Hybrid Calibration Method and Results
Within the framework of the validation methodology presented
earlier, we now focus on test analysis correlation. In this section,
we provide details on a hybrid approach for calibration of a blade
structural model using both static-load-deflection data and the
modal parameters.2
A beam finite-element model (FEM) was chosen to investigate
calibration of a blade structural model. The blade span-wise mass
distribution of the model was determined from measurements of a
sectioned blade that had been tested to failure. With measured mass
properties, the objective of the calibration was to determine the
blade span-wise stiffness properties, Young’s Modulus multiplied
by the area moment of inertia (EI).
The results of different calibration approaches in this calibration
study are given in Table 1; this is detailed in Reference 2. We
consider three approaches for calibration of the beam model:
• Using only load-deflection data from static tests.
• Using only natural frequencies from free boundary condition
modal tests.
• Hybrid approach using both load-deflection and natural frequencies.
When only static test data were used, the post calibration staticdeflection
residuals were small; however, predicting the first flapwise
mode for a free boundary condition was under predicted by