R Sivaprasad^1,2, S Venkatesha¹, C S Manohar^1,3

CMC-Computers, Materials & Continua, Vol.9, No.3, pp. 179-208, 2009, DOI:10.3970/cmc.2009.009.179

Abstract The problem of identifying parameters of time invariant linear dynamical systems with fractional derivative damping models, based on a spatially incomplete set of measured frequency response functions and experimentally determined eigensolutions, is considered. Methods based on inverse sensitivity analysis of damped eigensolutions and frequency response functions are developed. It is shown that the eigensensitivity method requires the development of derivatives of solutions of an asymmetric generalized eigenvalue problem. Both the first and second order inverse sensitivity analyses are considered. The study demonstrates the successful performance of the identification algorithms developed based on synthetic data on More >

F.R. Biglari¹, A. Agahi¹, O. Nikfarjam², B. M. Dariani¹, K. Nikbin³

Structural Durability & Health Monitoring, Vol.4, No.1, pp. 47-52, 2008, DOI:10.3970/sdhm.2008.004.047

Abstract A modified sensitivity analysis has been applied to an elastic-plastic finite element analysis 3D blank design in sheet metal forming. In recent literature, the sensitivity method has successfully been applied to several arbitrary shapes. However, in the present paper the sensitivity coefficients are not considered constant during the analysis. The presented approach computes the new coefficients from the two last iterations. This method can produce an initial blank boundary shape that has any arbitrary flange shape. A cup with uniform flange has been studied in detail and results show a faster solution convergence than the More >

S. Venkatesha¹, R. Rajender², C. S. Manohar³

CMES-Computer Modeling in Engineering & Sciences, Vol.37, No.2, pp. 113-152, 2008, DOI:10.3970/cmes.2008.037.113

Abstract The problem of structural damage detection based on measured frequency response functions of the structure in its damaged and undamaged states is considered. A novel procedure that is based on inverse sensitivity of the singular solutions of the system FRF matrix is proposed. The treatment of possibly ill-conditioned set of equations via regularization scheme and questions on spatial incompleteness of measurements are considered. The application of the method in dealing with systems with repeated natural frequencies and (or) packets of closely spaced modes is demonstrated. The relationship between the proposed method and the methods based More >

G.J.A. Loeven^1,2, H. Bijl³

CMES-Computer Modeling in Engineering & Sciences, Vol.36, No.3, pp. 193-212, 2008, DOI:10.3970/cmes.2008.036.193

Abstract In this paper a Two-Step approach is presented for uncertainty quantification for expensive problems with multiple uncertain parameters. Both steps are performed using the Probabilistic Collocation method. The first step consists of a sensitivity analysis to identify the most important parameters of the problem. The sensitivity derivatives are obtained using a first or second order Probabilistic Collocation approximation. For the most important parameters the probability distribution functions are propagated using the Probabilistic Collocation method using higher order approximations. The Two-Step approach is demonstrated for flow around a NACA0012 airfoil with eight uncertain parameters in the More >

Kai Wang¹, Shenjie Zhou^1,2, Zhifeng Nie¹, Shengli Kong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.26, No.2, pp. 107-122, 2008, DOI:10.3970/cmes.2008.026.107

Abstract The natural neighbour Petrov-Galerkin method (NNPG) is one of the special cases of the generalized meshless local Petrov-Galerkin method (MLPG). This paper demonstrates the NNPG can be successfully used in design sensitivity analysis in 2D elasticity. The design sensitivity analysis method based on the local weak form (DSA-LWF) in the NNPG context is proposed. In the DSA-LWF, the local weak form of governing equation is directly differentiated with respect to design variables and discretized with NNPG to obtain the sensitivities of structural responds. The calculation of derivatives of shape functions with respect to design variables More >

Bohdan Mochnacki¹, Grażyna Kaluża²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.1, pp. 15-20, 2007, DOI:10.3970/icces.2007.001.015

Abstract This article has no abstract. More >

B. Mochnacki¹, E. Majchrzak²

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.3&4, pp. 431-438, 2003, DOI:10.3970/cmes.2003.004.431

Abstract In the paper the analysis of transient temperature field in the domain of biological tissue subjected to an external heat source is presented. Because of the geometrical features of the skin the heat exchange in domain considered is assumed to be one-dimensional. The thermophysical parameters of successive skin layers (dermis, epidermis and sub-cutaneous region) are different, at the same time in sub-domains of dermis and sub-cutaneous region the internal heat sources resulting from blood perfusion are taken into account. The degree of the skin burn results from the value of the so-called Henriques integrals. The More >