THE PLANT FOR TESTING COATINGS SAMPLES UNDER VARIABLE LOADS

While in operation, the parts with the applied coatings often work under variable loads, which affects the service life of the products. Many papers deal with the study of fatigue properties of such products, however, the study of the influence of variable loads on the structure and properties of the coatings has a fragmented nature. As the determination of fatigue characteristics of samples with the applied coatings is still important, the goal of this paper is to develop the design of the plant for fatigue tests and the technique of testing the samples with coatings under the variable loads. To develop the technique of fatigue tests, the authors created a unique design plant. When developing the plant, the authors considered the fact that the loading of a sample should be regular that the base and the substrate materials will experience stresses constant along the full length of a sample. Using the analytical solution of the strength task, the authors developed the technique of determining the stresses in a coating and a substrate. To prove the appropriateness of using the suggested technique, the numerical methods were used. For this purpose, using the Comsol Multiphysics software in a 2-D setup, the authors were solving the task of determining stresses in a sample consisted of two layers of the materials. In the result of the study, the authors developed the design of an experimental plant for testing samples with coatings with the maximum tensile force of 5000 N and the possibility of smooth change of vibrational frequency. The authors developed and tested the technique of testing samples with coatings without separation of a coating from a substrate. The study showed that the application of the described technique is reasonable if the thickness of a coating is not more than 7 % of the thickness of a substrate.

electrolytic coatings, fatigue tests, coating fatigue, coating stresses, variable loads