Theory of the Lack of Knowledge : basic aspects and applications

Abstract : The concept of Lack Of Knowledge (LOK) was first introduced in [1, 2]. The basic principle consists in globalizing the various sources of errors on the substructure level using a scalar internal variable, called the LOK variable, defined over an interval whose upper and lower bounds follow probabilistic laws. The question of the impact of the structural model with LOKs on the prediction of the structural response can then be addressed. By a rigorous propagation of the intervals and the probability laws associated to the bounds, the envelope of the possible actual responses is defined, resulting in an interval with stochastic bounds including the structural response of interest. The comparison between these intervals and the experimental values available results in a reduction process of the basic LOKs, which considers the experimental data as additional information. In [3], we presented the first results of this strategy of reduction, starting from an initial overestimated LOK level, given by experience or a priori knowledge. This paper is focused on the reduction of the LOKs of a actual, industrial structure from the EADS Space Transportation division; this real-case study shows the effectiveness of the strategy of reduction used.
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Pierre Ladevèze, Guillaume Puel, Paul Enjalbert, Thierry Romeuf. Theory of the Lack of Knowledge : basic aspects and applications. 6th International Symposium on Launcher Technologies, 2005, Munich, Germany. pp.CD-ROM. ⟨hal-00258654⟩



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