Modeling small remotely piloted aircraft system to head impact for investigating craniocerebral response

Understanding small remotely piloted aircraft system (sRPAS) to human head impacts is needed to better protect human head during sRPAS ground collision accidents. Recent literature reported cadaveric data on sRPAS to human head impacts, which provided a unique opportunity for developing validated computational models. However, there lacks an understanding of skull stress and brain strain during these impacts. Meanwhile, how slight changes in sRPAS impact setting could affect human head responses remains unknown. Hence, a representative quadcopter style sRPAS finite element (FE) model was developed and applied to a human body model to simulate a total of 45 impacts. Among these 45 simulations, 17 were defined according to cadaveric setting for model validation and the others were conducted to understand the sensitivity of impact angle, impact location, and impacted sRPAS components. Results demonstrated that FE-model-predicted head linear acceleration and rotational velocity agreed with cadaveric data with average predicted linear acceleration 4.5% lower than experimental measurement and average predicted of rotational velocity 2% lower than experimental data. Among validated simulations, high skull stresses and moderate level of brain strains were observed. Also, sensitivity study demonstrated significant effect of impact angle and impact location with 3° variation inducing 30% changes in linear acceleration and 29% changes in rotational velocity. Arm-first impact was found to generate more than two times higher skull stresses and brain strains compared to regular body-shell-first impact.