A new test apparatus to measure the adhesive shear strength of impact ice on titanium 6Al-4V alloy

Abstract

We present a new shear test which may be used in an icing environment. Ice is formed on a jig containing the sample material and this is then loaded by a forcing mechanism to effect the adhesive test. It allows impact (atmospheric) ice adhesive shear tests to be undertaken without disturbance or delay, in icing conditions. Finite element analysis is used in order to evaluate the controlling shear stresses in the most highly stressed zone of the ice/substrate interface and some sample experimental data is given for the adhesion of some impact ices to Ti-6Al-4V alloy with different surface finishes. The adhesion forces reported, represent peak values rather than spatially averaged stress values. Therefore values of adhesive shear strength obtained are higher than previous authors (in the range from 2 to 14 MPa instead of 0.05 to 0.5 MPa).

Enabling sequential rupture for lowering atomistic ice adhesion

“…It should be noted that the critical crack length of ice adhesion varies on different materials. A recent study assumed the average grain size of ice as the flaw length for calculating ice adhesion strength, 18 the accuracy of which is subjected to further verification.…”

Characterization of Ice Adhesion: Approaches and Modes of Loading

“…The ice adhesion strength at the ice-solid interface is one of the critical parameters to gage the surface icephobic ability. The ice adhesion strength has been studied over the past 70 years through different types of mechanical testing configurations, including push-out, direct shear, cylindrical twist of normal interface, and centrifuge configuration [8][9][10][11][12][13][14][15][16]. The differences in experimental measurement techniques can be grouped into two major categories based on the application of the peel-off force; (a) centrifuge and vibration tests [17][18] to shear off the interface via centripetal forces or vibrational amplitude, and (b) direct mechanical tests such as 0° cone test (similar to the push-out configuration), and direct shear configuration [11,[19][20].…”

“…In addition, water contact angle measurements have been widely used to estimate ice adhesion and have shown a good correlation between water wettability and adhesion strength [21]. With diverse testing configurations and experimental testing environment, a wide range of ice adhesion shear strength on typical metallic surfaces was reported with more than an order of magnitude of variance of 70-2,500 kPa [15], as summarized on Fig. 1, for a typical ice-aluminum interface.…”

Application of fracture mechanics to interfacial ice adhesion and forensic physical match analysis

“…These tests are considered a strength-based measurement where the interfacial strength is reported by normalizing the peak load at which ice is detached from the substrate by the adhesion area. These types of tests lead to a wide range of values for the adhesive shear strength, which can range from 70 KPa to 2500 KPa for the same interface [58]. This wide range of scatter is due to difference in icing formation, substrate conditions (including cleanliness, material, roughness, surface structure, and the coating type), loading configurations, and the testing condition (such as loading rate, testing temperature, humidity, and ice type) [58][59][60].…”

“…These types of tests lead to a wide range of values for the adhesive shear strength, which can range from 70 KPa to 2500 KPa for the same interface [58]. This wide range of scatter is due to difference in icing formation, substrate conditions (including cleanliness, material, roughness, surface structure, and the coating type), loading configurations, and the testing condition (such as loading rate, testing temperature, humidity, and ice type) [58][59][60]. It is not easy to have a pure adhesive failure mode that is always combined with a cohesive failure mode which can contribute to the scatter within the reported data resulting from miss estimation of the adhesion area [58,61].…”