Numerical impact simulation of aircraft into reinforced concrete walls with different thicknesses

Aircraft impact analysis is needed for safety assessment of nuclear power plants. One of the items which should be analyzed for aircraft impact is physical damage to a reinforced concrete (RC) building and this can be estimated by numerical simulation. In the simulation, a simulation model which has been validated by some experimental data needs to be established. In 1988, an aircraft impact test using an F4 Phantom fighter was conducted at the Sandia National Laboratories in the US and a lot of important experimental data were measured. The numerical simulation results for this aircraft impact test are also introduced in this paper. The relationship between the thickness and the deceleration of the aircraft model is studied and then the differences in the deceleration between the simulation and test results are discussed. The relationship between the failure strain and the destruction modes of the aircraft and the target in the simulation are also studied, and then the differences between the simulation and test results are discussed as well. Through these parametric simulations, the validations of the aircraft and the target model are demonstrated. In evaluating the physical damage area inside the buildings, or discussing the necessary numbers of RC walls until the impacting aircraft stops, it is important to estimate whether the RC walls are perforated by an impacting aircraft. Besides numerical simulations, some empirical equations to estimate them are reported. One of them is the UKAEA equation. This equation estimates a dynamic punching strength of a RC wall. It is determined whether an impacting aircraft perforates a RC wall by comparing the dynamic punching strength with the dynamic impact load of the aircraft. In this paper, several aircraft impact simulations using the established aircraft model with different RC wall thicknesses are conducted. Dynamic punching strength of these RC walls are measured in each simulation. The obtained values in the simulations are compared with the estimated values by the UKAEA equation. The differences between them are investigated and the reasons of these differences are discussed.