Int. J. Crashworthiness 4(4), 379-393, 1999.


STUDY OF AXISYMMETRIC CRUSHING MECHANISMS BY SEQUENTIAL LIMIT ANALYSIS

M. Seitzberger and F.G. Rammerstorfer

Institute of Lightweight Structures and Aerospace Engineering,
TU Wien, Vienna, Austria


Abstract - The paper deals with the numerical simulation of crushing processes of axially compressed axisymmetric shells, by application of the upper bound theorem of limit analysis in combination with an FE-like discretization. In order to account for large deformations, a sequence of optimization problems, each followed by a geometrical update, is solved for the unknown velocity parameters. Frictionless contact can be taken into account simply through the enforcement of additional inequalities entering the optimization problems. In order to allow an accurate (though numerically relatively simple) computation of the internal energy dissipation, the exact form of the Ilyushin yield surface is applied, expressed exclusively in terms of kinematic quantities. The proposed numerical procedure allows to study crushing processes of general axisymmetric structures with great accuracy. Analytically based kinematic mechanisms, proposed in the literature, can be regarded as special cases, which allows to investigate the influence of simplifications used in such models.


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