L.A. de Lacerda¹, J. M. da Silva¹

CMES-Computer Modeling in Engineering & Sciences, Vol.14, No.3, pp. 153-160, 2006, DOI:10.3970/cmes.2006.014.153

Abstract A two-dimensional boundary element formulation is presented and coupled to a genetic algorithm to identify polarization curves of buried slender structures. The dual boundary element method is implemented to model the cathodic protection of the metallic body and the genetic algorithm is employed to deal with the inverse problem of determining the non-linear polarization curve, which describes the relation between current density and electrochemical potential at the soil metal interface. In this work, this non-linear relation resulting from anodic and cathodic reactions is represented by a classical seven parameters expression. Stratified soil resistivity is modeled with a piece-wise homogeneous domain.… More >

M.R. Hematiyan^1,2, A. Khosravifard¹, Y.C. Shiah³, C.L. Tan⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.87, No.1, pp. 55-76, 2012, DOI:10.3970/cmes.2012.087.055

Abstract An inverse technique, based on the boundary element method (BEM) and elastostatic experiments for identification of elastic constants of orthotropic and general anisotropic 2D bodies is presented. Displacement measurements at several points on the boundary of the body, obtained by a few known load cases are used in the inverse analysis to find the unknown elastic constants of the body. Using data from more than one elastostatic experiment results in a more accurate and stable solution for the identification problem. In the inverse analysis, sensitivities of displacements of only boundary points with respect to the elastic constants are needed. Therefore,… More >

W. Zhang¹, X. Han^1,2, J. Liu¹, R. Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.86, No.5, pp. 385-408, 2012, DOI:10.3970/cmes.2012.086.385

Abstract A novel inverse technique is presented for quantifying the uncertainty of the identified the results in an encounter condition identification problem. In this technique, the polynomial response surface method based on the structure-selection technique is first adopted to construct the approximation model of the projectile/target system, so as to reduce the computational cost. The Markov Chain Monte Carlo method is then used to identify the encounter condition parameters and their confidence intervals based on this cheap approximation model with Bayesian perspective. The results are demonstrated through the simulated test cases, which show the utility and efficiency of the proposed technique.… More >

Bing Li^1,2, Hongbo Dong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.3, pp. 205-228, 2012, DOI:10.3970/cmes.2012.084.205

Abstract Different from single crack identification method, the number of cracks should be firstly identified, and then the location and depth of each crack can be predicted for multiple cracks identification technology. This paper presents a multiple crack identification algorithm for rotor using wavelet finite element method. Firstly, the changes in natural frequency of a structure with various crack locations and depths are accurately obtained by means of wavelet finite element method; and then the damage coefficient method is used to determine the number and region of cracks. Finally, by finding the points of intersection of three frequency contour lines in… More >

Linjun Wang¹, Xu Han², Youxiang Xie³

CMES-Computer Modeling in Engineering & Sciences, Vol.82, No.3&4, pp. 179-194, 2011, DOI:10.32604/cmes.2011.082.179

Abstract In this paper, a new homotopy perturbation method (IHPM) is presented and suggested to solve an ill-posed problem of multi-source dynamic loads reconstruction. We propose a stable and reliable modification, and obtain a new regularization method, then employ it to find the exact solution for the multi-source dynamic load identification problem. Also, this present method only needs easy computations rather than successive integrations. Finally, the performances of two numerical examples are given. Comparisons are performed between the original homotopy perturbation method (HPM) and IHPM. The results verify that the present method is very simple and effective. More >

G.S. Li¹, D. Yao², Y.Z. Wang³, H.Y. Jiang²

CMES-Computer Modeling in Engineering & Sciences, Vol.51, No.1, pp. 53-72, 2009, DOI:10.3970/cmes.2009.051.053

Abstract In this paper, an undisturbed soil-column infiltrating experiment is investigated, and a mathematical model describing multi-components solutes transport behaviors in the column is put forward by combing hydro-chemical analysis with advection dispersion mechanisms, which is a group of advection-dispersion-reaction partial differential equations. Since the model involving six reaction coefficients which can not be obtained directly, an optimal perturbation regularization algorithm of determining these parameters is performed, and numerical simulations under different conditions are carried out. Furthermore, the inversion algorithm is applied to solve the real inverse problem by utilizing the measured breakthrough data. The reconstruction data basically coincide with the… More >

M.Galli , M.L.Oyen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.48, No.3, pp. 241-270, 2009, DOI:10.3970/cmes.2009.048.241

Abstract A novel approach is presented for the identification of constitutive parameters of linear poroelastic materials from indentation tests. Load-controlled spherical indentation with a ramp-hold creep profile is considered. The identification approach is based on the normalization of the time-displacement indentation response, in analogy to the well-known one-dimensional consolidation problem. The identification algorithm consists of two nested optimization routines, one in the time-displacement domain and the other in a normalized domain. The procedure is validated by identifying poroelastic parameters from the displacement-time outputs of finite element simulations; the new identification scheme proves both quantitatively reliable and fast. The procedure is also… More >

Dong Wei¹, Yinghua Liu^1,2, Zhihai Xiang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.46, No.1, pp. 77-106, 2009, DOI:10.3970/cmes.2009.046.077

Abstract Taking advantage of the parameter identification, a new numerical method is developed in this paper to estimate the maximal temperature gradients reached in fire-damaged concrete structures. This method can avoid the hypotheses of temperature-time curve and fire duration usually made in conventional numerical methods, availably evaluate the depth and degree of fire damage of concrete structures and consider the effects of localized fire. A material model taking into account the properties of fire-damaged concrete is firstly proposed in the present research. The least-squares estimation and the Gauss-Newton method are used to identify the material parameters of fire-damaged concrete by means… More >

F. Daghia¹, W. Hasan¹, L. Nobile¹, E. Viola^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.1, pp. 1-28, 2009, DOI:10.3970/cmes.2009.039.001

Abstract In this paper, a finite element model has been developed for analysing the flexural vibrations of a uniform Timoshenko beam-column on a two-parameter elastic foundation. The beam was discretized into a number of finite elements having four degrees of freedom each. The effect of end springs was incorporated in order to identify the end constraints. \newline The procedure for identifying geometric and mechanical parameters as well as the end restraints of a beam on two-parameter elastic foundation is based on experimentally measured natural frequencies from dynamic tests on the structure itself. \newline An iterative statistical identification method, based on the… More >

Vikas Namdeo^1,2, C S Manohar^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.32, No.3, pp. 123-160, 2008, DOI:10.3970/cmes.2008.032.123

Abstract The problem of identification of nonlinear system parameters from measured time histories of response under known excitations is considered. Solutions to this problem are obtained by using the force state mapping technique with two alternative functional representation schemes. These schemes are based on the application of reproducing kernel particle method (RKPM) and kriging techniques to fit the force state map. The RKPM has the capability to reproduce exactly polynomials of specified order at any point in a given domain. The kriging based methods represent the function under study as a random field and the parameters describing this field are optimally… More >