Publications

Quantifying uncertainty in an admittance model due to a test fixture

Simmons, Leslie A.; Smith, Gregory E.; Mayes, Randall L.; Epp, David E.

This paper addresses the coupling of experimental and finite element models of substructures. In creating the experimental model, difficulties exist in applying moments and estimating resulting rotations at the connection point between the experimental and finite element models. In this work, a simple test fixture for applying moments and estimating rotations is used to more accurately estimate these quantities. The test fixture is analytically "subtracted" from the model using the admittance approach. Inherent in this process is the inversion of frequency response function matrices that can amplify the uncertainty in the measured data. Presented here is the work applied to a two-component beam model and analyses that attempt to identify and quantify some of these uncertainties. The admittance model of one beam component was generated experimentally using the moment-rotation fixture, and the other from a detailed finite element model. During analytical testing of the admittance modeling algorithm, it was discovered that the component admittance models generated by finite elements were ill conditioned due to the inherent physics.