Experimental Strain Measurements of Highly-Curved Blades

This paper presents an experimental-numerical investigation on the axial strain of highly-curved blades. Models of the blades were analyzed using a 2-D finite element code, SectionBuilder, coupled with a comprehensive analysis code, Dymore, and first validated using strain measurements under a static tip load. Frequency responses were obtained under an impulsive load for each of the blades with multiple boundary conditions and compared with the numerical models. Experimental measurements under centrifugal loading from 0 up to 3300 RPM in a vacuum showed the effect of curvature on the axial strain, with significant bending strains observed in the responses for the curved blades that were also well captured by the numerical analysis. The present analysis shows that even moderate levels of out-of-plane curvature significantly increases the strain magnitudes, while higher levels of in-plane curvature have a much smaller impact.