On a Strategy of the Reduction of the Lack Of Knowledge (LOK) in Model Validation

The quantification of the quality of a structural dynamical model remains a major issue today, and increasingly numerous methods are being devised in order to validate a model by comparison with an experimental reference. This paper presents a theory based on the concept of Lack Of Knowledge, which 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. These intervals defined on the different substructures are then rigorously propagated through the mechanical model in order to determine intervals with stochastic bounds including a given quantity of interest defined on the whole structure. A general strategy of reduction of the lack of knowledge is then discussed and applied to academic examples as well as industrial cases.