Modeling impact of drones on flat plates

Abstract

Experiments on the impact of cannon-launched Phantom DJI 3 quadcopters onto 1-m square aircraft-grade aluminum flat plates (1.6 mm and 6.35 mm thick) at velocities of 130 m/s (250 knots) and 70 m/s (140 knots) are presented, and finite element modeling of the impacts is also described. Load histories at the corners of the plate, central deflection, and possible perforation of the plate are modeled and compared with experimental results. Failure of drone components was modeled, as they were significantly damaged in all of the tests. Failure of the plate was also modeled, as in the high-speed tests with thin plates, the drone perforated the plate. Predictions of the total peak load on the plates are within 20% of the experimental values and the central deflections are within 10% of the experimental values. Additionally, modal analysis reveals that the characteristic half period of 5-6 ms observed in the load histories corresponds to the natural frequencies of the structure that holds the plate in the test. Using the insights gained from the simulations, simple analytical models, wherein the components of the drone are modeled as blunt, rigid objects and the target is modeled as mass and dashpot, were developed. These yield second-order ordinary differential equations whose solutions provide rapid estimates of the peak load and deflection in all tests to within 15% of the experimental values. To estimate the threshold impact velocity to perforate the plate, an analytical model is presented. The major contributions of this article are validated work flows to develop drone finite element models that do not require extensive characterization of drone components, and simplified analytical models for rapid assessment of drone impacts.