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چکيده
مقاله:
In this paper the e,ect of random geometric imperfections on the limit loads of isotropic, thin-walled, cylindrical shells
under deterministic axial compression is presented. Therefore, a concept for the numerical prediction of the large scatter in
the limit load observed in experiments using direct Monte Carlo simulation technique in context with the Finite Element
method is introduced. Geometric imperfections are modeled as a two dimensional, Gaussian stochastic process with prescribed
second moment characteristics based on a data bank of measured imperfections. (The initial imperfection data bank at the
Delft Universityof Technology, Part 1. Technical Report LR-290, Department of Aerospace Engineering, Delft University
of Technology). In order to generate realizations of geometric imperfections, the estimated covariance kernel is decomposed
into an orthogonal series in terms of eigenfunctions with corresponding uncorrelated Gaussian random variables, known as
the Karhunen–Lo:eve expansion. For the determination of the limit load a geometricallynon-linear static analysis is carried
out using the general purpose code STAGS (STructural Analysis of General Shells, user manual, LMSC P032594, version
3.0, Lockheed Martin Missiles and Space Co., Inc., Palo Alto, CA, USA). As a result of the direct Monte Carlo simulation,
second moment characteristics of the limit load are presented. The numericallypredicted statistics of the limit load coincide
reasonablywell with the actual observations, particularlyin view of the limited data available, which is re=ected in the
statistical estimators. ? 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Non-linear >nite element analysis; Buckling of cylindrical shells; Random geometric imperfections; Axial compression |
