Analysis of the Stress State in the Deformed Coating Under Base Stretching with the Bending Effect Account

Coatings are used in various industries and medicine. Determining the stress concentration in structural elements and coated samples is important. The concentration of tangential stresses near the free edge of the coating affects the initiation and development of a crack in the adhesive contact zone and its subsequent delamination. A new model for determining tangential stresses in flat-coated specimens subjected to tensile forces has been developed. A specimen with a coating of the same thickness on the upper and lower surfaces is considered. The proposed computational model considers the bending deformations that occur in the coating due to the stretching of the substrate. When the substrate is loaded, the tensile forces parallel to the surface of the adhesive contact between the substrate and the coating are transferred to the latter and create tensile forces in it as well. The loads are transferred to the coating through shear along the adhesive contact surface. Considering the bending moment allows for more accurate results in determining the tangential stresses than other analytical methods. A differential equation was solved to determine the distribution of tangential stresses in the plane of adhesive contact between the base and the coating. A comparative analysis of the stresses obtained by the developed model with other analytical approaches to determining the tangential stresses in the plane of adhesive contact between the substrate and the coating was carried out. This model makes it possible to determine the maximum tangential stresses in the plane of adhesive contact that cause coating delamination and characterize its adhesive strength. Developing more efficient coatings for various industries is possible considering the strength criteria. It has been shown that the model can be used to study the adhesive strength of coatings for various functional purposes after tensile testing of flat-coated specimens.