Correlation of Full-Field Dynamic Strain Measurements with Reverse Engineered Finite Element Model Predictions

Conventionally strain measurements are done in an intrusive way, and, at one or a few discrete points. In this paper, use of a 3D laser measurement system is explored for direct and full-field dynamic strain measurements on compressor and turbine rotor blades. The results are correlated to corresponding FE predictions in a systematic and quantified manner. The ability to measure strain maps on real engine hardware is demonstrated not only for low frequency fundamental modes, but also for challenging high frequency modes. Correlation results show a high degree of agreement between measured and predicted strains, demonstrating the maturity of the technology and the validity of the method of integration used here. The measurements are repeated for a number of different loading amplitudes to assess the variations in strain fields. The actual component geometries are scanned and component-specific FE models are created. By correlating the measurement results to those predicted from the reverse engineered FE models, it is demonstrated that the results are improved when actual geometries are taken into account. Although the application of 3D laser systems to measurements of full-field strain were explored in previous studies, to the best knowledge of the authors, full-field numerical correlation of full-field strain on a wide range of real, sophisticated components to this extent is presented here for the first time.