Shear and tensile adhesion of dry and wet snow on metallic surfaces

Snow-sleeve formation on overhead power lines is promoted by wet-snow conditions and remains a key loading and reliability concern in cold-regions engineering. Here we present an experimental study comprising (i) a novel snow sample manufacturing system for producing reproducible dry and wet specimens and (ii) a portable adhesion rig enabling shear tests in both laboratory and field settings. Using snow with a liquid water content (LWC) ranging from 0 to 41%, we quantify snow-metal mechanical adhesion in shear and tension on three aluminum-alloy surface finishes spanning an arithmetic roughness (Ra) from 0.2 to 5 μm – a range which is highly relevant to substrate preparation prior to functionalization and ice−/snow-phobic coating deposition. To the best of our knowledge, this is the first study to systematically investigate both shear and tensile adhesion across such wide range of LWC and surface roughness. Shear adhesion increased with surface roughness and with LWC up to ≈28%, whereas tensile adhesion decreased with both parameters. These opposing trends are consistent with a capillary-bridging mechanism in which liquid distribution, effective contact area, and load transfer are controlled by the coupled effects of grain size and bulk density. The measurements can represent inputs for modelling snow-sleeve shedding and inform the design of snow-phobic surface treatments for electrical infrastructure, with increased practical relevance given the reported rise in wet-snow events associated with climate change.