Finite element model updating

The possibilities depend on the parameter type and on the element formulation.

The model updating method uses the discrepancy between FEA results and test, and sensitivities to determine a change in the update parameters that will reduce the discrepancy.

The FE model is then reformed using the new values of the update parameters, and the process repeats until some convergence criteria, analyzed by means of correlation functions, is met.

Other examples are a launcher tested with different levels of fuel, or differently shaped test specimens made of a composite material that needs to be identified.

From measured harmonic operational shapes, and an updated finite element model, a system of equations can be solved to obtain the excitation forces.

When working with large FE models, a bottom-up modeling, testing and assembly approach should be considered.

This is most efficient if superelements are used to model the parts that do not change.

If updating parameters are selected in the residual part (= elements that are not included in any superelement), then only the residual part is updated and combined with the superelements with every iteration.

Multi-Model Updating (MMU) is simultaneous updating of different versions of a finite model corresponding with different structural configurations. For example, solar panels for satellites can be tested during different stages of deployment and for each stage there is a FE model.

Sensitivity analysis is a technique that allows an analyst to get a feeling on how structural responses of a model are influenced by modifications of parameters like spring stiffness, material stiffness, geometry etc.

Sensitivity analysis can be used for the following purposes: Sensitivity coefficients quantify the variation of a response value (e.g.