ADHESIVE SHEAR-STRENGTH OF IMPACT ICE

A quasistatic experimental technique was developed to determine the adhesive shear strength of impact ices formed inside an icing wind tunnel. Parametric studies were carried out to determine the dependence of the adhesive shear strength with various factors: 1) tunnel air temperature, 2) wind speed, 3) water drop size, 4) substrate material, 5) substrate surface roughness, and 6) substrate/impact ice interface temperature. The adhesive shear strength property was found to be statistical in nature, and on the average the mean varies between 17 and 60 psi (0.12-0.41 MPa) for rime and glaze ice, respectively. The property is also found to be strongly dependent on substrate surface roughness and substrate/impact ice interface temperature above 25-degrees-F (-3.9-degrees-C). There is a weak statistical linear correlation between wind speed and droplet size (momentum), but the shear strength appears to be independent of tunnel air temperature, accreted thickness, and substrate material used. Comparison is made with values obtained by other investigators and differences are discussed.