Abstract
Aeroelastic scaling theory shows that the design problem of aeroelastically equivalent scaled aircraft can be treated as a structural-only design problem if the aerodynamic shape and airflow properties of the full scale aircraft are preserved. In that case, the theory shows that it is sufficient to match the scaled natural mode shapes, frequencies and mass of the reference aircraft. In this paper, we present a new method for the dynamic scaling of flexible structures where the objective function is based on the modal assurance criterion (MAC). This criterion is used for a mode tracking strategy during the optimization process. Finally, we apply this method to a scaled version (1:5) of the uCRM wing, achieving an agreement greater than 99% on the average MAC value of the first 5 modes.
Highlights
Aeroelastically scaled models have been used as a fast and reliable technique to determine the aeroelastic behavior of their full-size counterparts, especially in wind-tunnel testing
We highlight the new aspects that we introduce with respect to the traditional method described by Ricciardi et al [9], such as the use of the modal assurance criterion (MAC) in the definition of the objective function and the introduction of a mode tracking strategy to avoid potential problems during the optimization process
After running the previously described problem for the first N = 5 modes, we observe, in Figure 3, that the results in terms of the average MAC value are satisfactory: the average MAC value is greater than 0.99 (since f < 0.01, recall the definition in Eq (5)), allowing us to say that the modal matching of the first 5 modes has a good quality
Summary
Aeroelastically scaled models have been used as a fast and reliable technique to determine the aeroelastic behavior of their full-size counterparts, especially in wind-tunnel testing. Ricciardi et al [8] introduced a modification in the twostep approach used by Richards et al [7] to match the static deflections obtained by nonlinear analysis in the stiffness optimization loop These last two works are intended to establish the design of a flying scaled version of the joined-wing SensorCraft model. Ricciardi et al [9] considered a single-step approach in which the displacements obtained both by linear and nonlinear static analysis are matched, while ensuring— through optimization constraints—that the equality of the scaled natural frequencies is satisfied To evaluate the method, we apply it to obtain the scaled structural sizing of a scaled (1:5) version of the uCRM wing1 [13]
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