A methodology for the choice of the initial conditions in the model updating of welded joints using the fuzzy finite element method

The implementation of the fuzzy finite element method in the model updating procedure and its application to the modelling of welded joints has been highlighted in this paper, which describes a methodology for setting up the best possible initial conditions for the updating process. The subset selection and the estimation of the initial nominal values of the parameters, copes well with the problems of ill-conditioned matrices in the updating process. The novel aspect of this approach is the use of the fuzzy finite element method as a large scale sensitivity analysis in the preliminary updating exercise and as tool for tracking the initial lengths of the offsets employed in the partly rigid beams used for modelling the joints. The result is an updated model with physical meaning that may be used to predict the dynamics of big structures containing all kinds of different welded joints. The developed study is applied on a case study of a bus frame.