Displacement analysis of rotating RC helicopter blade using coupled CFD-FEA simulation and digital image correlation

Rotating structures are commonly used components in the transportation and energy generation fields. A better understanding of these structures behavior under dynamic loading due to rotation is advantageous for both design and the maintenance operations. The present contribution reports a comparison of results for the rotating blades of an RC helicopter obtained using fluid -structure interaction in a computer fluid dynamics (CFD) model with measurements performed in the physical object using a digital image correlation (DIC) methodology. In order to obtain an accurate representation of the blades, the material properties, namely Young's Coefficient, Poisson's Ratio and Density, were first obtained experimentally. These parameters were used in the simulation, where a fluid-structure interaction was defined between a fluid model using Reynolds Stress Transport viscosity formulation and a finite element model. Afterwards, the obtained results were compared with the experimental measurements and the differences between the two are analyzed. It was noticed that the major differences between these results are due to the coupling between the blades and the hub since the former are able to rotate freely in respect to the latter and small gaps, in the range of 0.05 mm, highly affect the results. Thus, the present work highlights the necessity of accurate representation of hub connections, even if the gaps are difficult to measure. Using live measurement techniques, it is possible to obtain the actual behavior of the blades, and either reflect the measured differences in computational models or detect issues with the physical specimen. (C) 2019 The Authors. Published by Elsevier B.V.