Experimental and theoretical similitude analysis for flexural bending of scaled-down laminated I-beams

In this paper, similitude theory is presented as a methodology on how to design a meaningful scaled-down subcomponent that emulates the strain field experienced in the full-scale component. The scaling laws for the flap-wise bending of a laminated composite I-beam with shear deformability are derived based on the similitude analysis. The set of scaling laws is treated as a criterion to design a scaled-down laminated I-beam that is partially similar to a full-scale I-beam that is representative of what is used in a utility-scale wind turbine rotor blade. The designed I-beam is manufactured and loaded using a three-point bending test while digital image correlation is used to measure the strain and displacement fields. The analytical solution is examined with the measured strain and displacement values and a finite element simulation for validation. With the derived scaling laws shown to be credible, they are then applied to the measured strain and displacement values of the scaled-down I-beam to predict the corresponding values of the full-scale I-beam. The scaled model is shown to replicate the strain field of its full-scale parent I-beam. Moreover, applicability of the scaled beam in predicting the displacement field of the full-scale I-beam using experimental data is demonstrated.