Novel approach for experimental measurement of sectional stiffness properties of composite rotor blades

Abstract

A novel experimental-numerical technique is presented for evaluating the full 6 _ 6 stiffness matrices for beams. The general formulation makes the method well suited for isotropic beams with simple cross-sectional configurations or beams made of anisotropic materials with complex geometries, as typically exhibited in composite rotor blades. A 2-D finite element code, SectionBuilder, is used to generate a finite element mesh of the cross-section and evaluate the warping field. The surface strain field is experimentally measured along the span of the beams using Digital Image Correlation (DIC). Stiffness matrices are then calculated based on the experimentally measured strain data and numerical model of the cross-section, with results presented for an isotropic beam, a composite beam with bending/torsion coupling, and a composite rotor blade.