Reframing ice adhesion mechanisms on a solid surface

Ice adhesion tests can be correctly understood only if the appropriate fracture mechanism is identified. Here we reframe the theoretical understanding of ice adhesion mechanisms, to predict the type of detachment mechanism for horizontal push tests. [Display omitted] •Identification of ice-substrate fracture mechanisms is critical for ice adhesion.•The critical shear stress is only meaningful in a stress-dominated fracture regime.•The theoretical understanding of ice adhesion mechanisms is reframed.•Fracture model for detachment mechanism prediction is provided.•Guidelines for the correct interpretation of ice adhesion results are provided. Mitigating icing hazards is of interest for many technological applications. One solution is to employ low ice adhesion coatings, either passively or in combination with active de-icing systems. Nevertheless, comparing different low ice adhesion surfaces can be challenging. Studies generally report the average shear stress, calculated as the ratio of applied force to the ice-substrate contact area; however, the fracture mechanism at the ice-substrate interface is rarely reported. There are two fracture mechanisms that can occur at the interface: stress-dominated and toughness-dominated. Average shear stress is only meaningful when performing adhesion tests in a stress-dominated regime; otherwise, interface stresses are underestimated and misleading. This study presents a new understanding of ice adhesion mechanisms combining experimental and numerical methods, demonstrating how the traditional ice adhesion reporting method can lead to errors up to 400%. Using a simple fracture model, the study shows that the stress-dominated fracture regime in the horizontal push test is favored by smaller ice diameter and greater ice thickness, and is also affected by the load force position. The identification of the two fracture regimes is required for the correct understanding and reproducibility of ice adhesion results, enabling better design and characterization of icephobic coatings and materials.