Semi-Analytical Study by Nonlinear Substructure Method Based on Frequency Response Functions to Determine Folding Wing Dynamic Behavior with Nonlinear Effects

Folding wings are used in the design of rockets or airplanes to increase space and maneuverability. To ensure proper operation of the folding wing mechanism, some free play is required, causing it to behave non-linearly. This research uses a nonlinear method based on frequency response functions, considering the structure connection's geometry, by creating a nonlinear dynamic model of the assembled structure and through the structural coupling method that includes free play in the connections. Also, a new technique is presented that uses the results of the substructure method to extract energy diagrams, which are useful in determining the frequency range in which linear and nonlinear modes are coupled. These results are significant for understanding the behavior of the structure under aerodynamic loads and optimizing its performance. To verify the results, nonlinear sinusoidal vibration experiments and finite element analysis were performed. The extracted dynamic model in each frequency mode allows for examining the linearity or nonlinearity, stiffness or softness of the modes, and determining the degree of nonlinearity.