Hsin-Yi Lai¹, C. K. Chen^1,2, Jung-Chang Hsu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.34, No.1, pp. 87-116, 2008, DOI:10.3970/cmes.2008.034.087

Abstract An innovative solver for the free vibration of an elastically restrained non-uniform Euler-Bernoulli beam with tip mass of rotatory inertia and eccentricity resting on an elastic foundation and subjected to an axial load is proposed. The technique we have used is based on applying the Adomian modified decomposition method (AMDM) to our vibration problems. By using this method, any$i$th natural frequencies can be obtained one at a time and some numerical results are given to illustrate the influence of the physical parameters on the natural frequencies of the dynamic system. The computed results agree well with those analytical and numerical… More >

X.G. Yuan^1,2, H.W. Zhang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.32, No.3, pp. 175-184, 2008, DOI:10.3970/cmes.2008.032.175

Abstract In this paper, a dynamic problem that describes void formation and motion in an incompressible hyperelastic solid sphere composed of a transversely isotropic Valanis-Landel material is examined, where the sphere is subjected to a class of periodic step tensile loads on its surface. A motion equation of void is derived. On analyzing the dynamical properties of the motion equation and examining the effect of material anisotropy on void formation and motion in the sphere, we obtain some new and interesting results. Firstly, under a constant surface tensile load, it is proved that a void would form in the sphere as… More >

Y. H. Liu^1,2, S. S. Chen¹, J. Li¹, Z. Z. Cen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.31, No.3, pp. 145-156, 2008, DOI:10.3970/cmes.2008.031.145

Abstract A novel meshless method for structural dynamic analysis is presented and discussed in this paper. It is called meshless local natural neighbour interpolation (MLNNI) method, which uses a meshless spatial approximation based only on nodes. The MLNNI is derived from the generalized meshless local Petrov-Galerkin (MLPG) method as a special case. Local weak forms are developed using weighted residual method locally from the dynamic partial differential equation. In the construction of trial functions, the natural neighbour interpolation (NNI) is employed to simplify the treatment of the essential boundary conditions. The domain integration is evaluated over included Delaunay triangles in each… More >

Ömer Civalek ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.31, No.1, pp. 25-36, 2008, DOI:10.3970/cmes.2008.031.025

Abstract In this paper, free vibration analysis of curvilinear or straight-sided quadrilateral membranes is presented. In the proposed approach, irregular physical domain is transformed into a rectangular domain by using geometric coordinate transformation. For demonstration of the accuracy and convergence of the method, some numerical examples are provided on membranes with different geometry such as skew, trapezoidal, sectorial, annular sectorial, and membranes with four curved edges. The results obtained by the DSC method are compared with those obtained by other numerical and analytical methods. More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.27, No.3, pp. 137-150, 2008, DOI:10.3970/cmes.2008.027.137

Abstract For the inverse vibration problem, a Lie-group shooting method is proposed to simultaneously estimate the time-dependent damping and stiffness functions by using two sets of displacement as inputs. First, we transform these two ODEs into two parabolic type PDEs. Second, we formulate the inverse vibration problem as a multi-dimensional two-point boundary value problem with unknown coefficients, allowing us to develop the Lie-group shooting method. For the semi-discretizations of PDEs we thus obtain two coupled sets of linear algebraic equations, from which the estimation of damping and stiffness coefficients can be written out explicitly. The present approach is very interesting, which… More >

Vadiraja D. N.¹, A. D. Sahasrabudhe²

CMES-Computer Modeling in Engineering & Sciences, Vol.27, No.1&2, pp. 49-62, 2008, DOI:10.3970/cmes.2008.027.049

Abstract Rotating beams are flexible structures, which are often idealized as cantilever beams. Structural modelling of rotating thin-walled composite beam with embedded MFC actuators and sensors using higher shear deformation theory (HSDT) is presented. A non-Cartesian deformation variable (which represents arc length stretch) is used along with two Cartesian deformation variables. The governing system of equations is derived from Hamilton's principle and solution is obtained by extended Galerkin's method. Optimal control problem is solved using LQG control algorithm. Vibration characteristics and optimal control for a box beam configuration are discussed in numerical examples. Gyroscopic coupling between lagging-extension motions is found to… More >

Shueei-Muh Lin¹, Sen-Yung Lee², Yu-Sheng Lin³

CMES-Computer Modeling in Engineering & Sciences, Vol.23, No.3, pp. 175-186, 2008, DOI:10.3970/cmes.2008.023.175

Abstract The blade of a horizontal-axis wind power turbine is modeled as a rotating beam with pre-cone angles and setting angles. Based on the Bernoulli-Euler beam theory, without considering the axial extension deformation and the Coriolis forces effect, the governing differential equations for the bending vibration of the beam are derived. It is pointed out that if the geometric and the material properties of the beam are in polynomial forms, then the exact solution for the system can be obtained. Based on the frequency relations as revealed, without tedious numerical analysis, one can reach many general qualitative conclusions between the natural… More >

Sharnappa¹, N. Ganesan², Raju Sethuraman³

CMES-Computer Modeling in Engineering & Sciences, Vol.18, No.2, pp. 121-144, 2007, DOI:10.3970/cmes.2007.018.121

Abstract This article presents the study on buckling and free vibration behavior of sandwich general shells of revolution under thermal environment using Wilkins theory. The temperature assumes to be uniform over the shell structure. The numerical analysis is based on the semi-analytical finite element method applicable to thick shells. The analysis is carried out for different geometry such as truncated conical and hemispherical shells with various facing and core materials under clamped-clamped boundary condition. The parametric study is carried out for different core to facing (t_c / t_f) thickness ratio by considering the temperature dependent and independent material properties of the… More >

U. Andreaus^1,3, R.C. Batra², M. Porfiri^{2, 3}

CMES-Computer Modeling in Engineering & Sciences, Vol.9, No.2, pp. 111-132, 2005, DOI:10.3970/cmes.2005.009.111

Abstract Structural health monitoring techniques based on vibration data have received increasing attention in recent years. Since the measured modal characteristics and the transient motion of a beam exhibit low sensitivity to damage, numerical techniques for accurately computing vibration characteristics are needed. Here we use a Meshless Local Petrov-Galerkin (MLPG) method to analyze vibrations of a beam with multiple cracks. The trial and the test functions are constructed using the Generalized Moving Least Squares (GMLS) approximation. The smoothness of the GMLS basis functions requires the use of special techniques to account for the slope discontinuities at the crack locations. Therefore, a… More >

L. F. Qian^1,2, R. C. Batra³, L. M. Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.5, pp. 519-534, 2003, DOI:10.3970/cmes.2003.004.519

Abstract We use a meshless local Petrov-Galerkin (MLPG) method to analyze three-dimensional infinitesimal elastodynamic deformations of a homogeneous rectangular plate subjected to different edge conditions. We employ a higher-order plate theory in which both transverse shear and transverse normal deformations are considered. Natural frequencies and the transient response to external loads have been computed for isotropic and orthotropic plates. Computed results are found to agree with those obtained from the analysis of the 3-dimensional problem either analytically or by the finite element method. More >