Ice break-up, shedding, and impact analysis for helicopters

A fluid-structure interaction (FSI) problem of interest is the break-up of ice accreted on the rotor blades of helicopter. Interest in ice shedding involves its three phases: ice detachment from the surface, tracking of the piece of ice as it is carried through the flowfield, and the subsequent impact forces if it hits a solid surface. We present a 3D finite element method (FEM) to predict the shed ice shape by using an FSI approach to determine the loads and linear fracture mechanics to track crack propagation. The mass and shape of shed ice is calculated for a typical icing condition. Furthermore, results of the trajectories of the ice shed are also presented. These calculations provide initial conditions for the subsequent impact analysis. Qualitative and quantitative impact analysis of shed ice on target consisting of aluminum, carbon fiber reinforced plastic (CFRP), glass, and human skull are performed. The results show that the shed ice will cause: significant damage to aluminum and CFRP, shattering of glass windows, and fatal trauma to human skull.