PARAMETER IDENTIFIABILITY IN FINITE ELEMENT MODEL ERROR LOCALISATION

✍ Scribed by A. LINDERHOLT; T. ABRAHAMSSON

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 204 KB
• Volume: 17
• Category: Article
• ISSN: 0888-3270
• DOI: 10.1006/mssp.2002.1522

✦ Synopsis

A fundamental question in finite element model updating and error localisation is whether sufficient identifiability of model parameters is at hand for a given set of test data. Under certain conditions, the dynamic properties (to be compared with test data) of a structural model, may change similarly when a certain model parameter or a combination of other parameters are modified. Since low confidence in identified parameters can also be expected for marginally identifiable systems, due to the omnipresent noise when real test data are used, one should seek such states so as to avoid them. Should the problem lack identifiability, then before a meaningful error localisation can be made; either complementary test data have to be added or new parameters chosen for the model. The latter is studied in this paper. An index, the orthogonality/colinearity index, was developed to facilitate finding the best way to reduce the number of parameters when there is low identifiability The use of the index is demonstrated on a six-degree-of-freedom system in a numerical example. The example shows that error localisation or model updating using a parameterisation which has insufficient parameter identifiability is pointless.