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• Open Access

ARTICLE

Geometrically Nonlinear Analysis of Reissner-Mindlin Plate by Meshless Computation

P. H. Wen1, Y. C. Hon2
CMES-Computer Modeling in Engineering & Sciences, Vol.21, No.3, pp. 177-192, 2007, DOI:10.3970/cmes.2007.021.177
Abstract In this paper, we perform a geometrically nonlinear analysis of Reissner-Mindlin plate by using a meshless collocation method. The use of the smooth radial basis functions (RBFs) gives an advantage to evaluate higher order derivatives of the solution at no cost on extra-interpolation. The computational cost is low and requires neither the connectivity of mesh in the domain/boundary nor integrations of fundamental/particular solutions. The coupled nonlinear terms in the equilibrium equations for both the plane stress and plate bending problems are treated as body forces. Two load increment schemes are developed to solve the nonlinear differential equations. Numerical verifications are… More >

• Open Access

ARTICLE

Asymptotic Analysis for the Coupled Wavenumbers in an Infinite Fluid-Filled Flexible Cylindrical Shell: The Axisymmetric Mode

Abhijit Sarkar1, Venkata R. Sonti1
CMES-Computer Modeling in Engineering & Sciences, Vol.21, No.3, pp. 193-208, 2007, DOI:10.3970/cmes.2007.021.193
Abstract The coupled wavenumbers of a fluid-filled flexible cylindrical shell vibrating in the axisymmetric mode are studied. The coupled dispersion equation of the system is rewritten in the form of the uncoupled dispersion equation of the structure and the acoustic fluid, with an added fluid-loading term involving a parameter$\epsilon$ due to the coupling. Using the smallness of Poisson's ratio$(\nu )$, a double-asymptotic expansion involving$\epsilon$ and$\nu ^2$ is substituted in this equation. Analytical expressions are derived for the coupled wavenumbers (for large and small values of$\epsilon$). Different asymptotic expansions are used for different frequency ranges with continuous transitions occurring between them. The… More >

• Open Access

ARTICLE

Analytical Investigation of Depth Non-homogeneity Effect on the Dynamic Stiffness of Shallow Foundations

CMES-Computer Modeling in Engineering & Sciences, Vol.21, No.3, pp. 209-218, 2007, DOI:10.3970/cmes.2007.021.209
Abstract The vertical response of a rigid circular foundations resting on a continuously non-homogenous half space is studied analytically. The half space is considered as a liner-elastic media with a shear modulus increasing continuously with depth. The system of governing differential equations, based on the mentioned assumption, consist of two partial differential equations, is converted to ordinary equations' system by employing Hankel Integral transform. Using the method of extended power series (Frobenius Method) led to the general solution for the latter system. The mixed boundary problem is solved by introduction of functional expansion for the stress distribution under the foundation using… More >

• Open Access

ARTICLE

On Hole Nucleation in Topology Optimization Using the Level Set Methods

S.Y. Wang1,2, K.M. Lim2,3, B.C. Khoo2,3, M.Y. Wang4
CMES-Computer Modeling in Engineering & Sciences, Vol.21, No.3, pp. 219-238, 2007, DOI:10.3970/cmes.2007.021.219
Abstract Hole nucleation is an important issue not yet fully addressed in structural topology optimization using the level set methods. In this paper, a consistent and robust nucleation method is proposed to overcome the inconsistencies in the existing implementations and to allow for smooth hole nucleation in the conventional shape derivatives-based level set methods to avoid getting stuck at a premature local optimum. The extension velocity field is constructed to be consistent with the mutual energy density and favorable for hole nucleation. A negative extension velocity driven nucleation mechanism is established due to the physically meaningful driving force. An extension velocity… More >

• Open Access

ARTICLE

An Inverse Problem in Estimating Simultaneously the Time-Dependent Applied Force and Moment of an Euler-Bernoulli Beam

Cheng-Hung Huang1,2, Chih-Chun Shih1
CMES-Computer Modeling in Engineering & Sciences, Vol.21, No.3, pp. 239-254, 2007, DOI:10.3970/cmes.2007.021.239
Abstract An inverse forced vibration problem, based on the Conjugate Gradient Method (CGM), (or the iterative regularization method), is examined in this study to estimate simultaneously the unknown time-dependent applied force and moment for an Euler-Bernoulli beam by utilizing the simulated beam displacement measurements. The accuracy of this inverse problem is examined by using the simulated exact and inexact displacement measurements. The numerical experiments are performed to test the validity of the present algorithm by using different types of applied force and moment, sensor locations and measurement errors. Results show that excellent estimations on the applied force and moment can be… More >

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