http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Added effect of uncertain geometrical parameter on the response variability of Mindlin plate
Noh, Hyuk Chun,Choi, Chang Koon Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.20 No.4
In case of Mindlin plate, not only the bending deformation but also the shear behavior is allowed. While the bending and shear stiffness are given in the same order in terms of elastic modulus, they are in different order in case of plate thickness. Accordingly, bending and shear contributions have to be dealt with independently if the stochastic finite element analysis is performed on the Mindlin plate taking into account of the uncertain plate thickness. In this study, a formulation is suggested to give the response variability of Mindlin plate taking into account of the uncertainties in elastic modulus as well as in the thickness of plate, a geometrical parameter, and their correlation. The cubic function of thickness and the correlation between elastic modulus and thickness are incorporated into the formulation by means of the modified auto- and cross-correlation functions, which are constructed based on the general formula for n-th joint moment of random variables. To demonstrate the adequacy of the proposed formulation, a plate with various boundary conditions is taken as an example and the results are compared with those obtained by means of classical Monte Carlo simulation.
Added effect of uncertain geometrical parameter on the response variability of Mindlin plate
Hyuk Chun Noh,Chang Koon Choi 국제구조공학회 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.20 No.4
In case of Mindlin plate, not only the bending deformation but also the shear behavior is allowed. While the bending and shear stiffness are given in the same order in terms of elastic modulus, they are in different order in case of plate thickness. Accordingly, bending and shear contributions have to be dealt with independently if the stochastic finite element analysis is performed on the Mindlin plate taking into account of the uncertain plate thickness. In this study, a formulation is suggested to give the response variability of Mindlin plate taking into account of the uncertainties in elastic modulus as well as in the thickness of plate, a geometrical parameter, and their correlation. The cubic function of thickness and the correlation between elastic modulus and thickness are incorporated into the formulation by means of the modified auto- and cross-correlation functions, which are constructed based on the general formula for n-th joint moment of random variables. To demonstrate the adequacy of the proposed formulation, a plate with various boundary conditions is taken as an example and the results are compared with those obtained by means of classical Monte Carlo simulation.
Noh, Hyuk-Chun 테크노프레스 2011 Steel and Composite Structures, An International J Vol.11 No.2
Considering the randomness of material parameters in the laminated composite plate, a scheme of stochastic finite element method to analyze the displacement response variability is suggested. In the formulation we adopted the concept of the weighted integral where the random variable is defined as integration of stochastic field function multiplied by a deterministic function over a finite element. In general the elastic modulus of composite materials has distinct value along an individual axis. Accordingly, we need to assume 5 material parameters as random. The correlations between these random parameters are modeled by means of correlation functions, and the degree of correlation is defined in terms of correlation coefficients. For the verification of the proposed scheme, we employ an independent analysis of Monte Carlo simulation with which statistical results can be obtained. Comparison is made between the proposed scheme and Monte Carlo simulation.
Response variability due to randomness in Poisson’s ratio for plane-strain and plane-stress states
Noh, Hyuk-Chun,Kwak, Hyo-Gyoung Elsevier 2006 International journal of solids and structures Vol.43 No.5
<P><B>Summary</B></P><P>In the ordinary structural materials, one of the parameters that can be assumed to have spatial uncertainty is Poisson’s ratio. Therefore the independent evaluation of the effects of this parameter on the response variability is of importance. The difficulties in obtaining the response variability due to randomness in Poisson’s ratio lie in the fact that the Poisson’s ratio enters the stiffness matrix as a non-linear parameter. In this paper, a formulation to determine the response variability in plane strain and plane stress states due to the randomness in the Poisson’s ratio is given. The formulation is accomplished by means of the stochastic decomposition of the constitutive matrix into several sub-matrices taking into consideration of the polynomial expansion on the coefficients of constitutive relation. To demonstrate the validity of the proposed formulation, some example structures are chosen and the results are compared with those obtained by means of Monte Carlo simulation. Through the formulation proposed in this study, it becomes possible for the weighted integral stochastic finite element analysis to consider all the uncertain material parameters in its application.</P>
Noh, Hyuk-Chun,Choi, Chang-Koon Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.22 No.2
Taking into account the geometrical and material nonlinearities, an ultimate behavior of reinforced concrete cooling tower shell in hyperbolic configuration is presented. The design wind pressures suggested in the guidelines of the US (ACI) and Germany (VGB), with or without the effect of internal suction, are employed in the analysis to examine the qualitative and quantitative characteristics of each design wind pressure. The geometrical nonlinearity is incorporated by the Green-Lagrange strain tensor. The nonlinear features of concrete, such as the nonlinear stress-strain relation in compression, the tensile cracking with the smeared crack model, an effect of tension stiffening, are taken into account. The biaxial stress state in concrete is represented by an improved work-hardening plasticity model. From the perspective of quality of wind pressures, the two guidelines are determined as highly correlated each other. Through the extensive analysis on the Niederaussem cooling tower in Germany, not only the ultimate load is determined but also the mechanism of failure, distribution of cracks, damage processes, stress redistributions, and mean crack width are examined.
Effect of Random Poisson's Ratio on the Response Variability of Composite Plates
Noh, Hyuk-Chun,Yoon, Young-Cheol Computational Structural Engineering Institute of 2010 한국전산구조공학회논문집 Vol.23 No.6
Together with the Young's modulus the Poisson's ratio is another independent material parameter that governs the behavior of a structural system. Therefore, it is meaningful to evaluate separately the influence of the parameter on the random response of the structural system. To this end, a formulation dealing with the spatial randomness in the Poisson's ratio in laminated composite plates is proposed. The main idea of the paper is to transform the fraction form of the constitutive coefficients into the expanded form in an ascending order of the stochastic field function. To validate the adequacy of the formulation, a square plate is chosen and the computation results are compared with those obtained using conventional Monte Carlo simulation. It is observed that the results show good agreement with those by the Monte Carlo simulation(MCS).