Ice Adhesion Characterization Using Mode-I and Mode-II Fracture Configurations

The ice buildup on airborne structures operating in cold weather conditions has detrimental impacts on their safety and performance. Due to practical applications, there has been a significant interest in ice removal strategies. However, the current body of literature lacks comprehensive insights into the mechanistic aspects of the ice adhesion/breakage process, resulting in a wide range of reported adhesion strengths that differ by two orders of magnitude. To address this gap, we employed a fracture mechanics-based approach to investigate the fracture behavior of a typical ice/aluminum interface in terms of mode-I and mode-II fractures. We examine a range of surface roughness values spanning from 0.05 to 5 micrometers. An experimental framework employing a single cantilever beam and direct shear tests were developed. The near mode-I and mode-II interfacial fracture toughness and strength values were extracted from the experimentally measured force and displacement by both analytical and numerical models employing cohesive surfaces. The combined experimental and numerical results show that ice adhesion is primarily driven by cohesive interfacial failure, which exhibits almost mode-independent fracture behavior. Mode-I fracture shows directional instability of crack propagation, which is attributed to thermally induced residual tensile stress at the ice layer-substrate interface. The fractographic inspection reveals similar ice-grain size over the examined range of substrate roughness values. For the examined range of surface roughness and temperature, which induces the Wenzel state with full surface wetting at the interface, the ice adhesion is insensitive to the interfacial roughness in both mode-I and mode-II fracture.