Publications

Griffith, Daniel G.; Smith, Gregory E.; Casias, Miguel E.; Simmermacher, Todd W.

This test report covers the SNL modal test results for two nominally identical TX-100 wind turbine blades. The TX-100 blade design is unique in that it features a passive braking, force-shedding mechanism where bending and torsion are coupled to produce desirable aerodynamic characteristics. A specific aim of this test is to characterize the coupling between bending and torsional dynamics. The results of the modal tests and the subsequent analysis characterize the natural frequencies, damping, and mode shapes of the individual blades. The results of this report are expected to be used for model validation--the frequencies and mode shapes from the experimental analysis can be compared with those of a finite-element analysis. Damping values are included in the results of these tests to potentially improve the fidelity of numerical simulations, although numerical finite element models typically have no means of predicting structural damping characteristics. Thereafter, an additional objective of the test is achieved in evaluating the test to test and unit variation in the modal parameters of the two blades.

Casias, Miguel E.; Smith, Gregory E.; Paquette, Joshua P.; Griffith, Daniel G.

Abstract not provided.

Conference Proceedings of the Society for Experimental Mechanics Series

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.

Griffith, Daniel G.; Casias, Miguel E.; Smith, Gregory E.; Paquette, Joshua P.; Simmermacher, Todd W.

Abstract not provided.

Smith, Gregory E.

Abstract not provided.

Smith, Gregory E.

Abstract not provided.