Parameters of failure of adhesive joints in symmetric peeling

1. A scheme of symmetric peeling of a coating from a substrate was proposed and examined in systems with a relatively weak adhesive reaction; it permits characterizing the failure of AJ with two values: the peeling force and angle, determined in simultaneous separation of two symmetric strips of coating from a flat substrate with force normal to the plane of the adhesive contact. 2. Important properties of the proposed scheme were established: preservation of the invariability of the direction of the effect of the total peeling force with respect to the plane of the adhesive contact during the entire process of failure of the AJ, despite the change in the slope of the peeled coating strips and movement of the boundaries of the peeling front, and the mutual compensation of the shear components of the peeling forces, which load the adhesive joint through the peeled coating strips, resulting in improvement of the metrological indexes. 3. It was shown that the process of failure of AJ in symmetric peeling of a coating from a substrate is characterized by the presence of a steady-state period with constant values of the peeling force and angle, which are parameters bearing information on the cohesive properties of the coating and its adhesion to the substrate for a given pair of coating and substrate materials. It was hypothesized that the value of the steady-state peeling angle is correlated with the ratio of the indexes of these properties.