METHOD FOR DETERMINING FATIGUE CHARACTERISTICS OF POLYMER COMPOSITE MATERIALS UNDER CYCLIC BENDING LOADING CONDITIONS Russian patent published in 2024 - IPC G01N3/20 

FIELD: polymers.

SUBSTANCE: invention relates to methods for determining the fatigue characteristics of flat samples of fibre-reinforced polymer composite materials of constant rectangular cross-section and can be used in assessing changes in their strength, the intensity of damage accumulation and the onset of local stress relaxation in the matrix material under conditions of multi-cycle bending loading in case of multi-cycle bending loading with a constant frequency and amplitude. In the method for determining the fatigue characteristics of polymer composite materials under conditions of cyclic bending loading, some of the test samples are preliminarily tested for static bending until failure, determining the bending strength and maximum deflection, the value of which determines the amplitude of the cyclic loading. Next, the remaining samples are subjected to cyclic loading. The total number of multi-cycle loading cycles is divided into equal blocks, after each of which the sample is tested for static three- or four-point bending to a given deflection equal to the amplitude of the cyclic loading. Based on the data obtained, a curve of changes in its bending force and/or strength at a given deflection versus the number of loading cycles is built. After all blocks of cyclic loading have been implemented, the sample is tested for static bending until failure and the residual strength is determined.

EFFECT: providing an ability to assess the intensity of damage accumulation and determine the stages of onset of local stress relaxation in the matrix material of fibre-reinforced polymer composite materials during cyclic bending loading, as well as the residual strength of fibre-reinforced polymer composite materials after cyclic bending.

1 cl, 1 dwg