax=b. The conditionerTis obtained in the course of the solution of the Laplace equation, through a boundary-collocation Trefftz method, leading to:Ty=x, whereyis the vector of coefficients in the Trefftz expansion, andxis the boundary data at the discrete points on a unit circle. We show that the quality of the conditionerTis greatly enhanced by using multiple characteristic lengths (Multiple Length Scales) in the Trefftz expansion. We further show thatTcan be multiplicatively decomposed into a dilationTDand a rotationTR. For an odd-orderedA, we More >

Hanqing Jiang¹, Junqiang Lu², Min-Feng Yu², Yonggang Huang³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.6, No.2, pp. 133-144, 2008, DOI:10.3970/icces.2008.006.133

Abstract The periodic lattice registry of multi-walled carbon nanotubes (MWCNTs) have been exploited for the possibilities of development of nanodevices. This paper studied the telescoping behaviors of double-walled carbon nanotubes (DWCNTs) by atomic-scale finite element and tight-bind Green function methods. It was found that telescoping a DWCNT (e.g., (6,3)/(12,6)) will induce a rotational motion of the inner CNT that has a chirl angle θ (0◦ < θ < 30◦). This telescoping-induced rotational motion does not exist for armchair and zigzag DWCNTs due to the symmetry of CNTs. The rotational angle is completely determined by the chirality More >

C.E. Majorana¹, V.A. Salomoni

CMES-Computer Modeling in Engineering & Sciences, Vol.33, No.1, pp. 49-84, 2008, DOI:10.3970/cmes.2008.033.049

Abstract A dynamic analysis of a thin shell finite element undergoing large displacements and rotations is here presented. The constitutive model adopted derives from the coupling of an hyperelastic basic model fulfilling a De Saint Venant-Kirchhoff criterion with a scalar damage function depending on the maximum value of a suitable strain measure attained through the deformation history; then plastic effects are included using an isotropic/kinematic hardening law. A conservative time integration scheme for the non-linear dynamics of the hyperelastic damaged-plastic thin shell is applied. The main characteristic of the scheme is to be conservative, since it More >

J.-M. Battini¹

CMES-Computer Modeling in Engineering & Sciences, Vol.33, No.1, pp. 1-16, 2008, DOI:10.3970/cmes.2008.033.001

Abstract This paper deals with the parameterisation of large rotations in corotational beam and shell elements. Several alternatives, presented in previous articles, are summarised, completed and compared to each other. The implementation of applied external moments and eccentric forces, consistent with the different parameterisations, is also considered. More >

X.Y. Cui^1,2, G. R. Liu^2,3, G. Y. Li^1,4, G. Zheng¹

CMES-Computer Modeling in Engineering & Sciences, Vol.38, No.3, pp. 217-230, 2008, DOI:10.3970/cmes.2008.038.217

Abstract In this paper, a gradient smoothed formulation is proposed to deal with a fourth-order differential equation of Bernoulli-Euler beam problems for static and dynamic analysis. Through the smoothing operation, the C¹ continuity requirement for fourth-order boundary value and initial value problems can be easily relaxed, and C⁰ interpolating function can be employed to solve C¹ problems. In present thin beam problems, linear shape functions are employed to approximate the displacement field, and smoothing domains are further formed for computing the smoothed curvature and bending moment field. Numerical examples indicate that very accurate results can be yielded when More >

G. M. Kulikov¹, S. V. Plotnikova¹

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.1, pp. 15-38, 2008, DOI:10.3970/cmes.2008.028.015

Abstract This paper presents a robust non-linear geometrically exact four-node solid-shell element based on the first-order seven-parameter equivalent single-layer theory, which permits us to utilize the 3D constitutive equations. The term "geometrically exact" reflects the fact that geometry of the reference surface is described by analytically given functions and displacement vectors are resolved in the reference surface frame. As fundamental shell unknowns six displacements of the outer surfaces and a transverse displacement of the midsurface are chosen. Such choice of displacements gives the possibility to derive strain-displacement relationships, which are invariant under arbitrarily large rigid-body shell More >

Hanqing Jiang¹, Junqiang Lu², Min-Feng Yu², Yonggang Huang³

CMES-Computer Modeling in Engineering & Sciences, Vol.24, No.2&3, pp. 95-102, 2008, DOI:10.3970/cmes.2008.024.095

Abstract The periodic lattice registry of multi-walled carbon nanotubes (MWCNTs) have been exploited for the possibilities of development of nanodevices. This paper studied the telescoping behaviors of double-walled carbon nanotubes (DWCNTs) by atomic-scale finite element and tight-bind Green function methods. It was found that telescoping a DWCNT (e.g., (6,3)/(12,6)) will induce a rotational motion of the inner CNT that has a chirl angle θ (0° < θ < 30°). This telescoping-induced rotational motion does not exist for armchair and zigzag DWCNTs due to the symmetry of CNTs. The rotational angle is completely determined by the chirality of More >