Fuzzy model updating and its application to the DLR Airmod structure

Abstract

This paper addresses the problem of fuzzy model updating and its application to the DLR AIRMOD structure. The theory of the method is first explained and its application is demonstrated in a three degree of freedom mass-spring system. The method is then applied to the DLR AIRMOD structure. In order to take into account the variability in measurements arising from the assembly process, the DLR AIRMOD structure is repeatedly disassembled and reassembled and modal testing was carried out for each case. This provided a database of modal variability due to uncertainty in joint and support stiffnesses and masses of cables and screws. The histograms of measured data are utilised to determine the fuzzy membership functions of the selected outputs and they have been used to update the fuzzy membership functions of input parameters. To this end, a fuzzy parameter is represented as a set of interval variables via the membership function and the Kriging meta-model is used to speed up the process of updating.