Material Properties of Granular Ice Layers Characterized Using a Rigid-Body-Penetration Method: Experiments and Modeling 2019-01-2034
Icing poses a severe problem for numerous engineering applications comprising aviation, road traffic, shipping, wind turbines, and high-voltage power lines and insulators. Not only ice accretion itself but also shedding of accreted ice layers represents a severe hazard. Ice layers shedding from interior jet engine parts may damage parts being downstream in the engine, while ice layers shedding from wind turbine blades may seriously harm pedestrians or technical systems nearby the wind turbine. The material properties of an ice layer play an important role for the adhesion of the ice layer to the substrate below, as well as the potential harm in the case of shedding.
In the present study, the strength of wet granular ice layers is characterized based on the measurement of dynamic projectile penetration into the ice layer. A certain amount of water is infused into a dry granular ice layer characterized in terms of grain size and porosity, resulting in a defined composition of the wet ice layer. The effective yield strength of the granular layer is estimated from the analysis of the normal penetration of a long rigid rod into the layer. A rod of defined size and nose-shape is shot by a pneumatic gun using pressurized gaseous nitrogen. The process of projectile penetration is captured in a side view using a high-speed video system. The ice layer yield strength is derived by applying theoretical models primarily developed for rigid projectile penetration into elastic-plastic substrates, which have been appropriately adapted for the present case.
Markus Schremb, Kenan Malicevic, Louis Reitter, Ilia Roisman, Cameron Tropea
Technical University of Darmstadt
International Conference on Icing of Aircraft, Engines, and Structures