Cross-sectional constants of composite blades using computed tomography technique and finite element analysis

The structural properties of Higher-harmonic Aeroacoustic Rotor Test (HART) II blades are determined using a finite element (FE) based cross-section analysis combined with the X-ray computed tomography technique. Three-dimensional, high-resolution digital images are constructed for this purpose. The detailed cross-section geometries are identified from a section segmentation process so that each pixel of the image is characterized by different attenuation coefficients according to the distribution of materials. The segmented section profiles are used to produce graphic data interfaces to create FE section model. A cross-section analysis is performed to compute the structural properties of the blade. The predicted mass and inertia results exactly reflect the manufactured configuration of the blade yielding semi-empirical data set of the blade. The stiffness properties measured using a cantilevered condition are correlated with the present predictions and the earlier estimated values. Good correlation is obtained between the predicted results and the measured data while a substantial deviation is observed with the earlier estimations. The possible source of discrepancy is identified from the analysis. The sensitivity of manufacturing defects and modeling deficiencies on the structural properties is examined. It is demonstrated that the proposed analysis offers a practical alternative for structural properties in non-destructive way.