A survey of numerical models for hail impact analysis using explicit finite element codes

Hailstone impact is an actual threat for the integrity of aircraft structures such as leading edges, and forward sections. Though the analysis of weather conditions reduces the occurrence of intersections between flight routes and hailstorm regions, sometimes the passage through a hailstorm becomes inevitable and, in such a case, it is mandatory that the aircraft structures show an appropriate level of tolerance to damages caused by a hail impact. Therefore, as experimental tests are both expensive and troublesome, it is important to develop numerical models, which eventually support the design of high-efficient and hail-proof structures. Accordingly, in the present research, using LSTC LS-Dyna, three numerical models of hailstone have been developed: finite element, arbitrary Lagrangian Eulerian, and smoothed particle hydrodynamics model. Initially, these three models had been validated referring to a documented experimental test and, subsequently, used to reproduce the impact of a hailstone with the nose-lip of a nacelle intake. Advantages and disadvantages of the three hail models have been evaluated and it has been concluded that the smoothed particle hydrodynamics model is the most efficient and effective for the analysis of the event.