Effects of nonlinear stores on the dynamics of a computational model airplane

It has been shown experimentally that local nonlinear stores attached to the wings of a model airplane enhance overall energy dissipation through global nonlinear modal energy exchanges. Here, a computational model is developed to investigate this effect. The dynamics of the airplane–store system is studied under impulse loading with both stores locked (L-L configuration), left-wing store unlocked (U-L), or both stores unlocked (U-U). Each store acts as a rigid mass when locked, or as a strongly nonlinear element otherwise. The results are in agreement with the experimental ones at different impulse levels. The simulated responses for the U-L and U-U configurations are then projected onto the normal modes of the underlying L-L system to study modal energy redistributions caused by the nonlinear stores. The U-L and U-U configurations exhibit irreversible nonlinear energy transfers from the airplane modes to the stores, with faster decay of total energy compared with the L-L configuration, corroborating the experimental results. The stores also drastically affect the distribution of energy among airplane modes, also contributing to enhanced energy dissipation. Finally, harmonic excitation is considered, and the nonlinear effects are confined to a specific frequency band. This work confirms the drastic dynamic effects that local nonlinear attachments can have on the dynamics of the (linear) structures to which they are attached. Whether such local strong nonlinearities are to be purposely designed to enhance energy dissipation or need to be accounted for to mitigate their possibly detrimental effects is of great practical significance in different applications.